Studies of various solid membrane supports to prepare stable sandwich liquid membranes and testing copper(II) removal from aqueous media

Abstract

Various solid membrane supports were used to assemble stagnant sandwich liquid membranes (SSwLMs) and compare them with supported liquid membranes (SLMs) with the aim to realize a liquid membrane (LM) system that combines high flux and high stability. Removal of copper(II) from aqueous media was used as model ion to test and compare the two LM systems. The SLM made with polypropylene (PP) Accurel support showed acceptable flux (28.7 mmol h −1 m −2) but limited stability (50 h) while, using the polyethersulphone (PES) Supor ® 200 support, higher flux (39.7 mmol h −1 m −2) but lower stability (22 h) were obtained. TOC results showed a release of the organic phase from the LM to both feed and strip aqueous solutions thus causing progressive system destabilization. SSwLM performance was tested using the Supor ® 200 support and two regenerated cellulose Spectra/Por 6 supports with different molecular weight cut off studying also the influence of module position. When the permeating module was horizontally positioned, copper release in the strip was inhibited. Probably water droplets caused a LM phase stratification reducing the contact area with the strip phase and delay of copper release happened. The vertical module orientation did not give the same problem. The SSwLM assembled with Supor ® 200 support gave the best results, combining both high flux (41.5 mmol h −1 m −2) and high stability (183 h) making such a system interesting in purification and concentration of ions in aqueous media.