Asymmetric PEEKWC membranes for treatment of organic solvent solutions

A phenolphthalein based poly(ether ether ketone) (PEEKWC) has been used for the preparation of asymmetric membranes for organic solvent nanofiltration, chemically stable membranes showing high retention of organic solute molecules. Integrally skinned asymmetric PEEKWC membranes were fabricated from concentrated solutions by phase separation induced by non-solvent. Two organic solutes with molecular weight in the range of NF application (i.e. 200–1000 g/mol) have been selected: safranine (MW 351 g/mol) and Rose Bengal, (MW 1017 g/mol). The membrane performance has been studied using water and alcohols as solvents (methanol, ethanol, iso-propanol and n-butanol). A nearly complete rejection for Rose Bengal in isopropanol (99.8%), higher than that observed in water (86%) and methanol (90%) has been obtained. However, an opposite trend has been found for the smaller safranine: the retention in water (71%) is higher than that in isopropanol (52%). The NF results have been interpreted in terms of membrane–solute, membrane–solvent and solute–solvent interactions.