Removal of bisphenol A by a nanofiltration membrane in view of drinking water production

The efficiency with which a nanofiltration membrane (Desal 5 DK) removes bisphenol A (BPA) was investigated, together with the mechanisms involved. Whereas high retention (>90%) was obtained at the beginning of the filtration, the observed retention coefficient (Robs) decreased to around 50% when the membrane became saturated, due to adsorption of BPA onto the membrane structure. The presence of ions (Na+, Cl−) affects the Robs, this effect being attributed to a change in BPA hydrodynamic radius. Moreover, in our operating conditions, the presence of natural organic matter (1 mg/L) in the feed solution does not lead to variation in BPA retention at steady state.