Factors influencing transport through liquid membranes and membrane based solvent extraction

Abstract

Based on experimental data from pertraction through liquid membranes and membrane based solvent extraction (MBSE) or solvent stripping (MBSS) of butyric acid (BA), phenylalanine (Phe), and heterocyclic carboxylic acid (HCA), the influence of the formulation of the membrane phase, kinetics of the acid/carrier complex decomposition, composition of the donor phase, and hydrodynamic conditions on pertraction and MBSE is discussed. The analysis of mass-transfer resistance including the resistance based on reaction kinetics in pertraction through bulk and supported liquid membranes and in MBSE and MBSS in hollow fibre contactors is presented. It has been found that mass-transfer resistance based on the reaction kinetics on the stripping interface represents about 38% of the overall resistance in pertraction of BA and about 60% in MBSS of BA from the complex with trioctylamine extractant. Aggregation and/or formation of a microemulsion at the concentration of DEHPA in the membrane phase above 1 kmol·m–3 substantially decrease the transport rate of Phe through the layered liquid membrane. Competitive transport of HCl decreases greatly the transport of HCA through liquid membrane with TOA as a carrier while the influence of the co-transport of H2SO4 is very small. Transport of the mineral acid from chloride media is much higher than from sulphate media.