One-step modification of electrospun PVDF nanofiber membranes for effective separation of oil–water emulsion

Abstract

At present, based on the excellent mechanical properties, high porosity and chemical stability of polyvinylidene fluoride (PVDF) nanofiber membranes, the development of simple methods to achieve hydrophilic modification of electrospun PVDF nanofiber membranes for the treatment of oily wastewater has become a hot but challenging subject of research. Herein, we report a simple one-step method to modify electrospun PVDF nanofiber membranes to change their wettability. Specifically, tannic acid (TA) and 3-aminopropyltriethoxysilane (APTES) are deposited on the membrane and the strong oxidizing property of sodium periodate (SP) is used to optimize the wettability of the membrane. Then, a series of characterization methods was used to study the change in the surface morphology and chemical composition of the membrane during the modification process. The modified membrane is superhydrophilic/underwater superoleophobic with excellent oil adhesion resistance. For the oil–water separation process, the modified membrane was employed in the treatment of oil–water emulsions containing surfactants, exhibiting high flux (1871 L m⁻² h⁻¹) and excellent separation efficiency (99.83%) only driven by gravity. Moreover, the membrane retains its separation efficiency (above 90.50%) after ten cycles and exhibits excellent recyclability. Herein, this simple modification method can not only improve the wettability of the PVDF membrane but also takes advantage of the large flux of electrospun membranes to achieve good oil and water separation performance. In addition, the membrane could maintain its stability under harsh conditions. This method can provide a strategy for more studies on electrospun polyvinylidene fluoride nanofiber membranes for oil–water separation.