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  • 251.
    Regali, Francesco
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Liotta, Leonarda Francesca
    Istituto per lo Studio dei Materiali Nanostrutturati, ISMN-CNR, Palermo, Italy.
    Venezia, Anna Maria
    Istituto per lo Studio dei Materiali Nanostrutturati, ISMN-CNR, Palermo, Italy.
    Montes, Vicente
    Organic Chemistry Department, University of Córdoba, Córdoba, Spain.
    Boutonnet, Magali
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Järås, Sven
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Effect of metal loading on activity, selectivity and deactivation behavior of Pd/silica-alumina catalysts in the hydroconversion of n-hexadecane2014Inngår i: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 223, s. 87-96Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bifunctional catalysts consisting of palladium on amorphous silica-alumina with different metal loadings (0 wt% to 1.2 wt%) were compared in the hydrocracking/hydroisomerization of n-hexadecane. The reaction conditions were: pressure = 30 bar; temperature = 310 degrees C; hydrogen-to-hexadecane feed molar ratio = 10. Metal loading was found to have a remarkable influence on the initial deactivation rate, which could be related to the formation of carbonaceous deposits. The dependence of activity on the metal-acid site ratio was the typical one for bifunctional hydrocracking where, after reaching a threshold value, the catalytic activity does not appreciably increase with increasing metal loading. On the Pd-containing catalysts, the methane space-time-yield showed a strong dependence on conversion, but no clear relationship with metal surface area, indicating that the formation of methane might not proceed by purely metal-catalyzed hydrogenolysis.

  • 252.
    Regali, Francesco
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Suaréz París, Rodrigo
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Aho, Atte
    Åbo Akademi.
    Boutonnet, Magali
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Järås, Sven
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Deactivation of a Pt/Silica–Alumina Catalyst and Effecton Selectivity in the Hydrocracking of n-Hexadecane2013Inngår i: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 56, nr 9-10, s. 594-601Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The deactivation behavior of a bifunctionalcatalyst consisting of platinum on amorphous silica–aluminawas studied in the hydrocracking of n-hexadecane.The initial decline in activity and the change in selectivitywere monitored at the following reaction conditions:pressure = 30 bar; temperature = 310 C; hydrogen-tohexadecanefeed molar ratio = 10. Initially, hexadecaneconversion and selectivity to cracking products decreasedrapidly with time-on-stream, and stabilized after 40 h onstream. This could be related to an initial loss of metalsurface area, which decreased the activity of monofunctionalhydrogenolysis generating cracking products. Theacidic function seemed to be unaffected under these reactionconditions. The stable catalyst was exposed to a lowerhydrogen-to-hexadecane ratio to accelerate deactivation bycoking. A decline in the activity of both functions wasobserved. The activity of the acidic function could bealmost completely recovered by oxidative regeneration,while the metal activity was only partially recovered.

  • 253.
    Rehnlund, David
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Nanostructured Cathodes: A step on the path towards a fully interdigitated 3-D microbattery2011Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The Li-ion field of battery research has in the latest decades made substantial progress and is seen to be the most promising battery technology due to the high volume and specific energy densities of Li-ion batteries. However, in order to achieve a battery capable of competing with the energy density of a combustion engine, further research into new electrode materials is required. As the cathode materials are the limiting factor in terms of capacity, this is the main area in need of further research. The introduction of 3-D electrodes brought new hope as the ion transportpath is decreased as well as an increased electrode area leading to an increased capacity. This thesis work has focused on the development of aluminium 3-D current collectors in order to improve the electrode area and shorten the Li-ion transportpath. By using a template assisted electrodeposition technique, nanorods of controlled magnitude and order can be synthesized. Furthermore, the electrodeposition brings excellent possibilities of upscaling for future industrial manufacturing of the batterycells. A polycarbonate template material which showed interesting properties,was used in the electrodeposition of aluminium nanorods. As the template pores were nonhomogeneously ordered a number of nonordered nanorods were expected to arise during the deposition. However, a surplus of nanorods in reference to the template pores was acquired. This behavior was investigated and a hypothesis was formed as to the mechanism of the nanorod formation. In order to achieve acomplete cathode electrode, a coating of an ion host material on the nanorods isneeded. Due to its high capacity and voltage, vanadium oxide was selected. Based on previous work with electrodeposition of V2O5 on platinum, a series of experiments were performed to mimic the deposition on an aluminium sample. Unfortunately, the deposition was unsuccessful as the experimental conditions resulted in aluminium corrosion which in turn made deposition of the cathode material impossible. The pH dependence of the deposition was evaluated and the conclusion was drawn, that electrodeposition of vanadium oxide on aluminium is not possible using this approach.

  • 254.
    Rexed, Ivan
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Applications for Molten Carbonate Fuel Cells2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Molten Carbonate Fuel cells are high temperature fuel cells suitable for distributed generation and combined heat and power, and are today being installed on commercial basis in sizes from 100kW to several MW. Novel applications for MCFC which have attracted interest lately are MCFC used for CO2 separation from combustion flue gas, and high temperature electrolysis with reversible fuel cells. In the first application, the intrinsic capability of the MCFC to concentrate CO2 from the cathode to the anode side through the cell reaction is utilized. In the second application, the high operating temperature and relatively simple design of the MCFC is utilized in electrolysis, with the aim to produce a syngas mix which can be further processed into hydrogen of synthetic fuels.

    In this thesis, the effect on fuel cell performance of operating a small lab-scale molten carbonate fuel cell in conditions which simulate those that would apply if the fuel cell was used for CO2 separation in combustion flue gas was studied. Such operating conditions are characterized especially by a low CO2 concentration at the cathode compared to normal operating conditions. Sulfur contaminants in fuel gas, especially H2S, are known poisoning agents which cause premature degradation of the MCFC. Furthermore, combustion flue gas often contains sulfur dioxide which, if entering the cathode, causes performance degradation by corrosion and by poisoning of the fuel cell. This makes poisoning by sulfur contaminants of great concern for MCFC development. In this thesis, the effect of sulfur contaminants at both anode and cathode on fuel cell degradation was evaluated in both normal and in low CO2 simulated flue gas conditions.     

    The results suggested that the poisoning effect of SO2 at the cathode is similar to that of H2S at the anode, and that it is possibly due to a transfer of sulfur from cathode to anode. Furthermore, in combination with low CO2 conditions at the cathode, SO2 contaminants cause fuel cell poisoning and electrolyte degradation, causing high internal resistance.

    By using a small lab-scale MCFC with commercial materials and standard fuel cell operating conditions, the reversible MCFC was demonstrated to be feasible. The electrochemical performance was investigated in both fuel cell (MCFC) and electrolysis cell (MCEC) modes. The separate electrodes were studied in fuel cell and electrolysis modes under different operating conditions. It was shown that the fuel cell exhibited lower polarization in MCEC mode than in MCFC mode, and a high CO2 concentration at the fuel cell anode reduced the polarization in electrolysis mode, which suggested that CO2 is reduced to produce CO or carbonate.

  • 255.
    Rexed, Ivan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Effect of sulfur contaminants on MCFC performance2014Inngår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 39, nr 23, s. 12242-12250Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Molten carbonate fuel cells (MCFC) used as carbon dioxide separation units in integrated fuel cell and conventional power generation can potentially reduce carbon emission from fossil fuel power production. The MCFC can utilize CO2 in combustion flue gas at the cathode as oxidant and concentrate it at the anode through the cell reaction and thereby simplifying capture and storage. However, combustion flue gas often contains sulfur dioxide which, if entering the cathode, causes performance degradation by corrosion and by poisoning of the fuel cell. The effect of contaminating an MCFC with low concentrations of both SO2 at the cathode and H2S at the anode was studied. The poisoning mechanism of SO2 is believed to be that of sulfur transfer through the electrolyte and formation of H2S at the anode. By using a small button cell setup in which the anode and cathode behavior can be studied separately, the anodic poisoning from SO2 in oxidant gas can be directly compared to that of H2S in fuel gas. Measurements were performed with SO2 added to oxidant gas in concentrations up to 24 ppm, both for short-term (90 min) and for long-term (100 h) contaminant exposure. The poisoning effect of H2S was studied for gas compositions with high- and low concentration of H-2 in fuel gas. The H2S was added to the fuel gas stream in concentrations of 1, 2 and 4 ppm. Results show that the effect of SO2 in oxidant gas was significant after 100 h exposure with 8 ppm, and for short-term exposure above 12 ppm. The effect of SO2 was also seen on the anode side, supporting the theory of a sulfur transfer mechanism and H2S poisoning. The effect on anode polarization of H2S in fuel gas was equivalent to that of SO2 in oxidant gas.

  • 256.
    Rhenlund, David
    et al.
    Uppsala Universitet.
    Lindgren, Fredrik
    Uppsala Universitet.
    Böhme, Solveig
    Uppsala Universitet.
    Nordh, Tim
    Uppsala Universitet.
    Zou, Yiming
    Uppsala Universitet.
    Pettersson, Jean
    Uppsala Universitet.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Boman, Mats
    Uppsala Universitet.
    Edström, Kristina
    Uppsala Universitet.
    Leif, Nyholm
    Uppsala Universitet.
    Improved Cycling Stability of Conversion and Alloying Anodes through the use of Nanomaterials2016Konferansepaper (Fagfellevurdert)
  • 257.
    Richards, Tobias
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Thermal pretreatment of black liquor: A conceptual design2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The recovery boiler is a vital part of the chemical recovery cycle and should produce a smelt of the cooking chemicals together with steam at high temperature and pressure. Part of these chemicals are found in the gases, either as small fume particles or as gases and this could cause problems such as deposits, corrosion and material losses. A thermal pre-treatment method is proposed to minimize the sodium and sulfur in the upper region of the boiler. Sulfur is released at temperatures below 600 °C in reducing atmospheres but most of this is recaptured by the black liquor droplets. The sodium losses are mostly by fume formation during char burning but a part could also be by physical ejection which would release sulfur as well.

  • 258.
    Richards, Tobias
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Neretnieks, Ivars
    Filtering of clay colloids in MX-80 detritus material2009Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Bentonite clay consists of two types of materials; the small nanoscale smectite particles and the larger accessory material particles. When used as a barrier, it is important that no material is lost. This might occur if water with low salinity is passing by the bentonite clay. First, the clay will first swell and then the smectite particles can be solubilised. This work investigates under which circumstances the material can form a filter cake of the accessory material and slow down or stop the penetration of smectite through the filter cake. We have showed that it is possible to form such a filter cake and that the filter cake can be further improved by adding other particles.

  • 259. Richards, Tobias
    et al.
    Theliander, Hans
    White liquor production: A comparison of the causticizing stages using gasifier and recovery boiler produced green liquor2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Green liquor, starting with sludge removal and ending with white liquor separation, has been investigated from a recovery boiler and a state-of-the-art gasification unit using the same black liquor for the two processes. This has been possible due to the co-location of a demonstration-sized pressurized gasification unit and a recovery boiler. Tests were performed under varying conditions in the gasifier while the conditions in the recovery boiler were assumed constant. Our investigation shows that the separation properties of green liquor sludge after a gasifier are almost similar to the separation properties after a recovery boiler. It is clear that the total load of reburned lime mud increases in the case of a gasifier, but the total concentration of the produced white liquor equals mill demand (i.e. is the same as recovery boiler produced white liquor). It was also found that causticizing efficiency was not affected by the increased load of reburned lime mud and the changed composition in the gasifier produced green liquor. Therefore, it can be concluded that the formation of sodium hydroxide in the white liquor produced from an entrained flow gasifier will not be limited by the existing process technology.

  • 260.
    Riedel, Andreas
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Predicting catastrophic failure in barrier coated packaging board and paper after creasing and folding: Proposing a methodology to predict barrier failure after creasing and folding2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Different methods to predict barrier failure in packaging board or paper after converting were investigated. The approach was to compare substrates before and after creasing/folding

    by applying different barrier tests and to propose a methodology to predict failure in the barrier layer. 

    Different coatings were used to develop and verify the methodology; a hemicellulose based dispersion barrier coating, a dispersion coated PVOH coating and an extrusion coated PE. Creasing was performed according to standard procedure using recommended creasing geometries. Folding of paper was performed by a gentle creasing with a board backing followed by folding the paper between two metal plates with a well defined distance.

    The first step in the evaluation was to visually inspect creased/folded substrates by light microscopy to search for coating failures in form of cracks. Both good and bad samples were then tested for grease resistance with a standard test, i.e. TAPPI 454. The TAPPI 454 test showed to be effective to expose barrier failure since oil would penetrate quite fast through the creasing line of cracked samples.

    Even some samples that appeared to have no cracks in the light microscope showed failure with the grease test. The results showed that only the PE coated samples could sustain a barrier after creasing and folding. This was probably due to a high ductility of the PE-coating combined with a high thickness.

    The water vapour transmission rate, WVTR, of the samples that passed the TAPPI 454 test was then measured on the samples that endured the grease resistance test. Since PE is a good water vapour barrier,

    WVTR-measurements were proper for detecting barrier defects. The VWTR of the creased/folded samples was slightly higher for the creased samples than the un-creased references despite the absence of cracks. This was probably due to that the barrier layer got thinner as a result of the strains applied on the coating during the creasing/folding operation. 

    A methodology to predict barrier failure in barrier coated packaging board and paper after creasing and folding was proposed. Well defined creasing and folding geometries were used in combination with screening for cracks in the barrier layer, first by visual inspection in light microscopy and then by a standard grease resistance test. The samples that passed then screening tests could then be analyzed using more exact but also more time consuming methods such as WVTR.

  • 261.
    Rifau, Ali
    et al.
    University Sains Malaysia.
    Zainal, Zainal
    University Sains Malaysia.
    Mutharasu, D.
    Fauzi, A.
    Kiros, Yohannes
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Zhu, Bin
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk reaktionsteknik.
    Zanzi Vigouroux, Rolando
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Performance study on an Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC) fabricated by dry pressing method2006Inngår i: American Journal of Applied Sciences, ISSN 1546-9239, E-ISSN 1554-3641, Vol. 3, nr 9, s. 2020-2024Artikkel i tidsskrift (Fagfellevurdert)
  • 262.
    Riva, Michele
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. Hong Kong University of Science and Technology.
    Phase field modelling of LLZO/LCO cathode-electrolyte interfaces in solid state batteries2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This work describes two phase field models for the simulation of the interface evolution between a LiCoO2 cathode (LCO) and a Li7La3Zr2O12 solid electrolyte (LLZO) in a Li-metal/LLZO/LCO battery during high temperature sintering. In these conditions atomic species tend to diffuse into the opposing material, creating an intermediate layer of mixed composition which resists the movement of lithium ions. This undesired effect prevents the resulting solid-state battery to achieve its theoretical performances and needs to be avoided. The first model is an adaptation of the work of J. M. Hu et alii [1] for a similar interface problem encountered between yttria-stabilized zirconia electrolytes (YSZ) and lanthanum-strontium-manganite cathodes (LSM) in solid oxide fuelcells (SOFC), while the second is based on the work of D. A. Cogswell [2][3] for phase separation in metal alloys, extended to include electrostatic effects due to internal charge unbalances and externally applied electric fields. Animplementation of the latter is however lacking, and the interested reader is encouraged to build one up on the theoretical framework presented in this paper. In the conclusion section it is possible to find insights on how to prevent the interfacial diffusion between LCO and LLZO with reference to experimental attempts and simulations, as well as future directions for the development of the models.

  • 263.
    Roos, Sandra
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, IVF. Chalmers University of Technology, Sweden.
    Peters, Gregory M.
    Chalmers University of Technology, Sweden.
    Validation of the results from toxicity assessment in LCA using triangulation2015Inngår i: SETAC Europe 25th Annual Meeting Abstract Book, 2015, s. 28-, artikkel-id 121Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The European Commission initiative for Product Environmental Footprint is based on life cycle assessment (LCA), with the USEtox consensus model as the recommended impact assessment method for toxicity. The confidence in the scientific robustness will be crucial for the intended users to take actions based on the results. This research work aims to validate the results from toxicity assessment within the context of LCA by benchmarking USEtox with two alternative approaches in a case study. While strictly speaking there can be no experimental validation of environmental damage predicted in an LCA of a generic product, comparison of the results of three different methods can be considered a form of triangulation in LCA which can potentially provide confidence in an individual method. A textile case was chosen as the textile industry is an intense user of chemicals.Three different quantitative or semi-quantitative methods for toxicity assessment were used: the USEtox model chosen for the European PEF work; the Score System presented in the European Commission's Reference Document on Best Available Techniques for the Textiles Industry; and the Strategy Tool presented by Askham. The results show that the three methods do not give a consistent toxicity assessment of the chemicals in the case study. For USEtox the result also depends on whether the practitioner uses the default method or add more characterization factors. The two semi-quantitative methods give more equal importance to the chemicals while the USEtox scores differ by several orders of magnitude. The Simple Score System and the Strategy Tool are very concerned with persistent pollutants and therefore the chemicals which are not readily biodegradable, receive a high score. The USEtox score on the other hand is relatively low for the persistent organic chemicals. Validation of results using triangulation can be used both to create confidence and/or help identify new challenges that were not previously perceived in the method. In this case we showed that the property of persistence is judged to have lower importance in USEtox compared to the two other methods, which is a finding that can be used to develop the fate modelling in USEtox. On the other hand, USEtox could provide additional advice compared to the two other methods, that one of the substances could be more environmentally problematic than what these semi-quantitative methods signals.

  • 264.
    Ros Gudmundsdottir, Tinna
    KTH, Skolan för kemivetenskap (CHE).
    Direct Catalytic Conversion of Biogas to Formaldehyde over Molybdenum Based Catalysts2013Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The importance of integrating sustainability into modern way of living is evident. In this diploma work the possibility of developing a method for green formaldehyde production by direct catalytic conversion of biogas was investigated. This process would not require the energy demanding syngas step in the methane to methanol process, but instead convert the methane to methanol in one step. Perstorp Formox produces iron molybdate catalysts that are successful in the methanol to formaldehyde process. In this study, three catalysts supplied by Perstorp Formox were investigated in turns of their potential for the direct catalytic conversion of methane to formaldehyde. Two of the catalysts where a blend of MoO3 and Fe2(MoO4)3, while the third was pure Fe2(MoO4)3. After having completed the process installation the system was run with the three catalysts under different temperatures and flows. The MoO3 + Fe2(MoO4)3 catalysts showed no significant conversion but the pure Fe2(MoO4)3 was a bit more promising. Change in characteristics and properties of the catalysts were investigated with focus on the effect of high temperature levels. This was done by calcining the catalysts at 700 ºC, observing their changes optically and performing XRD, BET surface, pore volume and pore size measurements. These measurements and observations led to the conclusion that the catalysts were not suitable for the direct catalytic conversion of methane due to their change in chemical and physical properties that occurred during the process.

  • 265.
    Rosén, Karl G
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    In-cabin air quality: electrostatic field to capture sub-micron size particles2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Traffic is regarded as the main reason for the air pollution problem and it seems obvious to try to reduce the particulate bioload affecting those travelling. Recently Volvo Cars introduced their Interior Air Quality System forcing the cabin air to be recirculated in case of a high level of noxious gases shutting out carbon monoxide, ground-level ozone and nitrogen dioxide. Ionization is another component of Mercedes AIR-BALANCE package. Considering the fact that it is the nano-size ultra-fine particles (UFP) that are known to cause the “oxidative” stress of the immune system one may ask if even the most well designed HEPA filter would sufficiently affect the in-cabin air particulates or is there a need for additional means by which the sub-micron class particles may be captured. An electrostatic field of sufficient strength may serve as an additional tool to clean the cabin air from sub-micron size particles.The initial data from the study indicate that electrostatic mechanisms substantially add to the in-cabin air cleaning properties of ultra-fine particulates compared to the standard filtering technology when recirculating the cabin air.

  • 266.
    Rovera, Cesare
    et al.
    Univ Milan, Dept Food Environm & Nutr Sci, DeFENS, Via Celoria 2, I-20133 Milan, Italy..
    Ghaani, Masoud
    Univ Milan, Dept Food Environm & Nutr Sci, DeFENS, Via Celoria 2, I-20133 Milan, Italy..
    Santo, Nadia
    Univ Milan, Dept Biosci, Via Celoria 26, I-20133 Milan, Italy..
    Trabattoni, Silvia
    Univ Milano Bicocca, Dept Mat Sci, Via R Cozzi 55, I-20125 Milan, Italy..
    Olsson, Richard
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Romano, Diego
    Univ Milan, Dept Food Environm & Nutr Sci, DeFENS, Via Celoria 2, I-20133 Milan, Italy.;Univ Milan, Local Unit, Natl Consortium Mat Sci & Technol, INSTM, Via Celoria 2, I-20133 Milan, Italy..
    Farris, Stefano
    Univ Milan, Dept Food Environm & Nutr Sci, DeFENS, Via Celoria 2, I-20133 Milan, Italy.;Univ Milan, Local Unit, Natl Consortium Mat Sci & Technol, INSTM, Via Celoria 2, I-20133 Milan, Italy..
    Enzymatic Hydrolysis in the Green Production of Bacterial Cellulose Nanocrystals2018Inngår i: ACS SUSTAINABLE CHEMISTRY & ENGINEERING, ISSN 2168-0485, Vol. 6, nr 6, s. 7725-7734Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, we extensively describe experimental models, with correlating experimental conditions, which were used to investigate the enzymatic hydrolysis of bacterial cellulose (BC) to obtain nanocrystals. Cellulase from Trichoderma reesei was used in five enzyme/BC ratios over a period of 74 h. The turbidity data was modeled using both logistic regression and empirical regression to determine the fractal kinetics, resulting in unique kinetic patterns for the mixtures that were richest in BC and in enzymes. The evolution of the yield was inversely related to the turbidity, as confirmed through a semiempirical approach that was adopted to model the experimental data. The yield values after 74 h of hydrolysis were higher for the substrate-rich mixtures (similar to 20%) than for the enzyme rich mixtures (similar to 5%), as corroborated by cellobiose and glucose quantification. Transmission electron microscopy and atomic force microscopy analyses revealed a shift from a fibril network to a needle-like morphology (i.e., aggregated nanocrystals or individual nanocrystals similar to 6 nm width and 200-800 nm in length) as the enzyme/BC ratios went from lower to higher. These results were explained in terms of the heterogeneous substrate model and the erosion model. This work initiated a promising, environmentally friendly method that could serve as an alternative to the commonly used chemical hydrolysis routes.

  • 267.
    Rupar-Gadd, Katarina
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Wiman, Bo
    Ibrahim, Muhammad Asim
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Laohaprapanon, Sawanya
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Hogland, William
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    A theoretical and experimental framework for the study of vegetation as a screen against aerosol pollution2014Rapport (Annet vitenskapelig)
    Abstract [en]

    It is well known that vegetation acts a sink for aerosol particles, with the particle-capture efficiency strongly related to vegetation characteristics (such as dimensions of needles and leaves) and to  particle size and aerodynamic conditions. However, there is a need for studies of ways to harness this sink capacity for constructing “green screens” to help reduce aerosol-particle concentrations, and thus health effects, in downwind residential areas. In this report we present a simplified mathematical model for the particle-capture processes involved and use results of model simulations to explore ways to address the problem through experiments with vegetation-filter components (“green filter packs”) placed in a windtunnel. Because of the exploratory nature of our work, the very limited logistics available, and the severe time constraints for the work (a few weeks only were available) the report is shaped as a kind of “scientific narrative” (rather than as a traditional technical paper). A series of tests is described wherein steps are taken towards practical implementation of experimental designs and procedures  based on a simple smoke-aerosol generator and measurements of smoke concentrations upwind and downwind of “green filter packs”. Measurements involve laser-based particle counters, two-stage Nuclepore filter systems, and Solid Phase Microextraction (SPME) techniques followed by Gas Chromatography-Mass Spectrometry. The main objective of the work was thus to illustrate ways to design experiments – rather than perform full-fledged experimental work – and to show how experimental data can be processed and used to assist in the study of vegetation as “pollution screens”. Despite the very limited time available for the work, the results show that our experimental approach is able to generate relevant information; for instance, a study of the particle-filtration capacity of a “green filter pack” consisting of an arrangement with Scots pine needles yielded interesting data.  Also, the  study suggests opportunities for more systematic comparisons between theory and practice, inasmuch it showed how, in principle, parameters involved in the mathematical model can be quantified. The SPME tests also provided interesting information with respect to chemical characteristics of the smoke-aerosol that was generated for the experiments. However, the tests with Nuclepore-filter sampling as well as the SPME applications showed needs for improving the smoke-generation method so that high and stable smoke-aerosol concentrations can be maintained over long periods (several hours).

     

     

    Our observations and findings imply that several refinements to the experimental design will be needed, including with  respect to methods for assessing the distribution of particle number and mass as a function of particle size (in the present study, the distribution is indicated by two particle-size classes only, 0.5 to 5 μm and >5 μm). Several other needs for improving the modelling as well experimental approach are also discussed in the report. Finally, a few observations on the needs for field-based studies are made together with remarks on the implications of the multi-disciplinary nature of this kind of work, with is linkages to the broader air-pollution context.

  • 268.
    Sababi, Majid
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Ejnermark, S.
    Andersson, J.
    Claesson, Per Martin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Pan, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Microstructure influence on corrosion behavior of a Fe-Cr-V-N tool alloy studied by SEM/EDS, scanning Kelvin force microscopy and electrochemical measurement2013Inngår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 66, s. 153-159Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Microstructure influence on corrosion behavior of an N-based tool alloy (Fe-Cr-V-N) has been studied. Electron microscopy analysis showed two types of hard phases in the alloy. One-pass mode scanning Kelvin force microscopy (KFM) was used to investigate relative nobility of the hard phases. Volta potential mapping indicates higher nobility for the hard phases than the alloy matrix, and, the V- and N-rich particles exhibit the highest Volta potential. Post-polarization analysis by SEM revealed localized dissolution initiated in matrix regions adjacent to hard phase particles, and the boundary region surrounding the Cr- and Mo-rich particles is more prone to localized corrosion.

  • 269.
    Sababi, Majid
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Pan, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Augustsson, Per-Erik
    Sundell, Per-Erik
    Claesson, Per M.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Influence of polyaniline and ceria nanoparticle additives on corrosion protection of a UV-cure coating on carbon steel2014Inngår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 84, s. 189-197Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Influence of a few percents additives of polyaniline doped with phosphoric acid (PAni-PA) and ceria nanoparticle on corrosion protection of a new ultraviolet (UV)-cure polyester acrylate coating have been studied for coil coating on carbon steel by electrochemical measurements during exposure to a NaCl solution. The results demonstrate that the presence of ceria nanoparticles improves the barrier property and stability of the coating. Adding the PAni-PA results in active corrosion protection for carbon steel due to passivation of the steel, and the combination of both additives greatly enhances the protection property over that of the coating matrix alone.

  • 270.
    Sadatgol, Seyedhani
    KTH, Skolan för kemivetenskap (CHE).
    Upgrading of Landfill Gas with Household Waste Slag2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Modern landfills produce landfill gas, LFG, on a smaller scale and with limited content of degradable organic materials in the waste. The waste deposit in the Sofielund landfill began in 2005 and the final coverage is not yet commenced. The landfill waste must contain up to 10% decomposable organic materials at most. In a previous experiment on Sofielund landfill in summer 2011, the measurements from four sample wells showed the landfill gas consisted of up to 45% Methane and about 17000 ppm of Hydrogen sulfide, and the rest was only carbon dioxide. During the earlier experiment in 2011 and during 2012 the smell of H2S got offensive periodically and apart from that, concentrations above 1000 ppm are toxic. Previous research, Bottom ash for biogas upgrading, BABIU, shows that bottom ash from municipal solid waste incinerator (MSWI) can effectively reduce CO­­2 and H2S contents of landfill gas. Bottom ash from MSWI can be utilized in upgrading landfill gas and reduce odor problems of landfills with high H2S production. In this study, an area of 15m x 12m was covered with weathered slag from bottom ash with thickness of about 30cm, to examine how this layer can reduce the concentrations of H2S and CO2. Gas samples were taken from depths of 10cm and 15cm below the surface of bottom ash. There were also samples taken from around the slag-covered area. The surface was laid out 5 days before the first measurement was performed. The experiment was carried out for 20 days, 5, 7, 11, 13, 18 and 20 days after establishment of the surface with bottom ash. The intensity of emissions in different parts of the landfill varied from time to time, due to compacting and changing the permeability of the surface, and it shows that LFG flow in the Sofielund is near the lowest limit of it. Considering the results from the tests in 2011 in deep wells, the recent measurements done in this study showed low contents of LFGs. The highest contents of LFGs in the measurements belong to a pipe, which was found in the waste area of the landfill. Those highest contents of LFG were 15.1% methane, 12.1% carbon dioxide, 0.4% oxygen and the hydrogen sulfide did not exceed 2 ppm. This shows that in deeper depths concentrations of LFG is higher than that of the surface and 10cm below the surface. In the slag covered area CO2 content increased day by day from the first day of the measurement to the last day due to carbonation of the slag and its role in CO2 sequestration.  According to the recent measurement, it can be suggested to cover the landfill with a layer of slag as a construction material, to minimize the LFG emissions and the bad smell from H2S. Therefore it can eliminate direct emissions of LFG to the atmosphere by diffusion through the slag layer. This diffusion allows adsorption of CO2 and oxidation of H2S.

  • 271.
    Sales, Alejandro
    KTH, Skolan för kemivetenskap (CHE).
    Production of biodiesel from sunflower oil and ethanol by base catalyzed transesterification2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Biodiesel is an attractive alternative fuel for diesel engines.The feedstock for biodiesel production is usually vegetable oil, pure oil or waste cooking oil, or animal fats

    The most common way today to produce biodiesel is by transesterification of the oils with an alcohol in the presence of an alkaline catalyst. It is a low temperature and low-pressure reaction. It yields high conversion (96%-98%) with minimal side reactions and short reaction time. It is a direct conversion to biodiesel with no intermediate compounds.

    This work provides an overview concerning biodiesel production. Likewise, this work focuses on the commercial production of biodiesel. The Valdescorriel Biodiesel plant, located in Zamora (Spain), is taken like model of reference to study the profitability and economics of a biodiesel plant.

    The Valdescorriel Biodiesel plant has a nominal production capacity of 20000 biodiesel tons per year. The initial investment for the biodiesel plant construction is the 4.5 millions €. The benefits are 2 million €/year. The investment is possible to recuperate in less than 3 years. The biodiesel yield can up to 98% with catalyst in excess. The energy used for the biodiesel production is 30% less than the obtained energy from the produced biodiesel. Replacing petro diesel by the biodiesel produced in the plant, the CO2 reduction can reach the 48%. It means that 55 000 tons CO2 per year can be reduced

    The production of biodiesel from sunflower oil and ethanol using sodium hydroxide as catalyst was performed in the laboratory and the results are discussed. The results are analyzed using the statistic method of Total Quality.

    The effect of the ethanol/oil ratio and the amount of used catalyst on the yield as well on the properties of the produced biodiesel is studied. The measured properties of the biodiesel are density, viscosity and refraction. The ethanol/oil ratio influences on the biodiesel production. The yield of biodiesel increases with the ethanol/oil ratio.  Regarding the influence of the amount of catalyst on biodiesel production in the studied condition is not possible to achieve a definitive conclusion. But a tendency showing an increasing of the biodiesel yield with the amount of catalyst can be appreciated.

    The study of the evolution of the transesterification during time shows that a reaction time of one hour is sufficient enough in order to reach the highest yield of biodiesel.

  • 272. Salminen, Eero
    et al.
    Virtanen, Pasi
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal2014Inngår i: Frontiers in Chemistry, E-ISSN 2296-2646, Vol. 2, artikkel-id 3Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat) benzalkonium [ADBA] (alkyldimethylbenzylammonium) was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs). Typically, a SILCA contains metal nanoparticles, enzymes, or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC). The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70% molar yield toward citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide.

  • 273. Sanchuan, Guo
    et al.
    Heijnesson-Hulten, Anette
    Basta, Jiri
    Greschik, Thomas
    Huaiyu, Zhan
    Germgård, Ulf
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    THE INFLUENCE OF STORAGE ON BAMBOO PULPS AND PAPER QUALITY2010Inngår i: RESEARCH PROGRESS IN PAPER INDUSTRY AND BIOREFINERY (4TH ISETPP), VOLS 1-3, SOUTH CHINA UNIV TECHNOLOGY PRESS , 2010, s. 734-738Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This study presents research dealing with the way in which storage affects bamboo pulp fibres and the quality of the resulting paper. Two bamboo pulps, cooked to different kappa numbers and then ECF-bleached to similar levels of ISO-brightness, were used to examine the relationship between refining, storage, pulp/fibre properties and the quality of the final paper sheet more closely. The results of this investigation showed that the effects of refining on pulp fibres are not stable: storing bamboo pulp fibres whilst under agitation had a considerably negative impact on properties such as tensile index, TEA, elongation and burst strength of the paper sheet. These effects were more pronounced at higher degrees of refining and for pulps with higher kappa numbers. The apparent density of the paper sheets decreased with agitated storage, whereas the relationship between density and tensile index strength was not affected. The decreases in strength properties after storage in this study are at least partly due to an increase in the number of kinks per mm fibre and a decrease in the effective fibre length and width. It should be observed that reversed latency in the paper industry introduces quality variations, and has an increased energy demand if a certain tensile index level is to be reached. It is easy for incorrect conclusions to be reached regarding the potential of substituting imported hardwood pulps with domestic bamboo pulps if they are not handled properly when used in a furnish for different final products.

  • 274.
    Sandin, Olof
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Optical and Mechanical Properties of Cool Roof Paint Containing Hollow Thermoplastic Microspheres2013Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This master thesis examines the effect of hollow thermoplastic microspheres in coolroof paints. These types of paints are characterized by their high reflectivity forwavelengths up to 2.5 micrometers and high absorptivity in the IR region. Thethermoplastic microspheres were produced by Expancel®, a unit withinAkzoNobel®. Optical properties were measured using a UV-VIS-NIRspectrophotometer and FTIR. The paint systems were kept as simple as possible, onlycontaining binder, pigment and additive, thus limiting the study to relativecomparisons. TiO2 was used as standard pigment. The additive component was variedbetween thermoplastic, glass or ceramic microspheres. The reference sample usedCaCO3 as additive. The microsphere particle size was found to have the greatestimpact on the paints reflectivity. The smallest microsphere tested in this study, with adiameter of around 10 micrometers was also the best performing. Absorptance andemittance were not found to be affected by incorporating microspheres into thepaint. Thermoplastic microspheres that where coated with TiO2, called coexpandedmicrospheres were also tested. The incorporation of coexpanded microspheresshowed no increase in reflectivity compared to other paints containing thermoplasticmicrospheres. Four different paint systems were color matched (blue) at a local paintshop in order to examine non-white paints as well. Paints containing thermoplasticmicrospheres performed better than paints using any of the other additives,regardless if the paints where white or non-white.

  • 275.
    Sandin, Staffan
    et al.
    KTH.
    Cheritat, Alicia
    KTH.
    Bäckström, Joakim
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Cornell, Ann
    KTH.
    Deposition efficiency in the preparation of ozone-producing nickel and antimony doped tin oxide anodes2017Inngår i: Journal of Electrochemical Science and Engineering, ISSN 1847-9286, Vol. 7, nr 1, s. 51-64Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of precursor salts in the synthesis of nickel and antimony doped tin oxide (NATO) electrodes using thermal decomposition from dissolved chloride salts was investigated. The salts investigated were SnCl45H2O, SnCl22H2O, SbCl3and NiCl26H2O. It was shown that the use of SnCl45H20 in the preparation process leads to a tin loss of more than 85 %. The loss of Sb can be as high as 90 % while no indications of Ni loss was observed. As a consequence, theconcentration of Ni in the NATOcoating will be much higher than in the precursor solution. This high and uncontrolled loss of precursors during the preparation process will lead to an unpredictable composition in the NATOcoating and will have negative economic and environmental effects. It was found that using SnCl22H20 instead of SnCl45H2Ocan reduce the tin loss to less than 50 %. This tin loss occurs at higher temperatures than when using SnCl45H2Owhere the tin loss occurs from 56–147°C causingthe composition to change both during the drying (80–110°C) and calcination (460 -550 °C) steps of the preparation process. Electrodes coated with NATObased on the two different tin salts were investigated for morphology, composition, structure, and ozone electrocatalytic properties.

  • 276.
    Sandin, Staffan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Karlsson, Rasmus K. B.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Cornell, Ann
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Catalyzed and uncatalyzed decomposition of hypochlorite in dilute solutions2015Inngår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 54, nr 15, s. 3767-3774Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hypochlorite decomposition has been investigated by the combined measurement of aqueous concentrations of total hypochlorite, chlorate, and chloride, as well as that of evolved oxygen. In all experiments, the initial concentrations of NaOCl and NaCl were 80 mM, and the temperature was 80°C. The pH was kept constant in the range 5-10.5. The uncatalyzed decomposition of hypochlorite and the formation of chlorate and oxygen were all found to be third order of the form r<inf>i</inf> = k<inf>i</inf>[HOCl]2[OCl-], and k<inf>O</inf><inf>2</inf> was determined to be 0.046 M-2 s-1. A reaction mechanism in which oxygen and chlorate formation share an intermediate is proposed. Several compounds were tested for catalytic effects. The addition of chloride salts of cobalt and iridium showed catalytic effects on oxygen formation. The addition of iridium chloride also catalyzed the formation of chlorate with increasing selectivity for chlorate with increasing pH.

  • 277.
    Sandström, Emma
    KTH, Skolan för kemivetenskap (CHE).
    Barriärbestrykning baserad på hemicellulosa för förnyelsebara förpackningsmaterial2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Fiber-based packaging materials have a need for barrier coatings to protect the packaged item from oxygen and contaminants to increase its shelf life. The material should preferably be from renewable resources. It is desirable to keep the solid content of the coating formulation as high as possible for environmental and technical reasons. However, when working with biopolymers, this can be difficult to combine with a reasonable viscosity and texture for application as well as the barrier properties required. In this project, the problem is attempted to be overcome by combining the biopolymers xylan and chitosan to form polyelectrolyte complexes through electrostatic interactions that result in crosslinked hydrogels. Formulations were evaluated and characterized and different methods of achieving mixtures of higher solid content were attempted. Results show that an advantageous method to keep the viscosity down at higher solid contents is to grind dry xylan-chitosan material into particles and dispersing them in water, but film formation was not successful. Mixing the two components directly and plasticizing with 20 wt% xylitol permits as high solid content as 21 wt% while still being possible to coat in a laboratory scale. Coatings on paperboard exhibit very good barrier properties against oxygen, oil and greases and are also insoluble in water which allows it better resistance towards moisture than water soluble formulations. The oxygen permeability (OP) of the xylan-chitosan coatings is comparable to poly(ethylene vinyl alcohol) (EVOH). Low OP values of 0.03 [cm3 µm/m2 day kPa] at 23 ᵒC and 50% RH were achieved, much owing to the low transmission of oxygen despite the very small thickness of the coatings. The combination of xylan and chitosan is promising for application as a barrier coating on packaging materials.

  • 278.
    Sandström, Robin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Innovations in nanomaterials for proton exchange membrane fuel cells2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Hydrogen technologies are rapidly receiving increased attention as it offers a renewable energy alternative to the current petroleum-based fuel infrastructure, considering that continued large-scale use of such fossil fuels will lead to disastrous impacts on our environment. The proton exchange membrane fuel cell should play a significant role in a hydrogen economy since it enables convenient and direct conversion of hydrogen into electricity, thus allowing the use of hydrogen in applications particularly suited for the transportation industry. To fully realize this, multiple engineering challenges as well as development of advanced nanomaterials must however be addressed.

    In this thesis, we present discoveries of new innovative nanomaterials for proton exchange membrane fuel cells by targeting the entire membrane electrode assembly. Conceptually, we first propose new fabrication techniques of gas diffusion electrodes based on helical carbon nanofibers, where an enhanced three-phase boundary was noted in particular for hierarchical structures. The cathode catalyst, responsible for facilitating the sluggish oxygen reduction reaction, was further improved by the synthesis of platinum-based nanoparticles with an incorporated secondary metal (iron, yttrium and cobalt). Here, both solvothermal and high-temperature microwave syntheses were employed. Catalytic activities were improved compared to pure platinum and could be attributed to favorably shifted oxygen adsorption energies as a result of successful incorporation of the non-precious metal. As best exemplified by platinum-iron nanoparticles, the oxygen reduction reaction was highly sensitive to both metal composition and the type of crystal structure. Finally, a proton exchange membrane based on fluorine and sulfonic acid functionalized graphene oxide was prepared and tested in hydrogen fuel cell conditions, showing improvements such as lowered hydrogen permeation and better structural stability. Consequently, we have demonstrated that there is room for improvement of multiple components, suggesting that more powerful fuel cells can likely be anticipated in the future.

  • 279.
    Sandström, Robin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Annamalai, Alagappan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Boulanger, Nicolas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Ekspong, Joakim
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Talyzin, Alexandr
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Mühlbacher, Inge
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Evaluation of Fluorine and Sulfonic Acid Co-functionalized Graphene Oxide Membranes in Hydrogen Proton Exchange Membrane Fuel Cell Conditions2019Inngår i: Sustainable Energy & Fuels, ISSN 2398-4902, Vol. 3, nr 7, s. 1790-1798Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of graphene oxide (GO) based membranes consisting of self-assembled flakes with a lamellar structure represents an intriguing strategy to spatially separate reactants while facilitating proton transport in proton exchange membranes (PEM). Here we chemically modify GO to evaluate the role of fluorine and sulfonic acid groups on the performance of H2/O2 based PEM fuel cells. Mild fluorination is achieved by the presence of hydrogen fluoride during oxidation and subsequent sulfonation resulted in fluorine and SO3- co-functionalized GO. Membrane electrode assembly performance in low temperature and moderate humidity conditions suggested that both functional groups contribute to reduced H2 crossover compared to appropriate reference membranes. Moreover, fluorine groups promoted an enhanced hydrolytic stability while contributing to prevent structural degradation after constant potential experiments whereas sulfonic acid demonstrated a stabilizing effect by preserving proton conductivity.

  • 280. Schwartz, W. R.
    et al.
    Persson, Katarina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Pfefferle, L. D.
    Combustion of methane over palladium based catalysts - A study of catalytic deactivation & the use of electrochemical oxygen pumping2007Inngår i: 5th US Combustion Meeting 2007, Combustion Institute , 2007, s. 1787-1794Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Methane oxidation over palladium is of interest due to its clean catalytic combustion properties, forming only carbon dioxide and water. A successful palladium based catalyst will virtually eliminate polluting by products including unburned hydrocarbons, carbon monoxide, soot, and NOx. These potential benefits have have not been realized, in part due to catalyst deactivation over time. In this study we identify a relationship between catalyst deactivation and hydroxyl formation on Pd/Al2O3 and Pd/TiO2 catalyst surfaces, using time series FTIR spectroscopy. FTIR analysis suggests that catalyst deactivation is caused by growth of surface hydroxyls at temperatures below 450°C, and that that oxygen mobility on the catalyst surface may correlate with the degree of catalytic deactivation. We also examine the use of electrochemical oxygen pumping through a yttrium stabilized zirconia (YSZ) membrane as a possible method of delivering oxygen to the methane catalytic combustion reaction and improving catalytic conversion. We observe that applying a potential across a YSZ membrane can result in moderate increases in methane conversion, and that oxygen concentration in reactant gas mixture has a dramatic effect on catalytic activity. Our study will also address electrochemical oxygen transport to determine its rate limiting impact on the methane catalytic combustion reaction.

  • 281. Shafiu, S.
    et al.
    Baykal, A.
    Sozeri, H.
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM. Yildirim Beyazit Univ, Dept Mat Sci & Engn, Ulus Ankara, Turkey.
    Triethanolamine Assisted Hydrothermal Synthesis of Superparamagnetic Co3O4 Nanoparticles and Their Characterizations2014Inngår i: Journal of Superconductivity and Novel Magnetism, ISSN 1557-1939, E-ISSN 1557-1947, Vol. 27, nr 9, s. 2117-2122Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present, for the first time, on a facile route for the fabrication of highly crystalline Co3O4 nanoparticles using trietanolamine (TEA) assisted hydrothermal synthesis route and single precursor. Synthesized material has been evaluated for its structural, morphological and magnetic properties using x-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM) techniques. The material has been identified as highly crystalline Co3O4, with superparamagnetic character due to size confinement. Estimated particle size from SEM is about 10 nm, which is close to the magnetic domain size (estimated from VSM as 8.4 +/- 1.7 nm) and the crystallite size (estimated from XRD as 11 pm 4 nm), which reveal nearly single crystalline character of Co3O4 nanoparticles. The suggested route is facile, which provides a good size control over the nanoparticles, and can be used for the fabrication of other ceramic materials.

  • 282.
    Shahid, Robina
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Gorlov, Mikhail
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    El-Sayed, Ramy
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Sugunan, Abhilash
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Microwave assisted synthesis of ZnS quantum dots using ionic liquids2012Inngår i: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 89, s. 316-319Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work we report results from microwave (MW) assisted synthesis of highly crystalline ZnS quantum dots (QDs) using ionic liquid (ILs) as MW absorbing medium. Two types of ionic liquids, imidazolium and phosphonium based, were used. The QDs are less than 5 nm in size and of wurtzite ZnS type, as characterized by high-resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED) pattern. The optical properties were investigated by UV-vis absorption and show a blue shift in absorption as compared to bulk wurtzite ZnS due to quantum confinement effects. The photoluminescence (PL) spectra of the QDs show different trap state emissions.

  • 283.
    Shahkarami, Pirouz
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Liu, Longcheng
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Moreno, Luis
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Neretnieks, Ivars
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Analytical solution for N-member decay chain transport in fracture in rock2013Inngår i: Rock Characterisation, Modelling and Engineering Design Methods - Proceedings of the 3rd ISRM SINOROCK 2013 Symposium, Taylor & Francis Group, 2013, s. 323-328Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A model is developed to describe the transport of an N-member radionuclide decay chain along a discrete fracture situated in a porous matrix. An analytical solution is presented and a series of simulations are performed to study the relative significance of diffusion process into rock matrix, stagnant water, chain decay and hydrodynamic dispersion. The results show that a simplified model that ignores the effect of stagnant water zone can lead to significant error in the estimated time of arrival and peak value of the nuclides. The results demonstrate that for a two-member decay chain, neglecting the parent and modeling its daughter as a single species can result in significant overestimation of peak value of the nuclide. Moreover, it is found that as the dispersion increases, the arrival time and peak time of daughter decrease, while the peak value increases.

  • 284.
    Shahkarami, Pirouz
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Liu, Longcheng
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Moreno, Luis
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Neretnieks, Ivars
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Radionuclide migration through fractured rock for arbitrary-length decay chain: Analytical solution and global sensitivity analysis: new2015Inngår i: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 520, s. 448-460Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study presents an analytical approach to simulate nuclide migration through a channel in a fracture accounting for an arbitrary-length decay chain. The nuclides are retarded as they diffuse in the porous rock matrix and stagnant zones in the fracture. The Laplace transform and similarity transform techniques are applied to solve the model. The analytical solution to the nuclide concentrations at the fracture outlet is governed by nine parameters representing different mechanisms acting on nuclide transport through a fracture, including diffusion into the rock matrices, diffusion into the stagnant water zone, chain decay and hydrodynamic dispersion. Furthermore, to assess how sensitive the results are to parameter uncertainties, the Sobol method is applied in variance-based global sensitivity analyses of the model output. The Sobol indices show how uncertainty in the model output is apportioned to the uncertainty in the model input. This method takes into account both direct effects and interaction effects between input parameters. The simulation results suggest that in the case of pulse injections, ignoring the effect of a stagnant water zone can lead to significant errors in the time of first arrival and the peak value of the nuclides. Likewise, neglecting the parent and modeling its daughter as a single stable species can result in a significant overestimation of the peak value of the daughter nuclide. It is also found that as the dispersion increases, the early arrival time and the peak time of the daughter decrease while the peak value increases. More importantly, the global sensitivity analysis reveals that for time periods greater than a few thousand years, the uncertainty of the model output is more sensitive to the values of the individual parameters than to the interaction between them. Moreover, if one tries to evaluate the true values of the input parameters at the same cost and effort, the determination of priorities should follow a certain sequence.

  • 285.
    Shahkarami, Pirouz
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Liu, Longcheng
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Moreno, Luis
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Neretnieks, Ivars
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    The effect of stagnant water zones on retarding radionuclide transport in fractured rocks: An extension to the Channel Network Model2016Inngår i: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 540, s. 1122-1135Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An essential task of performance assessment of radioactive waste repositories is to predict radionuclide release into the environment. For such a quantitative assessment, the Channel Network Model and the corresponding computer program, CHAN3D, have been used to simulate radionuclide transport in crystalline bedrocks. Recent studies suggest, however, that the model may tend to underestimate the rock retarding capability, because it ignores the presence of stagnant water zones, STWZs, situated in the fracture plane. Once considered, the STWZ can provide additional surface area over which radionuclides diffuse into the rock matrix and thereby contribute to their retardation.

    The main objective of this paper is to extend the Channel Network Model and its computer implementation to account for diffusion into STWZs and their adjacent rock matrices.

    In the first part of the paper, the overall impact of STWZs in retarding radionuclide transport is investigated through a deterministic calculation of far-field releases at Forsmark, Sweden. Over the time-scale of the repository safety assessments, radionuclide breakthrough curves are calculated for increasing STWZ width. It is shown that the presence of STWZs enhances the retardation of most long-lived radionuclides except for 36Cl and 129I.

    The rest of the paper is devoted to the probabilistic calculation of radionuclide transport in fractured rocks. The model that is developed for transport through a single channel is embedded into the Channel Network Model and new computer codes are provided for the CHAN3D. The program is used to (I) simulate the tracer test experiment performed at Äspö HRL, STT-1 and (II) investigate the short- and long-term effect of diffusion into STWZs. The required data for the model are obtained from detailed hydraulic tests in boreholes intersecting the rock mass where the tracer tests were made.

    The simulation results fairly well predict the release of the sorbing tracer 137Cs. It is found that over the short time-scale of the tracer experiment, the effect of diffusion into STWZs is not as pronounced as that of matrix diffusion directly from the flow channel, and the latter remains the main retarding mechanism. Predictions for longer time-scale, tens of years and more, show that the effect of STWZs becomes strong and tends to increase with transport time. It is shown that over the long times of interest for safety assessment of radioactive waste repositories, STWZs can substantially contribute to radionuclide retardation, though for the short time-scales the impact is not very strong and is not expected to affect the results of short-term field experiments.

  • 286.
    Shahkarami, Pirouz
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Neretnieks, Ivars
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Moreno, Luis
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Liu, Longcheng
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Channel Network Concept — an Integrated Approach to Visualize Solute Transport in Fractured RocksManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The advection-dispersion equation, ADE, has commonly been used to visualize solute transport in fractured rock. However, there is one key question that has to be addressed before the mathematical form of the so-called Fickian dispersion that underlies the ADE takes on physical meaning in fractures. What is the travel distance, or travel time, required before the Fickian condition is met and the ADE becomes physically reasonable? A simple theory is presented in this study to address this question in tapered channels. It is shown that spreading of solute under forced-gradient flow conditions is mostly dominated by advective mechanisms, though the ADE might be valid in the channels under natural flow conditions. This implies that the use of the ADE and macro dispersion coefficient might be misleading when applied to interpret field tracer experiment results. Furthermore, several concerns are raised in this paper with regard to utilizing the concept of field-scale matrix diffusion coefficient in fractured rocks. The concerns are mainly directed toward the uncertainties and potential bias involved in finding the continuum model parameters.

    In light of the findings of this study and empirical evidences, it is suggested that it is feasible and more realistic to describe flow and solute transport in fractured rocks as taking place in three-dimensional networks of channels, as embodied in the channel network concept, CN-concept. It is argued that this conceptualization provides a convenient framework to capture the impacts of spatial heterogeneities in fractured rocks and can accommodate the physical mechanisms underlying the behavior of solute transport in such porous media. All these issues are discussed in this paper in relation to analyzing and predicting actual tracer tests in fractured crystalline rocks.

  • 287.
    Sharifi, Tiva
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Kwong, Wai Ling
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Berends, Hans-Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsen, Christian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Messinger, Johannes
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Maghemite nanorods anchored on a 3D nitrogen-doped carbon nanotubes substrate as scalable direct electrode for water oxidation2016Inngår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, nr 1, s. 69-78Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A hybrid catalyst 3D electrode for electrochemical water oxidation to molecular oxygen is presented. The electrode comprises needle shaped maghemite nanorods firmly anchored to nitrogen doped carbon nanotubes, which in turn are grown on a conducting carbon paper that acts as efficient current collector. In 0.1 M KOH this hybrid electrode reaches a current density of 1 mA/cm(2) (geometric surface) at an overpotential of 362 mV performing high chronoamperometric stability. The electrochemical attributes point toward efficient catalytic processes at the surface of the maghemite nanorods, and demonstrate a very high surface area of the 3D electrode, as well as a firm anchoring of each active component enabling an efficient charge transport from the surface of the maghemite rods to the carbon paper current collector. The latter property also explains the good stability of our hybrid electrode compared to transition metal oxides deposited on conducting support such as fluorine doped tin oxide. These results introduce maghemite as efficient, stable and earth abundant oxygen evolution reaction catalyst, and provide insight into key issues for obtaining practical electrodes for oxygen evolution reaction, which are compatible with large scale production processes. 

  • 288. Shen, Hangjia
    et al.
    Gracia-Espino, Eduardo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Wang, Le
    Qin, Danfeng
    Gao, Sanshuang
    Mamat, Xamxikamar
    Ren, Wei
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Hu, Guangzhi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Chinese Acad Sci, Xinjiang Tech Inst Phys & Chem, Urumqi 830011, Peoples R China.
    Microwave-assisted synthesis of multimetal oxygen-evolving catalysts2017Inngår i: Electrochemistry communications, ISSN 1388-2481, E-ISSN 1873-1902, Vol. 81, s. 116-119Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Oxygen evolution reaction (OER) plays a pivotal role in water-splitting. Here, we report a facile method to synthesize multimetal supported on commercial carbon black via a time-saving microwave process. Crystalline FeNi3 nanoparticles homogeneously doped with Mo are formed via a microwave treatment and activated to metal oxyhydroxide in-situ during cyclic voltammetry test with overpotential of only 280 mV at 10 mA cm(-2) for OER in alkaline electrolyte, outperforming RuO2. Our synthesis methodology is a promising alternative for large-scale production, delivering a valuable contribution to catalyst preparation and electrocatalytic water oxidation research.

  • 289.
    Sideris, Dimitrios
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Hydrogen-rich materials as auxiliary reducing agents in the blast furnace2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 290.
    Silveira, Jose Luz
    et al.
    Sao Paulo State University (UNESP), Campus Guaratinguetá.
    Braga, Lucia Bollini
    Sao Paulo State University (UNESP), Campus Guaratinguetá.
    Caetano de Souza, Antonio Carlos
    Sao Paulo State University (UNESP), Campus Guaratinguetá.
    Antunes, Julio Santana
    Sao Paulo State University (UNESP), Campus Guaratinguetá.
    Zanzi, Rolando
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    The benefits of ethanol use for hydrogen production in urban transportation2009Inngår i: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 13, nr 9, s. 2525-2534Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The purpose of this paper is to describe the benefits of sugar cane ethanol in Brazil, appointing the productivity of this type of fuel based on hectares of plantation, its carbon dioxide cycle and the contribution to reduce the greenhouse effect. In the following step the uses of ethanol for hydrogen production by steam reforming is analyzed and some comparison with natural gas steam reforming is performed. The sugar cane industry in Brazil, in a near future, in the hydrogen era, could be modified according to our purpose, since besides the production of sugar, and ethylic and anhydric alcohol, Brazilian sugar cane industry will also be able to produce biohydrogen. Fuel cells appear like a promising technology for energy generation. Among several technologies in the present, the PEMFC (proton exchange membrane fuel cell) is the most appropriate for vehicles application, because it combines durability, high power density, high efficiency, good response and it works at relatively low temperatures. Besides that it is easy to turn it on and off and it is able to support present vibration in vehicles. A PEMFC's problem is the need of noble catalysts like platinum. Another problem is that CO needs to be in low concentration, requiring a more clean hydrogen to avoid fuel cell deterioration. One part of this paper was developed in Stockholm, where there are some buses within the CUTE (clean urban transport for Europe) project that has been in operation with FC since January 2004. Another part was developed in Guaratingueta, Brazil. Brazil intends to start up a program of FC buses. As conclusion, this paper shows the economical analysis comparing buses moved by fuel cells using hydrogen by different kinds of production. Electrolyze with wind turbine, natural gas steam reforming and ethanol steam reforming.

  • 291. Silveira, Jose Luz
    et al.
    Martinelli, Valdisley Jose
    Vane, Lucas Fachini
    Freire Junior, Jose Celso
    Zanzi Vigouroux, Rolando A.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Tuna, Celso Eduardo
    Lamas, Wendell de Queiroz
    Silva Paulino, Regina Francielle
    Incorporation of hydrogen production process in a sugar cane industry: Steam reforming of ethanol2014Inngår i: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 71, nr 1, s. 94-103Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work presents a technical, ecological and economic analysis of hydrogen production incorporation through ethanol steam reforming at a traditional sugarcane industry (sugar, ethanol). This proposal is reached through a reduction in the amount of fuel (bagasse) that is normally utilized to generate electricity without affecting the sugar and ethanol production processes, however. This surplus bagasse is utilized to produce steam for hydrogen production. In order to achieve this, it is calculated the available bagasse and maximum hydrogen amount and their inputs (hydrated and anhydrous ethanol). Based on the aforementioned, the investment needs are estimated, where the operation and maintenance cost, the operation period, the interest rate, and the annuity are considered. The incorporation of this new process is assessed through a comparison of this innovative plant with the traditional ones.

  • 292.
    Singh, Jagdeep
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekologi.
    Frostell, Björn
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekologi.
    Wennersten, Ronald
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekologi.
    Waste management as a part of a broader systems approach to production and consumption2011Inngår i: Book of Proceedings of the 1st International Conference: WASTES: Solutions, Treatments and Opportunities / [ed] Fernando Castro, Cândida Vilarinho & Joana Carvalho, Guimarães, Portugal: CVR – Centro para a valorização de Resíduos , 2011, s. 124-129Konferansepaper (Fagfellevurdert)
  • 293.
    Sobocinski, Maciej
    et al.
    Microelectronics and Material Physics Laboratories University of Oulu, Finland.
    Khajavizadeh, Lida
    Microelectronics and Material Physics Laboratories University of Oulu, Finland.
    Andersson, Mike
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad sensorvetenskap. Linköpings universitet, Tekniska fakulteten. Microelectronics and Material Physics Laboratories University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad sensorvetenskap. Linköpings universitet, Tekniska fakulteten. Microelectronics and Material Physics Laboratories University of Oulu, Finland.
    Juuti, Jari
    Microelectronics and Material Physics Laboratories University of Oulu, Finland.
    Jantunen, Heli
    Microelectronics and Material Physics Laboratories University of Oulu, Finland.
    Performance of LTCC embedded SiC gas sensors2015Inngår i: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 120, s. 253-256Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel approach to encapsulation/packaging of SiC field effect transistor gas sensors for high temperature applications, such as exhaust and fuel gas emissions monitoring, based on direct co-firing of sensor devices and Low-Temperature Co-fired Ceramics (LTCC) has been investigated. Structural (SEM, EDX, XPS), electrical (I/V, C/V) as well as gas sensing characterization of packaged devices has shown that the “one-step” packaging process forms a hermetic package with retained transducer functionality and gas sensing characteristics without the need for any separate die attachment, (wire) bonding, and/or sealing of the package. Long-term stability testing at elevated temperatures of packaged devices has also shown promising results.

  • 294.
    Sophonrat, Nanta
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Sandström, Linda
    RISE Energy Technol Ctr AB, Box 726, SE-94128 Pitea, Sweden..
    Svanberg, Rikard
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Han, Tong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Dvinskikh, Sergey
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Lousada, Claudio M.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Ex Situ Catalytic Pyrolysis of a Mixture of Polyvinyl Chloride and Cellulose Using Calcium Oxide for HCl Adsorption and Catalytic Reforming of the Pyrolysis Products2019Inngår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 58, nr 31, s. 13960-13970Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the context of chemical recycling of mixed plastics and paper, multitemperature step pyrolysis has shown good potential for the separation of oxygenated products from hydrocarbons. Here, we report results of an investigation of the first pyrolysis step at low temperature, which involves the dehydrochlorination of polyvinyl chloride (PVC) and the pyrolysis of cellulose, the main component of paper. Calcium oxide (CaO), selected for its chloride adsorption ability and its catalytic activity on biooil deoxygenation, was used for upgrading the downstream products from the pyrolysis. Additionally, we studied the performance of CaO for the simultaneous adsorption of HCl and for reforming cellulose pyrolysates in the temperature range of 300-600 degrees C with feedstock to CaO ratios of 1:0.2, 1:0.4, and 1:1. It was found that the suitable catalytic temperature for HCl and acetic acid adsorption is lower than 400 degrees C. This is due to the desorption of HCl from CaCl2 and Ca(OH)Cl in the presence of water and CO2 at 400 degrees C and higher. A larger amount of CaO resulted in a more efficient reduction of acids and the organic liquids were found to have lower amounts of oxygen. A comparison between the cases of neat and mixed feedstock showed that pyrolysis of mixed feedstock produced more water, H-2, CO, and polycyclic aromatic hydrocarbons (PAHs) when compared to the case of neat materials over CaO.

  • 295.
    Sotolongo, José Angel
    et al.
    CADETES, CITMA, Guantánamo, Cuba.
    Beatón Soler, Pedro
    CITMA, Santiago de Cuba, Cuba.
    Díaz, Armando
    Oriente University, Cuba.
    Montes de Oca, Sofía
    CADETES, CITMA, Guantánamo, Cuba.
    del Vallel, Yadiris
    CADETES, CITMA, Guantánamo, Cuba.
    García Pavón, Soraya
    CADETES, CITMA, Guantánamo, Cuba.
    Zanzi Vigouroux, Rolando
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Jatropha Curcas L. as a source for the production of biodiesel: a Cuban Experience2007Inngår i: 15th European Biomass Conference and Exhibition”, 2007, 7-10 May, Berlin, Germany, 2007, s. 2631-2633Konferansepaper (Fagfellevurdert)
  • 296. Sotres, J.
    et al.
    Pettersson, Torbjörn
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Lindh, L.
    Arnebrant, T.
    NanoWear of Salivary Films vs. Substratum Wettability2012Inngår i: Journal of Dental Research, ISSN 0022-0345, E-ISSN 1544-0591, Vol. 91, nr 10, s. 973-978Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The pellicle serves as a multifunctional protective layer, providing, e.g., lubrication and remineralization and also acting as a diffusion barrier. In addition, since the formation of the pellicle precedes the adhesion of micro-organisms, it is also important as a conditioning film. We present a novel approach to study the influence of the water wettability of solid surfaces on the strength of adsorbed salivary films. It is based on studying the wear resistance of the films with an atomic force microscope operated in the friction force spectroscopy mode. This methodology provides the strength of the films in terms of the forces needed for breaking and removing them. Our results indicate that these forces are highly dependent on the water wettability of the underlying substrata, decreasing with increasing hydrophobicity. Thus, this study provides valuable information for the design of materials exposed in the oral cavity, i.e., materials that will minimize plaque formation and be easy to clean.

  • 297.
    Souza Filho, Pedro
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Zamani, Akram
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Taherzadeh, Mohammad J
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Solid Precipitation from Potato Protein Liquor by Ethanol2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The production of starch in European Union (EU 28) was around 10 million tonnes in 2013, 12.6% of them being from potato1. During the potato processing, two main by-products which have high Biological Oxygen Demand (BOD) are formed, i.e. potato pulp (PP) and potato liquor (PL)2. Proteins can be partially recovered from PL, resulting in a concentrated residual material known as potato protein liquor (PoPL)2,3. The use of PoPL has been investigated to cultivate fungal4 and yeast3 biomass, and produce enzymes2. However, presence of nitrogen and phosphate containing materials as well as suspended solids at high concentrations4 limits its application in bioprocesses. The present study was proposed to investigate the precipitation of components from PoPL by ethanol in order to get an easily fermentable solution. PoPL from Lyckeby Starch AB was mixed with different amounts of ethanol and centrifuged at 3000 g for 5 min. The liquid obtained was put under a fume hood for 48 h at room temperature for ethanol evaporation. All the samples had their volumes adjusted to the same value using distilled water. The precipitate was dried at 105 °C. All experiments were done in duplicate. The precipitation of solids improved almost 500% for a mixture of equal volumes of PoPL and ethanol compared to PoPL without ethanol addition. The protein and ash contents of the precipitate were respectively higher than 245 g/kg and 420 g/kg in all the cases, making it eligible for production of fertilizer or animal feed. Most of the analysed sugars (glucose, fructose, and sucrose) stayed in the liquid phase. Ethanol concentration in the liquid phase remained close to initial value after the 48-hour evaporation. This indicates the need for a distillation column for ethanol recovery before the remaining sugar solution can be used for fermentation purposes.

  • 298.
    Spencer, Maximilian
    KTH, Skolan för kemivetenskap (CHE).
    Fuel Cell for Food Preservation2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    As foodstuffs are being produced, transported and stored in greater quantities than ever before in human history and with an alarming amount of food products being lost to spoilage every year, new, environmentally friendly ways of preserving food products are being actively researched and developed in today’s world.

    Oxygen is a key pathway towards food decay and destruction, due to its dual roles as a source of respiration for the multitude of microorganisms that can cause food spoilage and through direct destruction through oxidation reactions within food products that cause oxidative deterioration.

    Fuel cells have the theoretical potential to be an energy efficient and environmentally friendly way of preserving food, such as fish, fruit and vegetables.  Because of their nature to consume oxygen through the electrochemical reactions that produces their electrical power, they have the potential to be used to reduce localised oxygen content for the storage and transportation of foods, minimising their spoilage, as well as potentially providing electrical energy for other components in potential control systems for the fuel cell.

    The purpose of this project is to design and build a PEM fuel cell and examine its potential for lowering of oxygen concentrations at the gas output at the cathode.  The outcome of these experiments are designed to validate the  theoretical capacity of fuel cells to reduce output oxygen concentrations to levels that are able to aid in the preservation of foodstuffs.  It is hoped that this study, in conjunction with the researched literature, can be used as a guide for future food shipping and storage methods.

    The experimental stage of this diploma work was unsatisfactory. The fuel cell was unable to produce a voltage and the reactant gases were unable to flow through the fuel cell due to a design flaw. Therefore the effectiveness of a fuel cell for depletion of oxygen to levels able to preserve food is based on the theoretical basis of the internal PEM fuel cell reactions, as well as studying past literature and patents.

    If the theoretical ability of the fuel cell is proven, it can be asserted that PEM fuel cells have the potential to be a real contender in the field of food preservation in shipping and storage, as well as offering greater levels of control for supplies for how and when they can ship their product. However this will require more independent research development work on the effects of low oxygen concentrations on a fuel cell operation as well as the preservation effects on a greater variety of foodstuffs. Furthermore, more research is required for more efficient and cheaper fuel cell catalysts or innovative designs are required to avoid concentration losses that arise from oxygen reduction at low oxygen levels.

  • 299.
    Staffas, Louise
    et al.
    IVL, Sweden.
    Karlfeldt Fedje, Karin
    Chalmers University of Technology, Sweden.
    Pettersson, Anita
    University of Borås, Sweden.
    Johansson, Inge
    RISE - Research Institutes of Sweden, Samhällsbyggnad, Energi och cirkulär ekonomi.
    Behandling och återvinning av outnyttjade resurser i flygaska2016Rapport (Annet vitenskapelig)
    Abstract [sv]

    Föreliggande projekt har utgått från frågan "Hur kan användbara ämnen i flygaska från avfallsförbränning återföras till det industriella kretsloppet och restprodukten klassas som icke farligt avfall?"

    Sju askor har ingått i studien: en returträaska från fluidbäddpanna, en avfallsflygaska från fluidbäddpanna och fem avfallsflygaskor från rosterpannor.

    Askornas totalhalter av olika ämnen har mätts i syfte att undersöka vilka möjligt värdefulla substanser som finns. Cu, Ag, Al, Zn och Sb bedömdes som mest intressanta att återvinna. Metallhalterna i askorna är ofta låga utifrån återvinningsprocessaspekt, vilket gör att askorna ger mycket ballast i återvinningsaktörernas processer. Det finns andra sekundära råvaror, som t.ex. elektronik-skrot och slaggrus, som är mer intressanta för metall-återvinningsaktörer. För att kunna konkurrera med dessa strömmar måste askan upparbetas och/eller anrikas för att kunna passa i metallåtervinnings-processerna, vilket kan vara en framkomlig väg för några askor.

    Askorna lakades enligt SS-EN-127457-3 för att, tillsammans med totalhalterna, ge klarhet i vilka ämnen som förhindrar askorna att utgöra icke farliga avfall. Det är halterna av Cr och Pb, samt utlakningen av Cl-, Pb och SO42- som i de flesta fall utgör hinder för IFA-deponi av originalaskor.

    I syfte att undersöka möjligheten att laka ut metaller för återvinning lakades askorna med syra; dels olika koncentrationer av syra och dels med olika pH. Ingen av dessa metoder visade sig ge utlakning i sådan omfattning att det skulle vara en generellt framkomlig väg att utnyttja resurserna i flygaskorna från avfallsförbränning. I enskilda fall kan lakning för utvinning vara framgångsrikt.

    Som prioritet två låg att behandla askorna så att de uppfyller mottagningskriterierna för deponi för icke farligt avfall. Som ett första behandlingssteg tvättades askorna med vatten. Två tvätt-omgångar med vatten visade sig i vissa fall ge askor som uppfyller kriterierna. I andra fall skulle dispens för lakning av ett eller två ämnen per aska (Cl-, Cr, Pb, Sb och SO42-) behövas för att få tillstånd för deponering på IFA-deponi.

    Ett antal användningsområden för det salt som tvättas ut i vattentvättstegen har identifierats; bl.a. vägsalt, aluminiumåtervinning, PVC-tillverkning. Kravspecifikationer för dessa har jämförts med saltsammansättningen för saltet från askorna. PVC-tillverkning och aluminiumåtervinning är de två applikationer som bedöms vara mest intressanta att undersöka vidare.

    Flygaskor från avfallsförbränning måste undergå omfattande upparbetning för att utgöra attraktiva substrat för återvinning eller andra användningar.

  • 300.
    Strand, Michael
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Gustafsson, Eva
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Lin, Leteng
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Yang, Jingjing
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    High-Temperature extraction of aerosol particles from biomass combustion and gasification2011Inngår i: European Aerosol Conference 2011, 2011Konferansepaper (Fagfellevurdert)
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