Auswahl der wissenschaftlichen Literatur zum Thema „Solvent system“

Solvents play a crucial role in the Active Pharmaceutical Ingredient (API) manufacturing and are used in large quantities. Most of the industries incinerate the waste solvents or send it to waste management companies for destruction to avoid waste handling and cross-contamination. It is not a cost effective method and also hazardous to the environment. This study has been performed at AstraZeneca’s API manufacturing plant at Sodertalje, Sweden. In order to find a solution, a solvent recovery system is modeled and simulated using ASPEN plus and ASPEN batch modeler. The waste streams were selected based on the quantity and cost of the solvents present in them. The solvent mixture in the first waste stream was toluene-methanol in which toluene was the key-solvent whereas in the second waste stream, isooctane-ethyl acetate was the solvent mixture in which isooctane was the key-solvent. The solvents in the waste stream were making an azeotrope and hence it was difficult to separate them using conventional distillation techniques. Liquid-Liquid Extraction with water as a solvent followed by batch distillation was used for the first waste stream and Pressure Swing Distillation was used for the second waste stream. The design was optimized based on cost analysis and was successful to deliver 96.1% toluene recovery with 99.5% purity and 83.6% isooctane recovery with 99% purity. The purity of the solvents was decided based on the quality conventions used at AstraZeneca so that it can be recovered and recycled in the same system. The results were favorable with a benefit of €335,000 per year and preventing nearly one ton per year carbon dioxide emissions to the environment. A theoretical study for the recovery system of toluene-methanol mixture was performed. The proposed design was an integration of pervaporation to the batch distillation. A blend of polyurethane / poly(dimethylsiloxane) (PU / PDMS) membrane was selected for the separation of methanol and toluene mixture. The results of preliminary calculations show 91.4% toluene recovery and 72% methanol recovery with desired purity.

A management decision-support framework for a coal-fired power plant with solvent based post combustion CO2 capture (PCC) (integrated plant) is proposed and developed in this thesis. A brief introduction pertaining to the solvent-based PCC technology, thesis motivations and objectives are given in Chapter 1. Chapter 2 comprises a comprehensive literature review of solvent-based PCC plant from the bottom level (PCC instrumentation level) until the top level (managerial decision of PCC system). Chapter 3 describes the development of solvent-based PCC dynamic model via empirical methods. Open-loop dynamic analyses are presented to provide a deeper understanding of the dynamic behaviour of key variables in solvent-based PCC plant. Chapter 4 presents the design of the control architecture for solvent-based PCC plant. Two control algorithms developed, which utilise conventional proportional, integral and derivative (PID) controller and advanced model predictive control (MPC). Chapter 5 proposes a conceptual framework for optimal operation of the integrated plant. The MPC scheme is chosen as the control algorithm while mixed integer non-linear programming (MINLP) using genetic algorithm (GA) function is employed in the optimization algorithm. Both algorithms are integrated to produce a hybrid MPC-MINLP algorithm. Capability and applicability of the algorithm is evaluated based on 24 hours and annual operation of integrated plant. Chapter 6 extends the scope of Chapter 5 by evaluating the relevance of solvent-based PCC technology in the operation of black coal-fired power plant in Australia. This chapter considers a prevailing climate policy established in Australia namely Emission Reduction Fund (ERF). Finally, the concluding remarks and future extensions of this research are presented in Chapter 7.

The biocatalysis of commercially purified soybean lipoxygenase (LOX-1B: EC 1.13.11.12) in ternary micellar and neat organic solvent media, using linoleic acid as a substrate model, was investigated. The organic solvent, used throughout this study, was at different ratios in the ternary micellar system, composed of Tris-HCl buffer solution (0.1 M, pH 9.0) and 10 µM of Tween-40 as the surfactant. The results indicated a 1.4- and 1.7-fold increase in LOX activity when, respectively, 2% iso-octane or 2% hexane was used as the organic solvent in comparison to that in the aqueous medium. The kinetic parameters, including Km and Vmax values, the choice of the surfactant, the optimum reaction temperature and the optimum pH, were investigated. The effects of selected parameters, including initial water activity (aw, 0.23 to 0.75), agitation speed (0 to 200 rpm), reaction temperature (20 to 45ºC) and thermal stability of LOX activity in neat organic solvent, were also studied. The experimental findings showed that the Km and Vmax values in the ternary micellar system containing 2% hexane was calculated to be 7.7 µmol of linoleic acid and 30.0 nmol of linoleic acid hydroperoxides (HPODs)/mg protein/min, respectively, as compare to that of 20.7 µmol of linoleic acid and 8.3 nmol HPODs/mg protein/min in the neat organic solvent, respectively. The experimental results indicated that the major LOX specific activity, for both aqueous and ternary micellar systems, was measured at pH 9.0, with a minor one at pH 6.0 for the aqueous system and at pH 7.0 for the ternary micellar system. The activation energy (Ea) of the reaction system of LOX was 9.87 kJ/mol or 2.36 kcal/mol. The half-life (T50) for LOX was 27.61, 66.63 and 138.6 min for the aqueous, ternary micellar and neat organic media, respectively.<br>La biocatalyse de la lipoxygénase purifiée, obtenus à partir de la graine de soja (LOX-1B: EC 1.13.11.12), a été étudiée en milieux micellaire ternaire et en monophasique organique, en utilisant l'acide linoléique comme substrat modèle. Le solvant organique, utilisé dans cette étude, a été utilisé à différentes concentrations dans le système micellaire ternaire, composé d'une solution tampon Tris-HCl (0,1 M, pH 9,0) et 10 µM d'un surfactant, le Tween-40. Les résultats obtenus ont démontré qu'il y a une augmentation de 1,4 et 1,7 fois de l'activité enzymatique de la LOX en utilisant, respectivement, soit du l'iso-octane à 2% ou soit du l'hexane à 2%, comme le solvant organique en comparaison avec celle en milieux aqueux. Les paramètres cinétiques, comportant les valeurs de Km et de Vmax, le choix de surfactant ainsi que la température et le pH optimal de la réaction ont été étudiés. Les effets de différents paramètres tels que l'activité initiale de l'eau (aw) du 0,23 à 0,75, l'agitation du 0 à 200 rpm, la température de la réaction du 20 à 45ºC et la stabilité thermique de l'activité de la LOX en milieux monophasiques organiques ont été aussi étudiés. Les résultats obtenus tendent à montré que les valeurs de Km et de Vmax en système micellaire ternaire, contenant de l' hexane à 2%, ont été de 7,7 µmol d'acide linoléique et 30,0 nmol d'hydroperyde de l'acide linoléique (HPODs)/mg protéine/min, respectivement, en comparaison à des valeurs de 20,7 µmol d'acide linoléique et 8,3 nmol HPODs/mg protéine/min dans les milieux monophasiques organiques, respectivement. De plus, les résultats expérimentaux ont démontré que l'activité spécifique maximale de la LOX pour les deux systèmes aqueux et micellaire ternaire a été obtenue à pH 9,0, avec aussi une activité minimale à pH 6,0 pour le système aqueux et à pH 7,0 pour le système micellaire ternaire. L'énergie d'activation (Ea) du système de réaction de la LOX était d'une valeur de 9,87 kJ/mol ou 2,36 kcal/mol. La demi-vie (T50) de LOX a été déterminée à 27,61 min dans le milieu aqueux, 66,63 min dans le milieu micellaire ternaire et 138,6 min dans les milieux monophasiques organiques.