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  • 251.
    Jareman, Fredrik
    Luleå tekniska universitet.
    MFI-molecular sieve membranes: synthesis, characterization and modelling2002Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This work concerns evaluation by permeation measurements and modeling of thin (<2µm) MFI molecular sieve membranes and, to a smaller extent, synthesis of such materials. The membranes have been synthesized on graded a-alumina microfiltration filters using The seed film method. Scanning electron microscopy and x-ray diffraction were used for characterization in addition to permeation measurements. Mathematical models describing membrane flux for real membranes and defect distributions were developed. Defect distributions were calculated from porosimetry data and were further used for prediction of single gas permeation characteristics for real membranes. The models confirm the experimental findings, with respect to ideal selectivities as a measurement of membrane quality. Membrane permeation simulations indicate increasing ideal selectivities, with increasing film thickness, for quotients containing SF6. Thereby a high quality membrane could possess low ideal selectivities. This finding was confirmed by comparing experimental data of several membranes with varying thickness. The correlation between multi component separation data and commonly used quality criteria was investigated. It was found that commonly used single gas permeation quotients (ideal selectivity) between light inorganic gases, especially those containing sulphurhexaflouride (SF6), is less appropriate for membrane quality measurement. The porosimetry experiment showed on the other hand a good agreement between experimental data and separation performance of the membranes, as expected. ZSM-5 membranes with low aluminum content and silicalite-1 membranes with similar material properties, such as defect distribution and thickness were evaluated with multi component hydrocarbon isomers permeation. The ZSM-5 membrane had lower permeances and a slightly better butane isomer separation performance than the silicalite-1 membrane. The latter membrane showed a minimum in separation selectivity between two C6 isomers whereas the ZSM-5 membrane showed an almost constant selectivity, independent of temperature, but with lower permeances. ZSM-5 membranes with a high aluminum content catalyzed the formation of diethylether and ethylen at temperatures exceeding 150°C from a water/ethanol mixture. The membrane separated a mixture of C4 isomers with good performance at elevated temperatures. However these membranes suffered from temperature instability problems.

  • 252.
    Jareman, Fredrik
    Luleå tekniska universitet.
    Properties and modeling of MFI membranes2004Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The permeation properties of thin (<2µm) film MFI molecular sieve membranes have been studied in the present work and a model has been developed. The synthesis of such materials has been studied to a smaller extent. The films have been grown on graded a-alumina microfiltration filters using a seeding method. Scanning electron microscopy and x-ray diffraction were used in addition to permeation measurements for characterization of the materials. In particular, a simple and unique model describing single component permeation was developed. The model is a combination of simple and basic equations for permeation and adsorption. The important defect distribution of the membrane and the properties of the support are measured in separate experiments. The model is unique since it is accounting for the effect of defects and support on the permeation properties. The model can adequately describe the performance of various MFI membranes. The model indicates mass transfer limitations of the supports that strongly affect, for instance, permeance ratios. It was also found that these ratios are dependent on crystallographic orientation, film thickness and experimental conditions in addition to the amount of defects. Permeance ratios can thus only be used to compare membranes with similar morphology and tested under similar conditions. It was found that defects formed in thicker films. Membranes prepared on masked substrates were of higher quality than membranes prepared on unmasked substrates. MFI membranes with low and varying aluminum content with similar material properties, such as defect distribution and thickness, were evaluated with multi-component hydrocarbon isomers permeation. The silicalite-1 membrane showed a minimum in separation selectivity between two C6 isomers whereas the ZSM5 membrane showed an almost constant selectivity, independent of temperature, but with lower permeances. The effect of the calcination rate on the membrane quality was investigated for silicalite-1 membranes. Based on a number of permeation characterization techniques, the membrane quality was independent of the calcination rate. It was found that the permeation properties of membranes comprised of small crystals in several layers were different from membranes comprised of one layer of larger crystals, although the quality of the membranes was similar. ZSM-5 membranes with high aluminum content showed catalytic conversion of ethanol into diethylether and ethylene under simultaneous separation of the ethanol / water azeotrope

  • 253.
    Jareman, Fredrik
    et al.
    Luleå tekniska universitet.
    Andersson, Charlotte
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    The influence of the calcination rate on silicalite-1 membranes2005Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 79, nr 1-3, 1-5 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Silicalite-1 films with a thickness of 500 nm on asymmetric α-alumina micro filtration filters were calcined at 500 °C with heating and cooling rates varying between 0.2 °C/min and 5.0 °C/min. The membranes were characterized with single gas permeation, porosimetry, and xylene isomer separation experiments. It was found that the quality of the prepared membranes was independent of the heating/cooling rate according to the single gas permeation and porosimetry characterization. Xylene isomer separation data was found to vary between the samples, but none of the variations could be attributed to the heating/cooling rate during calcination since the variations did not follow a trend but occurred randomly. It is thus concluded that the calcination rate does not influence the quality of these membranes.

  • 254.
    Jareman, Fredrik
    et al.
    Luleå tekniska universitet.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Permeation of H2, N2, He and SF6 in real MFI membranes2005Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 83, nr 1-3, 326-332 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work shows that a previously developed model for single gas permeation in real MFI membranes is applicable to an arbitrary MFI membrane with a different film thickness and defect distribution. The model can predict the flow of H2, N2 and He resonably. Deviations in SF6 flux for thick and oriented films were observed and attributed to a lower diffusion coefficient for the narrower pores in the a-direction of the MFI crystals. By guidance from the model, variations in previously reported single gas permeance ratios for selected membranes can now be attributed to variations in feed pressure, film thickness preferred orientation and defect distribution. It was found that high feed pressures and thick oriented films resulted in large single gas permeance ratios with SF6 in the denominator, even though these membranes were more defective than thinner membranes with more randomly oriented crystals. In general, single gas permeance ratios are strongly dependent on material properties and experimental conditions. These ratios can only be used for comparison of membranes with similar morphology and the ratios must be measured under identical conditions.

  • 255.
    Jareman, Fredrik
    et al.
    Luleå tekniska universitet.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Single gas permeance ratios in MFI membranes: effects of material properties and experimental conditions2005Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 82, nr 1-2, 201-207 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A previously developed mathematical model with parameters fitted to experimental data was used to study effects of material properties and experimental conditions on single gas permeance ratios of MFI membranes. The model showed that single gas permeance ratios are highly dependent on substrate morphology, feed pressure, crystallographic orientation and defects in the film. It was found that the pore size and the thickness of the substrate affected permeance ratios, due to mass transfer resistance in the substrate. The applied feed pressure also had a significant effect on the permeance ratios. This is due to differences in mass transfer resistance of the substrate and adsorption characteristics with varying feed pressures. The crystallographic orientation of the zeolite film also affected permeance ratios due to changes in diffusivity with varying orientation of the crystals in the film. Finally, the effect of defects was investigated. As expected, it was found that the permeance ratios decreased when more defects were added in the model. However, if the membrane is not very defective, the permeance ratio is much more affected by the substrate and by variation in pressure drop than by defects. The results in the present work show that single gas permeance ratios cannot be used directly as a benchmark of membrane quality unless all other parameters are kept constant.

  • 256.
    Jareman, Fredrik
    et al.
    Luleå tekniska universitet.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Creaser, Derek
    Chalmers University of Technology.
    Sterte, Johan
    Modelling of single gas permeation in real MFI membranes2004Inngår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 236, nr 1-2, 81-89 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel permeation model for flow through defects and zeolite pores in real MFI membranes, also accounting for substrate effects has been developed. Defect distributions for two types of MFI membranes were determined from porosimetry data using the model, which incorporated the Horvath Kawazoe (micropores) or the Kelvin equation (mesopores). The narrowest (1.08 nm) and also most common defects were found to be separated with a distance of 10–40 μm according to the model. Diffusion coefficients for hydrogen, helium, nitrogen and SF6 in the zeolite were further determined from single gas permeation data using the model using the independently determined defect distribution. The coefficients are consistent with values previously reported in the literature.

  • 257.
    Jareman, Fredrik
    et al.
    Luleå University of Technology.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Sterte, Johan
    Effects of aluminum content on the separation properties of MFI membranes2003Inngår i: Separation and Purification Technology, ISSN 1383-5866, E-ISSN 1873-3794, Vol. 32, nr 1-3, 159-163 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    MFI membranes with almost identical film thickness and defect distribution but different Si/Al ratio were evaluated by separation of butane and hexane isomers. Film thickness was evaluated by SEM and defect distribution by porosimetry. When the temperature was varied, the membranes showed similar separation trends for butanes, but clear differences were observed for hexane separation. The hexane separation factor varied with temperature for the silicalite-1 membrane but was constant for the ZSM-5 membrane. It is believed that this difference may be a result of differences in adsorption properties.

  • 258.
    Jiang, Junfei
    et al.
    Chinese Academy of Sciences (CAS), China.
    Lang, Lin
    Chinese Academy of Sciences (CAS), China.
    Lin, Leteng
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Liu, Huacai
    Chinese Academy of Sciences (CAS), China.
    Yin, Xiuli
    Chinese Academy of Sciences (CAS), China.
    Wu, Chuangzhi
    Chinese Academy of Sciences (CAS), China.
    Partial oxidation of filter cake particles from biomass gasification process in the simulated product gas environment2018Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Filtration failure occurs when filter media is blocked by accumulated solid particles. Suitable operating conditions were investigated for cake cleaning by partial oxidation of filter-cake particles (FCP) during biomass gasification. The mechanism of the FCP partial oxidation was investigated in a ceramic filter and by using thermo-gravimetric analysis through a temperature-programmed route in a 2 vol.% O2–N2 environment. Partial oxidation of the FCP in the simulated product gas environment was examined at 300–600°C in a ceramic filter that was set and heated in a laboratory-scale fixed reactor. Four reaction stages, namely drying, pre-oxidation, complex oxidation and non-oxidation, occurred in the FCP partial oxidation when the temperature increased from 30°C to 800°C in a 2 vol.% O2–N2 environment. Partial oxidation was more effective for FCP mass loss from 275 to 725°C. Experimental results obtained in a ceramic filter indicated that the best operating temperature and FCP loading occurred at 400°C and 1.59 g/cm2, respectively. The FCP were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy and Brunaeur–Emmett–Teller before and after partial oxidation. Fourier-transform infrared spectroscopy analysis revealed that partial oxidation of the FCP can result in a significant decrease in C–Hn (alkyl and aromatic) groups and an increase in C=O (carboxylic acids) groups. The scanning electron microscopy and Brunaeur–Emmett–Teller analysis suggests that during partial oxidation, the FCP underwent pore or pit formation, expansion, amalgamation and destruction.

  • 259. Jiang, Xi
    et al.
    Kraft, Markus
    Yan, Jinyue
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Selected papers from the Twelfth International Conference on Combustion and Energy Utilisation (12th ICCEU) Preface2015Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 156, 747-748 s.Artikkel i tidsskrift (Annet vitenskapelig)
  • 260.
    Joakim, Gustavsson
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Niclas, Lager
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Absorption av CO2 i ammoniaklösning2017Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    I detta arbete studeras absorption av växthusgasen koldioxid (CO2) i ammoniaklösning. Målet med arbetet är att undersöka hur väl teknik med vegetabilisk olja kan förhindra avdunstning av ammoniaklösning vid absorptionen och på så vis främja grön kemi. En jämförelse görs sedan med en mer beprövad teknik med nedkylning. Därefter undersöks vilka salter som fälls ut vid absorptionen vid de båda teknikerna samt olika koncentration ammoniak (NH3).

    Genom att blanda ammoniak, etanol (C2H5OH) och vatten (H2O) i olika förhållanden i ett absorptionstorn erhölls den absorberande lösningen. CO2 i gasform fördes sedan in i reaktorn. I genomförda experiment gav teknik med vegetabiliskt oljemembran samma eller lägre materialförlust av ammoniaklösning som teknik med nedkylning.

    Högre halt av etanol innebar sänkt löslighet av ammoniumsalter vilket gav större utfällning av salter i utförda experiment. Detta kan observeras genom att jämföra kristallvikten i utförda experiment.

    Kristallerna analyserades med röntgendiffraktion (XRD). Salterna kunde identifieras genomatt jämföra erhållet resultat med standardprov från litteratur. Dock fanns avvikelser mellanresultatet och standardprov, vilket gjorde analysen svårtolkad.

  • 261.
    Johansson, Maria
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Kemiteknik.
    Jansson, Linda
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Kemiteknik.
    Elektrolytisk reduktion av zink vid reningsprocess2007Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    When cylinders for motor saws are manufactured there are high demands on the cylinders strength and wearing qualities. Aluminum is a material with low density and is used by Husqvarna AB for their motor saw cylinders. The aluminum is strengthening with nickel that is attached to the cylinders through electrolysis. When aluminum is in contact with oxygen a film of oxide is formed. To eliminate the oxide and to prevent formation of new oxide zinc is used. The cylinders are dipped into a bath of zinc before they pass on to a pre-nickel process, which purpose is to remove the excess of zinc so the “real” nickel process won’t be contaminated. In the process there is a selective bath where zinc is precipitated on sheet-metals through electrolysis. The problem is that while zinc is precipitated so is nickel and in a much greater extend, about 1 % zinc and 99 % nickel.

    Husqvarna AB needs a technique to increase precipitation of zinc and reduce the precipitation of nickel. A small copy of the selective bath was constructed where adjustments of different parameters were possible. In the bath there was an anode of nickel, a cathode, process liquid, a pump for stirring and a plant installation from an aquarium for the temperature. In the bath different voltages, distance between anode – cathode and different sheets of metal were tested. Every test were in progress for about three days and then pieces of sheet-metals were cut and sent for analysis of zinc/nickel percentage.

    A couple of the tested sheet-metals didn’t work and the ones that did work showed no special difference in zinc/nickel percentage. An increase in distance between the anode and cathode showed a small difference but not much. The alteration that showed to be most effective was to decrease the voltage. The normal voltage is 2, 8 V but when it was decreased to 2, 0 V it gave a much better result. The layer on the sheet-metal showed to contain 12 % zinc and 88 % nickel. A couple of other tests were performed with decreased voltage but no one gave as good result as 2, 0 V. If Husqvarna AB shall be able to use a lower voltage they need a greater cathode surface then they have today. That is because of the lower reaction rate. The lower reaction rate conducts an increasing amount of zinc in the bath and an electrolysis that doesn’t work completely.

    Other methods for precipitation could have been tested e.g. change of anode, precipitation of zinc as a salt or a powder that could have been filtrated or a process that reduces the excess of zinc. To test any of these methods big changes in the process structure would be needed which costs both time and money. The authors therefore concluded that the best thing for Husqvarna AB to do is to increase the cathode surface by connecting another bath next to the existent.

  • 262.
    JOOS LINDBERG, JOHAN
    KTH, Skolan för kemivetenskap (CHE).
    Design of an Advanced Oxidation Process for the Decomposition of PFAA2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The process of designing, constructing, and evaluating a novel catalyzed AOP (Advanced oxidation process) for decomposition of PFAAs (Perfluorinated alkyl acids) is covered in this master thesis study. A complete water treatment system with the capacity of treating polluted water was designed and constructed. Various parameters were investigated regarding the potential of the process to degrade PFAAs. A significant reduction of PFOS (perfluorooctanesulfonic acid) level (80 %) was achieved during the trial. Further studies are required to examine the main degradation mechanisms to improve the process.

  • 263.
    Ju, Minhua
    et al.
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing Tech University.
    Li, Yupeng
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing Tech University.
    Yu, Liang
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Wang, Chongqing
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing.
    Zhang, Lixiong
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing.
    Preparation of size-controllable monodispersed carbon@silica core-shell microspheres and hollow silica microspheres2017Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 247, 75-85 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Size-controllable monodispersed carbon@silica core-shell microspheres and hollow silica microspheres were prepared in a simple homemade T-type mixer by polymerization of furfuryl alcohol (FA) and hydrolysis of TEOS in H2SO4 water phase microdroplets to obtain polyfurfuryl alcohol (PFA)@silica microspheres, followed by carbonization and calcination. The FA and TEOS diffuse into the water phase from an oil phase. The flow rates of oil and water phase were 4 and 2 ml h−1, respectively. It was found that the concentration of FA has a more significant effect on the diameter of carbon@silica core-shell microspheres than TEOS due to the template effect of the PFA core. However, the diameter of the hollow silica microspheres was influenced by the concentration of TEOS more significantly. The obtained core-shell microspheres and hollow silica microspheres have large surface area of 555 and 769 m2 g−1, respectively. The hollow silica microspheres have both microporous and mesoporous structure, and the percentage of mesoporous volume was as high as 89%. In addition, based on the study results, a rational formation process of the carbon@silica core-shell microsphere and hollow silica microspheres was assumed.

  • 264.
    Kangas, Jani
    et al.
    University of Oulu.
    Sandström, Linda
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Malinen, Ilkka
    University of Oulu.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Tanskanen, Juha
    University of Oulu.
    Maxwell-Stefan modeling of the separation of H2 and CO2 at high pressure in an MFI membrane2013Inngår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 435, 186-206 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present study, a Maxwell-Stefan based model was developed for the separation of CO2 from H2 at high pressure in an MFI membrane. The usage of the Vignes interpolation formula for mixture surface diffusivities together with the IAST (ideal adsorbed solution theory) using bulk gas phase fugacities for mixture adsorption proved to be a feasible combination for this case. Both the effects of defects in the zeolite film and the mass transfer resistance caused by the support layers were studied and included in the model. Only pure component experimental data was used in the model building to predict the gas mixture permeation. The fitted diffusion parameters were in line with the literature values. The occupancy fraction dependence of CO2 surface diffusivity was utilized for the first time in the prediction of binary separation of H2/CO2 at high pressure on a real MFI membrane. Usage of an occupancy fraction dependence for CO2 surface diffusivity improved the model predictions. The adsorption parameter fitting for hydrogen based on the permeation measurements resulted in a feasible adsorption model, but should be used with caution. The model predicts binary separation measurement results relatively well. Both defects and support have a noticeable impact on the overall performance of the membrane.

  • 265.
    Kantarelis, Efthymios
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Catalytic Steam Pyrolysis of Biomass for Production of Liquid Feedstock2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The current societal needs for fuels and chemical commodities strongly depend on fossil resources. This dependence can lead to economic instabilities, political problems and insecurity of supplies. Moreover, global warming, which is associated with the massive use of fossil resources, is a dramatic “collateral damage” that endangers the future of the planet.

    Biomass is the main renewable source available today that can, produce various liquid, gaseous and solid products. Due to their lignocellulosic origin are considered CO2 neutral and thus can generate CO2 credits. Biomass processing can meet to the challenge of reducing of fossil resources by producing a liquid feedstock that can lessen the “fossil dependence” and /or meet the increased demand via a rapidly emerging thermochemical technology: pyrolysis.

    The ultimate goal of this process is to produce liquid with improved properties that could directly be used as liquid fuel, fuel additive and/or feedstock in modern oil refineries and petrochemical complexes.

    However, the liquids derived from biomass thermal processing are problematic with respect to their handling and end use applications. Thus, alternative routes of advanced liquid feedstock production are needed. Heterogeneous catalysis has long served the oil refining and petrochemical industries to produce a wide range of fuels and products. The combination of biomass pyrolysis and heterogeneous catalysis (by bringing in contact the produced vapours/liquids with suitable catalysts) is a very promising route.

    In this dissertation, the exploitation of biomass to produce of liquid feedstock via pyrolysis over a multifunctional catalyst and in a steam atmosphere is investigated. 

    Steam pyrolysis in a fixed bed reactor demonstrated that steam can be considered a reactive agent even at lower temperatures affecting the yields and the composition of all the products. The devolatilisation accelerates and the amount of final volatile matter in the char.

    Fast pyrolysis in the presence of steam results in improved and controlled thermal decomposition of the biomass; higher liquid yields and slightly deoxygenated liquid products are also obtained.

    Steam pyrolysis over a bi-metallic Ni-V catalyst can produce liquids of improved quality (lower O content) and also provide routes for selective deoxygenation. However, a decrease in liquid yield was observed.

    The combination of metal and acid catalysts (Ni-V/HZSM5) shows enhanced deoxygenation activity and increased H preservation in the produced liquid. The final O content in the liquid was 12.83wt% at a zeolite (HZSM5) loading of~75wt%; however, the yield of the obtained liquid was substantially decreased. Moreover, increased coke formation on the catalyst was observed at highest zeolite rate.

    The increased catalyst space time (τ) results in a lower liquid yield with reduced oxygen (7.79 wt% at τ =2h) and increased aromatic content. The coke deposited per unit mass of catalyst is lower for longer catalyst space times, while the char yield seems to be unaffected.

    The evaluation of the stability of the hybrid catalyst showed no significant structural defects and activity loss when the catalyst was regenerated at a low temperature (550οC).

  • 266.
    Kantarelis, Efthymios
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blasiak, Wlodzimierz
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Biomass pyrolysis  for energy and fuels production2013Inngår i: Technologies for Converting Biomass to Useful Energy: Combustion, Gasification, Pyrolysis, Torrefaction and Fermentation / [ed] Erik Dahlquist, CRC Press, 2013, 245-277 s.Kapittel i bok, del av antologi (Fagfellevurdert)
  • 267.
    Karim, Zoheb
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Claudpierre, Simon
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Nanocellulose based functional membranes for water cleaning: Tailoring of mechanical properties, porosity and metal ion capture2016Inngår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 514, 418-428 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multi-layered nanocellulose membranes were prepared using vacuum-filtration of cellulose nanofibers (CNF) suspensions followed by dip coating with cellulose nanocrystals having sulphate (CNCSL) or carboxyl surface groups (CNCBE). It was possible to tailor the specific surface area, pore structure, water flux and wet strength of the membranes based on drying conditions and acetone treatment. CNF coated with CNCBE showed the highest a tensile strength (95 MPa), which decreased in wet conditions (≈3.7 MPa) and with acetone (2.7 MPa) treatment. The water dried membranes showed pore sizes in nanofiltration range (74 Å) from liquid nitrogen adsorption/desorption data and the acetone treatment increased the average pore sizes to tight ultrafiltration range (194Å) with a concomitant increase (7000%) of the BET surface area. The water flux, also increased from zero to 25 Lm-2h-1 at a pressure differential of 0.45 MPa, for acetone treated ones. The membranes irrespective of the surface functionality showed exceptional capability (≈100%) to remove Ag+, Cu2+ and Fe3+ ions from mirror industry effluents. Surface adsorption followed by microprecipitation was considered as the possible mechanism of ion removal, which opens up a new generation of ultrafiltration membranes with high selectivity towards ions and low-pressure demands.

  • 268.
    Karim, Zoheb
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Chitosan based nanocomposite membranes with cellulose nanowhisker as nanoadditive2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Biobased nanocomposite membranes were prepared using chitosan as te matrix and cellulose nano whisker as the reinforcing phase. Cellulosee production. Atomic force microscopy of the nanowhiskers showed diameters of 10 -20nm and lengths of 250 - 350nm. Nanocomposites were prepared in 1:1, 1:2 and 1:3 ratios to investigate the effect of nanoadditive concentration on the membrane properties. The nanocomposites were prepared by solution mixing followed by freeze-drying, to obtain porous structures with high degree of internal surface area. These nanocomposites were further treated with ammonia vapours to prepare the crosslinked nanocomposites and thereby stabilize it towards moisture and pH variations. The morphology, surface area, crystallinity, porosity, and mechanical properties of prepared membranes were studied. The effect of the nanocomposite composition, crosslinking and the pore size distribution on the water transport through the membranes was also evaluated.

  • 269.
    Karim, Zoheb
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Nanoporous membranes with cellulose nanocrystals as functional entity in chitosan: removal of dyes from water2014Inngår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 112, 668-676 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fully biobased composite membranes for water purification were fabricated with cellulose nanocrystals (CNCs) as functional entities in chitosan matrix via freeze-drying process followed by compacting. The chitosan (10 wt%) bound the CNCs in a stable and nanoporous membrane structure with thickness of 250-270 μm, which was further stabilized by cross-linking with gluteraldehyde vapors. Scanning electron microscopy (SEM) studies revealed well-individualized CNCs embedded in a matrix of chitosan. Brunauer, Emmett and Teller (BET) measurements showed that the membranes were nanoporous with pores in the range of 13-10 nm. In spite of the low water flux (64 L m-2 h-1), the membranes successfully removed 98%, 84% and 70% respectively of positively charged dyes like Victoria Blue 2B, Methyl Violet 2B and Rhodamine 6G, after a contact time of 24 h. The removal of dyes was expected to be driven by the electrostatic attraction between negatively charged CNCs and the positively charged dyes.

  • 270.
    Karim, Zoheb
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Kokol, Vanja
    University of Maribor, Institute for Engineering Materials and Design, Smetanova ul. 17, SI-2000 Maribor, Slovenia.
    Wei, Jiang
    Alfa Laval Nakskov A/S, Business Center Membranes, Stavangervej 10, DK-4900, Nakskov, Denmark.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    High-flux affinity membranes based on cellulose nanocomposites for removal of heavy metal ions from industrial effluents2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 25, 20644-20653 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fully biobased affinity membrane processing and its application in the removal of heavy metal ions from mirror industry effluents were successfully demonstrated; indicating the potential use of these membranes in point-of-use or point-of-entry water cleaning products that are cheap, environmentally friendly and efficient. Layered cellulose nanocomposite membranes were fabricated using cellulose microfiber sludge as a support layer and cellulose nanocrystals (CNCSL, CNCBE or PCNCSL) in a gelatin matrix as the functional layer. Scanning electron microscopy (SEM) studies revealed the bi-layered morphology of the membrane and well-individualized nanocelluloses in the functional layer. Bubble point measurements confirmed the membrane pore structure in the microfiltration range (5.0-6.1 μm), which provided very high water permeability (900-4000 L h-1 m-2) at <1.5 bars. A tensile strength of 16 MPa in dry conditions and a wet strength of 0.2 MPa, was considered sufficient for use of these membranes in spiral wound modules. Mirror industry effluent laden with metal ions (Ag+ and Cu2+/Fe3+/Fe2+) when treated with cellulose nanocomposite membranes, showed high ion removal capacity, being 100% for PCNCSL followed by CNCBE than CNCSL. The removal of metal ions was expected to be driven by interactions between negatively charged nanocellulose and the positively charged metal ions.

  • 271.
    Karim, Zoheb
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Cellulose nanocrystals based nanocompositemembranes for water purification: Process-Property correlation2015Konferansepaper (Annet vitenskapelig)
  • 272.
    Karim, Zoheb
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Fully biobased nanocomposite membranes: removal of heavy metals from polluted water2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Biobased nanoparticles viz cellulose nanocrystals (CNCs) and cellulose nanofiber (CNFs) isolated by mechanical process (grinding) were used to fabricate of fully biobased nanocomposite membranes. Biobased nanofibers were used as support layer via a very simple process of vacuum filtration was used for the fabrication of CNF support layer. In order to coat CNCs or CNCbio on the two sides to CNF layer, the membrane was dipped in a solution of cellulose nanocrystals. Scanning electron microscopy (SEM) confirmed the infusion of functional layer within supportive layer. Tensile strength was measured in dry as well as in wet conditions, illustrated mechanical performances compareble to commercially available membranes. To increase the flux, membranes were treated with acetone for 24 and 72 h. The drastic increase in the flux for acetone treated membranes confirmed the discontinuities of hydrogen . The membranes succefully removed two metal ions Ag+ and As3- from real wastewater, from mirror making and mining industries respectively, within Europe. Complete removal of Ag+ was reported after 24 h of incubation. The study concludes that, the developed membranes having good mechanical stability in wet conditions, high water flux and adsorption efficiency are potential candidates for heavy metal ion remediation of industrial effluents.

  • 273.
    Karimi, Somayeh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Korelskiy, Danil
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mortazavi, Yadollah
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Khodadadi, Abbas Ali
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Sardari, Kaymar
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Esmaeili, Mohammad
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Antzutkin, Oleg
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    High flux acetate functionalized silica membranes based on in-situ co-condensation for CO2/N2 separation2016Inngår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 520, 574-582 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Acetate-functionalized silica membranes were prepared via co-condensation. The molar ratio of functional groups in the silica matrix was varied in the range of 0–0.6, denoted by x. The presence of functional groups bonded to the silica network was revealed by FTIR and 29Si and 13C solid-state NMR analysis. The stability of the groups was studied by TG analysis. The membranes were evaluated for CO2/N2 mixture separation in a temperature range of 253–373 K using a feed pressure of 9 bar and a sweep gas kept at atmospheric pressure on the permeate side. The membranes were found to be CO2-selective at all the conditions studied. The highest observed selectivity was 16 for x=0.4, with a CO2 permeance of 5.12×10−7 mol s−1 m−2 Pa−1. For x=0.2, a permeance of as high as 20.74×10−7 mol s−1 m−2 Pa−1 with a CO2/N2 selectivity of 7.5 was obtained. This permeance is the highest reported for CO2/N2 separation using functionalized silica membranes. It is proposed that the separation mechanism between CO2 and N2 was the preferential adsorption of CO2, which inhibited adsorption and permeation of N2 through the silica pore network. Permporometry results revealed that as the loading of functional groups increased, the He permeance decreased. It was also indicated that the quantity of micropores in the functionalized membrane was higher than that in the parent silica membrane.

  • 274.
    Karimi, Somayeh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Korelskiy, Danil
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Yu, Liang
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Khodadadi, Abbas Ali
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Mortazavi, Yadollah
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Esmaeili, Mohammad
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    A simple method for blocking defects in zeolite membranes2015Inngår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 489, 270-274 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The abatement of defects in zeolite membranes is essential for achieving high selectivity. In the present work, a simple and effective method for blocking defects in ultra-thin (ca. 0.5 μm) MFI zeolite membranes has been developed. The method is based on deposition of an ultra-thin (∼15 nm) layer of amorphous silica on the top surface of the membrane. Permporometry data indicated that the amount of defects, especially defects larger than 4 nm, in the membranes was significantly reduced after the modification. In mixture separation experiments, the CO2/H2 separation factor increased dramatically after blocking the defects in a defective membrane that was selected for the experiments. For instance, at 263 K and 9 bar feed pressure, the CO2/H2 separation factor increased from 8.5 to 36 after modification of the membrane, whereas the CO2 flux only decreased by ca. 40%.

  • 275.
    Karimineghlani, Parvin
    et al.
    Texas A&M University, Department of Material Science and Engineering, College Station, TX 77843, USA.
    Karimi Neghlani, Paria
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Azadmehr, Amirreza
    Amirkabir University of Technology, Department of Mining and Metallurgical Engineering,Tehran, Iran, 15875-4413.
    Optimization of lead ions adsorption on hydrolyzed polyacrylonitrile fibers using central composite design2017Inngår i: Desalination and Water Treatment, ISSN 1944-3994, E-ISSN 1944-3986, Vol. 83, 133-143 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Optimization of lead ions (Pb++) adsorption on the hydrolyzed polyacrylonitrile (PAN) fibers was reported by using statistical approach. Electrospinning of PAN solutions in dimethylformamide (DMF) was performed with different concentrations. The electrospun fibres, with various diame-ters, were then hydrolyzed in a sodium hydroxide solution (NaOH) for different reaction times and temperatures. Response surface methodology (RSM) helped optimizing the hydrolysis reaction con-ditions to maximize the adsorption capacity of the PAN fibers. The maximum value of adsorption capacity was experimentally determined to be 141 mg/g with the optimized values of hydrolysis reaction time, temperature and fiber diameter being 61.6°C, 82.1 min and 280 nm, respectively. The as-prepared electrospun fibers, hydrolyzed fibers and fibers after adsorption process were charac-terized by scanning electron microscope (SEM). Experimental adsorption data fit very well with the Langmuir isotherm model. It was found that Pb++ ions adsorption on the nanofibers was 20 times higher than that on microfibers under the same conditions. Adsorption kinetics followed the second order kinetics model. © 2017 Desalination Publications. All rights reserved.

  • 276.
    Karlsson, Christer
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Avelin, Anders
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    New Methods for Adaptation to Degeneration in Process Models for Process Industries2009Inngår i: Chemical Product and Process Modeling, Vol. Vol. 4, nr : Iss. 1, , Article 25.- s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The implementation of model-based control and diagnostics suffer strongly from the fact that models deteriorate as a function of process and sensor deterioration. Also, changes in the raw material (i.e. wood) may occur and often the process control is not addressing these variations in reality. It is thus vital for the model system to be robust in the sense that it is transparent and easy for the operator to maintain. Robustness is essential in many parts of the system, including measurement, process model validation, the ability of the model to adapt to changes in the process, optimization algorithms, and of course the model itself. In this paper, we first show three real-life applications of the utilization of models for diagnostics and control. Thereafter conditions for on-line adaptation of the models are discussed. The challenges when designing such a system are in achieving operator confidence, filtering of misleading measured data, adaptation of process parameters when the process parameters change, and combining validation of measurements and process models. These challenges are met by using a combination of physical and statistical models and methods based on them such as model predictive control (MPC) and parameter estimation. The model should be maintained by a qualified engineer who should be able to explain the system to the operator so that it is understood and confidence can be maintained.

  • 277.
    Kasedde, Hillary
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mekanisk metallografi.
    Characterization of Raw Materials for Salt Extraction from Lake Katwe, Uganda2013Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Uganda is well endowed with economic quantities of salt evident in the interstitial brines and evaporite deposits of Lake Katwe, a closed saline lake located in the western branch of the great East African rift valley. Currently, rudimentally methods of salt mining based on solar evaporation of brine continue to be used for salt extraction at the lake. These have proved to be hazardous and unsustainable to the salt miners and the environment. In this work, literature concerning the occurrence of salt and the most common available technologies for salt extraction is documented. Field studies were undertaken to characterize the salt lake deposit and to devise strategies of improving salt mining and extraction from the salt lake raw materials. The mineral salt raw materials (brines and evaporites) were characterized to determine their physical, chemical, mineralogical, and morphological composition through field and laboratory analyses. In addition, laboratory extraction techniques were undertaken to evaluate possibilities of future sustainable salt extraction from the lake deposit. Also, PHREEQC simulations using Pitzer models were carried out to determine the present saturation state of the lake brine and to estimate which salts and the order in which they precipitate from the brine upon concentration by evaporation.

    Results reveal that the raw materials from the salt lake contain substantial amounts of salt which can be commercialized for optimum production. The brines are highly alkaline and rich in Na+, K+, Cl-, SO42-, CO32-, and HCO3-. Moreover, they contain trace amounts of Mg2+, Ca2+, Br-, and F-. The lake is hydro-chemically of a carbonate type with the brines showing an intermediate transition between Na-Cl and Na-HCO3 water types. The evaporites are composed of halite mixed with other salts such as hanksite, burkeite, trona etc, with their composition varying considerably within the same grades. The laboratory extraction experiments indicate that various types of economic salts such as thenardite, anhydrite, mirabilite, burkeite, hanksite, gypsum, trona, halite, nahcolite, soda ash, and thermonatrite precipitate from the brine of Lake Katwe. The salts crystallize in the order following the sequence starting with sulfates, followed by chlorides and carbonates, respectively. Moreover, thermodynamic modeling in PHREEQC accurately predicted the solubility and sequence of the salt precipitation from the lake brine. Understanding the sequence of salt precipitation from the brine helps to control its evolution during concentration and hence, will lead to an improved operating design scheme of the current extraction processes. The work providesinformation towards future mineral salt exploitation from the salt lake.

     

  • 278.
    Kasedde, Hillary
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mekanisk metallografi.
    Towards the Improvement of Salt Extraction from Lake Katwe Raw Materials in Uganda2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Uganda is well endowed with economic quantities of mineral salts present in the interstitial brines and evaporite deposits of Lake Katwe, a closed (endorheic) saline lake located in the western branch of the great East African rift valley. Currently, rudimentally and artisanal methods continue to be used for salt extraction from the lake raw materials. These have proved to be risky and unsustainable to the salt miners and the environment and they have a low productivity and poor product quality. This work involves the investigation of the salt raw materials that naturally occur in the brines and evaporites of Lake Katwe. The purpose is to propose strategies for the extraction of improved salt products for the domestic and commercial industry in Uganda.

    The literature concerning the occurrence of salt and the most common available technologies for salt extraction was documented. Also, field investigations were undertaken to characterize the salt lake deposits and to assess the salt processing methods and practices. The mineral salt raw materials (brines and evaporites) were characterized to assess their quality in terms of the physical, chemical, mineralogical, and morphological composition through field and laboratory analyses. An evaluation of the potential of future sustainable salt extraction from the lake deposits was done through field, experimental, and modeling methods. Moreover, the mineral solubilities in the lake brine systems and dissolution kinetics aspects were investigated.

    The results reveal that the salt lake raw materials contain substantial amounts of salt, which can be commercialized to enable an optimum production. The brines are highly alkaline and rich in Na+, K+, Cl-, SO42-, CO32-, and HCO3-. Moreover, they contain trace amounts of Mg2+, Ca2+, Br-, and F-. The lake is hydro-chemically of a carbonate type with the brines showing an intermediate transition between Na-Cl and Na-HCO3 water types. Also, the evaporation-crystallization is the main mechanism controlling the lake brine chemistry. These evaporites are composed of halite mixed with other salts such as hanksite, burkeite, trona etc, but with a composition that varies considerably within the same grades. The laboratory isothermal extraction experiments indicate that various types of economic salts such as thenardite, anhydrite, mirabilite, burkeite, hanksite, gypsum, trona, halite, nahcolite, soda ash, and thermonatrite exist in the brine of Lake Katwe. In addition, the salts were found to crystallize in the following the sequence: sulfates, chlorides, and carbonates.

    A combination of results from the Pitzer’s ion-interaction model in PHREEQC and experimental data provided a valuable insight into the thermodynamic conditions of the brine and the sequence of salt precipitation during an isothermal evaporation. A good agreement between the theoretical and experimental results of the mineral solubilities in the lake brine systems was observed with an average deviation ranging between 8-28%. The understanding of the mineral solubility and sequence of salt precipitation from the brine helps to control its evolution during concentration. Hence, it will lead to an improved operating design scheme of the current extraction processes. The dissolution rate of the salt raw materials was found to increase with an increased temperature, agitation speed and to decrease with an increased particle size and solid-to-liquid ratio. Moreover, the Avrami model provided the best agreement with the obtained experimental data (R2 = 0.9127-0.9731). In addition, the dissolution process was found to be controlled by a diffusion mechanism, with an activation energy of 33.3 kJ/mol.

    Under natural field conditions, the evaporative-crystallization process at Lake Katwe is influenced by in-situ weather conditions. Especially, the depth of the brine layer in the salt pans and the temperature play a significant role on the brine evaporation rates. With the optimal use of solar energy, it was established that the brine evaporation flux can be speeded up in the salt pans, which could increase the production rates. Moreover, recrystallization can be a viable technique to improve the salt product purity. Overall, it is believed that the current work provides useful information on how to exploit the mineral salts from the salt lake resources in the future.

     

  • 279.
    Kasedde, Hillary
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mekanisk metallografi.
    Bäbler, Matthäus
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Kirabira, John Baptist
    Makerere University, Kampala, Uganda.
    Tilliander, Anders
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jonsson, Stefan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mekanisk metallografi.
    Mineral recovery from Lake Katwe brines using isothermal evaporation2013Inngår i: International Mine Water Association Annual Conference 2013: Reliable Mine Water Technology / [ed] Adrian Brown, Linda Figueroa, Christian Wolkersdorfer, IMWA International Mine Water Association , 2013, 855-860 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Lake Katwe is a saline lake within the East African Rift system in Western Uganda, with a rich source of mineral salts. The present work aims at evaluating possibilities of future salt extraction from the lake deposit. An isothermal evaporation experiment was conducted on the lake brines. The precipitated salts were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. Various economic salts such as thenardite, gypsum, mirabilite, burkeite, hanksite, anhydrite, trona, halite, nahcolite, thermonatrite, and soda ash precipitate from the lake brines. The experiments also reveal the sequence of mineral salt precipitation in the order sulfates→chlorides→carbonates.

  • 280.
    Kasedde, Hillary
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Kirabira, John Baptist
    Bäbler, Matthäus
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Tilliander, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Jonsson, Stefan
    Determination and thermodynamic modeling of mineral solubilities in aqueous ternary systems at 303 KManuskript (preprint) (Annet vitenskapelig)
  • 281. Kasedde, Hillary
    et al.
    Kirabira, John Baptist
    Bäbler, Matthäus
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Tilliander, Anders
    Jonsson, Stefan
    Dissolution kinetics of natural halite from Lake Katwe (Uganda) in aqueous salt solutionsManuskript (preprint) (Annet vitenskapelig)
  • 282.
    Kasedde, Hillary
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi. Makerere University, Kampala, Uganda.
    Kirabira, John Baptist
    Bäbler, Matthäus
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Tilliander, Anders
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jonsson, Stefan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mekanisk metallografi.
    Phase developments during natural evaporation simulation of Lake Katwe brine based on Pitzer's model2014Konferansepaper (Fagfellevurdert)
  • 283.
    Kasedde, Hillary
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mekanisk metallografi.
    Kirabira, John
    Mechanical Engineering, Makerere University, Uganda.
    Bäbler, Matthäus
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Tilliander, Anders
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jonsson, Stefan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mekanisk metallografi.
    A State of the Art Paper on Improving Salt Extraction from Lake Katwe Raw Materials In Uganda2012Rapport (Annet vitenskapelig)
    Abstract [en]

    The characteristics of Katwe salt lake are briefly discussed. The lake is the largest of the eight saline lakes in the Katwe-Kikorongo volcanic field and is a major source of salt production in Uganda. Today, salt production at the lake is carried out using traditional and artisanal mining methods. Attempts to mechanize the production of domestic and commercial grade salt at the lake were unsuccessful due to the use of a wrong technology. In this paper, the most common available technologies for salt extraction from brine are described. These are divided into four broad categories, namely thermal, membrane, chemical and hybrid processes. A review of the state of the art, previous research and developments in these technologies is presented. A detailed analysis of the processes used was done based on studies reported in the literature. From the analysis, it was observed that thermal salt production processes, especially distillation and solar evaporation have the highest share in installed capacities worldwide. Membrane technologies such as Electro-dialysis, Reverse Osmosis and chemical technologies have not found wide application in the commercial salt industry. Electro-dialysis and Reverse Osmosis have been used mainly as pre-concentration processes for subsequent thermal processes. Prospects for application of hybrid systems for salt production through integration of thermal desalting processes should be investigated for better performance efficiencies and recoveries at the salt lake.

  • 284.
    Kasedde, Hillary
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi. Makerere University, Kampala, Uganda.
    Lwanyaga, Joseph
    Kirabira, John Baptist
    Bäbler, Matthäus
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Optimization of Solar Energy for Salt Extraction from Lake Katwe, Uganda2014Inngår i: Global NEST. International Journal, ISSN 1108-4006, Vol. 16, nr 6, 1152-1168 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 285. Khattab, Ibrahim A.
    et al.
    Ghaly, Montaser Y.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ali, Mohamed E. M.
    Farah, Joseph Y.
    Zaher, Fatama M.
    Badawy, Mohamed I.
    Photocatalytic degradation of azo dye Reactive Red 15 over synthesized titanium and zinc oxides photocatalysts: a comparative study2012Inngår i: Desalination and Water Treatment, ISSN 1944-3994, E-ISSN 1944-3986, Vol. 48, nr 1-3, 120-129 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanoparticle TiO2 and ZnO were prepared by facile method. The XRD pattern study shows that there is no obvious difference in crystal composition of various shapes of TiO2 and ZnO. The photocatalytic degradation of Reactive Red 15, commonly used as a textile dye, using synthesized titanium and zinc oxides was investigated. The effects of influential parameters such as initial pH, catalyst loading, initial dye concentration and addition of hydrogen peroxide were studied. The degradation efficiency was expressed by the removal of color and chemical oxygen demand (COD). The study reveals that: (1) Both catalysts, under corresponding optimal conditions, can be employed as an effective photocatalyst for the elimination of color and COD from dye wastewater. Also, ZnO is more efficient catalyst than TiO2; (2) Addition of proper amount of hydrogen peroxide improves both the decolorization and the degradation of the dye; (3) The photocatalytic degradation of Reactive Red 15, in the presence of both photocatalysts, obeyed pseudo-first order kinetics. The biodegradability ratio BOD5/COD increases from original zero up to 0.52 and 0.6 within 90 minutes irradiation time using 1 and 0.75 g/L TiO2 and ZnO, respectively.

  • 286.
    Kirabira, John Baptist
    et al.
    Makerere University.
    Kasedde, Hillary
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mekanisk metallografi. Makerere University.
    Ssemukuuttu, Dominic
    Makerere University.
    Towards the improvement of salt extraction at Lake Katwe, Uganda2013Inngår i: International Journal of Scientific and Technology Research, ISSN 2277-8616, Vol. 2, nr 1, 76-81 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The occurrence of Lake Katwe salt deposit in Western Uganda is well-known through the East African region. Production of salt from this saline lake has been practiced for decades following traditional methods; however the quality and yield of the products are poor. There are also risks of burns, as the workers get into direct contact with the brine. Detail assessment and evaluation of the mine has been done through field studies, raw sample materials analysis. Results indicate that the raw brine from the lake is rich in sodium, chloride, potassium, carbonates, sulphate ions with traces of calcium, magnesium, and bicarbonate ions. This motivates the aspiration to properly extract salts from such a rich source. The lake brines contain impurities such as organic matter and suspended solids. With increasing demand for usage of sustainable technologies for saltextraction, the present study calls for the improvement of salt extraction at Lake Katwe through optimizing the use of the current solar evaporation technique while integrating it with a mechanized chemical separation process. This would ensure better recovery and process efficiencies, low costs and simple brine pre-treatment procedures.

  • 287.
    Kirm, Ilham
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Bioenergiteknik.
    Sanati, Mehri
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Bioenergiteknik.
    Shift catalysts in biomass generated synthesis gas2006Inngår i: 12th Nordic Symposium in Catalysis-May 28-30-Trondheim-Norway, NTNU , 2006, 144-145 s.Konferansepaper (Annet vitenskapelig)
  • 288.
    Ko, Jordan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Zahrai, Said
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Vomhoff, Hannes
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Literature review of the numerical studies on transport phenomena in hydrocyclones.Manuskript (preprint) (Annet vitenskapelig)
  • 289. Kocík, Jaroslav
    et al.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Bourajoini, Hasna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Pham, Tung Ngoc
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Faculty of Science and Engineering, Industrial Chemistry & Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Hájek, Martin
    Čapek, Libor
    Screening of active solid catalysts for esterification of tall oil fatty acids with methanol2017Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 155, nr 1, 34-38 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The paper is focused on the description of the activity/selectivity of mesoporous silica based materials loaded with various types of active species in the esterification of tall oil free fatty acids. The metals such as aluminium, molybdenum, gallium and zinc, including their combinations were impregnated on the mesoporous silica, which was tested in esterification reaction. All these catalysts preserved its tall oil free fatty conversion in the first and the second catalytic cycles. However, while only insignificant amount of gallium or molybdenum was lost from the solid catalyst into the liquid phases, zinc leached from every studied solid catalyst. In contrast to impregnated gallium on mesoporous silica, which exhibited higher acidity and higher tall oil free fatty acids conversion in the first catalytic cycle, but its value was not preserved in the second catalytic test.

  • 290.
    KOLAKOWSKI, MARCIN JANUSZ
    KTH, Skolan för kemivetenskap (CHE).
    CFD simulation of fluid flow in milliliter vials used for crystal nucleation experiments2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This work investigates the fluid flow in a cylindrical millilitre vial stirred by a magnetic stirred bar using Computational Fluid Dynamic (CFD). Stirred millilitre vials are used to study nucleation phenomena and crystallization as an outline of literature study of nucleation and crystallization phenomena and the role of stirring in this process. The baffle free vial was meshed with around 500,000 cells. To simulate the stirring a rotary frame and moving walls were used. Stirring speeds were between 100 and 1000 rpm where considered, correspondently to a stirrer Reynolds number between 260 and 2600. For stirring speeds bellow 500 rpm, simulations by both the both laminar flow model and the k-ε model where run, while above 500 rpm only k-ε was used. Results of the two models were very similar indicative the adequacy of k-ε to simulate the flow even at low Reynolds. The flow shows expected circulation pattern with upwards pumping close to side walls and downwards pumping in the centre of cylindrical vial. At 1000 rpm circulation patterns expands up to the top of the vial while at 300 rpm and lower the upper half of the vial is poorly mixed. The average turbulent energy of the flow is very low comparing with the squared stirrer tip speed and the power number decrees with Reynolds number, indicating that the flow is not fully turbulent.

  • 291.
    Korelskiy, Danil
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Development of permporometry for analysis of MFI membranes2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Zeolite membranes exhibiting high flux and high selectivity are of major interest for potential future applications. In order to achieve high flux and high selectivity, the zeolite film must be thin (< 1 µm) and free from flow-through defects. The development of thin defect free zeolite membranes requires powerful tools for characterization of flow-through defects in the membranes. Permporometry is one of the most straightforward and powerful techniques for characterization of flow-through pores in ceramic membranes. In permporometry, the flow of a non-condensable gas, e.g., helium, through the membrane is monitored as a function of the activity of a strongly adsorbing compound, e.g., hydrocarbon.In the present work, MFI membranes prepared by a seeding method were characterized by permporometry using helium as the non-condensable gas and n-hexane or benzene as the adsorbing compound. In order to appreciate permporometry data, the membranes were also characterized by scanning electron microscopy (SEM), single gas permeation and separation experiments. The permporometry data were then compared to the SEM morphology of the membranes, permeances of different probe molecules and membrane separation performance.In order to determine the conditions of the permporometry experiment leading to blocking of zeolite pores, a model describing helium transport in the zeolite pores in the presence of n-hexane or benzene was developed. The model is based on percolation theory and knowledge of the adsorption isotherms and adsorption sites for n-hexane and benzene in the zeolite pores. Parameters needed in the model were estimated by Density Functional Theory (DFT) using a Local-Density Approximation (LDA), the most sophisticated theory yet applied to this system. Based on the permporometry data, it was demonstrated that the model could adequately describe helium transport in zeolite pores in the presence of the hydrocarbons.The sensitivity of the permporometry technique towards the defect size has been improved considerably. It was revealed that high quality MFI membranes prepared in the present work contained mainly micropore defects which are most like the defects in the zeolite crystal lattice (intracrystalline defects).The work has shown how permporometry data could be used to estimate the area distribution of the flow-through defects in the membranes. The results on the defect distribution were corroborated by the SEM observations and the separation experiments. The width of cracks, including support cracks, and open grain boundaries observed by SEM was in excellent agreement with the defect width estimated from permporometry data. A straightforward correlation was observed between separation data and permporometry data, i.e. membranes of higher quality according to permporometry analysis exhibited greater separation performance. Also, the permeance of molecules diffusing through defects in the membrane in the separation experiment was found to scale with the permeance of helium through the defects measured in the permporometry experiment. In addition, this work showed that single gas permeance ratios could not detect slight variations in the membrane quality. For membranes with similar however slightly different amount of defects, the ratios are mainly affected by the membrane thickness and support morphology.To summarise, the present work demonstrates that permporometry data adequately reflect membrane quality and that permporometry is a very powerful technique for MFI membrane characterization.

  • 292.
    Korelskiy, Danil
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Quality and performance of zeolite membranes2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Zeolite membranes displaying high flux and high selectivity are of major interest for potential industrial applications, such as gas and liquid separations. In order to achieve high flux and high selectivity, the zeolite membrane must be thin (< 1 µm) and free from flow-through defects. The development of thin defect-free zeolite membranes requires powerful tools for characterisation of the defects in the membranes. Permporometry is one of the most straightforward, non-destructive and powerful techniques for characterisation of flow-through pores in inorganic membranes. In permporometry, the flow of a non-adsorbing gas, e.g., helium, through the membrane is monitored as a function of the activity of a strongly adsorbing compound, e.g., hydrocarbon.The work showed how permporometry can be used to quantify defects in the mesopore range in MFI membranes. The results were in excellent agreement with SEM observations and separation experiments. For the first time, it was also shown that flow-through defects down to 0.7 nm in size in MFI membranes could be detected by permporometry and quantified using the permporometry data. The total amount of defects in high quality MFI membranes was found to be small accounting for less than 1% of the total membrane area. In turn, defects with a width below 1 nm constituted as much as 97% of the total area of defects for the best membranes. The permporometry results were consistent with SEM observations and separation experiments, demonstrating that permporometry data adequately reflect membrane quality and that the technique is a very powerful and reliable characterisation tool.This work also illustrated that single gas permeance ratios could not detect slight variations in the membrane quality. For membranes with similar however slightly different amount of defects, the ratios are mainly affected by the membrane thickness and support morphology.The MFI membranes were also evaluated for separation of dilute aqueous solutions of n-butanol and ethanol, and 1 µm zeolite X membranes were evaluated for separation of water from ethanol using pervaporation. The MFI membranes were selective to n-butanol and ethanol, whereas zeolite X membranes were selective to water. The flux observed for the MFI membranes was about 100 times higher than those previously reported for n-butanol/water and about 5 times higher than the highest reported for ethanol/water separation by pervaporation. The zeolite X membranes showed good pervaporation performance in terms of both flux and selectivity. However, both flux and selectivity were found to be reduced by a significant mass transfer resistance in the support in all the pervaporation experiments. At the same time, heat transfer limitations were found to be negligible.

  • 293.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Characterization of flow-through micropores in MFI membranes by permporometry2012Inngår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 417-418, 183-192 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Permporometry was used for the first time to characterize flow-through micropore defects down to 0.7 nm in size in MFI zeolite membranes. Helium was used as the non-adsorbing gas and n-hexane or benzene was used as the adsorbate. The helium flow through zeolite pores was estimated using percolation theory and the remaining flow was assigned to flow-through defects. The area distribution of flow-through defects was estimated from the data using a simple model and similar results were obtained using both adsorbates. The total area of defects determined using n-hexane as the adsorbate was as low as about 0.7% of the membrane area and defects with a width below 1 nm constituted 97% of the total defect area for the best membrane. The permporometry results were supported by n-hexane/1,3,5-trimethylbenzene separation experiments. The permporometry data were also consistent with HR-SEM observations indicating the presence of narrow open grain boundaries, and absence of large cracks and pinholes

  • 294.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Ye, Pengcheng
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Zhou, Ming
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    A study of CO2/CO separation by sub-micron b-oriented MFI membranes2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 70, 65475-65482 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Separation of CO2 and CO is of great importance for many industrial applications. Today, CO2 is removed from CO mainly by adsorption or physical or chemical absorption systems that are energy-intensive and expensive. Membranes are listed among the most promising sustainable and energy-efficient alternatives for CO2 separation. Here, we study CO2/CO separation by novel sub-micron b-oriented MFI zeolite membranes in a temperature range of 258-303 K and at a feed pressure of 9 bar. Under all experimental conditions studied, the membranes were CO2-selective and displayed high CO2 permeance ranging from 17 000 to 23 000 gpu. With decreasing temperature, the CO2/CO selectivity was increasing, reaching a maximum of 26 at 258 K. We also developed a mathematical model to describe the membrane process, and it indicated that the membrane separation performance was a result of selective adsorption of CO2 on the polar zeolite. The heat of adsorption of CO2 on the zeolite is more negative due to the high quadrupole moment and polarisability of the molecule as compared to CO. At the same time, diffusional coupling (correlation effects) at high adsorbed loadings was found to favour the overall CO2/CO selectivity of the membranes by reducing the diffusivity of the lighter CO molecule in the ca. 0.55 nm pores in the zeolite. The model also indicated that the separation performance was limited by the mass transfer resistance in the support and concentration polarisation on the feed side of the membrane.

  • 295.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Leppäjärvi, Tiina
    Department of Process and Environmental Engineering, University of Oulu.
    Zhou, Han
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Tanskanen, Juha
    Department of Process and Environmental Engineering, University of Oulu.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    High flux MFI membranes for pervaporation2013Inngår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 427, 381-389 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    MFI membranes with a thickness of 0.5 μm prepared on a graded α-alumina support were evaluated for separation of feed mixtures of 3 wt.% n-butanol/water and 10 wt.% ethanol/water by pervaporation. The membranes were selective to n-butanol and ethanol. The flux observed in the present work was about 100 times higher than that previously reported for n-butanol/water separation by pervaporation and about 5 times higher than that for ethanol/water separation by pervaporation. At 60 °C, the observed n-butanol/water flux was about 4 kg m−2 h−1 and the n-butanol/water separation factor was about 10 for the best membrane. At the same temperature, the membrane displayed an ethanol/water flux of ca. 9 kg m−2 h−1 and an ethanol/water separation factor of ca. 5. A mathematical model indicated significant mass transfer resistance in the support, which reduced the flux and the selectivity of the membranes.

  • 296.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Hedlund, Jonas
    Characterization of small defects in MFI membranes by permporometry, separation experiments and XHR-SEM2010Konferansepaper (Fagfellevurdert)
  • 297.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Ye, Pengcheng
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Fouladvand, Shahpar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Karimi, Somayeh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Sjöberg, Erik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Efficient ceramic zeolite membranes for CO2/H2 separation2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2015, nr 3, 12500-12506 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Membranes are considered one of the most promising technologies for CO2 separation from industrially important gas mixtures like synthesis gas or natural gas. In order for the membrane separation process to be efficient, membranes, in addition to being cost-effective, should be durable and possess high flux and sufficient selectivity. Current CO2-selective membranes are low flux polymeric membranes with limited chemical and thermal stability. In the present work, robust and high flux ceramic MFI zeolite membranes were prepared and evaluated for separation of CO2 from H2, a process of great importance to synthesis gas processing, in a broad temperature range of 235–310 K and at an industrially relevant feed pressure of 9 bar. The observed membrane separation performance in terms both selectivity and flux was superior to that previously reported for the state-of-the-art CO2-selective zeolite and polymeric membranes. Our initial cost estimate of the membrane modules showed that the present membranes were economically viable. We also showed that the ceramic zeolite membrane separation system would be much more compact than a system relying on polymeric membranes. Our findings therefore suggest that the developed high flux ceramic zeolite membranes have great potential for selective, cost-effective and sustainable removal of CO2 from synthesis gas.

  • 298.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Ye, Pengcheng
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Nabavi, Mohammad Sadegh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Selective blocking of grain boundary defects in high-flux zeolite membranes by cokin2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 16, 7295-7299 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Commercial application of zeolite membranes has been hindered by the challenge of preparing defect-free membranes. Herein, we report a facile method able to selectively plug grain boundary defects in high-flux MFI zeolite membranes by coking of iso-propanol at 350 °C. After modification, the permeance via defects was reduced by 70%, whereas that via zeolite pores was reduced by only 10%.

  • 299.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Ye, Pengcheng
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Zhou, Han
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    An experimental study of micropore defects in MFI membranes2014Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 186, 194-200 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present work, two ultra-thin MFI membranes, prepared using hydroxide and fluoride ions as mineralizing agents, respectively, were carefully examined by permporometry. The amount of micropore defects, as determined by permporometry, differed significantly between the two different membranes. For the first time, it was demonstrated that the micropore defects determined by permporometry were most likely open grain boundaries. The results were verified by direct observation of the open grain boundaries by a state-of-the-art XHR-scanning electron microscopy instrument. In addition, the permporometry data were also consistent with permeation data using 1,3,5-trimethylbenzene (TMB) as a probe molecule, separation data using an equimolar mixture of n-hexane and TMB, and nitrogen adsorption data.

  • 300.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Ye, Pengcheng
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Zhou, Han
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Correction: An experimental study of micropore defects in MFI membranes2014Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 197, 358- s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present work, two ultra-thin MFI membranes, prepared using hydroxide and fluoride ions as mineralizing agents, respectively, were carefully examined by permporometry. The amount of micropore defects, as determined by permporometry, differed significantly between the two different membranes. For the first time, it was demonstrated that the micropore defects determined by permporometry were most likely open grain boundaries. The results were verified by direct observation of the open grain boundaries by a state-of-the-art XHR-scanning electron microscopy instrument. In addition, the permporometry data were also consistent with permeation data using 1,3,5-trimethylbenzene (TMB) as a probe molecule, separation data using an equimolar mixture of n-hexane and TMB, and nitrogen adsorption data

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