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  • 201.
    Mahmoudzadeh, Batoul
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Modeling Solute Transport in Fractured Rocks-Role of Heterogeneity, Stagnant Water Zone and Decay Chain2014Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    A model is developed to describe solute transport and retention in fractured rocks. It accounts for the fact that solutes not only can diffuse directly from the flowing channel into the adjacent rock matrix composed of different geological layers but can also at first diffuse into the stagnant water zone occupied in part of the fracture and then from there into the rock matrix adjacent to it. Moreover, the effect of radioactive decay-chain has also been studied in the presence of matrix comprising different geological layers. In spite of the complexities of the system, the analytical solution obtained for the Laplace-transformed concentration at the outlet of the flowing channel can conveniently be transformed back to the time domainby use of e.g. De Hoog algorithm. This allows one to readily include it into a fracture network modelorachannelnetwork model to predictnuclide transport through channels in heterogeneous fracturedmedia consisting of an arbitrary number of rock units withpiecewise constant properties. Simulations made in this study indicate that, in addition to the intact wall rock adjacent to the flowing channel, the stagnant water zone and the rock matrix adjacent to it may also lead to a considerable retardation of solute in cases with a narrow channel. The results further suggest that it is necessary to account for decay-chain and also rock matrix comprising at least two different geological layers in safety and performance assessment of the repositories for spent nuclear fuel. The altered zone may cause a great decrease of the nuclide concentration at the outlet of the flowing channel. The radionuclide decay, when accounted for, will drastically decrease the concentration of nuclides, while neglecting radioactive ingrowth would underestimate the concentration of daughter nuclides.

  • 202.
    Mahmoudzadeh, Batoul
    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.
    Solute transport in a single fracture involving an arbitrary length decay chain with rock matrix comprising different geological layers2014Inngår i: Journal of Contaminant Hydrology, ISSN 0169-7722, E-ISSN 1873-6009, Vol. 164, s. 59-71Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A model is developed to describe solute transport and retention in fractured rocks. It accounts for advection along the fracture, molecular diffusion from the fracture to the rock matrix composed of several geological layers, adsorption on the fracture surface, adsorption in the rock matrix layers and radioactive decay-chains. The analytical solution, obtained for the Laplace-transformed concentration at the outlet of the flowing channel, can conveniently be transformed back to the time domain by the use of the de Hoog algorithm. This allows one to readily include it into a fracture network model or a channel network model to predict nuclide transport through channels in heterogeneous fractured media consisting of an arbitrary number of rock units with piecewise constant properties. More importantly, the simulations made in this study recommend that it is necessary to account for decay-chains and also rock matrix comprising at least two different geological layers, if justified, in safety and performance assessment of the repositories for spent nuclear fuel.

  • 203.
    Mahmoudzadeh, Batoul
    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.
    Solute transport in fractured rocks with stagnant water zone and rock matrix composed of different geological layers-Model development and simulations2013Inngår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 49, nr 3, s. 1709-1727Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A model is developed to describe solute transport and retention in fractured rocks. It accounts for the fact that solutes can not only diffuse directly from the flowing channel into the adjacent rock matrix composed of different geological layers but also at first diffuse into the stagnant water zone occupied in part of the fracture and then from there into the rock matrix adjacent to it. In spite of the complexities of the system, it is shown that the analytical solution to the Laplace-transformed concentration at the outlet of the flowing channel is a product of two exponential functions, and it can be easily extended to describe solute transport through channels in heterogeneous fractured media consisting of an arbitrary number of rock units with piecewise constant geological properties. More importantly, by numerical inversion of the Laplace-transformed solution, the simulations made in this study help to gain insights into the relative significance and the different contributions of the rock matrix and the stagnant water zone in retarding solute transport in fractured rocks. It is found that, in addition to the intact wall rock adjacent to the flowing channel, the stagnant water zone and the rock matrix adjacent to it may also lead to a considerable retardation of solute in cases with a narrow channel.

  • 204.
    Malmström Jonsson, Eva E.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Bruce, Carl
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Carlsson, Linn
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Larsson, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Carlmark, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Fogelström, Linda
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Modification of cellulose substrates using polymers obtained by controlled radical polymerization: Covalent grafting or physiosorption of polyelectrolytes2014Inngår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 248Artikkel i tidsskrift (Annet vitenskapelig)
  • 205. Matindoust, Samaneh
    et al.
    Farzi, Ali
    Nejad, Majid Baghaei
    Abadi, Mohammad Hadi Shahrokh
    Zou, Zhuo
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Zheng, Li-Rong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Ammonia gas sensor based on flexible polyaniline films for rapid detection of spoilage in protein-rich foods2017Inngår i: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 28, nr 11, s. 7760-7768Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work details the fabrication and performance of a sensor for ammonia gas, based on conducting polymer. The fabrication procedure consists following steps; polyaniline synthesis via oxidative polymerization technique, then a sensitive polyaniline film was deposited on a printed circuit board and finally, polyaniline microdevice were assembled on an interdigitated electrode arrays to fabricate the sensor for amomonia gas detection. Response time of this chemiresistive devices and humidity impact were examined for NH3 sensitivity and compared with commercial gas sensors (Taguchi Model 826). Data export from sensor to the computer was carried out via data logger model ADC-24 and analyzed using SPSS software. The sensor was found to have a rapid (t = 40 s) and stable linear response to ammonia gas in the concentration range of interest (50-150 ppm) under room temperature operation condition. It was reviled also reliable results to the variation of environment humidity. Power consumption, sensitivity, dimension, flexibility and fabrication cost were used as most important parameters to compare the new polymer based device with those of other similar works and the results showed that small size, low cost, flexibility, low power consumption and high sensitivity are from the benefits of this innovative device. In real-time application conditions flexible polyaniline based gas sensor with polyimide substrate in thickness 0.25 mm exhibits relatively good performance and accurate evaluation of food spoilage.

  • 206. Mattsson, Tuve
    et al.
    Richards, Tobias
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    The separation of green liquor sludge: A comparison between liquors produced in a gasifier and a recovery boiler2009Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Green liquor is produced as when chemicals are recovered in the kraft pulp process. The industrial formed green liquor contains a solid, non-solvable phase, called green liquor dregs and are removed either by filtration, or by sedimentation. This work compares separation properties of green liquor produced in a gasifier unit with green liquor produced in a recovery boiler. The two types of green liquors were found to have almost similar separation properties with respect to both sedimentation and filtration. For filtration, the average specific filtration resistance was about 1012 m/kg at 1 bar filtration pressure.

  • 207. Mealey, Donal
    et al.
    Svärd, Michael
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära. University of Limerick, Castletroy, Ireland .
    Rasmuson, Åke C.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära. University of Limerick, Castletroy, Ireland .
    Thermodynamics of risperidone and solubility in pure organic solvents2014Inngår i: Fluid Phase Equilibria, ISSN 0378-3812, E-ISSN 1879-0224, Vol. 375, s. 73-79Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The solid-liquid solubility of the thermodynamically stable form I of the drug risperidone has been determined by a gravimetric method in nine pure organic solvents in the temperature range 278.15-323.15 K. The melting temperature and associated enthalpy of fusion of risperidone form I has been determined by differential scanning calorimetry (DSC) to be 442.38 K and 43.94 kJ mol(-1), respectively. The heat capacity of the solid form I and the melt have been determined over a range of temperatures by temperature-modulated DSC, and extrapolated data has been used to calculate the Gibbs energy, enthalpy and entropy of fusion from ambient temperature up to the melting point. The ideal solubility within a Raoult's law framework is obtained from the Gibbs energy of fusion, and the solution activity coefficient at equilibrium in the nine solvents quantified. Solutions in all solvents exhibit positive deviation from Raoult's law, with the highest solubility (closest to ideality) in toluene, an aprotic apolar solvent. The solubility curves plotted in a van't Hoff graph show non-linear behaviour and are well-approximated by a second order polynomial.

  • 208.
    Melin, Tim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Morphology of electrodeposited Na on Al electrodes2019Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The demand for alternative secondary batteries to lithium-ion batteries (LIBs) grows. Sodium-ion batteries (SIBs) have been studied for many years and could replace LIBsfor some application. Metallic anodes for both LIBs and SIBs are interesting due totheir high energy densities. Several aspects such as reactivity, stability and depositionmorphology must be properly addressed before metallic Na could be considered apossible anode material. This study aims to evaluate deposition of Na on Alelectrodes using fundamental electrochemical theories. Na deposition was studiedusing pouch cells and sodium triflate (NaOTf) in dimethyl glycol ether (diglyme) aselectrolyte. Galvanostatic deposition using different current densities, electrolyteconcentrations and potential pulses prior to galvanostatic deposition were tested. Theelectrochemical methods used in this study were galvanostatic deposition andchronoamperometry. The morphology of deposited Na was analyzed with ex-situscanning electron microscopy (SEM). A decrease of the size of deposited Na islandswas observed for both increasing current density and decreasing electrolyteconcentration. Fluctuations and poor stability in the deposition potential wereobtained when decreasing the electrolyte concentration under 0.5 M and also whenincreasing the current density over 1 mA cm-2. The most homogeneous depositionwas obtained with a 1030 ms potential pulse amplitude (-3 V vs. Na+/Na) prior togalvanostatic deposition (1 mA cm-2, 0.5 mAh cm-2) using 0.1 M NaOTf in diglyme aselectrolyte. Reproducibility was a major issue in this study and further investigation ofseveral parameters is needed.

  • 209.
    Melios, Christos
    et al.
    Natl Phys Lab, England; Univ Surrey, England.
    Panchal, Vishal
    Natl Phys Lab, England.
    Edmonds, Kieran
    Royal Holloway Univ London, England.
    Lartsev, Arseniy
    Chalmers Univ Technol, Sweden.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Kazakoya, Olga
    Natl Phys Lab, England.
    Detection of Ultralow Concentration NO2 in Complex Environment Using Epitaxial Graphene Sensors2018Inngår i: ACS SENSORS, ISSN 2379-3694, Vol. 3, nr 9, s. 1666-1674Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate proof-of-concept graphene (a) sensors for environmental monitoring of ultralow concentration NO2 in complex environments. Robust detection in a wide range of NO2 concentrations, 10-154 ppb, was achieved, highlighting the great potential for graphene-based NO2 sensors, with applications in environmental pollution monitoring, portable monitors, automotive and mobile sensors for a global real-time monitoring network. The measurements were performed in a complex environment, combining NO2/synthetic air/water vapor, traces of other contaminants, and variable temperature in an attempt to fully replicate the environmental conditions of a working sensor. It is shown that the performance of the graphene-based sensor can be affected by coadsorption of NO2 and water on the surface at low temperatures (amp;lt;= 70 degrees C). However, the sensitivity to NO2 increases significantly when the sensor operates at 150 degrees C and the cross-selectivity to water, sulfur dioxide, and carbon monoxide is minimized. Additionally, it is demonstrated that single-layer graphene exhibits two times higher carrier concentration response upon exposure to NO2 than bilayer graphene.

  • 210.
    Minkova, V.
    et al.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Marinov, S. P.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Zanzi, Rolando
    KTH, Tidigare Institutioner, Kemiteknik. KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Bjornbom, E.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk reaktionsteknik.
    Budinova, T.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Stefanova, M.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Lakov, L.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Thermochemical treatment of biomass in a flow of steam or in a mixture of steam and carbon dioxide2000Inngår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 62, nr 1, s. 45-52Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Simultaneous pyrolysis and gasification of biomass samples of different origin is performed in a flow of steam or in a mixture of steam and carbon dioxide. Wastes from birch wood, olive stones, bagasse, and pellets from straw and Miscanthus are used as feedstock. The raw materials are heated with 10 degrees C/min to 750 degrees C at atmospheric pressure and kept for a period of 2 h at this temperature, Laboratory experimental equipment with a horizontal rotating stainless steel reactor is used. The oxygen-containing functional groups in the solid products (-COOH, =CO and -OH) are determined using the method of Boehm. The results are compared with those obtained in treatment in inert atmosphere as well as with those obtained in a stationary reactor. The rotating pyrolysis reactor seems suitable for production of energy-rich gaseous products and activated carbons.

  • 211.
    Minkova, V.
    et al.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Razvigorova, M.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Bjornbom, E.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk reaktionsteknik.
    Zanzi, Rolando
    KTH, Tidigare Institutioner, Kemiteknik. KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Budinova, T.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Petrov, N.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Effect of water vapour and biomass nature on the yield and quality of the pyrolysis products from biomass2001Inngår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 70, nr 1, s. 53-61Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Slow pyrolysis/activation of biomass in a flow of steam is studied in laboratory equipment supplied with a fixed bed reactor. Forestry and agricultural residues of different origin are selected as raw materials (birch wood, olive stones, bagasse, pelletised straw and miscanthus). The final pyrolysis temperature is varied in the range 700-800 degreesC and the duration of the activation is 1 or 2 h. The effect of both the nature of the investigated biomass samples and the presence of water vapour on the quality of the pyrolysis products is in the focus of interest of this work. Column chromatography is used to characterize the liquid products. The surface area and the acid-base neutralization capacity of the solid products are determined by the adsorption capacity towards iodine and reactions with EtONa and HCl. The results are compared with those obtained in pyrolysis in inert atmosphere of nitrogen. It is shown that the presence of steam has strong effect on the yield and properties of the products. Significant part of the liquid product is found dissolved in the water phase obtained after condensation of the volatiles. The solid products obtained in the presence of steam have the properties of activated carbons.

  • 212.
    Mitraka, Evangelia
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Conducting Polymer Electrodes for Oxygen Reduction Reaction2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Both the pollution level of the environment and the increasing energy demands have stimulated intense research on the development of low-cost environmentally-friendly energy conversion and storage systems with high efficiency, such as metal-air batteries and fuel cells.

    One of the most essential parts of both fuel cells and metal–air batteries is the air-electrode which is responsible for the reduction of O2. The air-electrode can use O2 from air facilitating the layout of the device; however, the process taking place on it is significantly complex. Currently, platinum (Pt) is the benchmark for air-electrodes in such technologies, although it is expensive and exhibits other important disadvantages which diminish the fuel cell performance. Therefore, extensive research has been devoted to reduce the amount of Pt used in air-electrodes and to develop a noble metal-free version of these electrodes.

    The area of printed electronics could facilitate the development of low-cost electrodes produced in high volume for such applications. Conducting polymers are attractive materials for this technology because they may combine several desired properties, like electronic conduction, ionic conduction and catalysis of electrochemical reactions.

    Among other conducting polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) emerged as an alternative cathode catalyst material to Pt, due to its ability to effectively catalyze the oxygen reduction reaction (ORR), while it also exhibits high electrical and ionic conductivity.

    The focus of this thesis is to study the electrocatalytic activity and mechanism of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) when employed as an airelectrode in energy storage devices, such as fuel cells and metal-air batteries. Although PEDOT is extensively studied during the last decade as an air-electrode for fuel cell and metal-air batteries, vital pieces of the catalytic mechanism that PEDOT follows remain unknown, namely: (i) the sites of PEDOT on which O2 interacts and (ii) the intermediate species which are formed during the ORR. The content of this thesis tackles these topics, both from experimental and theoretical point of view. Moreover, it investigates the use of PEDOT as an active electrocatalyst in a polymer exchange membrane (PEM) fuel cell, by embedding the polymer in a cellulose matrix, aiming to fabricate a gas diffusion electrode for the ORR side of the device. Finally, the goal of the thesis surpasses the limit of the p-doped PEDOT and undertakes the evaluation of a n-type conjugated polymer of high electron affinity as a cathode in reduction processes.  

  • 213.
    Mogensen, Ronnie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    PTMC: A polycarbonate candidate for polymer electrolytes in sodium batteries?: A characterisation of the PTMC–NaFSI system2015Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The poly(trimethylene carbonate)–sodium bis(fluorosulfonyl)imide system has been

    investigated as polymer electrolytes for sodium batteries. The properties of

    poly(trimethylene carbonate) with salt concentrations ranging from 8.7wt% to 67wt%

    have been measured by DSC, FTIR, and EIS. Half-cells based on both high-salt and

    low-salt electrolytes have been tested in order to determine their performance in a

    realistic environment. The tests reveal two distinct regions in salt concentration and

    the best-performing electrolytes show a conductivity of 50 μS/cm at 25 °C and 1mS/

    cm at 100 °C. The report presents cell data from sodium–prussian blue half-cells

    with only 10% capacity fade after 80 cycles at 60 °C and additional tests of high-salt

    cells capable of cycling at reduced temperature with good rate capability.

  • 214.
    Mohsenzadeh, Abas
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Richards, Tobias
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Bolton, Kim
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    DFT study of the water gas shift reaction on Ni (111), Ni (100) and Ni (110) surfaces2016Inngår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 644, s. 53-63Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Density functional theory (DFT) calculations were used to study the water gas shift (WGS) reaction on Ni(111), Ni(100) and Ni(110) surfaces. The adsorption energy for ten species involved in thereaction together with activation barriers and reaction energies for the nine most important elementary steps were determined using the same model and DFT methods. The results reveal that these energies are sensitive to the surface structure. In spite of this, the WGS reaction occurs mainly via the direct (also referred to as redox) pathway with the CO + O → CO2 reaction as the rate determining step on all three surfaces. The activation barrier obtained for this rate limiting step decreases in the order Ni(110) > Ni(111) > Ni(100). Therefore, if O species are present on the surfaces then the WGSreaction is fastest on the Ni(100) surface. However, the barrier for desorption of H2O (which is the source of the O species) is lower than its dissociation reaction on the Ni(111) and Ni(100) surfaces, but not on the Ni(110) surface. Hence, at low H2O(g) pressures, the direct pathway on the Ni(110) surface will dominate and will be the rate limiting step. The calculations also show that the reason that the WGS reaction does not primarily occur via the formate pathway is that this species is a stable intermediate on all surfaces. The reactions studied here support the Brønsted-Evans-Polanyi (BEP) principles with an R2 value of 0.99. © 2015 Elsevier B.V. All rights reserved.

  • 215. Montes, V.
    et al.
    Boutonnet, M.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Järås, Sven
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Lualdi, Matteo
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Marinas, A.
    Marinas, J. M.
    Urbano, F. J.
    Mora, M.
    Preparation and characterization of Pt-modified Co-based catalysts through the microemulsion technique: Preliminary results on the Fischer-Tropsch synthesis2014Inngår i: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 223, s. 66-75Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of the addition of small amounts of platinum (0.1-0.25% wt) to cobalt-based systems on Fischer-Tropsch synthesis was investigated. The solids were synthesized through microemulsion technique using TiO2 as the support. The best catalytic performance was achieved using Synperonic 13/6.5 as the surfactant. In all cases, the presence of platinum led to an increase in CO conversion which could be ascribed to the promotion of cobalt reducibility as evidenced by XPS. Moreover, the simultaneous reduction of cobalt and platinum precursors during synthetic procedure (ME1) was preferable to the consecutive one (ME2) probably as a result of a better Co-Pt interaction in the former case, as evidenced by TPR. TPR, Raman and XPS data also suggested that not only the presence of Co-0 but also the appearance of Co-TiO2 interactions favor the catalytic performance and that in general those interactions are stronger for ME1 solids.

  • 216. Montes, V.
    et al.
    Boutonnet, Magali
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Järås, Sven
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Marinas, A.
    Marinas, J. M.
    Urbano, F. J.
    Selective transformation of glycerol into 1,2-propanediol on several Pt/ZnO solids: Further insight into the role and origin of catalyst acidity2015Inngår i: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 257, s. 246-258Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Microemulsion technique allowed us to synthesize different ZnO solids with similar particle sizes and textural properties. Platinum was subsequently incorporated by deposition-precipitation and impregnation methods and solids tested for glycerol selective transformation into 1,2-PDO. Incorporation of platinum led to the creation of new (mainly Lewis) acid sites. A good correlation between conversion and acidity of Pt/ZnO solids was obtained. Interestingly, despite exhibiting some acidity, supports alone were inactive in the process which evidenced the role of the metal in dehydration of glycerol into acetol. Furthermore, as the reaction proceeded some chlorine coming from the precursor (H2PtCl6) was leached which led to the disappearance of the strongest acid sites, associated to side reactions (catalytic cracking) thus resulting in an increase in selectivity to 1,2-PDO. Eventual formation of Pt-Zn alloy upon reduction of the systems at ca. 400 degrees C was beneficial to 1,2-PDO selectivity.

  • 217. Montes, V.
    et al.
    Checa, M.
    Marinas, A.
    Boutonnet, Magali
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Marinas, J. M.
    Urbano, F. J.
    Järås, Sven
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Pinel, C.
    Synthesis of different ZnO-supported metal systems through microemulsion technique and application to catalytic transformation of glycerol to acetol and 1,2-propanediol2014Inngår i: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 223, s. 129-137Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Different systems consisting of diverse metals (Au, Pt, Pd, Rh) supported on ZnO (5% by weight) were synthesized through the microemulsion technique (ME) and tested for glycerol hydrogenolysis, the main products being hydroxyacetone (acetol) and 1,2-propanediol (1,2-PDO). The solids synthesized using sodium borohydride as the reducing agent (B series) had smaller particle sizes as compared to the use of hydrazine (H series) which, in turn, resulted in a better catalytic performance. This synthetic method allowed us to obtain similar metal particle sizes (2-4 nm) for Pt, Pd and Rh solids in B series, whereas average gold metal particle was higher (> 8 nm) which probably accounts for Au-containing systems being inactive under our experimental conditions. Reactivity order followed the sequence Rh > Pt > Pd. A comparison of the systems synthesized in the present paper through ME technique with those obtained in a previous work through the deposition-precipitation process revealed a higher activity and selectivity to acetol for the former solids which could be related to the presence of surfactant. Moreover, results suggested that metal sites could participate not only in hydrogenation of acetol to 1,2-propanediol but also in the previous dehydration step of glycerol to acetol.

  • 218.
    Moro, Fabrizio
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska fakulteten. Univ Nottingham, England.
    Bhuiyan, Mahabub A.
    Univ Nottingham, England.
    Kudrynskyi, Zakhar R.
    Univ Nottingham, England.
    Puttock, Robert
    Natl Phys Lab, England.
    Kazakova, Olga
    Natl Phys Lab, England.
    Makarovsky, Oleg
    Univ Nottingham, England.
    Fay, Michael W.
    Univ Nottingham, England.
    Parmenter, Christopher
    Univ Nottingham, England.
    Kovalyuk, Zakhar D.
    Natl Acad Sci Ukraine, Ukraine.
    Fielding, Alistar J.
    Sch Pharm and Biomol Sci, England.
    Kern, Michal
    Univ Stuttgart, Germany; Univ Stuttgart, Germany.
    van Slageren, Joris
    Univ Stuttgart, Germany; Univ Stuttgart, Germany.
    Patane, Amalia
    Univ Nottingham, England.
    Room Temperature Uniaxial Magnetic Anisotropy Induced By Fe-Islands in the InSe Semiconductor Van Der Waals Crystal2018Inngår i: ADVANCED SCIENCE, ISSN 2198-3844, Vol. 5, nr 7, artikkel-id 1800257Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The controlled manipulation of the spin and charge of electrons in a semiconductor has the potential to create new routes to digital electronics beyond Moores law, spintronics, and quantum detection and imaging for sensing applications. These technologies require a shift from traditional semiconducting and magnetic nanostructured materials. Here, a new material system is reported, which comprises the InSe semiconductor van der Waals crystal that embeds ferromagnetic Fe-islands. In contrast to many traditional semiconductors, the electronic properties of InSe are largely preserved after the incorporation of Fe. Also, this system exhibits ferromagnetic resonances and a large uniaxial magnetic anisotropy at room temperature, offering opportunities for the development of functional devices that integrate magnetic and semiconducting properties within the same material system.

  • 219.
    Mussa, Abdilbari Shifa
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Klett, Matilda
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Wreland Lindström, Rakel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Effects of external pressure on the performance and ageing of single-layer lithium-ion pouch cells2018Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 385, s. 18-26Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of external compression on the performance and ageing of NMC(1/3)/Graphite single-layer Li-ion pouch cells are investigated using a spring-loaded fixture. The influence of pressure (0.66, 0.99, 1.32, and 1.98 MPa) on impedance is characterized in fresh cells that are subsequently cycled at the given pressure levels. The aged cells are analyzed for capacity fade and impedance rise at the cell and electrode level. The effect of pressure distribution that may occur in large-format cells or in a battery pack is simulated using parallel connected cells. The results show that the kinetic and mass transport resistance increases with pressure in a fresh cell. An optimum pressure around 1.3 MPa is shown to be beneficial to reduce cyclable-lithium loss during cycling. The minor active mass losses observed in the electrodes are independent of the ageing pressure, whereas ageing pressure affects the charge transfer resistance of both NMC and graphite electrodes and the ohmic resistance of the cell. Pressure distribution induces current distribution but the enhanced current throughput at lower pressures cell does not accelerate its ageing. Conclusions from this work can explain some of the discrepancies in non-uniform ageing reported in the literature and indicate coupling between electrochemistry and mechanics.

  • 220.
    Ngo, Carolin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    In Vitro Starch Digestion for Analysis of Healthy Carbohydrates2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The health impact of carbohydrates is often debated in questions regarding nutrition and health. One reason is that intake of carbohydrates affect the blood glucose level to different extent depending on the characteristics of the carbohydrate. Starch is the most common carbohydrate and it can be categorized as rapidly digested starch (RDS), slowly digested starch (SDS) and resistant starch (RS) where the speed parameter refers to how easily enzymes hydrolyze the starch is and thus how fast the blood glucose level is affected.

    However, RS does not affect the blood glucose level but instead becomes substrate for microbial fermentation of the gut microbiota. Long term consumption of resistant starch decreases the risk of intestinal diseases. The aim of this project was therefore to investigate different in vitro methods for determination of RS content in samples. The impact which particle size and extrusion have on the amount of RS were investigated since the factors can increase or decrease the amount of RS.

    Sorghum and cowpea were of interest to analyze since the crops are important nutrient sources in both Africa and Asia. Two methods were investigated for determination of RS content where the method developed by Megazyme International Ireland Ltd. was more stable than the method developed by Goñi et al. Modifications of the Megazyme method were performed in order to obtain more reliable values which was achieved when enzymes from Sigma-Aldrich were used. Samples of sorghum of the particle sizes 125 µm and 250 µm resulted in values ranging between 11.44 – 11.94 g RS/100 g sample and 8.49 – 9.02 g RS/100 g sample after extrusion was performed. Samples of the larger particle size resulted in lower amount of RS, most likely due to starch-protein associations. Cowpea resulted in 11.05 g RS/100 g sample and 9.20 g RS/100 g sample before and after extrusion.

    Determination of the amylose and amylopectin ratio showed that sorghum contained 53.3 – 59.3 % (w/w) amylose and cowpea 53.2 % (w/w) amylose. A ratio favoring amylose also favors the formation of RS. However, the particle size has larger impact on the RS content than the amylose content and sorghum of particle size 125 µm was shown to be the healthiest regarding amount of RS. Cowpea showed the lowest amount of amylose yet the highest amount of RS among the extrudates and the lowest set back value of -0.5 which leads to an assumption towards unstable methods.

    Further development of the methods should be carried out in forms of modifications. Optimization of treatments regarding sorghum of particle size 125 µm should be continued in order to obtain even higher RS content.

  • 221.
    Nielsen, Katrine
    et al.
    Technical University of Denmark, Denmark.
    Mikkelsen, Peter Steen
    Technical University of Denmark, Denmark.
    Baun, Anders
    Technical University of Denmark, Denmark.
    Eriksson, Eva
    Technical University of Denmark, Denmark.
    Sorption of PAHs to humic acid- and iron(III)carbonate particles by using passive dosing vials for investigating the transport of organic contamination in stormwater runoff2013Inngår i: Interdisciplinary Discourse on Current Environmental Challenges, Krakow: SETAC , 2013Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    During the last decades, the growing urbanisation a nd increasing anthropogenic activities in urban areas have turned urban stormwater runoff int o a surface water quality contamination problem. The concerns of urban stormwater runoff as a source of contamination in the receiving surface water (lakes, rivers or sea) have been raised by researchers throughout the world (e.g. Broman et. al., 1987, and Xanthopoulos et. al., 1990), and have in Europe gained increased interest in relation to the implementatio n of the Water Framework Directive (WFD, 2000/60/EC). Particles (often defined as >0.45 μm) has been foun d to facilitate transport of organic contaminants and metals in stormwater runoff system s, but little is known about the role of the colloidal fraction including nano-sized particl es (0.001-1 μm). Based on the large specific surface area of colloids and nanosized particles, t heir abundance, and knowledge about their facilitated transport of persistent organic polluti on in natural waters, they are likely to diminish the efficiency of engineered treatment sys tems unless appropriately accounted for. In this work organic and inorganic nanosized partic les were investigated for their ability to sorb polycyclic aromatic hydrocarbons (PAH’s) in an aqueous solution. These particles were used as indicators for stormwater particles which a re diverse in size and composition. For controlling the sorption onto the particles, passiv e doing vials were used (Birch et. al., 2010). Using passive dosing vials gives the possible to co ntrol freely dissolved analyte by equilibrium partitioning from a preloaded silicone membrane. It has been found that the presence of humic acid particles (80 nm) leads to an increasing amount of two PAHs (fluoranthene and phenanthrene) in the suspension. For iron(III)carbo nate particles (22 nm) sorption experiments are ongoing. Based on these results and a literature review, the importance of including particulate fractions for surface water q uality assessment in relation to the WFD will be discussed.

  • 222.
    Niklasson, Lovisa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Characterization of the gas composition inside NiMH batteries during charge using GC-MS2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The aim of the project was to develop a method to measure and studythe degree of activation of the negative electrode (MH) in a NiMH battery.This was done by characterization of the gases produced during charge of a battery – O2 and H2 – using a Gas Chromatograph. The current applied in the very first charge of the battery was varied in order to examine how this affects the gas evolution. In the developed method, batteries were charged to 8Ah with 9A, after which a gas sample was taken and analyzed with Gas Chromatography. An additional goal was to use the method to examine the difference in activation between virgin and recycled negative electrode material. A module charged stepwise with 0.07C followed by 0.2C had the lowest share of H2 after two cycles, indicated best activation. However, a higher amount of H2 in the beginning of the activation process could possibly enhance the degree of activation during the following cycles. The method indicated that the module with recycled MH was better activated than the virgin MH. To improve the technique, repeated measurements to get better statistics should be done. Gas samples should be taken at dV/dt=0 in order to take samples at same SoC. The charge current should be adjusted so that the same C rate is always used. This would make the results easier to interpret.

  • 223.
    Nilsson, Oskar
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Radiation induced corrosion of steel2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The aim of this thesis was to investigate the influence of aqueous radiation induced oxidants on stainless steel. This was done by exposing the steel to both radiation and chemically added oxidants under ambient conditions, i.e. in and near room temperature. When water is exposed to radiation several oxidizing species are formed, including hydrogen peroxide, which have been known to increase the risk for corrosion of other materials. Stainless steel is used in many parts in a nuclear power plant, and the results from this thesis could be useful when elucidating whether the steel is an appropriate material to use for these applications.

  • 224.
    Nordh, Nicki
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Development of a cell cultureplatform in PDMS: Microfluidic systems for in vitro productionof platelets2015Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    To be able to effectively study blood platelets in different environments adevelopment of an in vitro model of a microfluidic system for plateletproduction was started. The purpose of this thesis was to fabricate systemsand then characterize them and visualize the flow. The system consists of twochannels, one in the middle and the other one enclosing it. They are connectedthrough pores where Megakaryocytes can protrude through and produce platelets.The designs were produced in PDMS. This was done by first transfer the designsas structures onto a silicon wafer through UV lithography. The wafer served asa mould for casting PDMS that later was bonded to glass. The systems were thenstudied with three different methods. Computer simulations, flow tests andultimately tests with cells. From the results new designs were made andfabricated. The new designs were then tested the same ways as the first ones.The systems can most probably produce platelets with some optimisation of thetest parameters. No definite results were gathered to prove plateletproduction. Different flow speeds were tested and the flow profile atdifferent flow rates was visualised. The full capability of the new designscould not be fully studied due to unforeseen debris of PDMS clogging thechannels. A few things need to be done to achieve better results and establishfor sure if this method of producing platelets is possible. This thesis is agood ground for future work to stand on.

  • 225.
    Nordh, Tim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Li4Ti5O12 as an anode material for Li ion batteries in situ XRD and XPS studies2013Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis examines parts of the kinetics and performance in Li-battery cells using lithium titanate anodes and lithium manganese oxide cathodes. Lithium titanate (Li4Ti5O12) is a candidate for battery applications in automotive vehicles due to its long lifetime and its suggested zero-strain ability. The zero-strain ability, meaning no volume changes in the material during cycling, would allow for the high charge/discharge rates required in electric vehicles. Two approaches of analysis have been performed. In situ XRD-analysis was used to verify the zero-strain ability of lithium titanate and XPS studies were used to analyze the surface chemistry of lithium titanate after cycling. It is known that lithium titanate/lithium manganeseoxide battery cells suffer from abnormal gas evolution and power degradation, and it is therefore of interest to find ways to prevent this. To be able to find methods of preventing the performance degradation deeper understanding of the kinetics are needed, since the mechanism behind this is not fully understood. The results in this thesis strengthen the understanding of lithium titanate as a zero-strain material. Furthermore, it is seen that the performance degradation possibly can be avoided or postponed by ALD deposition of aluminium oxide on the surface of the lithium manganese oxide electrode.

  • 226.
    Nordh, Tim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Lithium titanate as anode material in lithium-ion batteries: -A surface study2015Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The ever increasing awareness of the environment and sustainability drives research to find new solutions in every part of society. In the transport sector, this has led to a goal of replacing the internal combustion engine (ICE) with an electrical engine that can be powered by renewable electricity. As a battery for vehicles, the Li-ion chemistries have become dominant due to their superior volumetric and gravimetric energy densities. While promising, electric vehicles require further improvements in terms of capacity and power output before they can truly replace their ICE counterparts. Another aspect is the CO2 emissions over lifetime, since the electric vehicle itself presently outlives its battery, making battery replacement necessary. If the lifetime of the battery could be increased, the life-cycle emissions would be significantly lowered, making the electric vehicle an even more suitable candidate for a sustainable society. In this context, lithium titanium oxide (LTO) has been suggested as a new anode material in heavy electric vehicles applications due to intrinsic properties regarding safety, lifetime and availability. The LTO battery chemistry is, however, not fully understood and fundamental research is necessary for future improvements. The scope of this project is to investigate degradation mechanisms in LTO-based batteries to be able to mitigate these and prolong the device lifetime so that, in the end, a suitable chemistry for large scale applications can be suggested. The work presented in this licentiate thesis is focused on the LTO electrode/electrolyte interface. Photoelectron spectroscopy (PES) was applied to determine whether the usage of LTO would prevent anode-side electrolyte decomposition, as suggested from the intercalation potential being inside the electrochemical stability window of common electrolytes. It has been found that electrolyte decomposition indeed occurs, with mostly hydrocarbons of ethers, carboxylates, and some inorganic lithium fluoride as decomposition products, and that this decomposition to some extent ensued irrespective of electrochemical battery operation activity. Second, an investigation into how crossover of manganese ions from Mn-based cathodes influences this interfacial layer has been conducted. It was found, using a combination of high-energy x-ray photoelectron spectroscopy (HAXPES) and near-edge x-ray absorption fine structure (NEXAFS) that although manganese is present on the LTO anode surface when paired with a common manganese oxide spinel cathode, the manganese does little to alter the surface chemistry of the LTO electrode.

  • 227.
    Nordh, Tim
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Younesi, Reza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Hahlin, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Duarte, Roberto Felix
    Helmholz Zentrum Berlin Mat & Energie GmbH, D-14109 Berlin, Germany.
    Tengstedt, Carl
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. Scania CV AB, S-15187 Sodertalje, Sweden.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Manganese in the SEI layer of Li4Ti5O12 studied using combined NEXAFS and HAXPES techniques2016Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, nr 6, s. 3206-3213Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A combination of hard X-ray photoelectron spectroscopy (HAXPES) and near edge X-ray absorption fine structure (NEXAFS) are here used to investigate the presence and chemical state of crossover manganese deposited on Li-ion battery anodes. The synchrotron based experimental techniques-using HAXPES and NEXAFS analysis on the same sample in one analysis chamber-enabled us to acquire complementary sets of information. The Mn crossover and its influence on the anode interfacial chemistry has been a topic of controversy in the literature. Cells comprising lithium manganese oxide (LiMn2O4, LMO) cathodes and lithium titanate (Li4Ti5O12, LTO) anodes were investigated using LP40 (1 M LiPF6, EC:DEC 1:1) electrolyte. LTO electrodes at lithiated, delithiated, and open circuit voltage (OCV-stored) states were analyzed to investigate the potential dependency of the manganese oxidation state. It was primarily found that a solid surface layer was formed on the LTO electrode and that this layer contains deposited Mn from the cathode. The results revealed that manganese is present in the ionic state, independent of the lithiation of the LTO electrode. The chemical environment of the deposited manganese could not be assigned to simple compounds such as fluorides or oxides, indicating that the state of manganese is in a more complex form.

  • 228.
    Odenbrand, Ingemar
    et al.
    Lund University.
    Brandin, Jan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Deactivation of SCR catalysts used in municipal waste incineration applications2016Inngår i: Proceeding of the 17th Nordic Symposium on Catalysis: Book of Abstracts / [ed] Ingemar Odenbrand, Christian Hulteberg, Lund University , 2016, s. 108-109Konferansepaper (Fagfellevurdert)
  • 229.
    Ohlin, Hanna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Exploratory synthesis and characterisation in the Gd-Au-Si-system: A quest for quasicrystals2017Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The field of crystallography has recently been expanded to include the science of quasicrystals, crystalline structures lacking unit cells and conventional periodicity. This resulted in a paradigm shift in the field, opening up for a whole new branch on the subject of structural chemistry. Despite this, not much is known about the abilities of quasicrystalline and approximant materials. Quasicrystalline approximants in the RE-Au-SM system have previously shown promising results regarding magnetic properties. To explore and discover properties like this is key to further improve the understanding of quasicrystalline materials.

     

    The scope of the project was to explore the Gd-Au-Si system with compositions theoretically calculated to yield possible quasicrystals. In three batches with varying composition ratios, crystals were synthesised, using an arc-melting self-flux method. These were then analysed with powder X-ray diffraction, single crystal X-ray diffraction and electron dispersive spectroscopy (EDS) to characterise the synthesised compounds using diffraction data and composition data respectively.

    The resulting crystals were determined to be of a ternary composition close to what was theoretically calculated. The phase synthesised is yet to be found in any previous work or database, possibly marking it out as a new phase, albeit the structure not being quasicrystalline in nature. Thus, the exploratory study yielded a so for unobserved composition in the Gd-Au-Si system.

  • 230.
    Olsson, Alexander
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    An evaluation of solar powered irrigation as carbon offset projects2016Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Carbon offsets have been developed as one tool to incentivise investments by developed nations in climate change mitigation activities in developing countries. The carbon offsets can be used towards the countries’ own mitigation targets but are also meant to benefit developing countries by providing a pathway to clean development.

    Photovoltaic water pumping (PVWP) technology is a solution to use PV for irrigation, which can be used to restore degraded grasslands and help farmers adapt to climate change. Restoration of degraded grasslands increases the production of grass and will therefore increase the amount of carbon in the soil, a process that may mitigate climate change. However, poor farmers often have limited access to irrigation technology and this thesis assesses how carbon offsets may bring revenues to increase adaption of PVWP technology in remote areas of the Chinese grasslands.

    PV modules can be used to mitigate climate change in different ways; the most common is to produce electricity to replace fossil fuel power capacity. The novelty of this thesis is that it assesses the alternative mitigation possibilities for the PVWP project proposed here. Further, consideration of water constraints that limit the applicability of the technology and a framework to assess the trade-offs between potential downstream water impacts and environmental co-benefits of the project add to the novelty of this thesis. Policy barriers for the project will also be considered.

     Used to restore severely degraded grasslands, PVWP projects show high carbon sequestration potential and successfully compete with grid electricity as carbon offset projects. A case is analysed and it shows that the carbon market could play a role in increasing the feasibility of PVWP projects. However, water issues make project implementation very site-specific and some indicators to determine feasibility is proposed to be blue water availability, evaporation recycling ratio and water productivity. Water use must also be looked at with respect to climate, food and energy security, calling for a nexus approach to evaluate the project suitability. In May 2016, grassland management projects are excluded from the Clean Development Mechanism to the Kyoto Protocol, and this limits project implementation to the voluntary markets.

  • 231.
    Olsson, Johanna
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Pallarés, David
    Johnsson, Filip
    Digital Image Analysis of Bubble Flow Distribution: Influence of operational parameters2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In a first step towards investigating the lateral fuel mixing in fluidized bed (FB) boilers, this work applies digital image analysis to study the bubble flow properties in a 2D FB unit. The work investigates the influence of gas-distributor pressure drop, bed height and fluidization velocity on the volume fraction and lateral distribution of bubbles.

  • 232.
    Olsson, Mirja
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Chemical stability of grain boundariesin β-tricalcium phosphate ceramics: β-TCP as bone substitute material2012Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    β – Tricalcium phosphate (β-TCP, Ca3(PO4)2) is a commonly used bone substitute material due to its biocompatibility and resorption. This study focused on the production of almost fully dense β-TCP ceramics with varying degrees of impurities (Ca/PO4 ratio, addition of 5% Mg). Three methods were used to produce the β-TCP ceramics, uniaxial pressing, slip-casting and isostatic pressing. In this study the isostatic pressing and sintering at 1150ºC for 20h and 15min, resulted in the densest β-TCP ceramics (97.7-99.2%). No significant differences of grain size and density could be detected between the samples produced with various compositions. These isostatically pressed samples sintered at 1150ºC were then dissolved in 0.08M aceticacid solution to simulate the in vivo resorption. It was found that the samples containing extra Mg dissolved slower. Attempts to determine the chemical composition of the grain boundaries were made without success. However, SEM observations of partly dissolved β-TCP ceramics revealed that the grain boundaries dissolved faster than the grains. The study was performed at the RMS foundation in Switzerland.

  • 233. Ordóñez, J. I.
    et al.
    Moreno, Luis
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Gálvez, E. D.
    Cisternas, L. A.
    Seawater leaching of caliche mineral in column experiments2013Inngår i: Hydrometallurgy, ISSN 0304-386X, E-ISSN 1879-1158, Vol. 139, s. 79-87Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Caliche is a mineral that contains a high fraction of soluble minerals and that is exploited in Northern Chile through vat or heap leaching for the production of iodine and nitrate. In this zone, the water availability is scarce, being a critical issue for the mining industries and whereby the use of other leaching agents as seawater may be a viable alternative. For this reason in the present study, column-leaching experiments using seawater were performed, including different irrigation rates and column heights. It is found that the highly soluble minerals such as nitrate and iodate are rapidly leached, while for other minerals like sulphate and chloride, the outlet concentration increased once that part of the sodium has been removed. Crystals of sodium sulphate were found at the column bottom, when this was dismantled. An existing phenomenological model (Gálvez et al., 2012) was used to analyse the changes of concentration of nitrate and iodine (as iodate) with a good agreement between the experiments and the simulations. On the other hand, for sulphate and chloride a new model was developed, which takes into account the dissolution and precipitation phenomena of these ions. The model was able to capture the trends observed in the experiments for the outlet concentrations of the modelled ions.

  • 234.
    Osadolor, Osagie Alex
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Lundin, Magnus
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Lennartsson, Patrik
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Taherzadeh, Mohammad
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Membrane stress analysis of collapsible tanks andbioreactorsInngår i: Biochemical engineering journal, ISSN 1369-703X, E-ISSN 1873-295XArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Collapsible tanks, vessels or bioreactors are finding increasing usage in small/medium scaleprocesses because they offer flexibility and lower cost. However, if they are to be used atlarge scale, they need to be shown capable of handling the physical stress exerted on them.Because of their nonconventional shape and non-uniform pressure distribution, thin shellanalysis cannot be used in calculating their stress. Defining curvature in terms of pressureaddressed these challenges. Using curvature and numerical analysis, the membrane stress incollapsible tanks designed as bioreactors of volumes between 100-1000 m3 were calculated.When the liquid/gas height and static pressure are known, an equation for calculating tensionper length was developed. An equation that could calculate the liquid height from thebioreactor’s volume, dimensions and working capacity was generated. The equation gavevalues of liquid height with a maximum deviation of 3% from that calculated by curvatureanalysis. The stress values from the liquid height and tension equations had a maximumdeviation of 6% from those calculated by curvature analysis. The calculated tensile stress in a1000 m3 collapsible tank was 14.2 MPa. From these calculations, materials that optimize bothcost and safety can be selected when designing collapsible tanks.

  • 235.
    Osong, Sinke Henshaw
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Development of nanofibrillated cellulose/nanographite composites for paper applications2015Inngår i: TAPPI International Conference on Nanotechnology for Renewable Materials 2015, TAPPI Press, 2015, Vol. 1, s. 35-55Konferansepaper (Fagfellevurdert)
  • 236.
    Parsland, Charlotte
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Study of the activity of catalysts for the production of high quality biomass gasification gas: with emphasis on Ni-substituted Ba-hexaaluminates2016Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The fossil hydrocarbons are not inexhaustible, and their use is not without impact in our need of energy, fuels and hydrocarbons as building blocks for organic materials. The quest for renewable, environmentally more friendly technologies are in need and woody biomass is a promising candidate, well provided in the boreal parts of the world. To convert the constituents of wood into valuable gaseous products, suitable for the end use required, we need a reliable gasification technology. But to become an industrial application on full scale there are still a few issues to take into account since the presence of contaminants in the process gas will pose several issues, both technical and operational, for instance by corrosion, fouling and catalyst deactivation. Furthermore the downstream applications may have very stringent needs for syngas cleanliness depending on its use. Therefore, the levels of contaminants must be decreased by gas cleanup to fulfil the requirements of the downstream applications.

    One of the most prominent problems in biomass gasification is the formation of tars – an organic byproduct in the degradation of larger hydrocarbons. So, tar degrading catalysts are needed in order to avoid tar related operational problems such as fouling but also reduced conversion efficiency. Deactivation of catalysts is generally inevitable, but the process may be slowed or even prevented. Catalysts are often very sensitive to poisonous compounds in the process gas, but also to the harsh conditions in the gasifier, risking problems as coke formation and attrition. Alongside with having to be resistant to any physical and chemical damage, the catalyst also needs to have high selectivity and conversion rate, which would result in a more or less tar-free gas. Commercial tar reforming catalysts of today often contain nickel as the active element, but also often display a moderate to rapid deactivation due to the causes mentioned.

  • 237.
    Pascoa Dos Santos, Magaia
    KTH, Skolan för kemivetenskap (CHE).
    Pyrolysis and thermogravimetric analysis of wood and its components2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The present study investigates the thermochemical conversion of spruce wood and its extracted components by thermogravimetric analysis. The extracted components are two pulps, three xylan-lignin samples and one lignin sample; they were produced by the kraft cooking method with different cooking times. The study involves characterization of the biomass through proximate analysis and pyrolysis. A qualitative comparison between the thermal behaviours of the extracted components and wood is also performed. The study showed that the thermal behaviour of the biomass was highly influenced by the content of cellulose and lignin in the samples. Compounds rich in cellulose produced large quantities of volatiles and had a higher rate of pyrolysis compared to compounds rich in lignin, which produced more char and had a slower rate of pyrolysis. It was also shown that, the amount of char is not solely depending on the amount of the lignin; the structure of the compound also plays a role. On the other hand, the original wood sample showed some deviations regarding the trends in volatile and char production and these deviations were attributed to component interactions. Both cellulose and lignin rich compounds had an increase in thermal stability with increasing cooking time. For the pulps the increase in thermal stability is believed to be caused by increase in crystallinity, while for the lignin rich samples is believed to be caused by the increase in lignin content and structural changes in the compounds. The results also show that although changes are introduced in the cooking process, the extracted component still retain properties exhibited by the source biomass.

  • 238.
    Paulraj, Alagar Raj
    et al.
    KTH Royal Inst Technol, Dept Chem Engn, SE-10044 Stockholm, Sweden.
    Kiros, Yohannes
    KTH Royal Inst Technol, Dept Chem Engn, SE-10044 Stockholm, Sweden.
    Göthelid, Mats
    KTH Royal Inst Technol, Mat Phys, SCI, S-16440 Kista, Sweden.
    Johansson, Malin B
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    NiFeOx as a Bifunctional Electrocatalyst for Oxygen Reduction (OR) and Evolution (OE) Reaction in Alkaline Media2018Inngår i: CATALYSTS, ISSN 2073-4344, Vol. 8, nr 8, artikkel-id 328Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article reports the two-step synthesis of NiFeOx nanomaterials and their characterization and bifunctional electrocatalytic activity measurements in alkaline electrolyte for metal-air batteries. The samples were mostly in layered double hydroxide at the initial temperature, but upon heat treatment, they were converted to NiFe2O4 phases. The electrochemical behaviour of the different samples was studied by linear sweep voltammetry and cyclic voltammetry on the glassy carbon electrode. The OER catalyst activity was observed for low mass loadings (0.125 mg cm(-2)), whereas high catalyst loading exhibited the best performance on the ORR side. The sample heat-treated at 250 degrees C delivered the highest bi-functional oxygen evolution and reduction reaction activity (OER/ORR) thanks to its thin-holey nanosheet-like structure with higher nickel oxidation state at 250 degrees C. This work further helps to develop low-cost electrocatalyst development for metal-air batteries.

  • 239.
    Paulraj, Alagar Raj
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Kiros, Yohannes
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Göthelid, Mats
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Material- och nanofysik.
    Johansson, Malin B
    Division of Physical Chemistry, Department of Chemistry, The Ångström Laboratory, Uppsala University, P.O. Box 523, SE-75120 Uppsala, Sweden.
    NiFeOx as a Bifunctional Electrocatalyst for Oxygen Reduction (OR) and Evolution (OE) Reaction in Alkaline Media2018Inngår i: catalyst, Vol. 8, nr 8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article reports the two-step synthesis of NiFeOx nanomaterials and their characterization and bifunctional electrocatalytic activity measurements in alkaline electrolyte for metal-air batteries. The samples were mostly in layered double hydroxide at the initial temperature, but upon heat treatment, they were converted to NiFe2O4 phases. The electrochemical behaviour of the different samples was studied by linear sweep voltammetry and cyclic voltammetry on the glassy carbon electrode. The OER catalyst activity was observed for low mass loadings (0.125 mg cm−2), whereas high catalyst loading exhibited the best performance on the ORR side. The sample heat-treated at 250 °C delivered the highest bi-functional oxygen evolution and reduction reaction activity (OER/ORR) thanks to its thin-holey nanosheet-like structure with higher nickel oxidation state at 250 °C. This work further helps to develop low-cost electrocatalyst development for metal-air batteries

  • 240.
    Pendergraph, Samuel A.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Klein, Gregor
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Johansson, Mats K. G.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Carlmark, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Mild and rapid surface initiated ring-opening polymerisation of trimethylene carbonate from cellulose2014Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, nr 40, s. 20737-20743Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Surface initiated ring-opening polymerisation (SI-ROP) of trimethylene carbonate (1,3-dioxane-2-one, TMC) from cellulose surfaces has been studied for the first time. Specifically, organocatalytic systems employing 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) were implemented in the ROP of TMC, initiated by the hydroxyl groups on the cellulose chain, to form polymer grafts on the surface of filter papers. A sacrificial initiator was added to the reaction solution, resulting in the formation of free, unbound polymer formed in parallel to the surface grafting. The properties of the polymer grafted paper were studied utilising infrared spectroscopy, thermal gravimetric analysis, scanning electron microscopy and contact angle measurements. The free polymers were characterised with nuclear magnetic resonance spectroscopy and size exclusion chromatography. The grafting resulted in hydrophobic papers in as little as one minute and the ability to control the grafting length of the polymer from the surface was demonstrated by either altering the time of the polymerisation or the ratio of free initiator to monomer. This polymerisation route provides milder conditions than conventional metal-catalysed ROP, greatly reduces reaction times and thus is an attractive method for modification of natural biopolymers compared to previously described methods.

  • 241.
    Persson, Erik
    et al.
    Holmen Paper Development Center.
    Engstrand, Per
    Holmen Paper Development Center.
    Karlsson, Lennart
    Holmen Paper AB.
    Fredrik, Nilsson
    Holmen Paper AB.
    Wahlgren, Mikael
    Holmen Paper AB.
    Utilization of the natural variation in wood properties–a comparison between pilot plant and mill scale trials2003Inngår i: Proceedings of International Mechanical Pulping Conference, Quebec City, 2003, s. 83-90Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Four different pulpwood classes of Norway spruce (Picea abies (L.) Karst). were tested in mill scale production of TMP at Hallsta Papermill. The objectives of the trial were to evaluate both rather extreme and more traditional roundwood classes in a full-scale TMP-plant with respect to pulp properties and energy requirements. The experiment was partly based on the results from the proceeding pilot plant trial within the EuroFiber project. The results generally confirmed the findings in the pilot plant trial. Young wood with a high proportion of juvenile wood gave a pulp with attractive optical properties, but somewhat lower tear index and higher energy consumption. The other extreme, sawmill chips from old trees of heavy dimensions, required lower energy input and gave higher tear index, but inferior optical properties. The two more traditional classes gave pulps with properties between the two extremes.

  • 242.
    Persson, Linda
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för analytisk farmaceutisk kemi.
    Bioremediation optimization of diclofenac using Trametes versicolor with emphasis on analytical pharmaceutical chemistry2016Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Diclofenac has been reported to give adverse effects to water-living organisms at

    environmentally relevant concentrations and the removal rate of this substance in

    sewage treatment plants is poor, and therefor other techniques needs to be

    examined. The purpose of this study was to evaluate the ability of the white rot

    fungus Trametes versicolor to degrade diclofenac. An enzymatic assay was developed,

    where the activity of laccase was monitored. The concentration of diclofenac in

    E-flask and bioreactor experiments was measured using UHPLC-Q-Tof with a C18

    column. Three controls were used to fully investigate the observed diclofenac

    concentration decrease. Fungal mycelia were grown in nutrient solution and

    immobilized on polyurethane carriers. The initial concentration of diclofenac was 10

    mg/L and samples were taken at determined intervals during one week. The results

    showed a fast decrease in diclofenac concentration, and a clear difference could be

    seen between the active culture and the controls in the E-flask experiments. The

    E-flask experiments also had a high enzymatic activity throughout the week, while the

    enzymatic activity exponentially decreased in the bioreactor experiment. The

    enzymatic activity decrease corresponded well with the diclofenac concentration in

    the bioreactor, which was lower than the controls within the first four hours, and

    thereafter increased to the same level as the controls. Four degradation products of

    diclofenac were found in the E-flask experiments and the fungi was also capable to

    degrade other aromatic substances that originated from the carrier material.

  • 243.
    PHOUNGLAMCHEIK, Aekjuthon
    KTH, Skolan för kemivetenskap (CHE).
    Modellering av pyrolys i roterande trumma2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This project focuses on the numerical modeling of a rotary kiln pyrolyzer such as found in the e.g. WoodRoll multistage gasification process. The model consists of two parts: a granular flow model, and a pyrolyzer model. In the first part, Saeman's equation was employed to develop a model which can describe the behavior of solid granular flow in a rotary kiln without reaction. Residence-time distribution (RTD) is the main aim to study in this part, which was simulated by axial dispersion model (ADM). The model requires only one fitting parameter that is dispersion coefficient (Dax), which was studied in parallel by two cases: constant value of Dax, and Dax as a function of kiln's length. The result of both models show good predictable in comparison to experimental data from literature, and represent narrow distribution of residence times that behave similar to plug flow reactor. Unfortunately, the result still cannot claim which model of Dax is the best model to describe RTD in rotary drum. The second part of the thesis purpose to design the model of rotary kiln pyrolyzer, which contains specific behavior of granular flow, heat transport in a kiln, and primary pyrolysis of wood. The model of steady-state condition with constant wall temperature was simulated to generate temperature profile and conversion along a kiln. This model included all heat transport features such as conduction, convection, and radiation. According to the result, supplied energy from outer surface of the kiln essentially transfer through the kiln via heat conduction, which occur between solid bed and rotating surface of the kiln. Temperature profile that generated by this model looks reasonable to the process of rotary kiln pyrolyzer, which affected by heating system and heat of reaction along the kiln. The result also demonstrated that conversion of wood is strongly dependent of wall temperature or heating rate of the system. Nonetheless, kinetics data for wood pyrolysis still a debatable issue in many research, and this model required validation by experiment of rotary kiln pyrolyzer.

     

  • 244.
    Pourrahimi, Amir Massoud
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Göteborg, 41296, Sweden.
    Andersson, Richard L.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Tjus, Kåre
    Ström, Valter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Björk, A.
    Olsson, Richard T.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Making an ultralow platinum content bimetallic catalyst on carbon fibres for electro-oxidation of ammonia in wastewater2019Inngår i: Sustainable Energy and Fuels, ISSN 2398-4902, Vol. 3, nr 8, s. 2111-2124Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electrocatalysis of wastewater containing ammonia is a promising alternative to chemical and biological water purification for several reasons, one being that energy-rich hydrogen gas is generated as a by-product while the reaction can be strictly controlled to meet demands. An objective has been to reduce the loading of expensive platinum (Pt) in the catalyst electrodes, and to reduce the poisoning of the metal surface during the electrolysis. Herein, the co-deposition of a copper-platinum (Cu-Pt) bimetallic alloy onto carbon filaments, stripped from their polymeric coating, is shown to give an electrocatalytic performance superior to that of pure Pt at a content of less than 3 wt% Pt. The key to the enhanced performance was to take advantage of micrometer-sized carbon filaments to distribute a very large bimetallic alloy surface uniformly over the filaments. The Cu-Pt-alloy-coated filaments also suffer less electrode poisoning than pure Pt, and are bonded more strongly to the carbon fibre due to better mechanical interlocking between the bimetallic alloy and the carbon filaments. High-resolution electron microscopy studies combined with a tuned electro-deposition process made it possible to tailor the catalyst micro/nano morphology to reach a uniform coverage, surrounding the entire carbon filaments. The results are promising steps towards large-scale wastewater treatment, combined with clean energy production from regenerated hydrogen.

  • 245. Qin, Danfeng
    et al.
    Xu, Ruiyu
    Shen, Hangjia
    Mamat, Xamxikamar
    Wang, Le
    Gao, Shanshuang
    Wang, Ying
    Yalikun, Nuerbiya
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Zhang, Shiguo
    Yuan, Qunhui
    Li, Yongtao
    Hu, Guangzhi
    Protic salt-based nitrogen-doped mesoporous carbon for simultaneous electrochemical detection of Cd(II) and Pb(II)2017Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, nr 59, s. 36929-36934Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nitrogen-doped mesoporous carbon (NMC) derived from a single small-molecule protic salt (p-phenylenediamine bisulfate) is used for sensing toxic heavy metal ions. Using Nafion, bismuth and NMC to anchor the glassy carbon electrode surface, the fabricate electrode shows high sensitivity for detecting Cd(II) and Pb(II). The limits of detection (S/N = 3) are estimated to be 0.3 mu g L-1 for Cd(II) and 0.4 mu g L-1 for Pb(II), respectively, which are 10 and 25 times lower than the maximum acceptable content for drinking water recommended by the WHO. Furthermore, the sensor is successfully used to analyze Cd(II) and Pb(II) in tap-water with high anti-interference capability and good recovery.

  • 246.
    Qiu, Zhen
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Tai, Cheuk-Wai
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    Niklasson, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Direct observation of active catalyst surface phases and the effect of dynamic self-optimization in NiFe-layered double hydroxides for alkaline water splitting2019Inngår i: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 12, nr 2, s. 572-581Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Earth-abundant transition metal-based compounds are of high interest as catalysts for sustainable hydrogen fuel generation. The realization of effective electrolysis of water, however, is still limited by the requirement of a high sustainable driving potential above thermodynamic requirements. Here, we report dynamically self-optimized (DSO) NiFe layered double hydroxide (LDH) nanosheets with promising bi-functional performance. Compared with pristine NiFe LDH, DSO NiFe LDH exhibits much lower overpotential for the hydrogen evolution reaction (HER), even outperforming platinum. Under 1 M KOH aqueous electrolyte, the bi-functional DSO catalysts show an overpotential of 184 and -59 mV without iR compensation for oxygen evolution reaction (OER) and HER at 10 mA cm(-2). The material system operates at 1.48 V and 1.29 V to reach 10 and 1 mA cm(-2) in two-electrode measurements, corresponding to 83% and 95% electricity-to-fuel conversion efficiency with respect to the lower heating value of hydrogen. The material is seen to dynamically reform the active phase of the surface layer during HER and OER, where the pristine and activated catalysts are analyzed with ex situ XPS, SAED and EELS as well as with in situ Raman spectro-electrochemistry. The results show transformation into different active interfacial species during OER and HER, revealing a synergistic interplay between iron and nickel in facilitating water electrolysis.

  • 247.
    Ragnarsson, Micael
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Engström, Gunnar
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Järnström, Lars
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Effects of the Partial Replacement of SB latex with Dextrin Starch on the Thickness Distribution of Coating Layers2008Inngår i: Tappi 2008 Advanced Coatings Fundementals Symposium Proceedings, Atlanta: Tappi press , 2008, s. 154-163Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A pilot coating trial has been carried out where the synthetic binder in the coating colour was partially replaced with dextrin starch. The coating thickness and the coating thickness distribution were investigated by means of burnout tests and mercury porosity measurements. The coating thickness distribution is governed by the surface profile of the base paper underneath the blade; this surface profile is controlled by the compressibility of the base paper and the blade pressure. Dewatering of the coating colours plasticises the paper and increases its compressibility; a linear relationship between dewatering and the standard deviation in the coating thickness was found for a given blade pressure. The characterization of the coating layers showed a small but measurable increase in the thickness variation for increasing starch content, which was caused by the higher water retention of the starch colours. The surface profile of the uncoated and coated paper was investigated with an optical profilometer. The data from those measurements and the coating thickness distribution investigation were used analytically to calculate the roughness change of the base paper during coating. The roughness change was found to be inversely proportional to the original base paper roughness, indicating that the rougher base paper was more compressible.

  • 248.
    Ramos, Boris
    KTH, Skolan för kemivetenskap (CHE).
    Production of biodiesel from vegetable oils2012Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The production of biodiesel using vegetables oils is studied.

    Palm oil and its use for production of biodiesel have been focused. Palm tree is very productive and one of the most profitable for biodiesel production. Among the oilseed crops palm tree produce more oil per hectare. Palm oil has a good availability and a competitive price. The production of palm oil at the industrial plantation level has caused environmental damage. The Roundtable on Sustainable Palm Oil has established principles and criteria in order to certify a sustainable cultivation of the palm oil.

    The experimental work involves the production of biodiesel using corn oil. Ethanol and methanol are used as alcohols. Sodium and potassium hydroxides are selected as catalyst.

    The ratio alcohol to oil is the most important parameter in the production of biodiesel.  An excess of alcohol is required to drive the reaction to the right.  In the experiments with ethanol the yield of biodiesel increased with the ratio ethanol/oil achieving the highest yield at a molar ratio ethanol/oil: 7.78. In the experiments with methanol, using 0.9 g NaOH and 1 hour reaction time the highest yield was obtained with  a molar ratio methanol:oil = 9. Using KOH as catalyst and 2 hour reaction time a very good yield is already obtained with a molar ratio methanol:oil = 4.5

    The amount of catalyst is another studied parameter. In the experiments with ethanol, the amount of 0.8 mg NaOH and 1.2 mg KOH for 200 ml corn oil (0.22 mol) is enough in order to obtain a good yield. An increase of the amount of catalyst does not produce an increase of the yield of biodiesel. In experiments with methanol, using the lowest tested amount catalyst (0.85 g KOH and 0.23 g NaOH) a good yield of biodiesel is obtained.

    The effects of the reaction time, rate of mixing and the reaction temperature were studied in the experiments with methanol. The yield of biodiesel increased when the reaction time is increased from 1 to 2 hours. The yield of produced biodiesel increased from 90% to 94% when the rate of mixing was increased from 500 to 1500 rpm. Often the transesterification is carried out at a temperature near the boiling point of alcohol. The highest yield was obtained at 60 oC with KOH and at 55 oC using NaOH but already at 40 oC a good yield was obtained (89%).

  • 249.
    Rashtchi, Hamed
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Acevedo Gomez, Yasna
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Raeissi, Keyvan
    Shamanian, Morteza
    Eriksson, Björn
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Zhiani, Mohammad
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Wreland Lindström, Rakel
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Performance of a PEM fuel cell using electroplated Ni–Mo and Ni–Mo–P stainless steel bipolar plates2017Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, nr 13, s. F1427-F1436Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The performance and durability of 316L stainless steel bipolar plates (BPP) electroplated with Ni–Mo and Ni–Mo–P coatings are investigated in a proton exchange membrane fuel cell (PEMFC), using a commercial Pt/C Nafion membrane electrode assembly (MEA). The effect of the BPP coatings on the electrochemical performance up to 115 h is evaluated from polarization curves, cyclic voltammetry and electrochemical impedance spectroscopy together with interfacial contact resistance (ICR) measurements between the coatings and the gas diffusion layer. The results show that all the coatings decrease the ICR in comparison to that of uncoated 316L BPP. The Ni-Mo coated BPP shows a low and stable ICR and the smallest effects on MEA performance, including catalyst activity/usability, cathode double layer capacitance, and membrane and ionomer resistance build up with time. After electrochemical evaluation, the BPPs as well as the water effluents from the cell are examined by Scanning Electron Microscopy, Energy Dispersive and Inductively Coupled Plasma spectroscopies. No significant degradation of the coated surface or enhancement in metal release is observed. However, phosphorus addition to the coating does not show to improve its properties, as deterioration of the MEA and consequently fuel cell performance losses is observed.

  • 250.
    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.
    Boutonnet, Magali
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Järås, Sven
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Hydroconversion of n-hexadecane on Pt/silica-alumina catalysts: Effect of metal loading and support acidity on bifunctional and hydrogenolytic activity2014Inngår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 469, s. 328-339Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bifunctional catalysts based on platinum and amorphous silica-alumina were studied in the hydroconversion of n-hexadecane. The influence of platinum loading and support acidity on activity and selectivity were assessed. The contribution of hydrogenolysis reactions on top of bifunctional hydrocracking was shown to depend not only on metal loading, but also on the effect of support acidity on the intrinsic activity of the platinum sites. The yield of cracking products, and their linear alkane fraction, increased with metal loading, while the isomerization yield was practically independent of the metal content. On a support of high Bronsted acidity, the rate of formation of methane was proportional to the platinum surface area, indicating that dernethylation occurred by metal-cataly ed hydrogenolysis. On the other hand, the methane site-time yield was one order of magnitude lower on a catalyst with negligible Bronsted acidity. Pt-catalyzed hydrogenolysis was also investigated during selective poisoning of acid sites by cofeeding pyridine and comparing the effect of hydrogen partial pressure on reaction rates. In the presence of pyridine, total hydroconversion activity was reduced by one order of magnitude while rates to methane and linear cracking products remained relatively high. These observations indicate that acid sites do not intervene in the mechanism, but that support acidity affects the hydrogenolytic activity of platinum sites.

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