Sustainable zein/chitosan/polyvinyl alcohol nanofiber composite membrane for efficient water-in-oil emulsion separation and heavy metal adsorption

The development of super-wetting membranes has become a promising treatment material for the emulsions separation and heavy metals absorption. However, it is often limited by the slow separation flux and the non-degradable material in practical applications. Based on this, this paper proposed a superhydrophobic biodegradable zein/chitosan/polyvinyl alcohol @ carnauba wax modified titanium dioxide (ZCP@CW/TiO 2 -s) composite membrane for emulsion separation and heavy metal adsorption. The prepared ZCP@CW/TiO 2 -s membrane demonstrated outstanding superhydrophobicity, featuring a WCA of 154 o and a rolling angle as low as 3 o . Surprisingly, the composite membrane exhibited rapid emulsion separation performance under the low pressure (0.1 bar), with a flux of 23524 L·m -2 ·h -1 ·bar -1 and separation efficiency exceeding 98.2 %. The ZCP@CW/TiO 2 -s membrane achieved a high heavy metal adsorption capacity, particularly for Cu 2+ ions, with an adsorption capacity of 149.93 mg/g. The composite membrane also maintained a stable separation performance under 25 times of wear resistance test. In addition, the ZCP@CW/TiO 2 -s membrane had a great photodegradation ability, which could remove organic pollutants adsorbed on the composite membrane. Meanwhile, the composite membrane could be buried in soil after disposal, enabling rapid degradation and preventing secondary pollution. Moreover, the composite membrane is capable of effectively separating emulsions and removing heavy metal ions, thereby tackling the problem of complex oily wastewater pollution. Therefore, the biodegradable composite membrane can be used as candidate materials for future sustainable development.