Carboxylic acids separation using hollow fiber supported liquid membrane

Abstract

The experimental and modeling studies for extraction of different carboxylic acids using hollow fiber supported liquid membrane operated in a recycle mode has been described here. Characterization of membrane has been carried out to find the pore size. Tri-n-butyl phosphate (TBP), tri-n-octylamine (TOA) and tri-n-octylphosphine oxide (TOPO) are used as extractants for extraction studies. A generalized methodology for the extraction of carboxylic acids has been proposed. The extraction equilibrium studies for carboxylic acids are carried out to find the distribution coefficient (k_d) and the equilibrium constant (K_ex). A mathematical model has been developed by considering the mass transfer as well as the complexation and de-complexation reactions. The equilibrium results show that the extractants plays an important role in extraction of carboxylic acids, and thus influence the extraction of carboxylic acids. Almost 99% extraction of carboxylic acids has been achieved using 1% TOPO as an extractant. Effect on transport of carboxylic acids under various conditions, including acid concentrations, extractant concentrations, feed/strip flow rate, feed volume, scale up etc. has been investigated. Scale-up experiment show that flux obtained at both scales is the same and hence the rate of extraction is significantly faster in a module with high surface area.