The Experts below are selected from a list of 1002 Experts worldwide ranked by ideXlab platform
P E M Overdevest - One of the best experts on this subject based on the ideXlab platform.
-
separation of racemic mixture by ultrafiltration of enantioselective micelles 1 effect of ph on separation and regeneration
Industrial & Engineering Chemistry Research, 2001Co-Authors: P E M Overdevest, T J M De Bruin, K Van T Riet, J T F Keurentjes, A Van Der PadtAbstract:Many enantiomer separation Systems are studied to meet the increasing demand for enantiopure compounds. One way to obtain pure enantiomers is to apply enantioselective micelles in ultrafiltration Systems. We have studied the separation of phenylalanine (Phe) enantiomers by the ultrafiltration of nonselective nonionic micelles containing selector molecules, cholesteryl-L-glutamate:CuII (CLG:CuII). Because the net charges of enantiomer and CLG are pH-dependent, it is foreseen that pH will be an important factor in the design of a cascaded separation process that yields enantiopure products. Experiments at pH 7, 9, and 11 showed that the complexation can be described by multicomponent Langmuir isotherms. The CLG enantioselectivity for D-Phe increases with decreasing pH, being 1.4, 1.7, and 1.9 for pH 11, 9, and 7, respectively. Accordingly, the saturation concentration and the affinity constants decrease with decreasing pH, finally resulting in no complexation at pH 6. To design an economically attractive separation process, the regeneration of D-Phe-saturated micelles leaving the Multistage System is inevitable. Regeneration, i.e., recovery of enantioselective micelles for reuse, is possible at pH 4. To keep salt production to a minimum, the shift in pH between the separation and regeneration processes must be minimized. Therefore, a separation process at pH 7 seems most attractive.
-
separation of racemic mixture by ultrafiltration of enantioselective micelles 2 de complexation kinetics
Industrial & Engineering Chemistry Research, 2001Co-Authors: P E M Overdevest, J T F Keurentjes, Mai Schutyser, De Tjm Bruin, Van Klaas T K Riet, Van Der A PadtAbstract:The application of enantioselective micelles in ultrafiltration Systems can be an alternative route to meet the increasing demand for enantiopure products. We have studied the separation of D,L-phenylalanine (Phe) by cholesteryl-L-glutamate:CuII (CLG:CuII) anchored in nonionic micelles (intrinsic enantioselectivity D/L,int = 1.9). A cascaded System is needed to complete the separation, as a single stage is insufficient to obtain >99␘ptically pure products. It is shown that the complexation and decomplexation processes are not instantaneous; hence, elucidation of the complexation kinetics is essential to the design of a Multistage System. Linear driving force (LDF) models describe both the complexation and decomplexation rates of enantiomers. It can be concluded that the complexation rates of D- and L-Phe, (32 ± 11) x 10-5 s-1 and (28 ± 14) x 10-5 s-1, respectively, are not limited by enantiomer diffusion in the hydrophilic shell of the micelles. Consequently, the formation and rearrangement of the chelate complexes must be rate-limiting. In addition, decomplexation of both enantiomers is even slower, on the order of 10-6 s-1. Fortunately, ultrafiltration experiments indicate that a rapid exchange rate of bound L-Phe by unbound D-Phe improves the decomplexation of L-Phe to (360 ± 250) x 10-5 mM-1 s-1. This exchange process can be described by a second-order LDF model.
A Van Der Padt - One of the best experts on this subject based on the ideXlab platform.
-
separation of racemic mixture by ultrafiltration of enantioselective micelles 1 effect of ph on separation and regeneration
Industrial & Engineering Chemistry Research, 2001Co-Authors: P E M Overdevest, T J M De Bruin, K Van T Riet, J T F Keurentjes, A Van Der PadtAbstract:Many enantiomer separation Systems are studied to meet the increasing demand for enantiopure compounds. One way to obtain pure enantiomers is to apply enantioselective micelles in ultrafiltration Systems. We have studied the separation of phenylalanine (Phe) enantiomers by the ultrafiltration of nonselective nonionic micelles containing selector molecules, cholesteryl-L-glutamate:CuII (CLG:CuII). Because the net charges of enantiomer and CLG are pH-dependent, it is foreseen that pH will be an important factor in the design of a cascaded separation process that yields enantiopure products. Experiments at pH 7, 9, and 11 showed that the complexation can be described by multicomponent Langmuir isotherms. The CLG enantioselectivity for D-Phe increases with decreasing pH, being 1.4, 1.7, and 1.9 for pH 11, 9, and 7, respectively. Accordingly, the saturation concentration and the affinity constants decrease with decreasing pH, finally resulting in no complexation at pH 6. To design an economically attractive separation process, the regeneration of D-Phe-saturated micelles leaving the Multistage System is inevitable. Regeneration, i.e., recovery of enantioselective micelles for reuse, is possible at pH 4. To keep salt production to a minimum, the shift in pH between the separation and regeneration processes must be minimized. Therefore, a separation process at pH 7 seems most attractive.
J T F Keurentjes - One of the best experts on this subject based on the ideXlab platform.
-
separation of racemic mixture by ultrafiltration of enantioselective micelles 1 effect of ph on separation and regeneration
Industrial & Engineering Chemistry Research, 2001Co-Authors: P E M Overdevest, T J M De Bruin, K Van T Riet, J T F Keurentjes, A Van Der PadtAbstract:Many enantiomer separation Systems are studied to meet the increasing demand for enantiopure compounds. One way to obtain pure enantiomers is to apply enantioselective micelles in ultrafiltration Systems. We have studied the separation of phenylalanine (Phe) enantiomers by the ultrafiltration of nonselective nonionic micelles containing selector molecules, cholesteryl-L-glutamate:CuII (CLG:CuII). Because the net charges of enantiomer and CLG are pH-dependent, it is foreseen that pH will be an important factor in the design of a cascaded separation process that yields enantiopure products. Experiments at pH 7, 9, and 11 showed that the complexation can be described by multicomponent Langmuir isotherms. The CLG enantioselectivity for D-Phe increases with decreasing pH, being 1.4, 1.7, and 1.9 for pH 11, 9, and 7, respectively. Accordingly, the saturation concentration and the affinity constants decrease with decreasing pH, finally resulting in no complexation at pH 6. To design an economically attractive separation process, the regeneration of D-Phe-saturated micelles leaving the Multistage System is inevitable. Regeneration, i.e., recovery of enantioselective micelles for reuse, is possible at pH 4. To keep salt production to a minimum, the shift in pH between the separation and regeneration processes must be minimized. Therefore, a separation process at pH 7 seems most attractive.
-
separation of racemic mixture by ultrafiltration of enantioselective micelles 2 de complexation kinetics
Industrial & Engineering Chemistry Research, 2001Co-Authors: P E M Overdevest, J T F Keurentjes, Mai Schutyser, De Tjm Bruin, Van Klaas T K Riet, Van Der A PadtAbstract:The application of enantioselective micelles in ultrafiltration Systems can be an alternative route to meet the increasing demand for enantiopure products. We have studied the separation of D,L-phenylalanine (Phe) by cholesteryl-L-glutamate:CuII (CLG:CuII) anchored in nonionic micelles (intrinsic enantioselectivity D/L,int = 1.9). A cascaded System is needed to complete the separation, as a single stage is insufficient to obtain >99␘ptically pure products. It is shown that the complexation and decomplexation processes are not instantaneous; hence, elucidation of the complexation kinetics is essential to the design of a Multistage System. Linear driving force (LDF) models describe both the complexation and decomplexation rates of enantiomers. It can be concluded that the complexation rates of D- and L-Phe, (32 ± 11) x 10-5 s-1 and (28 ± 14) x 10-5 s-1, respectively, are not limited by enantiomer diffusion in the hydrophilic shell of the micelles. Consequently, the formation and rearrangement of the chelate complexes must be rate-limiting. In addition, decomplexation of both enantiomers is even slower, on the order of 10-6 s-1. Fortunately, ultrafiltration experiments indicate that a rapid exchange rate of bound L-Phe by unbound D-Phe improves the decomplexation of L-Phe to (360 ± 250) x 10-5 mM-1 s-1. This exchange process can be described by a second-order LDF model.
Vitor J P Vilar - One of the best experts on this subject based on the ideXlab platform.
-
assessment of a Multistage System based on electrocoagulation solar photo fenton and biological oxidation processes for real textile wastewater treatment
Chemical Engineering Journal, 2014Co-Authors: Diego Ricieri Manenti, Aparecido Nivaldo Modenes, Petrick A Soares, Fernando Rodolfo Espinozaquinones, Rui A R Boaventura, Rosângela Bergamasco, Vitor J P VilarAbstract:Abstract The performance of a Multistage treatment System for textile wastewater was investigated in this study. The processes of electrocoagulation (EC), photo-Fenton oxidation, and activated sludge biological degradation were integrated in batch mode. The integrated treatment System performance was assessed according to three response variables: dissolved organic carbon (DOC), chemical oxygen demand (COD) and biodegradability index. Based on preliminary tests, the EC-based wastewater treatment was suitable as the first stage of the integrated treatment System, followed by the photo-Fenton process. A lab photo-reactor was used to assess the influence of photo-Fenton variables on the process performance. Based on the better lab photo-Fenton reactor conditions, the improvement of some biological indicators related to the organics biodegradability of treated wastewater was investigated in a pilot-scale photoreactor. An activated sludge-based biological reactor at lab-scale was used as a final treatment stage, in order to achieve the legislated limits for discharge into water bodies. Partial degradation of the organic pollutants was achieved by the EC process, with a 36% reduction in COD. In the second treatment stage, a 70% biodegradability index was attained by setting the photo-Fenton reaction conditions at 100 mg Fe 2+ L −1 , pH 2.8, 12 mM H 2 O 2 and 6.9 kJ L −1 accumulated energy. Finally, a residual COD of 139 mg O 2 L −1 was achieved at the outlet of the biological process, which is below the maximum limit established by the Portuguese legislation.
Van Der A Padt - One of the best experts on this subject based on the ideXlab platform.
-
separation of racemic mixture by ultrafiltration of enantioselective micelles 2 de complexation kinetics
Industrial & Engineering Chemistry Research, 2001Co-Authors: P E M Overdevest, J T F Keurentjes, Mai Schutyser, De Tjm Bruin, Van Klaas T K Riet, Van Der A PadtAbstract:The application of enantioselective micelles in ultrafiltration Systems can be an alternative route to meet the increasing demand for enantiopure products. We have studied the separation of D,L-phenylalanine (Phe) by cholesteryl-L-glutamate:CuII (CLG:CuII) anchored in nonionic micelles (intrinsic enantioselectivity D/L,int = 1.9). A cascaded System is needed to complete the separation, as a single stage is insufficient to obtain >99␘ptically pure products. It is shown that the complexation and decomplexation processes are not instantaneous; hence, elucidation of the complexation kinetics is essential to the design of a Multistage System. Linear driving force (LDF) models describe both the complexation and decomplexation rates of enantiomers. It can be concluded that the complexation rates of D- and L-Phe, (32 ± 11) x 10-5 s-1 and (28 ± 14) x 10-5 s-1, respectively, are not limited by enantiomer diffusion in the hydrophilic shell of the micelles. Consequently, the formation and rearrangement of the chelate complexes must be rate-limiting. In addition, decomplexation of both enantiomers is even slower, on the order of 10-6 s-1. Fortunately, ultrafiltration experiments indicate that a rapid exchange rate of bound L-Phe by unbound D-Phe improves the decomplexation of L-Phe to (360 ± 250) x 10-5 mM-1 s-1. This exchange process can be described by a second-order LDF model.
