Fabrication of ion-exchange ultrafiltration membranes for water treatment: I. Semi-interpenetrating polymer networks of polysulfone and poly(acrylic acid)

This paper reports a simplified, efficient and economical method for fabricating ion-exchange ultrafiltration membranes for pollutant removal from water. To obtain these membranes by the phase inversion method, polysulfone (PSf) and poly(acrylic acid) (PAA) were separately dissolved in dimethylformamide (DMF), then the two solutions were mixed in desired proportions. The membranes have an asymmetric structure and rugous surface, as demonstrated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses. Their ion-exchange capacity was in the 0.70–1.0 meq/g range. The retention ratio of lead ions (Pb2+) and Ponceau S dye were 99% and 90%, respectively, in the ultrafiltration process under 0.5 × 105 Pa (0.5 bar), with an average pure water flux of 18 L/(m2 h). These performances, obtained at such a low pressure, make the fabricated membranes attractive for water treatment.