Multifunctional charged hydrogel nanofibrous membranes for metal ions contained emulsified oily wastewater purification

Efficiently purifying metal ions contained emulsified oily wastewater has become a great challenge. Herein, a novel charged hydrogel nanofibrous membrane (CHNM) with negative surface charges, favorable mechanical ability and anti-fouling capacity was prepared via electrospinning and twice crosslinking process. The obtained CHNM with a surface potential of -32.9 mV at pH = 7.2 possesses outstanding oil-in-water emulsion separation performance with high permeation flux of around 10800 L h-1 m-2 bar-1 for surfactant free emulsion and high permeation flux of around 7100 L h-1 m-2 bar-1 for surfactant stabilized emulsion. The excellent oil/water emulsion separation performance can be attributed to the surface charge demulsification (SCD), which is theoretically demonstrated by a finite element analysis simulation. In addition, CHNM can absorb many kinds of metal ions (Fe3+, Ni2+ and Al3+) due to the chelation effect between high-density phosphate groups and metal ions. With outstanding separation performance for oil/water emulsion and good adsorption capacity for metal ions, the multifunctional CHNM may offer a promising approach to develop a new-generation membrane for treating metal ions contained oily wastewater. [Display omitted] •A multifunctional negative charged hydrogel nanofibrous membrane was prepared.•The membrane can separate anionic surfactant stabilized oil/water emulsion.•The mechanism of surface charge demulsification was studied.•The membrane can separate emulsion and absorb metal ions simultaneously.