O presente trabalho teve como objetivo avaliar o uso combinado de processos de separação, visando a adequação do substrato rico em xilose (hidrolisado de bagaço de cana) para a obtenção de produtos por via fermentativa. Foram estudados processos como coagulação e precipitação seletiva de impurezas coloidais, separação com membranas de microfiltração e ultrafiltração e resinas de troca iônica, tendo como ponto de partida o hidrolisado concentrado 5,56 vezes (hidrolisado H1). Na avaliação dos ensaios de coagulação e precipitação foi utilizado planejamento fatorial fracionado, o qual auxiliou o estudo da performance de agentes coagulantes (policloreto de alumínio e polieletrólito aniônico), em diferentes concentrações, pHs e temperaturas. Como variável resposta foi determinado a redução de compostos fenólicos, resultando numa diminuição final de 32,67% e num modelo matemático que representa os parâmetros envolvidos no processo:[C. Fenólicos] = 13,82 + 4,54xpH + 0,03xPAC - 0,58xpH2 + 0,19xPAC2 - 0,25xpHxPAC. Após a determinação das melhores condições experimentais desta etapa, aplicou-se este modelo numa escala 36 vezes maior, resultando em uma diminuição de 10,49% destes contaminantes, produzindo o hidrolisado H2. Este hidrolisado foi percolado por resinas, e assim, determinou-se a série de resinas de troca iônica mais eficiente (série I: Amberlyst 15Wet, Amberlite FPA98, Amberlite 252Na e Amberlite IRA96). Esta etapa proporcionou uma redução de 96,29% no índice de cor, 98,72% dos compostos fenólicos, 74,19% do hidroximetilfurfural, 55,56% de furfural e 52,03% de ácido acético, utilizando um volume de leito de 20 mL, por coluna de resina. O hidrolisado H2, também, foi utilizado para a determinação do melhor modo de permeação por membranas de separação. Neste caso, optou-se em utilizar somente a membrana de ultrafiltração. A permeação do hidrolisado H2 por esta membrana resultou no hidrolisado H3, e em reduções de 12,50% de ácido acético, 33,00% de compostos fenólicos e 54,29% no índice de cor. Assim, o hidrolisado H3 foi percolado pela série de resinas mais eficiente, obtendo ao final uma diminuição de 63,29% do ácido acético, 75,86% de furfural, 77,78% de hidroximetilfurfural e 88,09% dos compostos fenólicos, promovendo uma redução de 90,90% no índice de cor. A seguir, o hidrolisado purificado foi submetido a fermentações para a produção de xilitol e etanol. Essas bioconversões foram aptas a produzir 0,250g/L.h de xilitol e 0,265g/L.h de etanol além de apresentarem rendimentos de 0,68g/g de xilitol por xilose consumida e 0,30g/g de etanol por xilose consumida. Estes resultados indicam a boa fermentabilidade do hidrolisado tratado pelo processo combinado proposto. / This study evaluated the combined use of separation processes, seeking the adequacy of the substrate rich in xylose (hydrolysate of sugar cane bagasse) in the attainment of products from fermentative processes. During this research processes as coagulation and precipitation of selective colloidal impurities, microfiltration and ultrafiltration membranes separations and ion exchange resins were studied, taking as its starting point a hydrolysate concentrate 5.56 times (hydrolysate H1). During the tests of coagulation and precipitation a fraction factorial design was applied, which helped the study of coagulating agents performance (aluminum polychloride and anionic polyelectrolyte) in different concentrations, pH and temperatures. The response variable utilized was phenolic compounds reduction resulting in a drop of 32.67% and the mathematical model that represents the parameters involved in the process was: [C. Fenólicos] = 13.82 + 4.54 xpH + 0.03 xPAC - 0.58 xpH2 + 0.19 xPAC2 - 0.25 xpHxPAC. After determining the best experimental conditions of this step, this model was applied on a scale 36 times greater resulting in a decrease of 10.49% on contaminants, producing the hydrolysate H2. This hydrolysate was percolated through resins and determined the sequence of ion exchange resins more efficient; Serie I (Amberlyst 15Wet, Amberlite FPA98, Amberlite 252Na and Amberlite IRA96). This step reduced 96.29% in the index of color, 98.72% of phenolic compounds, 74.19% of hydroxymethylfurfural, 55.56% of furfural and 52.03% acetic acid, using a bed volume of 20 mL for each resin column. The hydrolysate H2 also was used to determine the best way of membranes permeation. In this case, opted to use only the ultrafiltration membrane. The permeation of the hydrolysate H2 through membrane resulted the hydrolysate H3, and showed reductions of 12.50%, 33.00% and 54.29% in acetic acid, phenolic compounds and index of color, respectively. Thus, the hydrolysate H3 was percolated through the resins series more efficient, obtaining a decrease of 63.29% of acetic acid, 75.86% of furfural, 77.78% of hydroxymethylfurfural and 88.09% of phenolic compounds, promoting a reduction of 90.90% in the index of color on the finish treatment. So this hydrolysate purified was subjected to fermentations for the production of xylitol and ethanol. These bioconversions were able to produce 0.250 g/L.h of xylitol and 0.265g/L.h of ethanol and showed xylitol yield from xylose of 0.68g/g and ethanol yield from xilose of 0.30g/g in ethanol. Theses results indicate the good fermentability of the hydrolysate treated by proposed combined process.

O presente trabalho teve como objetivo avaliar o uso combinado de processos de separação, visando a adequação do substrato rico em xilose (hidrolisado de bagaço de cana) para a obtenção de produtos por via fermentativa. Foram estudados processos como coagulação e precipitação seletiva de impurezas coloidais, separação com membranas de microfiltração e ultrafiltração e resinas de troca iônica, tendo como ponto de partida o hidrolisado concentrado 5,56 vezes (hidrolisado H1). Na avaliação dos ensaios de coagulação e precipitação foi utilizado planejamento fatorial fracionado, o qual auxiliou o estudo da performance de agentes coagulantes (policloreto de alumínio e polieletrólito aniônico), em diferentes concentrações, pHs e temperaturas. Como variável resposta foi determinado a redução de compostos fenólicos, resultando numa diminuição final de 32,67% e num modelo matemático que representa os parâmetros envolvidos no processo:[C. Fenólicos] = 13,82 + 4,54xpH + 0,03xPAC - 0,58xpH2 + 0,19xPAC2 - 0,25xpHxPAC. Após a determinação das melhores condições experimentais desta etapa, aplicou-se este modelo numa escala 36 vezes maior, resultando em uma diminuição de 10,49% destes contaminantes, produzindo o hidrolisado H2. Este hidrolisado foi percolado por resinas, e assim, determinou-se a série de resinas de troca iônica mais eficiente (série I: Amberlyst 15Wet, Amberlite FPA98, Amberlite 252Na e Amberlite IRA96). Esta etapa proporcionou uma redução de 96,29% no índice de cor, 98,72% dos compostos fenólicos, 74,19% do hidroximetilfurfural, 55,56% de furfural e 52,03% de ácido acético, utilizando um volume de leito de 20 mL, por coluna de resina. O hidrolisado H2, também, foi utilizado para a determinação do melhor modo de permeação por membranas de separação. Neste caso, optou-se em utilizar somente a membrana de ultrafiltração. A permeação do hidrolisado H2 por esta membrana resultou no hidrolisado H3, e em reduções de 12,50% de ácido acético, 33,00% de compostos fenólicos e 54,29% no índice de cor. Assim, o hidrolisado H3 foi percolado pela série de resinas mais eficiente, obtendo ao final uma diminuição de 63,29% do ácido acético, 75,86% de furfural, 77,78% de hidroximetilfurfural e 88,09% dos compostos fenólicos, promovendo uma redução de 90,90% no índice de cor. A seguir, o hidrolisado purificado foi submetido a fermentações para a produção de xilitol e etanol. Essas bioconversões foram aptas a produzir 0,250g/L.h de xilitol e 0,265g/L.h de etanol além de apresentarem rendimentos de 0,68g/g de xilitol por xilose consumida e 0,30g/g de etanol por xilose consumida. Estes resultados indicam a boa fermentabilidade do hidrolisado tratado pelo processo combinado proposto. / This study evaluated the combined use of separation processes, seeking the adequacy of the substrate rich in xylose (hydrolysate of sugar cane bagasse) in the attainment of products from fermentative processes. During this research processes as coagulation and precipitation of selective colloidal impurities, microfiltration and ultrafiltration membranes separations and ion exchange resins were studied, taking as its starting point a hydrolysate concentrate 5.56 times (hydrolysate H1). During the tests of coagulation and precipitation a fraction factorial design was applied, which helped the study of coagulating agents performance (aluminum polychloride and anionic polyelectrolyte) in different concentrations, pH and temperatures. The response variable utilized was phenolic compounds reduction resulting in a drop of 32.67% and the mathematical model that represents the parameters involved in the process was: [C. Fenólicos] = 13.82 + 4.54 xpH + 0.03 xPAC - 0.58 xpH2 + 0.19 xPAC2 - 0.25 xpHxPAC. After determining the best experimental conditions of this step, this model was applied on a scale 36 times greater resulting in a decrease of 10.49% on contaminants, producing the hydrolysate H2. This hydrolysate was percolated through resins and determined the sequence of ion exchange resins more efficient; Serie I (Amberlyst 15Wet, Amberlite FPA98, Amberlite 252Na and Amberlite IRA96). This step reduced 96.29% in the index of color, 98.72% of phenolic compounds, 74.19% of hydroxymethylfurfural, 55.56% of furfural and 52.03% acetic acid, using a bed volume of 20 mL for each resin column. The hydrolysate H2 also was used to determine the best way of membranes permeation. In this case, opted to use only the ultrafiltration membrane. The permeation of the hydrolysate H2 through membrane resulted the hydrolysate H3, and showed reductions of 12.50%, 33.00% and 54.29% in acetic acid, phenolic compounds and index of color, respectively. Thus, the hydrolysate H3 was percolated through the resins series more efficient, obtaining a decrease of 63.29% of acetic acid, 75.86% of furfural, 77.78% of hydroxymethylfurfural and 88.09% of phenolic compounds, promoting a reduction of 90.90% in the index of color on the finish treatment. So this hydrolysate purified was subjected to fermentations for the production of xylitol and ethanol. These bioconversions were able to produce 0.250 g/L.h of xylitol and 0.265g/L.h of ethanol and showed xylitol yield from xylose of 0.68g/g and ethanol yield from xilose of 0.30g/g in ethanol. Theses results indicate the good fermentability of the hydrolysate treated by proposed combined process.

Separation of dissolved metals from aqueous solutions using liquid membrane technology is highly advantageous owing to the degree of separation achieved, efficiency and application potential. In the present investigation four types of liquid membranes - bulk liquid membrane (BLM), emulsion liquid membrane (ELM), electrostatic pseudo liquid membrane (ESPLIM) and unified liquid membrane (ULM) have been extensively studied, for their application in extraction and concentration of dissolved metals from effluents. Experiments were conducted with various metal systems to optimize both system and process conditions and to find out the effect of various parameters on the performance of the process. Different mass transport models were proposed for each type, taking diffusional and kinetic resistances into account. Models were extended for simultaneous extraction systems and were verified by different metal-carrier experiments. Good agreement was found between the concentration profiles obtained from the models and the experimental data, thereby establishing the validity of models for all the four types of liquid membranes. The stirred cell employed in BLM process eliminates emulsification and demulsification processes. It also provides simultaneous contact of the organic liquid membrane phase with aqueous feed and strip phases. Overall rate expressions for extraction and stripping in BLM are based on an assumed kinetic mechanism to explain the process qualitatively. It was found that the magnitude^ of diffusional and kinetic resistances determines the overall mass transfer coefficient. The relative magnitude of mass transfer coefficient, reaction rate constants and equilibrium constants enables to visualize the controlling regime of the process. The problem of low flux rate due to high diffusion resistances, inefficient operation and exorbitant costs encountered in bulk and supported liquid membranes (SLM) are overcome in an ELM. In the ELM process, an emulsion of organic membrane phase and aqueous inner phase, is dispersed in the continuous aqueous feed phase. This gives a highly selective and ultra thin liquid film generating a large mass transfer area for separation. Experimental results on membrane instability and emulsion swelling indicate that volumetric leakage rate depends linearly on the stirring speed and that the nature of surfactant does not have any appreciable effect on emulsion swelling. A general permeation model was developed taking into account the external mass transfer around the emulsion drop, diffusion in the drop, reaction at the aqueous-organic interface, leakage of the internal phase to the external phase due to membrane breakup and emulsion swelling due to osmotic pressure difference. Model equations with appropriate boundary conditions were numerically solved by orthogonal collocation technique for a set of model parameters obtained either from known correlations or from independent experiments. Comparison of the model predictions with experimental data from the batch permeation of chromium and other metals using carrier Alamine 336 or LIX 64N, shows that the model predictions are in very good agreement with the experimental findings. Further this model can be used to simulate the effects of various experimental conditions such as metal and hydrogen ion concentrations, carrier concentration, drop diameters, etc., for similar systems. Studies on ESPLIM were conducted with the aim of demonstrating the effectiveness of this new separation process and to develop a simple transport model for metal permeation. In the ESPLIM process, a high electrical field (3-5 kV A.C.) is used for phase dispersion. This system consists of a rectangular reactor filled with membrane solution divided into extraction and stripping cells by a centrally placed integrated type baffle which also acts as an electrode. Two more electrodes were placed in the extraction and stripping cells, where feed and strip phases are introduced from the top of the reactor. When high electrical field is applied across the electrodes, fine droplets of feed and strip are formed and are dispersed in extraction and stripping cells where simultaneous extraction and stripping occurs. The process can be viewed as simultaneous counter current extraction and stripping. The aqueous drops coalesce in the settlers at the bottom of the reactor and are removed continuously. Steady state mass transport model proposed for ESPLIM system accounts for the vertical counter-current extraction and stripping processes taking place in the extraction and stripping cells, together with the lateral transport process of the metal-complex and carrier across the two cells through the integrated baffle zone. The model equations were solved analytically to obtain concentration profiles as a function of the height of the reactor. The required parameters such as mass transfer coefficients, diffusion coefficients etc. were estimated using different correlations. Model predictions agreed remarkably well with the experimental data under various process conditions. From this investigation, it was found that ESPLIM is a simple, efficient and economical process and can be applied in a variety of situations. Based on a suitable combination of solvent extraction, dispersion and liquid membrane technique, a new type of separation system called " Unified Liquid Membrane " was developed. The ULM unit was designed and fabricated, and experiments were conducted to evaluate its performance. The ULM is basically derived from ESPLIM by changing the reactor, baffle design and dispersion technique. Aqueous feed and strip phases were atomized using compressed air through a fine nozzle and are dispersed on either side of an integrated baffle plate that divides the reactor into extraction and stripping cells. Tapering bottom of the reactor reduces the dead volume of the liquid in the settlers and the baffle plate remarkably reduces the leakage problem as well as the resistance through the baffle. Experiments were conducted using LIX 64N and Alamine 336 as carriers for copper and chromium and / or zinc. Mass transport model proposed considers both chemical and phase equilibria in extraction and stripping cells, vertical and lateral transport of carrier and complex across the extraction and stripping cells through the baffle zone. The model equations were solved using initial conditions at the top of the reactor, and equilibrium data for extraction and stripping cells. Effect of various experimental conditions and process parameters was simulated using this model and the model predictions are found to be in excellent agreement with the experimental data. The ULM system developed in this investigation overcomes the major limitations encountered with the other types of liquid membranes while retaining all the advantages of this technology. The problem of high mass transfer resistance from bulk phase to metal permeation as in the case of BLM was eliminated by good phase dispersion. Additional resistance to mass transport from solid membrane as in the case of SLM was removed by using an integrated baffle which also avoids problems of membrane instability, pore clogging and selectivity. The complex problems of emulsification and demulsification were completely eliminated making the system much simpler and efficient. Very good phase dispersion was obtained by atomization without the need for either stirring the whole system or application of high electrical field in the reactor. The membrane liquid within the integrated baffle elements allows easy transport of different species between extraction and stripping cells while completely preventing the mixing of the two aqueous phases. The problems of leakage, swelling and occlusion were avoided due to very short residence time of the aqueous drops in the reactor. It was found that the new ULM configuration is simple, elegant, highly efficient and superior to the other types of liquid membrane systems.

Nitrogen trifluoride (NF3) is frequently used as a source of fluorine in the electronics device manufacturing industry as a dry etchant during plasma assisted etching of silicon wafers, or during the plasma cleaning of chemical vapor deposition chambers. As a result of the electrochemical synthesis procedures in which carbon anodes are used in a fluorine-rich environment, NF3 product streams are frequently contaminated with ppm-amounts of carbon tetrafluoride (CF4). The electronics manufacturing industry, however, requires NF3 of exceptional purity, i.e. so-called VLSI-grade (very large scale integration) NF3, with CF4 concentrations of 20 ppm and below. Due to the close chemical and physical similarities of the two compounds, the removal of CF4 from NF3 has proven to be rather difficult, and current NF3 purification technologies are relatively inefficient. Although membrane gas separation has proven to be competitive in terms of operating costs and energy efficiency, its use for the purification of NF3 seems to have remained unexplored to date. In this study, the use of high free volume glassy perfluoropolymers of Teflon AF2400, Teflon AF1600, and Hyflon AD60 was therefore investigated. To be able to measure the pure and mixed gas permeabilities and selectivities of the solution-cast membranes towards NF3 and CF4, a custom built experimental setup was used, in which a newly developed gas chromatographic (GC) analysis method was implemented. Using divinylbenzene-styrene co-polymer stationary phases in the form of Super Q, a reliable quantification of mixtures of NF3 and CF4 were achieved without requiring additional fluorocarbon liquid stationary phases, as is commonly used in NF3 production environments. Furthermore, by implementing a dual-channel configuration it was possible to quantify a wide range of NF3 and CF4 concentrations. Using the newly developed technique, NF3 and CF4 concentrations of ca. 1 mol% and upwards could be quantified using a Thermal Conductivity Detector (TCD) on one channel, and NF3 and CF4 concentrations of between ca. 40 vppm and 4000 vppm could be measured using a Pulsed Discharge Helium Ionisation Detector (PDHID) on the second channel of the GC method. The glassy perfluoropolymer membranes of Teflon AF2400, Teflon AF1600, and Hyflon AD60 were prepared by a solution casting method, and it was found that annealing at sufficiently high temperatures (170 – 200 °C) ensured optimum permeability selectivity. In contrast, thermal analysis of the solution-cast Hyflon AD60 membranes that were heated to only 95 °C confirmed that the polymer matrix was significantly swollen due to a residual amount of the casting solvent. Consequently, considerably reduced selectivity and increased permeability of both NF3 and CF4 were observed for such solvent-swollen Hyflon AD60 membranes in comparison with the non-swollen membranes that were annealed at 170 °C. Nonetheless, the measured He/N2 permeability and permeability selectivity of all the membranes studied compared favourably with literature values, and selectively permeated NF3 rather than CF4 wherein the pure and mixed gas permeability selectivity displayed a clear dependence on the fractional free volume (FFV) of the polymer matrices. Thus, in accordance with the decreasing FFV of the perfluoropolymers in the order Teflon AF2400 > Teflon AF1600 > Hyflon AD60, the NF3 permeability decreased from 227 Barrer for Teflon AF2400, to 29 Barrer for Teflon AF1600, to 1.9 Barrer for Hyflon AD60. In contrast, the NF3/CF4 selectivity, α(NF3/CF4), increased inversely from 4.5 for Teflon AF2400, to 6.0 for Teflon AF1600, to the highest selectivity of 12 which was obtained using Hyflon AD60. To elucidate the mechanism of separation, the transport properties of NF3 and CF4 in Teflon AF2400 and Teflon AF1600 w.r.t. diffusion and solubility were studied using Molecular Dynamics (MD), Grand Canonical Monte Carlo (GCMC), and statistical thermodynamic techniques. The results indicated that NF3/CF4 diffusion selectivity (DNF3/DCF4) was favoured by the lower free volume of Teflon AF1600, whereas poor correlation was achieved between the GCMC calculated sorption isotherms of CF4 and the experimentally determined isotherms as reported in the literature. Consequently, the non-equilibrium lattice fluid (NELF) model, which more accurately described the sorption isotherms of CF4, was used to evaluate the solubility selectivity. It was found that by adjusting the NELF model interaction parameter, Ψ, favourable NF3/CF4 solubility selectivities (SNF3/SCF4) were predicted. Furthermore, by combining the solubility selectivity values with the diffusion selectivities calculated from the MD results, permeability selectivity predictions that correlated well with the experimentally determined values were obtained. Based on a semi-quantitative technological evaluation, it was concluded that although good NF3/CF4 mixed gas permeability selectivity was obtained with Hyflon AD60, further research into improving the NF3 solubility, and hence permeability will aid in the development of an efficient membrane gas separation process for the purification of NF3. / PhD (Chemistry),North-West University, Potchefstroom Campus, 2013.

Nitrogen trifluoride (NF3) is frequently used as a source of fluorine in the electronics device manufacturing industry as a dry etchant during plasma assisted etching of silicon wafers, or during the plasma cleaning of chemical vapor deposition chambers. As a result of the electrochemical synthesis procedures in which carbon anodes are used in a fluorine-rich environment, NF3 product streams are frequently contaminated with ppm-amounts of carbon tetrafluoride (CF4). The electronics manufacturing industry, however, requires NF3 of exceptional purity, i.e. so-called VLSI-grade (very large scale integration) NF3, with CF4 concentrations of 20 ppm and below. Due to the close chemical and physical similarities of the two compounds, the removal of CF4 from NF3 has proven to be rather difficult, and current NF3 purification technologies are relatively inefficient. Although membrane gas separation has proven to be competitive in terms of operating costs and energy efficiency, its use for the purification of NF3 seems to have remained unexplored to date. In this study, the use of high free volume glassy perfluoropolymers of Teflon AF2400, Teflon AF1600, and Hyflon AD60 was therefore investigated. To be able to measure the pure and mixed gas permeabilities and selectivities of the solution-cast membranes towards NF3 and CF4, a custom built experimental setup was used, in which a newly developed gas chromatographic (GC) analysis method was implemented. Using divinylbenzene-styrene co-polymer stationary phases in the form of Super Q, a reliable quantification of mixtures of NF3 and CF4 were achieved without requiring additional fluorocarbon liquid stationary phases, as is commonly used in NF3 production environments. Furthermore, by implementing a dual-channel configuration it was possible to quantify a wide range of NF3 and CF4 concentrations. Using the newly developed technique, NF3 and CF4 concentrations of ca. 1 mol% and upwards could be quantified using a Thermal Conductivity Detector (TCD) on one channel, and NF3 and CF4 concentrations of between ca. 40 vppm and 4000 vppm could be measured using a Pulsed Discharge Helium Ionisation Detector (PDHID) on the second channel of the GC method. The glassy perfluoropolymer membranes of Teflon AF2400, Teflon AF1600, and Hyflon AD60 were prepared by a solution casting method, and it was found that annealing at sufficiently high temperatures (170 – 200 °C) ensured optimum permeability selectivity. In contrast, thermal analysis of the solution-cast Hyflon AD60 membranes that were heated to only 95 °C confirmed that the polymer matrix was significantly swollen due to a residual amount of the casting solvent. Consequently, considerably reduced selectivity and increased permeability of both NF3 and CF4 were observed for such solvent-swollen Hyflon AD60 membranes in comparison with the non-swollen membranes that were annealed at 170 °C. Nonetheless, the measured He/N2 permeability and permeability selectivity of all the membranes studied compared favourably with literature values, and selectively permeated NF3 rather than CF4 wherein the pure and mixed gas permeability selectivity displayed a clear dependence on the fractional free volume (FFV) of the polymer matrices. Thus, in accordance with the decreasing FFV of the perfluoropolymers in the order Teflon AF2400 > Teflon AF1600 > Hyflon AD60, the NF3 permeability decreased from 227 Barrer for Teflon AF2400, to 29 Barrer for Teflon AF1600, to 1.9 Barrer for Hyflon AD60. In contrast, the NF3/CF4 selectivity, α(NF3/CF4), increased inversely from 4.5 for Teflon AF2400, to 6.0 for Teflon AF1600, to the highest selectivity of 12 which was obtained using Hyflon AD60. To elucidate the mechanism of separation, the transport properties of NF3 and CF4 in Teflon AF2400 and Teflon AF1600 w.r.t. diffusion and solubility were studied using Molecular Dynamics (MD), Grand Canonical Monte Carlo (GCMC), and statistical thermodynamic techniques. The results indicated that NF3/CF4 diffusion selectivity (DNF3/DCF4) was favoured by the lower free volume of Teflon AF1600, whereas poor correlation was achieved between the GCMC calculated sorption isotherms of CF4 and the experimentally determined isotherms as reported in the literature. Consequently, the non-equilibrium lattice fluid (NELF) model, which more accurately described the sorption isotherms of CF4, was used to evaluate the solubility selectivity. It was found that by adjusting the NELF model interaction parameter, Ψ, favourable NF3/CF4 solubility selectivities (SNF3/SCF4) were predicted. Furthermore, by combining the solubility selectivity values with the diffusion selectivities calculated from the MD results, permeability selectivity predictions that correlated well with the experimentally determined values were obtained. Based on a semi-quantitative technological evaluation, it was concluded that although good NF3/CF4 mixed gas permeability selectivity was obtained with Hyflon AD60, further research into improving the NF3 solubility, and hence permeability will aid in the development of an efficient membrane gas separation process for the purification of NF3. / PhD (Chemistry),North-West University, Potchefstroom Campus, 2013.

A produção de petróleo no pré-sal pode ser associada a contaminantes como o CO2. As plataformas instaladas neste polo possuem o sistema de remoção de CO2 usando permeação em membrana polimérica, que separa a corrente de gás em uma pobre em CO2 e outra rica neste. Este trabalho propõe um modelo para simulação da separação de gases utilizando permeador de gases do tipo espiral em contra-corrente. Este modelo utiliza equações baseadas em fenômenos de transporte e termodinâmica, tais como: comportamento real dos gases, variação da permeância com temperatura, transferência de calor dentro do equipamento e efeito Joule-Thomson. A validação foi feita utilizando dados da literatura para separações isotérmicas e dados obtidos em permeador instalado em plataforma de petróleo. Utilizou-se metodologia de reconciliação de dados e agrupamento para tratamento dos dados industriais, o que permitiu maior eficiência na reconciliação dos parâmetros do modelo. A partir da modelagem proposta determinaram-se os parâmetros de processos mais relevantes, permitindo a simulação de condições operacionais diferentes das utilizadas na regressão e a verificação da influência da variação de cada uma das condições operacionais. / The production of oil in pre-salt field is associated with contaminants such as CO2. The rigs installed in this field have a CO2 removal system using permeation on polymer membrane, which separates the gas stream in a stream with low CO2 content and another one with high CO2 content. This paper proposes a model for simulation of gas separation using spiral type permeator of gases in countercurrent flow. This model uses equations based on transport and thermodynamic phenomena such as: real behavior of gases, permeance dependence with temperature, heat transfer inside the equipment and Joule-Thomson effect. The validation was performed using literature data for isothermal separations and data from permeator installed on the oil rig. Was used data reconciliation methodology and clusterization for treatment of industrial data, allowing more efficient reconciliation of the model parameters. From the proposed model were determined the most relevant process parameters, allowing the simulation of operating conditions different than those used in the regression and verification of the influence of the change of each of the operating conditions.