Preparation of microporous polypropylene membrane via thermally induced phase separation as support of liquid mebranes used for metal ion recovery

Abstract

Microporous polypropylene (PP) membranes were prepared by the thermally induced phase separation (TIPS) technique and used as supports of liquid membranes. Several different quenching temperatures were used in the preparation of the microporous membranes. Membranes prepared by air-cooling and quenching in a water bath of 353 K showed higher porosity at the membrane surface compared with those made by quenching in a water bath of 303 K and in ice-water. A simplified one-dimensional heat transfer equation was solved to evaluate the temperature profile within the membrane to demonstrate the effect of quenching temperature on the final pore size distribution. The calculated result suggested that the asymmetric membrane structure formed by quenching in 303 K water and ice-water was not attributable to the temperature gradient. Supported liquid membranes (SLMs) were prepared by impregnating a carrier solution in the prepared porous polypropylene membranes, and uphill transport of Ce(III) was investigated using octyl(phenyl)-N,N-diisobutyl-carbamoyl-methylphosphine oxide (CMPO) as a carrier, tributyl phosphate (TBP) as a modifier, and dodecane as a solvent. The membranes prepared by air-cooling showed higher permeability of Ce(III) than the commercial membrane.