Novel superwetting nanofibrous skins for removing stubborn soluble oil in emulsified wastewater

Abstract

Superwetting porous membranes are highly desirable for purifying oily wastewater discharged from industrial and domestic sources. However, the sustainability of this technology remains challenging due to its incapability of eliminating residual soluble oils in post-purified water. The critical limitation that the filtrate cannot meet stringent emission standards is neglected by previously reported studies. Herein, nanostructured superwettable skins are developed to provide filtration membranes with the comprehensive performance of soluble oil removal. According to a newly proposed separation mechanism of unlockable-hydration hydrophobic assembly, membranes are employed to separate various surfactant stabilized oil-in-water emulsions with ultralow residual oil content (<0.5 mg L⁻¹), superior permeation flux (∼1400 L m⁻² h⁻¹), and robust reusability for long-term work solely under the driving force of gravity (∼1.5 kPa). This study should provide distinctive insights into the functional wetting modification and pioneer a promising strategy to design high-performance separation materials for thorough oily wastewater remediation.