Treatment of concentrated arsenic(V) solutions by micellar enhanced ultrafiltration with high molecular weight cut-off membrane

In this work arsenic removal by micellar enhanced ultrafiltration (MEUF) was investigated using cetylpyridinium chloride (CPC) and a cross-flow polyethersulphone (PES) membrane apparatus. The effects of some operating factors on permeate flux, arsenic and CPC rejections were investigated and, in particular, transmembrane pressure, pH, CPC concentration, As concentration and ionic strength. The novel aim of this work is evaluating the possible advantages of using large molecular weight cut-off membrane (100 kDa) and reduced surfactant concentrations (1-3 mM) for treating high fluxes of concentrated arsenic-bearing solutions (6-10 ppm). The experimental results reported in this paper show that PES membrane apparatus with high molecular weight cut-off allowed to treat large fluxes of concentrated arsenic-bearing solutions (6-10 ppm) even by using low surfactant concentration (1-3mM). In particular arsenic removal ranged from 93-98% to 70-74% depending on initial As concentration (6 and 10 ppm, respectively). In addition surfactant leakage in the permeate was always below CMC due to presieving of concentration polarisation layer. The favourable combination of high MWCO membranes and low surfactant concentration can benefit to overall process economics for the lower membrane area requirement (due to greater flux) and the reduced surfactant consumption.