Polysulfone/Brij-58 blend nanofiltration membranes: preparation, morphology and performance

In present research, novel asymmetric polysulfone (PSF) membranes with high hydrophilicity and noticeable rejection of arsenic, as one of the major environmental problems, were prepared from PSF/Brij-58/NMP (1-methyl-2-pyrrolidone) system via immersion precipitation. Pure water was used as gelation media. The variation effect of coagulation bath temperature (CBT) and addition of Brij-58 on morphology, wettabiliy, pure water permeation flux and rejection of As (III) and As (V), as two dominant states of arsenic in the nature, were studied by scanning electron microscopy, contact angle measuring instrument and experimental setup. The results demonstrated that both hydrophilicity and rejection properties of the prepared membranes were significantly enhanced by small addition of Brij-58 surfactant in the casting solution along with using the lowest level of CBT. Addition of 4 wt. % of Brij-58 and using cold coagulation bath resulted in the highest rejection of As (V). Initial increase in Brij-58 concentration, from 0 wt. % to 2 wt. %, resulted in higher rejection of As (III). However, higher Brij-58 concentrations than 2 wt. % (increase from 2 wt. % to 6 wt. %) led to lower rejection of As (III). Also, it was found out that addition of Brij-58 in the casting solution along with increasing the CBT resulted in formation of membranes with high permeability and sub-layer porosity and thin top layer. Copyright (c) 2012 John Wiley & Sons, Ltd.