Preparation of a Ph-Responsive and Anti-Fouling Nanofiltration Membrane and Its Application in Acid Mine Water Treatment

Membrane fouling is one of the critical problems that restricts the developments and applications of nanofiltration (NF) membranes. Surface modification has been proved to be an effective strat - egy to enhance the anti-fouling properties of NF membranes. Herein, the pH-responsive material of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) was synthesized via atom transfer radical polymerization of 2-(N,N-dimethylamino)ethyl methacrylate, and PDMAEMA was coated on the surface of commercial NF membranes via method of dip-coating. By this strategy, NF mem - branes with pH-responsibility and excellent anti-fouling properties were successfully fabricated. The results show that modified NF membrane showed remarkable pH-sensitivity in the pH range of 5–8, which could increase anti-fouling properties. In the testing period of 32 h by dead-end filtra - tion for 1,000 mg/L Bovine Serum Albumin, the flux decay rate of modified NF membranes is only 7.6% while the virgin NF membrane is 15.6%. Meanwhile, basing on the pH difference between the acid mine water and the alkaline cleaning fluid could realize the high-efficiency removal of diva - lent ions and self-cleaning of the NF membrane. After 120 h filtering of acid mine water, the flux recovery ratio (FRR) remained basically 93.2% of the modified NF membranes, but FRR declines to 57.8% obviously of the virgin NF membranes.