Preparation of polysulfone ultrafiltration membranes modified by silver particles

In this article, polysulfone-silver composite ultrafiltration membranes were successfully prepared with phase inversion technique through two steps. First, silver particles were prepared in N,N-dimethylformamide (DMF) through reducing silver nitrate via situ reduction method at 120 degrees C. Then, the casting solution was prepared with polysulfone (PSF), N-methyl-2-pyrrolidone, polyvinyl pyrrolidone (PVP) (K10, K30, K50 and K70) and the DMF solution containing the formed silver particles. The effects of molecular weight of PVP on the separation performances and break strength of the membranes were investigated. As a result, for both of PSF membranes and silver composite membranes, with the increase in the molecular weight of PVP, the pure water flux and rejection ratio to bovine serum albumin (68 KDa) solution first increased and then decreased. When the same kind of PVP was added, the rejection ratio of all composite membranes was higher than the rejection ratio of PSF membranes. Moreover, when PVP K30 was added, the water flux and the rejection ratio of the silver composite membrane reached the maximum values, 159 L m(-2) h(-1) and 94%, respectively. It was also found that the break strength of all of the composite membranes was significantly improved by 38-48% compared with the PSF membranes.