Preparation of Microporous Polypropylene Membrane via Thermally Induced Phase Separation as Support of Liquid Membranes 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.

Effects of cooling temperature and aging treatment on the morphology of nano‐ and micro‐porous poly(ethylene‐co‐vinyl alcohol) membranes by thermal induced phase separation method

“…EVOH membranes prepared by the TIPS process have been extensively studied by Matsuyama and Shang et al Various porous structures, stemming both from solid–liquid (S–L) phase separation (i.e., polymer crystallization) and/or liquid–liquid (L–L) phase separation mechanisms, were obtained by changing the preparation conditions, such as polymer concentration, ethylene content of EVOH, cooling rate, solvent type, etc. For example, for the EVOH‐glycerol binary system, membranes prepared from EVOH with high ethylene contents (e.g., 38%) often exhibited a cellular morphology; yet, those with low ethylene contents (e.g., 27%) tend to give particulate morphology.…”