Hollow fiber ultrafiltration membranes made from blends of PAN and PVP

Polyacrylonitrile (PAN) hollow fiber ultrafiltration (UF) membranes have been made from a new dope solution containing PAN/N,N-dimethylformamide (DMF)/poly(vinyl pyrrolidone) (PVP 360K)/1,2-propanediol by using a dry-jet wet spinning process. The as-spun fibres were post-treated by means of hypochlorite solutions with different concentrations. The experimental results showed that water flux of a membrane decreased but retention for the same solute increased with increasing air gap. The flux of a treated membrane was about twice higher than that of an untreated membrane. Retentions of an untreated membrane and a treated membrane for PEG 35K were 94 and `1%, respectively. There was an optimum hypochlorite concentration for the treatment to achieve a PAN membrane with a pure water flux of over 200 x 10(-5) l m(-2) h(-1) Pa-1. The experimental results also showed that the treated membranes experienced higher fouling tendencies than the untreated membrane, mainly due to an increase in contribution of fouling resistance from surface adsorption and pore plugging to the total relative flux reduction. (C) 2003 Elsevier B.V. All rights reserved.