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  • 1.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Group of Forest Products2018Conference paper (Other academic)
  • 2.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Utilisation of renewable biomass and waste materials in furniture and construction composites2018Conference paper (Other academic)
  • 3.
    Ahlgren, Maria
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Remediation of diclofenac in a non-sterile bioreactor using the white rot fungus Trametes versicolor2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    From an environmental perspective, it is interesting to assess new methods for efficient removal of drugs from wastewater. The purpose of this project was to assess the possibility of using the white rot fungus Trametes versicolor  to degrade diclofenac in a lab scale bioreactor. Two methods for quantitative analysis of diclofenac were developed, using GC-MS and UHPLC-Q-TOF (C18-column). Both methods were partly validated, with regard to sensitivity, linearity, accuracy and precision, which highlighted the superiority of UHPLC-Q-TOF over GC-MS. Two HILIC columns were also assessed, but proved unsuitable for quantitative analysis of diclofenac under the used conditions. The fungal mycelia were immobilized on plastic carriers in a nutrient solution. In initial E-flask experiments, 10 mg/L diclofenac was added to an active culture and a heat-killed control of T. versicolor . Samples were analyzed, and the results from the active culture indicated a 98% removal of diclofenac after 48 hours. The lab scale bioreactor was used in a semi-continuous mode with the influent containing 10 mg/L diclofenac. Samples were collected from the effluent to monitor the concentration over 7 days. The results showed a decline in concentration to a stable level of approximately 2 mg/L. The initial experiments showed that most of the removal (85%) was due to sorption of diclofenac, but a clear difference was seen between the active and heat-killed culture. It was impossible to conclude from the bioreactor experiment if the observed removal was due to sorption or to a combination of sorption and enzymatic remediation.

  • 4.
    Ahlström, Peter
    et al.
    University of Borås, School of Engineering.
    Aim, Karel
    Dohrn, Ralf
    Elliott, J Richard
    Jackson, George
    Jaubert, Jean Noël
    Rebello de A. Macedo, Maria Eugénia
    Pokki, Juha-Pekka
    Reczey, Kati
    Victorov, Alexey
    Fele Zilnik, Ljudmila
    Economou, Ioannis
    A Survey of the Role of Thermodynamics and Transport Properties in ChE University Education in Europe and the USA2010In: Chemical Engineering Education, ISSN 0009-2479, Vol. 44, no 1, p. 35-43Article in journal (Refereed)
    Abstract [en]

    Thermodynamics and Transport Properties (TTP) is a central subject in the majority of chemical engineering curricula worldwide and it is thus of interest to know how it is taught today in various countries if chemical engineering education is to be improved. A survey of graduate thermodynamics education in the USA was performed a few years ago by Visco et al. [1] but as far as we know no systematic study of the undergraduate thermodynamics education has been performed, at least in recent years. In the present study, a survey about TTP education in Europe and the USA is presented. Results were obtained from nearly twenty different European countries and the USA and in total answers from about 150 universities were used for this study. The study is performed under the auspices of the Working Party of Thermodynamics and Transport Properties of the European Federation of Chemical Engineering. The survey was performed using a web based surveying system for which invitations were sent out to the universities by local representatives who were responsible for one or more countries each. Of the universities that answered more than 70 % offer BSc education 65 % offer MSc education and 55 % offer PhD education. Most universities offer at least two courses of thermodynamics. The following discussion is mainly based on the first two (undergraduate) courses reported. Half of these are taught to chemical engineers exclusively whereas the rest are taught with other branches of engineering, mainly mechanical and / or process engineering. In general two sets of course lengths were observed, corresponding either to a full semester of full time studies or to quarter of a semester. Most courses are centered around lectures and exercise classes with little or no laboratory work whereas home assignments are given in the vast majority (70-80 %) of the courses. The first course is mainly centered around the first and second law of thermodynamics whereas the second course is frequently more concentrated on phase equilibria. Both of these courses are mainly comprising of classical thermodynamics whereas the molecular interpretation often is touched upon. An analysis of the differences between thermodynamics education in Europe and the USA in presently being undertaken and results from this will also be presented. An investigation of the use of thermodynamics within industry is also on-going within the Working Party and results will be reported in the near future. [1] S.K.Dube, D.P. Visco, Chem. Eng. Ed., 2005, 258-263.

  • 5.
    Ahlström, Peter
    et al.
    University of Borås, School of Engineering.
    Moodley, Suren
    University of Borås, School of Engineering.
    Bolton, Kim
    University of Borås, School of Engineering.
    Ramjugernath, D.
    University of Borås, School of Engineering.
    Computer Simulations of Vapor-Liquid-Liquid Equilibria Involving Hydrocarbons and Water2008In: Proceedings of the 100th Annual Meeting of the American Institute for Chemical Engineering, 2008, CHPC National Meeting, Durban, South Africa, December 9-10, 2008, AlChe Annual Meeting, Philadelphia, November 15-21, 2008, 2008Conference paper (Other academic)
  • 6.
    Akhand, Victoria
    KTH, School of Chemical Science and Engineering (CHE).
    Mass Balance Model of Impurities for the WoodRoll Process2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The depletion time for fossil fuels calculated from 2009 is 35 years for oil, 37 years for gas

    and 107 years for coal. Hence, it has become essential to reduce the dependence on fossil

    fuels by switching over to renewable resources. This in turn will also help in combating the

    negative effects on the environment like global warming. Thermochemical processes such as

    pyrolysis and gasification of biomass are considered the most efficient technology for

    converting biomass to useful energy carriers. Cortus Energy AB is a Swedish company that

    has developed a patented gasification technology called WoodRoll

    ® for gasification of fuels derived from biomass. However, ash in a thermochemical conversion process can cause

    corrosion, sintering, slag and poisoning of catalysts, which leads to operational problems. In

    addition, heavy metals such as Zn, Pb and Cd are environmentally problematic. These metals

    contribute to environmental pollution by contaminating the soil, which in turn can harm

    humans and the ecosystem via the food chain. The undesired elements should therefore be

    identified to minimize their impact on the overall thermochemical process and to reduce the

    emission of these harmful substances.

    The objective of this master thesis project, on behalf of Cortus Energy AB, was to investigate

    possible key numbers that can be used to describe and predict how the ash behaves in their

    patented WoodRoll® process. The key numbers that have been identified are empirically

    developed based on experience of coal combustion. These key numbers are regularly used for

    fuel derived from biomass by companies specializing in analyzing, although knowledge about

    whether they can actually be used on biomass is limited. In order to ensure that the use of

    these for biomass is correct, they must be experimentally verified in the future. In addition, a

    theoretical investigation is conducted to study which species can form and in what phase this

    occurs. The investigation reveals that there are no clear trends for how the inorganic elements

    behave since contradicting results from different studies have been reported. Formation of

    species and their phase depends on several parameters such as temperature, heating rate,

    particle size, volatility, quantity and interaction between the elements in the biomass. The

    thesis project ends with a mass balance model on selected inorganic elements for wood

    residues, as well as for bark. The model could be a tool for Cortus Energy AB to identify

    approximately how much of each element is present in each stream in the WoodRoll® process.

    The models are verified with analysis results. Inorganic elements that affect the

    overall process and its equipment have been selected for modelling. The volume percent of

    H2, CO, CO2 and CH4 in the models agree well with the values obtained by Cortus Energy

    AB. This shows that the thermodynamic equilibrium calculations performed are reasonable.

  • 7. Aldea, Steliana
    et al.
    Snåre, Mathias
    Eränen, Kari
    Grenman, Henrik
    Rautio, Anne-Riika
    Kordás, Krisztian
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, 20500 Åbo-Turku, Finland.
    Salmi, Tapio
    Murzin, Dmitry Y.
    Crystallization of Nano-Calcium Carbonate: The Influence of Process Parameters2016In: Chemie Ingenieur Technik, ISSN 0009-286X, E-ISSN 1522-2640, Vol. 88, no 11, p. 1609-1616Article in journal (Refereed)
    Abstract [en]

    Precipitated calcium carbonate was synthesized by carbonation of calcium hydroxide in the presence and absence of ultrasound (conventional stirring) at atmospheric as well as at elevated pressures and different initial concentrations of Ca(OH)2. Spherical morphology of the formed calcite was favored at high Ca(OH)2 concentrations and low CO2 pressures. The presence of ultrasound did not show any influence on the reaction rate in case of efficient mixing. A small increase of the reaction rate was observed at lower CO2 pressures. Elevated pressures in combination with ultrasound did not lead to notable changes of reaction rate or particle morphology.

  • 8.
    Ali Soomro, Razium
    et al.
    University of Bristol, England; University of Sindh, Pakistan.
    Richard Hallam, Keith
    University of Bristol, England.
    Hussain Ibupoto, Zafar
    University of Sindh, Pakistan.
    Tahira, Aneela
    University of Sindh, Pakistan.
    Jawaid, Sana
    University of Sindh, Pakistan.
    Tufail Hussain Sherazi, Syed
    University of Sindh, Pakistan.
    Sirajjuddin,
    Univ Sindh, Natl Ctr Excellence Analyt Chem, Jamshoro 76080, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    A highly selective and sensitive electrochemical determination of melamine based on succinic acid functionalized copper oxide nanostructures2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 127, p. 105090-105097Article in journal (Refereed)
    Abstract [en]

    This study presents the development of a highly selective and sensitive electrochemical sensor for the determination of melamine from aqueous environments. The sensor system is based on functionalised marigold-like CuO nanostructures fabricated using a controlled hydrothermal process, where the utilised succinic acid is considered to play a dual role as a functionalising and growth controlling agent (modifier). The fabricated nanostructures exhibit sharp and well-ordered structural features with dimensions (thickness) in the range of 10-50 nm. The sensor system exhibits strong linearity within the concentration range of 0.1 x 10(-9) to 5.6 x 10(-9) M and demonstrates an excellent limit of detection up to 0.1 x 10(-10) M. The extreme selectivity and sensing capability of the developed sensor is attributed to the synergy of selective interaction between succinic acid and melamine moieties, and the high surface area of marigold-like CuO nanostructures. In addition to this, the developed sensor was also utilised for the determination of melamine from real milk samples collected from different regions of Hyderabad, Pakistan. The obtained excellent recoveries proved the feasibility of the sensor for real life applications. The sensor system offers an operative measure for detecting extremely low melamine content with high selectivity in food contents.

  • 9.
    Andersson Krohn, Robert
    KTH, School of Chemical Science and Engineering (CHE).
    Biomethane via Woodroll® - Investigation of Revenues & Profitability Analysis2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Woodroll® is a gasification technology developed by Cortus that produces synthetic gas (syngas) from biomass. Syngas can be used in several different applications. One interesting option is to convert it further into biomethane, which can be used as automotive fuel or replace natural gas in gas grids. The revenues and profitability of biomethane production is heavily dependent on policy instruments and support schemes. These subsidies can be either direct, where the producer receives a feed-in tariff for biomethane production, or indirect, where consumption rather than production is stimulated.

    This work has investigated which revenues that can be expected from biomethane production via Woodrooll® in Sweden, the Netherlands, Germany, the UK, France and Italy, both in terms of amounts and risks. A profitability analysis have also been carried out to preliminary compare the returns in the different countries, where two different scenarios for different revenues have been analyzed for two different feedstock prices.

    The results showed that the Netherlands and Italy provides the potentially highest revenues. However, there are uncertainty factors associated with all cases. Sweden and Germany offers indirect support and negative market trends. The Netherlands and the UK are the only options that provide a feed-in tariff for biomethane production via gasification. In the Netherlands the tariff can be secured before making investment decision but is only disbursed for 12 years. The UK offers a fixed feed-in tariff for 20 years but the tariff is secured first after plant start-up and the tariff may be reduced on a quarterly basis. In fact, the tariff has been reduced with 40 % over the last 24 months, but there are discussions on introducing a separate tariff for gasification. Italy has the support schemes that potentially offer the highest revenues, but gasification is currently not eligible for support. The latter also holds for France, which may be an interesting case in the future.

    If risk is to be minimized, Cortus may either focus on the Netherlands or await the discussions in the UK and France on introducing a gasification tariff. The work on standardization of biomethane use should also be followed since Italy offers the potentially highest return of the investigated countries. It is also recommended to look further for other cases. The best-case scenario for the risk averse is the one that provides a fixed tariff for 20 years and in which the tariff can be secured before an investment decision is taken.

  • 10.
    Andersson, Rassmus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Silicon-based graphite electrodes for Li-ion batteries2018Independent thesis Basic level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The cycling performance of silicon containing graphite electrodes as the anode in lithium-ion batteries has been investigated. Different electrode compositions of silicon, graphite, carbon black, sodium carboxymethylcellulose (CMC-Na), styrene–butadiene rubber (SBR) and using water as the solvent have been prepared and evaluated electrochemically by constant-current-constant-voltage (CCCV) cycling. To understand the impact on the cycling performance of the electrodes, the process parameters in the coating process have been evaluated by rheological measurements of the electrode slurries.

    The highest and most stable capacity was found for the electrode containing 5 wt% silicon (vs. graphite), 3 wt% binder, equal amount of the binders CMC-Na and SBR and 70 wt% solvent in the initial electrode slurry. It showed a stable capacity retention of 360 mAh/g after 315 cycles, before it faded. It was found that the CMC-Na and the solvent have a strong impact on the properties of the electrode slurry and the processing parameters. CMC-Na, the solvent and SBR were also found to be important for the adhesion of the electrode coating on the current collector. The worst cycling performance was obtained for electrodes containing 15 wt% silicon, a solvent amount below 65 wt% and a binder ratio of CMC-Na:SBR below 1:1. Different rheological behaviour for different silicon particles was found to depend on the surface area of the particles.

    The full text will be freely available from 2020-06-01 08:00
  • 11.
    Andersson, Sven
    et al.
    SP.
    Bäfver, Linda
    SP.
    Davidsson, Kent
    SP.
    Pettersson, Jens
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Schmidt, Hans
    SP.
    Strand, Michael
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Yngvesson, Johan
    SP.
    Skrubberintegrerat vått elfilter, WESP2012Report (Other academic)
  • 12.
    Ascue Avalos, Katia
    KTH, School of Chemical Science and Engineering (CHE).
    Avfallshanteringens miljöpåverkan - Fem avfallstypers koldioxidutsläpp i SÖRABs återvinningsprocess2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The climate change is one of the biggest environmental problems we face today and is due to the increased greenhouse effect caused by mainly carbon dioxide.  SÖRAB is a waste management company in Sweden who has been getting questions from its customers about the amount of carbon dioxide that is emitted when different types of waste is recycled through their process. This thesis answers this question for five different waste types: gypsum, plastic, textile, concrete and tires. In addition to the emissions from the recycling process in SÖRAB the emissions from another alternative process for each waste is estimated. The alternative process will be either incineration or landfill. With the help of both the alternative process and SÖRABs process an environmental benefit is calculated where a positive environmental benefit means that a saving of carbon dioxide emissions has been made by not sending the waste to incineration or landfill.

     

    The carbon emission from the following parts of the process is included:

    • Transportation of the waste (includes transport by truck and ferry)

      • Transportation within SÖRABs different facilities

      • Transportation from SÖRABs facilities external recycling companies.

    • The energy consumption from ”waste crusher” machine in SÖRAB

    • Fuel consumption from the machines in SÖRAB

    •  The carbon dioxide emissions from the external companies where the waste is recycled. This also includes the transportation in the case a part of the waste is further transported to be incinerated and the emission from the incineration itself.

     

    The results showed that the carbon dioxide emissions for each waste differed very much. The differences were due to each waste recycling process in SÖRAB, which differed in the transported weights, transport lengths, and emission levels in the external company. For plastics, textiles and tires, it was the transportation to the external companies which was the factor that contributed the most to the total carbon dioxide emission. For gypsum and concrete it was the emissions in the external companies that contributed the most, which is due to transport length being shorter for their recycling processes.

     

    The environmental benefit was the highest for the recycling of tires, 611 kg C02/ton plastic is saved by not sending it to incineration and instead recycle it through SÖRABs process.  The result is mainly due to the alternatives process emission from the ferry and incineration.

     

    The environmental benefits were positive for all the waste types except for plastic

     (-9,85)  kg CO2/ton textile) which had a long transportation length in comparison to the alternative process which was to send to incineration. In this report it was nevertheless concluded that this doesn’t mean that it would be a better option to incinerate the plastic since the real environmental benefit of plastic and all the other waste types is in the amount of carbon dioxide that is being saved by not needing to manufacture more of the material that is being regenerated through the recycling process.

     

  • 13.
    Barrientos, Javier
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Deactivation of cobalt and nickel catalysts in Fischer-Tropsch synthesis and methanation2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

                A potential route for converting different carbon sources (coal, natural gas and biomass) into synthetic fuels is the transformation of these raw materials into synthesis gas (CO and H2), followed by a catalytic step which converts this gas into the desired fuels. The present thesis has focused on two catalytic steps: Fischer-Tropsch synthesis (FTS) and methanation. The Fischer-Tropsch synthesis serves to convert synthesis gas into liquid hydrocarbon-based fuels. Methanation serves instead to produce synthetic natural gas (SNG). Cobalt catalysts have been used in FTS while nickel catalysts have been used in methanation.

                The catalyst lifetime is a parameter of critical importance both in FTS and methanation. The aim of this thesis was to investigate the deactivation causes of the cobalt and nickel catalysts in their respective reactions.

                The resistance to carbonyl-induced sintering of nickel catalysts supported on different carriers (γ-Al2O3, SiO2, TiO2 and α-Al2O3) was studied. TiO2-supported nickel catalysts exhibited lower sintering rates than the other catalysts. The effect of the catalyst pellet size was also evaluated on γ-Al2O3-supported nickel catalysts. The use of large catalyst pellets gave considerably lower sintering rates. The resistance to carbon formation on the above-mentioned supported nickel catalysts was also evaluated. Once again, TiO2-supported nickel catalysts exhibited the lowest carbon formation rates. Finally, the effect of operating conditions on carbon formation and deactivation was studied using Ni/TiO2 catalysts. The use of higher H2/CO ratios and higher pressures reduced the carbon formation rate. Increasing the temperature from 280 °C to 340 °C favored carbon deposition. The addition of steam also reduced the carbon formation rate but accelerated catalyst deactivation.

                The decline in activity of cobalt catalysts with increasing sulfur concentration was also assessed by ex situ poisoning of a cobalt catalyst. A deactivation model was proposed to predict the decline in activity as function of the sulfur coverage and the sulfur-to-cobalt active site ratio. The results also indicate that sulfur decreases the selectivity to long-chain hydrocarbons and olefins.

  • 14. Barsberg, S.T.
    et al.
    Andersson, M.L.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Anna, Trubetskaya
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Modeling of radical structures in biochar using DFT calculations2017In: ECI conference, Biochar: Production, Characterization and Applications, Alba, Italy, 2017; Alba, Italy, 2017Conference paper (Other academic)
  • 15.
    Bastuck, Manuel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. Saarland Univ, Germany.
    Baur, T.
    Saarland Univ, Germany.
    Richter, M.
    Bundesanstalt Mat Forsch and Prufung BAM, Germany.
    Mull, B.
    Bundesanstalt Mat Forsch and Prufung BAM, Germany; Fraunhofer Wilhelm Klauditz Inst, Germany.
    Schuetze, A.
    Saarland Univ, Germany.
    Sauerwald, T.
    Saarland Univ, Germany.
    Comparison of ppb-level gas measurements with a metal-oxide semiconductor gas sensor in two independent laboratories2018In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 273, p. 1037-1046Article in journal (Refereed)
    Abstract [en]

    In this work, we use a gas sensor system consisting of a commercially available gas sensor in temperature cycled operation. It is trained with an extensive gas profile for detection and quantification of hazardous volatile organic compounds (VOC) in the ppb range independent of a varying background of other, less harmful VOCs and inorganic interfering gases like humidity or hydrogen. This training was then validated using a different gas mixture generation apparatus at an independent lab providing analytical methods as reference. While the varying background impedes selective detection of benzene and naphthalene at the low concentrations supplied, both formaldehyde and total VOC can well be quantified, after calibration transfer, by models trained with data from one system and evaluated with data from the other system. The lowest achievable root mean squared errors of prediction were 49 ppb for formaldehyde (in a concentration range of 20-200 ppb) and 150 mu g/m(3) (in a concentration range of 25-450 mu g/m(3)) for total VOC. The latter uncertainty improves to 13 mu g/m(3) with a more confined model range of 220-320 mu g/m(3). The data from the second lab indicate an interfering gas which cannot be detected analytically but strongly influences the sensor signal. This demonstrates the need to take into account all sensor relevant gases, like, e.g., hydrogen and carbon monoxide, in analytical reference measurements.

  • 16.
    Bastuck, Manuel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. University of Saarland, Germany.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Schuetze, A.
    University of Saarland, Germany.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Characterizing the Influence of Gate Bias on Electrical and Catalytical Properties of a Porous Platinum Gate on Field Effect Gas Sensors2016In: 2016 IEEE SENSORS, IEEE , 2016Conference paper (Refereed)
    Abstract [en]

    In this work, we exposed an MIS capacitor with porous platinum as gate material to different concentrations of CO and NH3. Its capacitance and typical reaction products (water, CO2 and NO) were monitored at high and low oxygen concentration and different gate bias voltages. We found that the gate bias influences the switch-point of the binary CO response usually seen when either changing the temperature at constant gas concentrations or the CO/O-2 ratio at constant temperature. For NH3, the sensor response as well as product reaction rates increase with bias voltages up to 6 V. A capacitance overshoot is observed when switching on or off either gas at low gate bias, suggesting increasing oxygen surface coverage with decreasing gate bias.

  • 17.
    Bastuck, Manuel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. University of Saarland, Germany.
    Reimringer, W.
    3S GmbH, Germany.
    Conrad, T.
    3S GmbH, Germany.
    Schuetze, A.
    University of Saarland, Germany.
    Dynamic multi-sensor operation and read-out for highly selective gas sensor systems2016In: PROCEEDINGS OF THE 30TH ANNIVERSARY EUROSENSORS CONFERENCE - EUROSENSORS 2016, ELSEVIER SCIENCE BV , 2016, Vol. 168, p. 1685-1688Conference paper (Refereed)
    Abstract [en]

    We describe hardware and algorithms which enable highly selective and sensitive operation of the two gas sensor types used in the SENSIndoor project. The resistance of a metal-oxide semiconductor (MOS) type can rise above 1 G Omega in temperature cycled operation (TCO), which is measured using a logarithmic amplifier. A silicon-carbide based, gas-sensitive field-effect transistor (SiC-FET) driven with a combination of TCO and gate-bias cycled operation (GBCO) is used as second, complimentary sensor. The cyclic sensor signals exhibit distinct shape changes depending on the gas present which is captured by pattern recognition. In this study we use Linear Discriminant Analysis (LDA) for discrimination and Partial Least Squares Regression (PLSR) for quantification of ppb concentrations of target VOCs in changing ppm concentrations of interfering gases for indoor air quality assessment. (C) 2016 The Authors. Published by Elsevier Ltd.

  • 18.
    Becker, Sebastian
    KTH, School of Chemical Science and Engineering (CHE).
    Inverkan av olika joner och jonconcentrationer på porstorleksfördelningen i trämassa-fibrer2011Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The basic ingredient of paper is the individual wood fibers. The property of the fibers depends on a variety of factors e.g., method of pulp production and processing. The final sheet quality depends in part on how the fibers interface between each other and therefore factors that affect the fiber size are of interest.

    The flexibility of the fibers depends in part on the pore water i.e., the fiber swelling. The sheet becomes less flexible at low water content which gives a loss in strength. Thus it becomes desirable to increase the water uptake.

    The experimental investigation described in this report consists of exposing the wood fibers to different ions and ionic strength and then measure the pore size by thermoporosimetry where a DSC (Differential Scanning Calorimeter) is used. DSC measures the freezing point of water in the pores of the wood fibers. As the freezing point varies with the pore size the size distribution can be determined.

    The results show that there are complications with thermoporosimetry measurements at different ion concentrations. The strength of the ionic solutions will contribute to a fictitious pore volume, which makes analysis difficult to interpret.

  • 19.
    Bengtsson, Katarina
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Electrokinetic devices from polymeric materials2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    There are multiple applications for polymers: our bodies are built of them, plastic bags and boxes used for storage are composed of them, as are the shells for electronics, TVs, computers, clothes etc. Many polymers are cheap, and easy to manufacture and process which make them suitable for disposable systems. The choice of polymer to construct an object will therefore highly influence the properties of the object itself. The focus of this thesis is the application of commonly used polymers to solve some challenges regarding integration of electrodes in electrokinetic devices and 3D printing.

    The first part of this thesis regards electrokinetic systems and the electrodes’ impact on the system. Electrokinetic systems require Faradaic (electrochemical) reactions at the electrodes to maintain an electric field in an electrolyte. The electrochemical reactions at the electrodes allow electron-to-ion transduction at the electrode-electrolyte interface, necessary to drive a current at the applied potential through the system, which thereby either cause flow (electroosmosis) or separation (electrophoresis). These electrochemical reactions at the electrodes, such as water electrolysis, are usually problematic in analytical systems and systems applied in biology. One solution to reduce the impact of water electrolysis is by replacing metal electrodes with electrochemically active polymers, e.g. poly(3,4-ethylenedioxythiophene) (PEDOT). Paper 1 demonstrates that PEDOT electrodes can replace platinum electrodes in a gel electrophoretic setup. Paper 2 reports an all-plastic, planar, flexible electroosmotic pump which continuously transports water from one side to the other using potentials as low as 0.3 V. This electroosmotic pump was further developed in paper 3, where it was made into a compact and modular setup, compatible with commercial microfluidic devices. We demonstrated that the pump could maintain an alternating flow for at least 96 h, with a sufficient flow of cell medium to keep cells alive for the same period of time.

    The second part of the thesis describes the use of 3D printers for manufacturing prototypes and the material requirements for 3D printing. Protruding and over-hanging structures are more challenging to print using a 3D printer and usually require supporting material during the printing process. In paper 4, we showed that polyethylene glycol (PEG), in combination with a carbonate-based plasticizer, functions well as a 3D printable sacrificial template material. PEG2000 with between 20 and 30 wt% dimethyl carbonate or propylene carbonate have good shear-thinning rheology, mechanical and chemical stability, and water solubility, which are advantageous for a supporting material used in 3D printing.

    The advances presented in this thesis have solved some of the challenges regarding electrokinetic systems and prototype manufacturing. Hopefully this will contribute to the development of robust, disposable, low-cost, and autonomous electrokinetic devices.

  • 20.
    Benyahia Erdal, Nejla
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Adolfsson, Karin H.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Green Strategy to Reduced Nanographene Oxide through Microwave Assisted Transformation of Cellulose2018In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 6, no 1, p. 1245-1255Article in journal (Refereed)
    Abstract [en]

    A green strategy for fabrication of biobased reduced nanographene oxide (r-nGO) was developed. Cellulose derived nanographene oxide (nGO) type carbon nanodots were reduced by microwave assisted hydrothermal treatment with superheated water alone or in the presence of caffeic acid (CA), a green reducing agent. The carbon nanodots, r-nGO and r-nGO-CA, obtained through the two different reaction routes without or with the added reducing agent, were characterized by multiple analytical techniques including FTIR, XPS, Raman, XRD, TGA, TEM, AFM, UV-vis, and DLS to confirm and evaluate the efficiency of the reduction reactions. A significant decrease in oxygen content accompanied by increased number of sp2 hybridized functional groups was confirmed in both cases. The synergistic effect of superheated water and reducing agent resulted in the highest C/O ratio and thermal stability, which also supported a more efficient reduction. Interesting optical properties were detected by fluorescence spectroscopy where nGO, r-nGO, and r-nGO-CA all displayed excitation dependent fluorescence behavior. r-nGO-CA and its precursor nGO were evaluated toward osteoblastic cells MG-63 and exhibited nontoxic behavior up to 200 μg mL-1, which gives promise for utilization in biomedical applications.

  • 21.
    Beretta, A.
    et al.
    Dipartiemento Energia- Politecnico di Milano.
    Groppi, G.
    Dipartiemento Energia- Politecnico di Milano.
    Lualdi, Matteo
    Dipartiemento Energia- Politecnico di Milano.
    Tavazzi, I.
    Dipartiemento Energia- Politecnico di Milano.
    Forzatti, P.
    Dipartiemento Energia- Politecnico di Milano.
    Experimental and modeling analysis of methane partial oxidation: transient and steady-state behavior of rh-coated honeycomb monoliths2009In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 48, no 8, p. 3825-3836Article in journal (Refereed)
    Abstract [en]

    The present study consists of an experimental and theoretical study of the performance of Rh-coated honeycomb monoliths for methane partial oxidation. The thermal behavior of Rh-coated honeycomb monoliths was studied under representative operating conditions, at steady state and during light-off. Model analysis (based on a dynamic heterogeneous reactor model that incorporates a kinetic scheme of the process independently developed, and well-assessed correlations for heat and mass transfer) provided a key for interpreting the observed effects. The comprehension of how transport phenomena and surface kinetics affect the reactor behavior leads to the conclusion that the feasibility of small-scale production of syngas via CH(4) catalytic partial oxidation relies on thermal management of the short contact time reactor and not the obtainment of high syngas yields (which is not a challenging task). Severe operating conditions (and high surface temperatures) can deplete the catalyst activity and cause unstable reactor operation. Guidelines for optimal reactor design are proposed.

  • 22.
    Bergström, Lars Magnus
    et al.
    KTH, Superseded Departments, Chemistry. YKI, Institute for Surface Chemistry, Sweden .
    Eriksson, Jan Christer
    KTH, Superseded Departments, Chemistry. YKI, Institute for Surface Chemistry, Sweden .
    Synergistic effects in binary surfactant mixtures2004In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 123, p. 16-22Article in journal (Refereed)
    Abstract [en]

    By considering the main contributions to the micellar free energy we have analysed the synergistic effect often seen on the CMC of a binary surfactant mixture. The synergistic effects are due mainly to the entropic free energy contributions related with the surfactant head groups. Several cases have been treated: (i) For a mixture of a monovalent ionic and a non-ionic surfactant in the absence of added salt we obtain, entirely because of electrostatic reasons, a negative deviation from the ideal behaviour corresponding to an interaction parameter β≈-1. Upon adding an inert salt we found that the magnitude of the synergistic effect first increases, reaches a maximum and eventually decreases. (ii) For mixtures of two ionic surfactants with the same charge number but with different hydrocarbon moieties β-values as low as -10 may arise. (iii) For mixtures of an anionic and a cationic surfactant enormous effects are anticipated yielding β≤-20 depending on the CMCs of respective pure surfactant. (iv) Synergistic effects due to different cross-section areas of the head groups are found to be rather small, with 0 > β > -1, provided the difference in head group size is modest but can become more significant when the size difference is larger.

  • 23. Bertram, F.
    et al.
    Zhang, Fan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Evertsson, J.
    Carla, F.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Messing, M. E.
    Mikkelsen, A.
    Nilsson, J-O
    Lundgren, E.
    In situ anodization of aluminum surfaces studied by x-ray reflectivity and electrochemical impedance spectroscopy2014In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 116, no 3, p. 034902-Article in journal (Refereed)
    Abstract [en]

    We present results from the anodization of an aluminum single crystal [Al(111)] and an aluminum alloy [Al 6060] studied by in situ x-ray reflectivity, in situ electrochemical impedance spectroscopy and ex situ scanning electron microscopy. For both samples, a linear increase of oxide film thickness with increasing anodization voltage was found. However, the slope is much higher in the single crystal case, and the break-up of the oxide film grown on the alloy occurs at a lower anodization potential than on the single crystal. The reasons for these observations are discussed as are the measured differences observed for x-ray reflectivity and electrochemical impedance spectroscopy.

  • 24.
    Bessman, Alexander
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Interactions between battery and power electronics in an electric vehicle drivetrain2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The electric machine and power electronics in electric and hybrid electric vehicles inevitably cause AC harmonics on the vehicle's DC-link. These harmonics can be partially filtered out by large capacitors, which today are overdimensioned in order to protect the vehicle's battery pack. This is done as a precaution, since it is not known whether ripple-current has any harmful effect on Li-ion  cells.

    We have measured and analyzed the ripple-current present in a hybrid electric bus, and found that a majority of the power was carried by frequencies in the range 100~Hz to 1~kHz. The single most energetic harmonic in this particular vehicle is believed to have been caused  by a misaligned resolver in the motor.

    We have also designed and built an advanced experimental set-up in order to study the effect of ripple-current on Li-ion cells in the lab. The set-up can cycle up to 16 cells simultaneously, with currents of up to 50~A including a superimposed AC signal with a frequency of up to 2~kHz. The cells' temperatures are controlled by means of a climate chamber. The set-up also includes a sophisticated safety system which automatically acts to prevent dangerous situations before they arise.

    Using this set-up we tested whether superimposing AC with a specific frequency improves the charging performance of Li-ion cells. Statistical analysis found no improvement over regular DC cycling, and a physics-based model explains the experimental findings.

    We have also investigated whether ripple-current accelerates the aging of Li-ion cells. Twelve cells were either calendar or cycle  aged for one year, with some cells being exposed to superimposed AC with a frequency of 1~Hz, 100~Hz, or 1~kHz. No effect was observed on any of capacity fade, power fade, or aging mechanism.

    Finally we also tested whether it is possible to heat Li-ion cells from low temperatures using only AC. We propose a method for AC heating of Li-ion cells, and open the discussion for generalizing the technique to larger battery packs.

    In conclusion, ripple-current has negligible effect on Li-ion cells, except for heating them slightly.

  • 25.
    Bessman, Alexander
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Soares, Rúdi
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Vadivelu, Sunilkumar
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Svens, Pontus
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Ekström, Henrik
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Challenging Sinusoidal Ripple-Current Charging of Lithium-Ion Batteries2018In: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, Vol. 65, no 6, p. 4750-4757Article in journal (Refereed)
    Abstract [en]

    Sinusoidal ripple-current charging has previously been reported to increase both charging efficiency and energy efficiency and decrease charging time when used to charge lithium-ion battery cells. In this paper, we show that no such effect exists in lithium-ion battery cells, based on an experimental study of large-size prismatic cells. Additionally, we use a physics-based model to show that no such effect should exist, based on the underlying electrochemical principles.

  • 26.
    Bessman, Alexander
    et al.
    KTH.
    Soares, Rúdi
    KTH.
    Wallmark, Oskar
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Svens, Pontus
    KTH.
    Lindbergh, Göran
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Aging effects of AC harmonics on lithium-ion cellsManuscript (preprint) (Other academic)
  • 27.
    Bhasin, Aditi
    KTH, School of Chemical Science and Engineering (CHE).
    Recovery of Phosphorus from Incineration of Sewage Sludge2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The primary source of phosphorus, phosphate rock, is a non-renewable resource which is expected to get exhausted in the next 50 – 100 years. Sewage sludge in Sweden constitutes 25% of the annual phosphorus in the country, making it a potentially significant source for phosphorus recovery. The aim of this project was to identify the potential for phosphorus recovery from incineration of dewatered and digested sewage sludge in Fortum Värme’s power plants in Stockholm. The study was limited to two boilers located at Bristaverket, Stockholm - boiler B1, a bio-fired fluidized bed boiler and boiler B2, a waste-fired grate incinerator. A theoretical analysis for boiler B1 showed that it is possible to reach a concentration of 4.6% phosphorus in fly ash if sludge and recycled wood fuel are mixed in the ratio 48:52. A test program was executed in boiler B2 to burn up to 12.5% sludge with a mixture of household waste and industrial waste. A total of 755 tons of sludge was used over a period of three weeks during the test in boiler B2. The test was successful in terms of combustion and emissions. There was no increase in the emissions of nitrogen oxides, sulphur dioxide and hydrochloric acid in the flue gas. Mercury emissions in the chimney increased with an increase in the share of sludge, nevertheless, the emission level was below the limit set by the Swedish Environmental Protection Agency. Decrease in the amount of unburnt materials in bottom ash and in the emission of carbon monoxide showed that the burning of fuel was more efficient with input of sludge. The maximum phosphorus concentration was 0.7% in both bottom ash and fly ash from boiler B2 and occurred at an input of 12.5% sludge. This concentration is close to the expected theoretical value, however it is not expected to be feasible to recover phosphorus at such a low concentration. The ashes were sent to Fortum Waste Solutions and Ragn-Sells for recovery of phosphorus, however the results are not included in this report due to time constraints for thesis study. In order to increase the concentration of phosphorus in the ashes, a system approach is recommended, for instance, recirculation of bottom ash into the incinerator.

  • 28.
    Biasi, P.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Åbo Akad Univ, Dept Chem Engn, Lab Ind Chem & React Engn, Johan Gadolin Proc Chem Ctr PCC, Biskopsgatan 8, FI-20500 Turku, Finland.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Åbo Akad Univ, Dept Chem Engn, Lab Ind Chem & React Engn, Johan Gadolin Proc Chem Ctr PCC, Biskopsgatan 8, FI-20500 Turku, Finland.
    Sterchele, S.
    Salmi, T.
    Gemo, N.
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Centomo, P.
    Zecca, M.
    Canu, P.
    Rautio, A. -R
    Kordàs, K.
    Revealing the role of bromide in the H2O2 direct synthesis with the catalyst wet pretreatment method (CWPM)2017In: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 63, no 1, p. 32-42Article in journal (Refereed)
    Abstract [en]

    A tailor-made Pd0/K2621 catalyst was subjected to post synthesis modification via a wet treatment procedure. The aimwas the understanding of the role of promoters and how—if any—improvements could be qualitatively related to the cat-alyst performance for the H2O2direct synthesis. The Catalyst Wet Pretreatment Method was applied in different metha-nolic solutions containing H2O2, NaBr, and H3PO4, either as single modifiers or as a mixture. The catalyst wascharacterized by Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy. It was concluded that themodified catalysts give rise to higher selectivities compared to the pristi ne reference catalyst thus opening a possibilityto exclude the addit ion of the undesirable selectivity enhancers in the reaction medium. This work provides original evi-dence on the role of promoter s, especially bromide, allowing the formulation of a new reaction mechanism for one ofthe most challenging reactions recognized by the world.

  • 29.
    Björn, Annika
    et al.
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Hörsing, Maritha
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Karlsson, Anna
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Mersiowsky, Ivo
    Hamburg, Germany.
    Ejlertsson, Jörgen
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Impacts of temperature on the leaching of organotin compounds from poly(vinyl chloride) plastics – A study conducted under simulated landfill conditions. Journal of Vinyl and Additive Technology 2007In: Journal of Vinyl & Additive Technology, ISSN 0193-7197, E-ISSN 1548-0577, Vol. 13, no 4, p. 176-188Article in journal (Refereed)
    Abstract [en]

    The aim of the study was to investigate whether organotin-stabilized poly(vinyl chloride) (PVC) products could contribute to the pool of organotins observed in landfill leachates, and if the possible release could be related to different temperatures and landfill degradation phases. Small-scale anaerobic reactors filled with generic household waste, a mixture of inocula, and different PVC plastics were used in the study and incubated at 20, 37, 55, and 70°C. The reactor units incubated at temperatures of 20–55°C underwent the anaerobic degradation phases that are characteristic for the aging of landfilled waste material. There were, however, differences in the duration of the phases as well as in the total biogas production among the units. Under methanogenic conditions greater losses of organotin compounds were observed as compared to acidogenic conditions. It was shown that the release of organotin stabilizers increases considerably at temperatures above the glass transition of the PVC products. A dealkylation from di- into monoalkyltin species was observed, as well as a possible methylation of inorganic tin. However, the main part of the organotins was adsorbed into the solid waste matrix. J. VINYL ADDIT. TECHNOL., 13:176–188, 2007. © 2007 Society of Plastics Engineers

  • 30.
    Bohlin, Erik
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences, Paper Surface Centre.
    Johansson, Caisa
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences, Paper Surface Centre.
    Lestelius, Magnus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences, Paper Surface Centre.
    Evaluation of ink penetration in porous coatings2012Conference paper (Refereed)
  • 31.
    BOOG RUDBERG, SUSANN
    KTH, School of Chemical Science and Engineering (CHE).
    Kylanläggning för småskalig ölproduktion anpassad för jäsning och lagring av lageröl2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There has been a large increase of microbreweries in Sweden in the past few years, most of which produce great beers such as ales and stouts. This is however a bit strange since most Swedes seem to prefer to drink lager; at least if you study the statistics of the Swedish alcohol monopoly’s top hundred most drunken beers last year. There might be several reasons for microbreweries not brewing lagers but one reason is the equipment needed for lager brewing. Apart from the regular brewing equipment needed for brewing ales, a cooling system is needed in lager brewing in order to reach the ideal temperatures for fermentation, 10°°C, and lagering. Lagering is a process where beer is stored for weeks or months in a cold place, typically around 0°C.  The cooling systems on the market are expensive and small start-up microbreweries do not have the funds to purchase these. One example of such a microbrewery is Brewing Költur, and this study aims to solve the cooling problem for them.

    The goal was to design a cheaper alternative for cooling a 300-litre batch of beer but without severe changes in quality. The product needs to be able to hold stable temperatures and also lower the temperatures from 10°°C to 0°°C, both without major fluctuations in temperature within the vessel. The project did not aim at solving other lager brewing related problems.

    The result was a Bag-in-Box: a chest freezer in which a disposable plastic bag, big enough to fit 300 litres of beer, was placed. An air gap was created in between the inside walls of the freezer and the bag to keep the sudden cold walls from damaging the yeast by cooling it to quickly.

    A prototype was put together in order to test the most important features of the product. The tests showed that the product could keep stable temperatures very well in the lower temperature intervals, while it needed manual stirring in the higher regions to avoid temperature gradients, especially when the temperature was lowered.

    The cost of the product is overall very low. The investment cost is very low, however since the disposable bags are somewhat costly the variable cost is fairly high, yet still significantly cheaper than the alternatives on the market.

    It is believed that the product could be used by many smaller microbreweries in the future due to the low investment cost, its ability to keep the temperatures relatively stable and also because it is easy to assemble.

     

  • 32.
    BORIS ERIC ALAIN, BIZET
    KTH, School of Chemical Science and Engineering (CHE).
    From Sugar to Furfural Compounds Using Flow Chemistry2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Due to the need to find alternatives for the current fossil-based chemical industry, the use of blo-sourced platform chemicals as building blocks for the synthesis of a wide range of industrial and consumer chemicals has gained significantly in importance over the past years.

    In this context, 5-(chloromethyl)furfural (CMF) could become a very interesting target for  the implementation of a sugar-based biorefinery. Originating from the dehydration of cellulose,  hemlcellulose or sugar, it can for example be a precursor of bio-fuels and/or fuel additives. However, there are very few published examples on the CMF synthesis as well as its ability to be further converted in interesting derivatives.

    A simple procedure for the conversion of sugar-based feedstocks to CMF, using flow chemistry, is reported in this  master  thesis.  Sucrose  and  High  Fructose  Corn  Syrup  (HFCS-90  and  HFCS-55)  were  shown  to  be suitable feedstocks. The use of HFCS-90 has been demonstrated to be particularly promising, as it could be converted in a stable process which yields 70% of CMF.

    As a proof of concept, condensation reactions of 5-methylfurfural (MF) and CMF were performed with amine compounds, thus expanding the existing pool of CMF derivatives. MF condensations could be performed under harsh conditions, whereas CMF required milder treatments. Very high conversions were observed, especially when using aliphatic amines as starting materials.

  • 33.
    Borén, Eleonora
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University Industrial Doctoral School for Research and Innovation.
    Yazdanpanah, Fahimeh
    Lindahl, Roger
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Schilling, Christoph
    Chandra, Richard P.
    Ghiasi, Bahman
    Tang, Yong
    Sokhansanj, Shahabaddine
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Larsson, Sylvia H.
    Off-gassing of VOCs and permanent gases during storage of torrefied and steam exploded wood2017In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 10, p. 10954-10965Article in journal (Refereed)
    Abstract [en]

    Thermal treatment for upgrading of low-value feedstocks to improve fuel properties has gained large industrial interest in recent years. From a storage and transport perspective, hazardous off-gassing could be expected to decrease through the degradation of reactive biomass components. However, thermal treatment could also shift chemical compositions of volatile organic components, VOCs. While technologies are approaching commercialization, off-gassing behavior of the products, especially in terms of VOCs, is still unknown. In the present study, we measured off-gassing of VOCs together with CO, CO2, CH4, and O2 depletion from torrefied and steam exploded softwood during closed storage. The storage temperature, head space gas (air and N2), and storage time were varied. VOCs were monitored with a newly developed protocol based on active sampling with Tenax TA absorbent analyzed by thermal desorption-GC/MS. High VOC levels were found for both untreated and steam exploded softwood, but with a complete shift in composition from terpenes dominating the storage gas for untreated wood samples to an abundance of furfural in the headspace of steam exploded wood. Torrefied material emitted low levels of VOCs. By using multivariate statistics, it was shown that for both treatment methods and within the ranges tested, VOC off-gassing was affected first by the storage temperature and second by increasing treatment severity. Both steam exploded and torrefied biomass formed lower levels of CO than the reference biomass, but steam explosion caused a more severe O2 depletion.

  • 34.
    Boström, Dan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Grimm, Alejandro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Ash transformation chemistry during energy conversion of biomass2010In: Impacts of Fuel Quality on Power Production and the Environment, Saariselkä, Finland, August 29–September 3, 2010, 2010Conference paper (Refereed)
  • 35. Braovac, Susan
    et al.
    Fackler, Karin
    Bader, Thomas K.
    Ters, Thomas
    Chemical Composition of the Archaeological Oak Wood from the Oseberg Ship2011In: Cultural Heritage Preservation.EWCHP - 2011: Proceedings of the European Workshop on Cultural Heritage Preservation. Berlin, Germany, September 26 to 28, 2011, Fraunhofer IRB Verlag, 2011, p. 156-163Conference paper (Refereed)
  • 36.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Effects of alkali chlorides in biomass and waste-fired boilers2009Licentiate thesis, comprehensive summary (Other academic)
  • 37.
    Bur, Christian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology. Saarland University, Saarbruecken, Germany.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Helwig, Nikolai
    Saarland University, Saarbruecken, Germany.
    Schütze, Andreas
    Saarland University, Saarbruecken, Germany.
    Detecting Volatile Organic Compounds in the ppb range with platinum-gate SiC-Field Effect Transistors2013In: SENSORS, 2013 IEEE, IEEE , 2013, p. 1-4Conference paper (Refereed)
    Abstract [en]

    In this work, the use of a platinum gate gas-sensitive SiC Field Effect Transistor (SiC-FET) was studied for the detection of low concentrations of hazardous Volatile Organic Compounds (VOC). For this purpose, a new gas mixing system was built providing VOCs down to sub-ppb levels by permeation ovens and gas pre-dilution. Measurements have shown that benzene, naphthalene and formaldehyde can be detected in the ppb range and indicate a detection limit of 1-2 ppb for benzene and naphthalene. The sensitivity is high with a response of 5.5 mV for 10 ppb naphthalene in a humid atmosphere (at 20% relative humidity) and with additional 2 ppm ethanol the response to naphthalene was still 1.3 mV. Formaldehyde can be detected down to approximately 100 ppb under humid conditions. This is the first time that a metal gated SiC-FET was used to detect hazardous VOCs in the low ppb range making SiC-FETs suitable candidates for indoor air quality applications.

  • 38.
    Bur, Christian
    et al.
    Saarland University, Saarbrücken, Germany.
    Bastuck, Manuel
    Saarland University, Saarbrücken,, Germany.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Schütze, Andreas
    Saarland University, Saarbrücken, Germany.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Influence of a Changing Gate Bias on the Sensing Properties of SiC Field Effect Gas Sensors2012In: IMCS 2012, 2012, p. 140-143Conference paper (Other academic)
    Abstract [en]

    Field effect transistors based on silicon carbide have previously been used with temperature cycled operation to enhance the selectivity. In this study the influence of a changing gate bias on the sensing properties of a platinum gate FET has been studied in order to extend the virtual multi-sensor approach. The sensor exhibits gas specific hysteresis when changing the gate bias indicating that additional information regarding selectivity is contained in the transient behavior. Measurements also showed that especially the shape of the sensor signal changes dramatically with different gas exposures (e.g. H2, CO or NH3) during relaxation after step changes of the gate bias. The changing shape primarily reflects the gas itself and not the concentration so that the selectivity of the sensor is increased.

  • 39.
    Bur, Christian
    et al.
    Saarland University, Saarbrücken, Germany.
    Bastuk, Emanuel
    Saarland University, Saarbrücken, Germany.
    Schütze, Andreas
    Saarland University, Saarbruecken, Germany.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Combination of temperature cycled and gate bias cycled operation to enhance the selectivity of MISiC-FET gas sensors2013In: Transducers 2013 & Eurosensors XXVII, IEEE , 2013, p. 2041-2044Conference paper (Other academic)
    Abstract [en]

    In this paper temperature modulation and gate bias modulation of a gas sensitive field effect transistor are combined in order to increase the selectivity. Data evaluation was performed using multivariate statistics, here by Linear Discriminant Analysis. It was found that both temperature cycling and gate bias cycling are suitable for quantification of different concentrations of carbon monoxide. However, combination of both approaches enhances the quality of the separation. In addition, the presented method allows discrimination of carbon monoxide, nitrogen dioxide and ammonia independent of the gas concentration.

  • 40. Bylin, Susanne
    et al.
    Olsson, Carina
    Westman, Gunnar
    Theliander, Hans
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Solvation behavior of cellulose and xylan in the MIM/EMIMAc ionic liquid solvent system: Parameters for small-scale solvation2014In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 9, no 1, p. 1038-1054Article in journal (Refereed)
    Abstract [en]

    Ionic liquid treatment has been reported by several researchers as a possible step in the process of fractionating lignocellulosic biomass within the biorefinery concept. However, understanding how solvation can be achieved and how the feedstock biopolymers are affected is needed prior to a viable implementation. An effective two-component solvent system for the wood components cellulose and xylan has been developed. Furthermore, the solvation of these components in the system consisting of the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate (EMIMAc) in a novel combination with the co-solvent 1-methylimidazole (MIM) is investigated. Focused beam reflectance measurement (FBRM) particle characterization in combination with microscopic analysis and molecular weight determinations (xylan) shows that cellulose and xylan can be most efficiently solvated using only 3 to 4% IL (n/n anhydro-glucose units and n/n anhydro-xylose units) and 9% IL, respectively, while still avoiding any significant polymer degradation. A model for a two-step process of cellulose solvation in the present system is proposed.

  • 41.
    Bäck, Andreas
    et al.
    Alstom Power Sweden AB.
    Grubbström, Jörgen
    Alstom Power Sweden AB.
    Ecke, Holger
    Vattenfall Research and Development.
    Strand, Michael
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Pettersson, Jens
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Operation of an Electrostatic Precipitator at a 30 MWth Oxyfuel Plant2011In: International Journal of Plasma Environmental Science and Technology, ISSN 1881-8692, Vol. 5, no 2, p. 141-145Article in journal (Refereed)
    Abstract [en]

    The performance of a full-scale ESP was studied at the Vattenfall AB oxyfuel pilot plant in Schwarze Pumpe. The lignite-fired boiler has a 30 MWth top-mounted pulverized coal burner and was operated under conventional air combustion as well as oxyfuel combustion. The ESP was operated with varying numbers of fields in service and at different current/voltage settings. Particle number size distributions downstream the ESP were established on-line in the size range 0.015-10 m, using an electrical mobility spectrometer and an aerodynamic particle sizer. The particle size distribution at oxyfuel operation was qualitatively very similar to the results obtained for air-firing. Gravimetric measurements of total fly ash concentration showed outlet emissions below 5 mg/Nm3 when the ESP was operated with two fields in service at oxyfuel conditions.

  • 42.
    Bäckström, Marie
    KTH, School of Chemical Science and Engineering (CHE).
    Global Manufacturing Training: The localization of the Powerformer Field Operator curricula at the Notre Dame de Gravenchon Refinery2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Global Manufacturing Training (GMT) project aims at homogenizing and raising the level of competency of the workforce at ExxonMobil plants in all countries where the company is active. This report presents and introduces the main structures of the GMT venture. It deals with important aspects of the project on a global scale, but it also details the implementation of training on a local level. The different pedagogical strategies are outlined, along with the resulting system of training documents.

    A global team of experts developed general training documents, called global modules in order to set the standard for the various training documents. The inherent differences between the plants in the ExxonMobil corporation makes it necessary to adapt the global modules to fit with the site in question. The differences between the plants are of both technical character, but also concern working procedures. The process of adapting each document according to the GMT outline is called Localization.

    In the current work, the localization of training documents for the Powerformer at the refinery in Notre Dame de Gravenchon-Port Jérôme (NDG-PJG) is detailed and explained. At the NDG-PJG refinery there are two units containing a Powerformer. The training documents concern the field operator, working on what is locally called the Reforming 2 position. The ensemble of the documents localized will be used for the habilitation of the process operator. Habilitation refers the preparatory training needed in order to be able to perform the tasks and procedures of a specific position. The work has resulted in the localization of 90 percent of the global documents concerning the Reforming 2 position.

  • 43.
    Caetano de Souza, Antonio Carlos
    et al.
    Department of Energy, São Paulo State University (UNESP), Brazil.
    Silveira, José Luz
    Department of Energy, São Paulo State University (UNESP), Brazil.
    Kiros, Yohannes
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Zanzi Vigouroux, Rolando
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    A low cost & safe system of hydrogen production utilizing NaBH4 and CoO catalysis2007In: 2nd International Congress University-Industry Cooperation (UNIDU07), 2007Conference paper (Refereed)
    Abstract [en]

    The objective of this study was to evaluate the hydrogen production through hydrolysisof sodium borohydride (NaBH4) utilizing catalysts containing CoO. The reactant is safe and stable(when dry) at room temperature. Few works and studies have presented results of investigationsutilizing catalysts containing cobalt; however utilizing catalysts containing CoO were not found yet.In this work simple and cheap hydrogen generation system was developed having reactions atnormal conditions of temperature and pressure. A solution containing a gravimetric composition of10% wt. NaOH, 10% wt. NaBH4 and 80% wt. H2O was utilized. The reaction was carried out atvarious times using the same catalyst to evaluate its performance. This catalyst presented highrates of hydrogen production, especially at its start-up (about 99% of the theoretical hydrogenvolume was produced) at room temperature. After start-up, e.g., when more solution was put, rateof hydrogen production decreased having its production performance also decreased. Probablythis fact occurred due to the formation of the solid phase products such as NaBO2 which might fillthe porous catalyst structure; decreasing the catalytic area. This catalyst is suggested in situationswhere high production rates are necessary such as start-up of fuel cells.

  • 44.
    Caetano de Souza, Antonio Carlos
    et al.
    Department of Energy, São Paulo State University (UNESP), Brazil.
    Silveira, José Luz
    Department of Energy, São Paulo State University (UNESP), Brazil.
    Kiros, Yohannes
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Zanzi Vigouroux, Rolando
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Hydrogen production through hydrolysis of NaBH4: The use of catalysts containing Pt and Pt-Ru2007In: 2nd International Congress University-Industry Cooperation (UNIDU07), 2007Conference paper (Refereed)
    Abstract [en]

    Several works about hydrolysis of NaBH4 utilizing various catalysts (such as catalysts containing Pt or Ru) are available in the literature. Investigations involving NaBH4 has increased due to the possibility to produce hydrogen using simple and safe systems, even at room temperatures with very high efficiencies. A solution containing a gravimetric  composition of 10%wt. NaOH, 10%wt. NaBH4 and 80%wt. H2O was utilized and the reaction was initiated immediately as soon as this solution was put in the chosen catalysts, in this case, catalysts containing Pt and mixtures of Pt-Ru. Catalysts containing Pt and Pt-Ru presented high yields of hydrogen after the solution being inserted in the reaction vessel several times. In this study it was found out that the rates of hydrogen production were increased with catalysts containing Pt and Pt-Ru (99 and 96% of theoretical hydrogen production respectively). The catalysts containing Pt presented higher production rate, while the catalysts containing the mixed Pt-Ru presented a quasi-linear production, e.g., stable production rate.

  • 45.
    Carlson, Annika
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Shapturenka, Pavel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Eriksson, Björn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lagergren, Carina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Wreland Lindström, Rakel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Electrode parameters and operating conditions influencing the performance of anion exchange membrane fuel cells2018In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 277, p. 151-160Article in journal (Refereed)
    Abstract [en]

    A deeper understanding of porous electrode preparation and performance losses is necessary to advance the anion exchange membrane fuel cell (AEMFC) technology. This study has investigated the performance losses at 50 °C for varied: Tokuyama AS-4 ionomer content in the catalyst layer, Pt/C loading and catalyst layer thickness at the anode and cathode, relative humidity, and anode catalyst. The prepared gas diffusion electrodes in the interval of ionomer-to-Pt/C weight ratio of 0.4–0.8 or 29–44 wt% ionomer content show the highest performance. Varying the loading and catalyst layer thickness simultaneously shows that both the cathode and the anode influence the cell performance. The effects of the two electrodes are shown to vary with current density and this is assumed to be due to non-uniform current distribution throughout the electrodes. Further, lowering the relative humidity at the anode and cathode separately shows small performance losses for both electrodes that could be related to lowered ionomer conductivity. Continued studies are needed to optimize, and understand limitations of, each of the two electrodes to obtain improved cell performance.

  • 46. Castro, A.
    et al.
    Vilaplana, Francisco
    KTH, School of Biotechnology (BIO), Glycoscience.
    Nilsson, L.
    Characterization of a water soluble, hyperbranched arabinogalactan from yacon (Smallanthus sonchifolius) roots2017In: Food Chemistry, ISSN 0308-8146, E-ISSN 1873-7072, Vol. 223, p. 76-81Article in journal (Refereed)
    Abstract [en]

    Yacon (Smallanthus sonchifolius Poepp. & Endl.) roots are largely grown in Andean countries and have attracted recent interest due to their antioxidant and prebiotic effects. Yacon is typically consumed as a fruit due to its sweet taste and juiciness. The macromolecular properties of an aqueous extract of yacon are investigated using asymmetric flow field-flow fractionation (AF4) coupled to UV, multiangle light scattering (MALS) and differential refractive index (dRI) detection. The method allows for determination of molar mass and size over the size distribution. Three major populations were found of which one strongly dominates in concentration. Through collection of fractions from AF4, carbohydrate composition and glycosidic linkage analysis for the dominating population was performed. The results show that the dominating population consists of a highly branched arabinogalactan (type 2) with a molar mass of approximately 1–2 · 105 g/mol, a hydrodynamic radius of approximately 6–10 nm and a relatively high apparent density (approx. 70–150 kg/m3).

  • 47.
    Cedervall, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Synthesis and characterizationof rare earth free magnetic materialsfor permanent magnet applications2013Independent thesis Basic level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis the compounds Fe5SiB2 and Fe5PB2 have beensynthesized via high temperature synthesis, including arc melting anddrop synthesis. The structure for both compounds are of Cr5B3 typewith the space group I4/mcm. The cell parameters were refined toa = 5.5533 Å and c = 10.3405 Å for Fe5SiB2 and a = 5.4903 Å andc = 10.3527 Å for Fe5PB2. The saturation magnetization at roomtemperature for Fe5SiB2 has been measured to 138.8 Am2/kg and theanisotropy constant has been estimated to 79 kJ/m3. Theferromagnetic properties and the high anisotropy constant makesthese materials promising as permanent magnet materials, but moreinvestigations are necessary.

  • 48.
    Chamoun, Ninus
    et al.
    KTH, School of Chemical Science and Engineering (CHE).
    Kjellvertz, Viktor
    KTH, School of Chemical Science and Engineering (CHE).
    Mahajan, William
    KTH, School of Chemical Science and Engineering (CHE).
    Song, Yuanchao
    KTH, School of Chemical Science and Engineering (CHE).
    Fate of Heavy Metals in Waste to Energy (WtE) Processes2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study was made to increase the understanding of how heavy metals in the aqueous phase are removed at low initial concentrations in different pH and Eh values. The reaction that has been studied is mainly hydroxide precipitation and adsorption in a condensate treatment. In the study, data from one of Vattenfalls waste incinerators was analysed and the results from the data were then compared to previous studies. To increase the understanding, modelling of the heavy metals behaviour in the given concentrations was then made with Medusa and PHREEQC. The heavy metals that were analysed were Sb, As, Pb, Zn, Cr, and Cd. The low initial concentration that vary between 36.1-23600 μg/l complicates the removal process because it corresponds in a low driving force and the results are hard to compare to other studies since the initial concentrations vary between 10-100 mg/l.

    From the modelling and the measurement data it can be seen that Pb, Zn, Cr, and Cd was removed by hydroxide precipitation at pH 10. According to the speciation calculations, the dominant species at this pH are Pb(OH)

    2 , Cd(OH)2, Zn(OH)2 and Cr(OH)3. For arsenic a clear conclusion could not be drawn from the modelling and the measurement data because of low precision. Due to the limited thermodynamic parameters of antimony in comparison with other heavy metals in the database of Medusa and PHREEQC, the modelling of antimony behaviour in condensate treatment has relatively larger uncertainty is low. The modelling results show that the main species in acidic solutions for antimony is Sb(OH)3 and in basic solutions Sb(OH)-6. Further investigation for antimony in needed for a clear conclusions to be drawn

  • 49.
    Cho, Sung-Woo
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Protein-based Packaging Films, Sheets and Composites: Process Development and Functional Properties2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The depletion of the petroleum resources and a number of environmental concerns led to considerable research efforts in the field of biodegradable materials over the last few decades. Of the diverse range of biopolymers, wheat gluten (WG) stands out as an alternative to synthetic plastics in packaging applications due to its attractive combination of flexibility and strength, high gas barrier properties under low humidity conditions and renewability. The availability of raw materials has also been largely increased with an increase in the production of WG as a low-cost surplus material due to increasing demand for ethanol as fuel. In this study, WG was processed into films, sheets and composites using some of the most widely used techniques including solution casting, compression molding, extrusion and injection molding, accompanying process optimizations and characterization of their functional properties. This thesis consists mainly of six parts based on the purpose of the study. The first part addresses the aging and optical properties of the cast film in order to understand the mechanisms and reasons for the time-dependant physical and chemical changes. The films plasticized with glycerol were cast from acidic (pH 4) and basic (pH11) solutions. The film prepared from the pH 11 solution was mechanically more stable upon aging than the pH 4 film, which was initially very ductile but became brittle with time. It was revealed that the protein structure of the pH 4 film was initially less polymerized/aggregated and the polymerization increased during storage but it did not reach the degree of aggregation of the pH 11 film. During aging, the pH 4 film lost more mass than the pH 11 film mainly due to migration of glycerol but also due to some loss of volatile mass. In addition the greater plasticizer loss of the pH 4 film was presumably due to its initial lower degree of protein aggregation/polymerization. Glycerol content did not significantly change the opacity and pH 4 films showed good contact clarity because of less Maillard reaction. In the second part, the heat-sealability of WG films was investigated, using an impulse-heat sealer, as the sealability is one of the most important properties in the use of flexible packaging materials. It was observed that the WG films were readily sealable while preserving their mechanical integrity. The sealing temperature had a negligible effect on the lap-shear strength, but the peel strength increased with sealing temperature. The lap-shear strength increased with increasing mold temperature and the failure mode changed. The third part describes the possibility of using industrial hemp fibers to reinforce wheat gluten sheets based on evaluation of the fiber contents, fiber distribution and bonding between the fibers and matrix. It was found that the hemp fibers enhanced the mechanical properties, in which the fiber contents played a significant role in the strength. The fiber bonding was improved by addition of diamine as a cross-linker, while the fiber distribution needed to be improved. The fourth part presents a novel approach to improve the barrier and mechanical properties of extruded WG sheets with a single screw extruder at alkaline conditions using 3-5wt.% NaOH with or without 1 wt.% salicylic acid. The oxygen barrier, at dry conditions, was improved significantly with the addition of NaOH, while the addition of salicylic acid yielded poorer barrier properties. It was also observed that the WG sheets with 3 wt.% NaOH had the most suitable combination of low oxygen permeability and relatively small time-dependant changes in mechanical properties, probably due to low plasticizer migration and an optimal protein aggregation/polymerization. In the fifth part WG/PLA laminates were characterized for the purpose of improving the water barrier properties. The lamination was performed at 110°C and scanning electron microscopy showed that the laminated films were uniform in thickness. The laminates significantly suppressed the mass loss and showed promising water vapor barrier properties in humid conditions indicating possible applications in packaging. The final part addresses the development of injection molding processes for WG. Injection-molded nanocomposites of WG/MMT were also characterized. WG sheets were successively processed using injection molding and the process temperatures were found to preferably be in a range of 170-200°C, which was varied depending on the sample compositions. The clay was found to enhance the processability, being well dispersed in the matrix. The natural clay increased the tensile stiffness, whereas the modified clay increased the surface hydrophobicity. Both clays decreased the Tg and increased the thermal stability of the nanocomposites. The overall conclusion was that injection molding is a promising method for producing WG items of simple shapes. Further studies will reveal if gluten can also be used for making more complex shapes.

  • 50.
    Chondrogiannis, Georgios
    KTH, School of Chemical Science and Engineering (CHE).
    Pretreatmenteffect on induction time and polymorphic outcome of tolbutamide crystallizationin 1-propanol2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this project, the effect of solution thermal and structural history on nucleation was investigated. Many researchers have shown that temperature and duration of pretreatment has an influence on induction time, polymorphic outcome and metastable zone width. Here, solution of tolbutamide in 1-propanol was first prepared with same conditions, to “standardize” and control the initial solution history. Next, pretreatment of varied duration and temperature was applied to introduce different solution history. Then, nucleation began in 9℃, and induction time and polymorphic outcome were measured. Two batches of 30 isolated nucleation experiments each, were done per set of conditions. The results showed an impact on induction time and polymorphic outcome. However, this change cannot be clearly correlated with the conditions of pretreatment. Furthermore, the deviation between series of experiments that were performed under the same set of conditions, showed that the parameters affecting induction time and polymorphism were not controlled sufficiently to reach a safe conclusion.

    Moreover, the effect of solution filtration right before nucleation was investigated. This filtration step decreased experimental induction time from 160 minutes to less than 5. It is possible that this filtration step removed the solution’s structural memory, which accelerated nucleation. However, the effect of evaporation on concentration for example, or other parameters was not investigated.

    Furthermore, the effect of using filtration with 0.1 and 0.2 μm filters was examined. It was found that using 0.1 filter results in decreased median induction time by a factor of 4. Finally, filtration before standardization resulted in a 1.5% increase in concentration compared to solution that was not filtered. Filtration with 0.1 μm filter before standardization decreased median induction time by a factor of 4, as compared to using a 0.2 μm filter.

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