[final] Kemian tekniikan korkeakoulu / CHEM

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    Treatments for enhancing accesibility an reactivity of cellulose and their analysis
    (2015) Debnath, Subham; Rantanen, Juuso; Kemian tekniikan korkeakoulu; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Maloney, Thaddeus
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    Thermodynamical modeling of alkalonamine solution
    (2013) Dominguez Alabern, Laura; Jakobsson, Kaj; Kemian laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Alopaeus, Ville
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    Methanol steam reforming for polymeric electrolyte membrane fuel cells applications
    (2013) Vidal Vázquez, Francisco de Sáles; Lehtonen, Juha; Simell, Pekka; Biotekniikan ja kemian tekniikan laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Koskinen, Jukka
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    Electrochemical oxidation of refractory gold concentrate
    (2013) Ferrer Munoz, Gerard; Rintala, Lotta; Materiaalitekniikan laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Aromaa, Jari
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    Alkaline pre-extraction of birch wood prior to alkaline pulping
    (2013) Costabel Cabrera, Luciana; Ruuttunen, Kyösti; Biotekniikan ja kemian tekniikan laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Sixta, Herbert
    The existing chemical pulp mills offer a unique starting point for the implementation of future multi-product biorefineries. For the pulp industry, the biorefining process may be envisaged as the removal and use of material that does not contribute to paper and cellulose products, particularly the material which is normally dissolved in the black liquor and combusted in the recovery boiler. In that sense, the recovery of dissolved hemicelluloses in a separate stage prior to pulping for the production of added-value products may potentially improve the overall economy of a chemical pulp mill. The alkaline extraction of hemicelluloses prior to alkaline pulping provides an additional possibility to isolate carbohydrates from wood in reasonably high yields, besides the currently widely investigated acid- and auto-catalyzed prehydrolysis. Furthermore, the use of aqueous sodium hydroxide solution in a pre-extraction process is compatible with kraft or soda-anthraquinone pulping processes, and particularly for the production of paper grade pulp, this process is more likely to preserve fibre strength properties than prehydrolysis followed by alkaline pulping. The objective of this work was the recovery of high molecular weight hemicelluloses, mainly xylan, through alkaline extraction. At the same time, the amount of co-extracted lignin was to be minimized. Birch wood chips were used for the optimization of the pre-extraction conditions. In addition to temperature and sodium hydroxide concentration, the effect of chip thickness was studied. The optimized extraction conditions were found to be NaOH concentration of 2.5 M at 95 °C. Lignin and carbohydrate mass balances were calculated for pre-extraction trials performed at these conditions. Approximately 6% of the original dry wood material was measured in the extracted liquor as polymeric xylan and 1% as co-extracted lignin. The selectively precipitated xylan revealed a weight average molecular weight (Mw) of 20 kDa as determined by size exclusion chromatography. For further purifying the extracted xylan, the diluted solution was concentrated by a factor of 8 by means of pressure-driven membrane filtration. This separation process allows the recovery of a large part of the sodium hydroxide in the permeate stream and makes a subsequent xylan precipitation via acidification more economical. The permeate stream containing the recovered sodium hydroxide may be recycled to the cooking liquor preparation. Preliminary tests confirmed that xylan can be isolated in higher purity when the pH is maintained at a higher level during the precipitation step since lignin remains more soluble under these conditions.
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    Catalytic wet oxidation of black liquor
    (2013) Viader Riera, Gerard; Melin, Kristian; Sarwar, Golam; Biotekniikan ja kemian tekniikan laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Koskinen, Jukka
    Aspects of wet air oxidation and catalytic wet air oxidation have been reviewed in this work paying special attention to the reaction mechanisms, kinetics and the industrial process. In the experimental section a set of heterogeneous catalysts have been tested in the wet oxidation of non-wood black liquor. The oxidation runs were performed batch wise in a laboratory-scale mechanically stirred slurry reactor for 1 h at a temperature of 170°C and total pressure of 12 bar. Pure oxygen was used as oxidant agent. Results showed that Fe/AC, AC and CuO promote the formation of acids, whereas CeO2 was found to be effective for the complete oxidation of black liquor. It was also observed that highly concentrated streams cause catalyst deactivation due to active sites blockage.
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    CO2 absorption enthalpies measurements for carbon capture thermodynamic model validation
    (2013) Ferrer Serrano, Norma; Uusi-Kyyny, Petri; Kemian laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Alopaeus, Ville
    The capture of carbon dioxide from post-combustion emission is one of the challenges for reducing the release of greenhouse gases into the atmosphere. It is a mature technology but studies are still needed particularly in order to reduce gas treatment costs. In the present work, densities and enthalpies of absorption of CO2 in aqueous solutions of several systems of alkanolamines were measured at 298,15K. The experiments were carried out using a flow mixing calorimetric technique (Setaram C80) that permits measuring enthalpies of absorption of CO2 in a sorbent solution as a function of loading charge (moles of CO2 per mole of amine). Measurements were performed by increasing the loading charge up to the saturation of the solution. Saturated loading point can be determined from the experimental enthalpy data and the values of enthalpies of absorption were found independents of the amine concentration. Experimental enthalpies and densities data were compared with literature values.
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    Organocatalytic enantioselective Robinson annulation
    (2013) Gillard, Laurent; Joensuu, Pekka; Kemian laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Koskinen, Ari
    The aim of the research was to find a catalytic and enantioselective way for the Robinson annulation reaction, our target molecule is the aspidospermine. The use of amino-acid is really useful in enamine chemistry, because they are chiral amino-compounds and can be easily substituted. Several primary and secondary amines were used as catalyst and a plethora of conditions were used to achieve this reaction. It was observed that the relativities of primary and secondary amine were really different indicated their mechanisms are different. No catalytic way to perform the reaction was found. It was improved and now this path allows us to reach 88% of the desired product. The catalytic way was developed with a sterically hindered catalyst. However, the conditions to achieve this are not the best. Attempts were performed to improve it, without any success. The enantioselectivities reached by those catalysts was low. The discovery of a possible interaction between the function of the catalyst and the enantioselectivity was established. However only low enantiomer excess was developed. The options are extensive, even if no very good e.e was achieved; there are still lots of opportunities in this field of research.
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    Desulfurization of heavy fuel oil for power generation
    (2013) Gamero Rodriguez, Maria del Carmen; Koskinen, Jukka; Sundell, Juha-Pekka; Biotekniikan ja kemian tekniikan laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Lehtonen, Juha
    Gasification is a technologically advanced, environmentally friendly and proven technology for disposing high sulphur heavy fuel oils by converting them into clean combustible gas products, avoiding corrosion problems and environmental emissions. Due to the high sulphur content of heavy fuel oil, it is essential to find efficient technologies to remove H2S from synthesis gas prior to its utilization within gas engines for power generation, since their absolute H2S limit is 500 ppm. This thesis intends to provide realistic solutions for clean power generation and simultaneously for the problems of heavy residues in refineries. For this purpose different approaches were adopted and presented. In the literature part, several technologies to remove H2S from synthesis gas were reviewed, such as absorption, adsorption and catalytic hydro treatment. In the experimental part a complete process of gasification, syngas purification by means of absorption and power generation was modeled and simulated with ASPEN plus. Moreover, the overall performance was studied and an economic study based on CAPEX/OPEX was performed in order to evaluate the feasibility of the process and provide reliable results.
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    Thermal decomposition of sodium acid salts from black liquor
    (2013) Guxens Valero, Montserrat; Sarwar, Golam; Melin, Kristian; Biotekniikan ja kemian tekniikan laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Koskinen, Jukka
    Biofuels production seems the better alternative to fuels consumption realized from non-renewable sources. Black liquor obtained during the pulping is a good resource, because contain a large amount of organic matter. Black liquor can be pre-treated in a partial wet oxidation process to obtain carboxylic salts. These salts can be treated to produce biofuels, such as syngas and methane. This final project is a research of different ways to obtain carboxylic salts, for example from black liquor treatment. Subsequent conversion process of carboxylic acid salts is focus in thermal decomposition process and the kinetic solid reaction study, from an experimental thermo gravimetric curve. Results comparison with literature is done to validate the methods used in this study. Kinetic triplet has been further used to predict the residence time needed in a reactor to obtain 40% conversion of the sample at 450°C and 1 bar. Thermal decomposition process has been simulated in Aspen Plus to study the energy requirements and production in the process.
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    Simulation and optimization of basic oxygen converter process using consim software
    (2012) Vallejo Vitaller, Ana; Jalkanen, Heikki; Kruskopf, Ari; Väyrynen, Petri; Materiaalitekniikan laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Louhenkilpi, Seppo
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    Influence of the molecular weight distribution of cellulose on the rheological properties of cellulose-ionic liquid solutions
    (2012) Arnoul-Jarriault, Benoit; Hummel, Michael; Puunjalostustekniikan laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Sixta, Herbert
    Ionic liquids are a novel class of solvents which have attracted a large interest from industrials and researchers side during the last few years. Indeed, their desirable properties such as high thermal stability or non-detectable vapour pressures make Ionic liquids a perfect alternative solvent to organic ones in the concept of green chemistry. Moreover, wood cellulosic fibres for textile application are nowadays in the focus of new interest due to the green aspect of wood as material. However, their manufacturing processes are environmentally questionable. Thus, an alternative process has to be found. The production of wood cellulosic textile fibre by direct dissolution of cellulose in ionic liquids (ILs) and subsequent regeneration combine two major green chemistry principles: using environmentally preferable solvents and bio-renewable feed-stocks. While it has been already proved that some ionic liquids are efficient non-derivatizing solvents for cellulose, only little is known about the rheological behaviour of cellulose-ILs solutions, which is a pre-request for processing and regenerating cellulose in the form of textile fibre. In this study, cellulose blends of different molecular mass distribution were dissolved at commercially relevant concentrations of 10 w/w % in 1-ethyl-3-methylimidazolium acetate (EMIM OAc). The dissolution performed in a vertical kneader at 80°C, showed a limited degradation of the cellulose chains. The extensional rheological properties of cellulose-EMIM OAc solutions measured with a capillary break-up extensional rheometer (CaBER), were compared to classical oscillatory shear rheology in order to study the influence of the molecular mass distribution of cellulose on rheological properties. It was observed that the high molecular weight fractions of cellulose have an impact on the rheological properties of cellulose-EMIM OAc solutions, confirming the previous observation found in the literature.
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    Cellulose stabilization during alkaline pulping for the production of high-purity dissolving-grade pulp
    (2012) Bardot, Fanny; Borrega, Marc; Puunjalostustekniikan laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Sixta, Herbert
    In view of the increasing competition between forest companies all over the world, it becomes essential to transform even the very small element of the wood into a high value-added product. The hot water extraction is a good way to extract hemicelluloses from wood, to recover them easily and to convert them in by-products. The wood residue after the extraction, composed mostly of cellulose and lignin, can be further subjected to pulping and then potentially used as dissolving pulp. However, the crucial point is the amount of reducing end group after this pre-treatment under severe extraction conditions, which leads to further cellulose depolymerization during subsequent alkaline pulping. Thus, stabilization of cellulose is required by using some additives during pulping. In this study, the performance of two different additives, sodium borohydride and anthraquinone monosulfonate, was investigated during soda-anthraquinone (SAQ) pulping of pre-extracted birch wood chips. These chips had been pre-treated over a wide range of extraction intensities. Stabilization was carried out in-situ by the addition of the stabilizing agents to the soda-anthraquinone pulping liquor. Pulp analysis (Kappa number, intrinsic viscosity, residual alkali) were performed and the chemical composition was determined to characterize the obtained pulps. Based on the results, addition of sodium borohydride (BH) gave the highest yields, the lowest ratios reject/pulp as well as the lowest Kappa numbers. However, this additive gave also the lowest viscosities. The chemical composition revealed that BH enhances cellulose content and hence leads to cellulose stabilization. Xylans content were also found to be improved by using the two additives. Effects of two different H-factors and two soda (NaOH) charges were further investigated on one selected pre-treated wood sample. The results showed that optimization in terms of energy and chemicals may be possible.
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    Wet pressing strategies for microfibrillates cellulose based furnishes
    (2012) Jarovisky, Matias; Rantanen, Juuso; Puunjalostustekniikan laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Maloney, Thad
    The main objective of this work was to make a first approach to the micro fibrillated cellulose (MFC) impact on wet pressing when added to termomechanical pulp (TMP) based furnishes. In this research two types of MFC in a concentration ranging from 0% to 20 % were tested. TMP fines and cationic starch were also used to evaluate if the interaction of them with the MFC affects the water removal during wet pressing. The wet pressing simulation was done using a MTS 810, which was also developed further, with which two different pulses were applied to all furnishes. Results indicated that MFC addition to TMP furnishes can, in some conditions, improve dewatering during wet pressing. The interaction between the furnish components present a great dependence on the controlling mechanism of dewatering during wet pressing. In order to achieve good water removal, it is fundamental to determine what is the mechanism controlling dewatering, whether flow or pressure controlled, for the furnish to be pressed. Both types of MFC tested had similar behaviour in most wet pressing experiments, neither presented higher dewatering constantly.
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    Embodied energy counting of sustainable heat, power and steel processes
    (2011) Losowska, Magdalena; Sha, Sha; Kemian laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Hurme, Markku
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    Transition metal catalyzed direct aldol reaction
    (2010) Creixell Valls, Xavier; Joensuu, Pekka; Kemian laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Koskinen, Ari
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    Treatment of printed circuit boards from waste computers
    (2010) Pencak, Vladimir; Pehkonen, Antero; Materiaalitekniikan laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Forsén, Olof
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    Screening of ionic liquids for the dissolution and fiber spinning of cellulose
    (2016-09-13) Le Boulch, Kadvaël; Hummel, Michael; Kemian tekniikan korkeakoulu; Sixta, Herbert
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    Optimization and modeling of recombinant protein production in Pichia pastoris
    (2016-06-14) Fita Pizarro, Laia; Mollerup, Filip; Usvalampi, Anne; Kemian tekniikan korkeakoulu; Frey, Alexander
    Recombinant proteins, produced in heterologous expression systems, have currently multiple industrial applications and potential to further improve the chemical industry. However, their main drawback is the high production costs, and thus efficient, cost-effective and well-controlled production processes are of importance to the bioeconomy. Some novel biocatalyst, used for the development of sustainable materials, are yet to be expressed with a significant yield and efficiency thus require further development of the production processes. Accordingly, the aim of this thesis was to optimize the expression of recombinant proteins in the methylotrophic yeast Pichia pastoris through optimization of expression conditions and optimizing substrate feed-rate in bioreactor fed-batch cultivations. This thesis features a comprehensive literature review of the yeast Pichia pastoris and compares Prokaryotic to Eukaryotic expression systems in terms of their cell structures. Furthermore, the bioreactor processes and the cultivation parameters are presented. Additionally, fed-batch cultivation strategies are also explained. The experimental part of this thesis examines the expression of a member of the carbohydrate active enzyme family AA5 from the fungus Penicillium Wisconsin in Pichia pastoris using a bioreactor system. Initially, the best expression strain was identified along with the best temperature and pH conditions. The main part focused on the development of new strategies for methanol feeding in bioreactor cultivation process of the chosen expression strain. Subsequently, the two best strategies were tested for the expression of the α-fucosidase SMDfucA in P. pastoris for comparison with another fungal gene. The recombinant protein expression in Pichia pastoris was simulated using commonly verified and published algorithms from the literature (Carlsson, 2012) (Kargi & Shuler, 2008) (Maurer, Kühleitner, Gasser, & Mattanovich, 2006). Simulation work was performed on the Matlab™ software and parameters and initial conditions were based on the experimental strategies. Although the simulation gave coherent results, the model has certain limitations as the methanol feed rate in the model only accounted for a constant feed rate. Finally, the two best strategies were: modified Invitrogen guidelines and constant profile with a feed rate of (3.6 ml MeOH·h-1) because of their better performance between activity and cellular concentration. Moreover, these two strategies were the ones yielding the highest specific growth rate, extracellular activity and cellular productivity. With another carbohydrate active enzyme, the alpha-fucosidase, using the same P. pastoris SMD1168H strain, the modified Invitrogen guidelines was selected as the best strategy because in both cases the activity and soluble protein analysis gave higher values than with the other strategies tested.
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    Modelling and analysis of behaviour of biomedical scaffolds
    (2015-06-11) Reali, Luca; Bilotsky, Yevgen; Kemian tekniikan korkeakoulu; Gasik, Michael
    Since articular cartilage related diseases are an increasing issue and they are nowadays treated by invasive prosthesis implantations, there is a strong demand for new solutions such as those offered by scaffold engineering. This work deals with the characterization and modelling of polymeric fabrics for cartilage repair. Creep tests data at three different applied forces were successfully modelled both analytically, using viscoelastic models, and by finite element analysis which embraced the theory of poroelasticity. A linear correlation between the viscoelastic parameters brought to the definition of a time dependent effective modulus function of the applied force and based on a set of four material parameters, whereas a finite element parametric analysis lead to the estimation of the matrix intrinsic permeability. Finally the behaviour of the material in both creep and dynamic loading configurations was studied using the finite element method, starting from the results of the previous characterization for the setup of the simulations. The attention was mainly focused on the fluid related quantities pore pressure and velocity field because of their importance in transferring mechanical stimuli to cells eventually present in a further stage.