Selective transport of Zn2+ through liquid and solid membranes containing pyrazole-tetrazole hybrid carriers

Abstract

Both liquid (ML) and solid (MS) membranes bearing a pyrazole-tetrazole hybrid molecule as carrier are developed. The ML membrane is composed of CH2Cl2 solution inserted between an aqueous solution of metal nitrate, as a source phase, and a receiving phase containing deionized water. The MS membrane was prepared by photopolymerisation of pyrazole-tetrazole monomer and a polyacrylonitrile support. Being thermally stable up to 330 °C, the MS membrane exhibits an asymmetric amorphous structureIt was found that both membranes selectively transport Zn2+ over Cu2+, Pb2+, Cd2+, and Co2+ cations. At 25 °C and neutral pH, the permeate flux of Zn2+ reached 6.1 10-4 mol.h−1.m−2 for the ML membrane and 1.88 10-2 mol.h−1.m−2 for the MS membrane. Although the MS membrane exhibits more efficient Zn2+ permeate flux and higher stability than those of the ML membrane, the selectivity to Zn2+ transport of the MS membrane was found to be lower.