A novel process for the post-treatment of polyacrylonitrile-based membranes: Performance improvement and possible mechanism

摘要

To obtain much better performance, post-treatment on microporous membrane is often carried out. Treatment with hypochlorite has normally been used to increase the flux of polymer membrane containing poly(N-vinyl-2-pyrrolidone) (PVP). However, the membrane retention sharply decreases after the treatment. In this paper, a novel post-treatment method, which endowed the membrane with both high flux and relatively high retention, was reported. Blending membranes from polyacrylonitrile with PVP were fabricated and their morphologies, fluxes, and BSA retentions were characterized. Treating the membranes with ammonium persulphate (APS) at 60 and 40 degrees C were performed and, for comparison, those with hot water and sodium hypochlorite were also carried out. It was found that treatment with APS led to a remarkable increase of flux and only a slight decrease of BSA retention for the membranes. Changes on the pore size were confirmed by field emission scanning electron microscopy. The untreated and treated membranes were carefully studied with FT-IR-ATR. It was proposed that, not only the leaching out of PVP induced by chain scission but also the hydrolysis and cyclization of cyano in polyacrylonitrile took place during the process of APS treatment on the studied membranes. (c) 2005 Elsevier B.V. All rights reserved.