Microporous polyarylate membrane with nitrogen-containing heterocycles to enhance separation performance for organic solvent nanofiltration

Abstract

The removal of small molecular weight impurities via organic solvent nanofiltration is urgently needed. 9,9-bis(4-hydroxyphenyl)fluorene (BHPF) was modified to synthesize a novel nitrogen-containing heterocyclic monomer (mBHPF). Microporous polyarylate thin-film composite (TFC) membranes of trimesoyl chloride and mBHPF were prepared via interfacial polymerization. The enhanced microporosity and hydrophilicity were achieved by using nitrogen-containing heterocyclic building blocks. Rejections to dyes with a molecular weight greater than 700 remained remarkable (over 98%) in methanol while the permeances of methanol, ethyl alcohol and acetone improved to 14.49, 4.57 and 10.06 L m−2 h−1 bar−1, respectively, much higher than the typical-used commercial membranes, such as MPF-44 or MPF-50 from Koch. Moreover, based on physical properties of solvents and the structure of polyarylate membranes, a model that had great potential in the prediction of pure organic solvent flux was established. This method provides ways to form microporous TFC membranes and predict separation performance for organic solvent nanofiltration.