A self-cleaning polyacrylonitrile fiber membrane modified by photocatalytic nanoparticles and zwitterionic polymer brushes for oil/water separation

Abstract

Membrane separation technique has been widely used in recent years for oily wastewater treatment because of the advantages of simplicity of operation, lack of residual contamination and high separation efficiency. However, membrane fouling and pore plugging can cause serious problems, such as short membrane life and decreased flux. Therefore, in this paper, a self-cleaning polyacrylonitrile (PAN) composite membrane with excellent oil–water emulsion separation properties was prepared. The PAN membrane modified with AgI/UiO-66-NH₂ was first prepared using electrospinning. The zwitterionic poly(sulfobetaine methacrylate) (pSBMA) was then modified onto the prefabricated electrospinning membrane by atom transfer radical polymerization (ATRP) to prepare hydrophilic polymer brush grafted PAN/AgI/UiO-66-NH₂ composite membranes after 2-bromoisobutyryl bromide (BiBB) was introduced to the composite membrane. The membrane possesses a self-cleaning capacity because AgI/UiO-66-NH₂ has the ability of visible light driven catalytic degradation. The powerful hydration ability of the pSBMA and the surrounding water molecules enhance the wettability of the composite membrane. The existence of a photocatalyst and hydration of a zwitterionic polymer brush greatly improve the resistance of the membrane towards contamination. The as prepared membrane was used to treat oil/water emulsions and the results revealed that the membrane has high permeability to four kinds of different oil/water emulsions when driven by gravity. The mentioned membrane might have potential application prospects in oily water treatment.