The carrier mediated transport of Cu2+ ions from an aqueous medium has been examined. The ability of Erythromycin Ethyl Succinate (EES) as a carrier to form a complex with Cu2+ ions and transport them to the receiving phase is reported. The fundamental parameters influencing the transport of Cu2+ ions such as the pH in the source and receiving phases and concentration of the stripping agent in the receiving phase have been optimized and accordingly, the amount of Cu2+ transported across the liquid membrane after 5 h was 94.3 ± 1.8% in the presence of L-histidine as a suitable stripping agent. Moreover, the selectivity and efficiency of Cu2+ ions transport from aqueous solution over other cations in ternary and quaternary mixtures have been investigated. The results indicate that our fabricated membrane is very sensitive toward Cu+2 ions in the presence of heavy metal ions. 相似文献
Blends of plasticized soy protein isolate (PSPI) and poly(butylenes succinate) (PBS) were prepared in a 70:30 wt.‐% ratio via co‐rotation (CR) and counter‐rotation (CTR) twin‐screw extrusion. The novelty in this research suggests that CTR extrusion provides enhanced interfacial adhesion, tensile elongation and prolonged onset (Tonset) and end (Tend) thermal degradation temperatures. The average tensile strain at break showed to be ≈40% higher for PSPI‐CTR material and ≈55% higher for PBS:PSPI‐CTR (70:30) blends. Both Tonset and Tend for CTR processed PBS:PSPI(70:30) and PSPI were ≈10 °C greater than those of CR. These results suggest that the enhanced shear rate and radial motion associated with CTR allows for better destructurization and blending of PSPI within the PBS matrix, resulting in enhanced structural integrity due to the formation of possible amide and ester linkages. Scanning electron microscopy (SEM) provides further support based on evidence of reduced voids on the surface of all CTR blends
Vitamin E succinate was synthesized in organic solvents using a modified Novozym-435 as catalyst.In order to improve the catalytic performance of Novozym-435,the enzyme was modified using acetic anhydride, propionic anhydride and succinic anhydride separately.We found that both the hydrolytic activity and the thermal stability of the modified Novozym-435 were enhanced compared with the unmodified enzyme.The modified Novozym-435 catalysts were used to synthesize the succinate derivative of vitamin E.Compared with the native Novozym-435,the catalytic activity of the modified novozym-435 in promoting the synthesis of vitamin E succinate was dramatically increased,with the novozym-435 modified with succinic anhydride(N435-S)as the most active catalyst.Conditions for the synthesis of vitamin E succinate were also optimized.A mixture of tert-butanol and DMSO(volume ratio of 2︰3)was the most suitable medium for the reaction,whereas the appropriate molar ratio of vitamin E to succinic anhydride and reaction temperature were 1︰5 and 40°C,respectively.Under these reaction conditions,the yield of vitamin E succinate reached 94.4%.N435-S could be reused for five batches. 相似文献