A facile method for polyamide membrane modification by poly(sulfobetaine methacrylate) to improve fouling resistance

• A membrane modification method to resist protein adsorption is developed.
• The water permeability of such membranes is higher than of the untreated membrane.
• The lower salt rejection rate is suppressed by high working pressure.
• This new method could be applied in most interfacial polymerization method.

Membrane fouling is a long-standing problem in many industrial and fundamental applications. In this work, a zwitterionic poly(sulfobetaine methacrylate) (pSBMA) is grafted on the surface of an aromatic polyamide membrane to improve membrane fouling using surface-initiated atom transfer radical polymerization (SI-ATRP). The resulting pSBMA-coated polyamide membrane exhibits excellent surface resistance to protein adsorption and high water permeability. As compared to untreated membrane, the adsorption amount of irreversible proteins on the pSBMA-coated membrane is significantly reduced by ∼97% and water flux is also greatly improved by ∼65%, while rejection rate remains unchanged as large fouling molecules (humic acid, bovine serum albumin) in the solution are filtrated. More importantly, the pSBMA-coated polyamide membrane consistently retains a much higher water flux and improves the rejection rate of NaCl at high operating pressure. These results demonstrate that new pSBMA-coated membrane with easy synthesis can serve as potential promising membranes for membrane industry.