Fabrication of mechanically stable fabric-based hydrogel membranes based on dual network toughening strategy for high efficient oil–water emulsion separation

Abstract

Massive discharge of oily wastewater originating from oil-related industry, residential sewage and frequent oil spill accidents leads to serious environmental problems and health concerns. Amphoteric polyelectrolytes and hydrogel materials have been employed in the context of oil–water separation to resist oil pollution. However, the weak mechanical properties limit their practical application in complex environments. To address this, the design of a mechanically stable superhydrophilic/underwater superoleophobic composite membrane (PSBMA/PAM@CF) was been proposed by ingeniously in-situ growth of 3- [N, N-dimethyl −[2-(2-methylpropyl-2-enoxyloxy) ethyl] ammonium] propane-1-sulfonate (PSBMA)/polyacrylamide (PAM) dual network (DN) hydrogel on cotton fabric. The DN hydrogel strategy increased the stress of PSBMA hydrogel from 0.200 Mpa to 5.80 Mpa. The toughening effect of the DN hydrogel and its entanglement with cotton fibers endowed the membranes with excellent mechanical properties, and resulted in stable underwater superoleophobic and antifouling properties even after mechanical stability test. The PSBMA/PAM@CF membrane exhibited a separation efficiency exceeding 98.0 % for all types of oil-in-water emulsions stabilized by surfactants, and the membrane’s permeance remained at 1.75 × 103 L·m−2·h−1·bar−1 after 30 cycles. Additionally, the membrane exhibited a high permeance recovery rate of 98.2 %, surpassing general membranes. More significantly, we visualized the separation process through fluid dynamics simulations and revealed the separation mechanism of oil–water emulsions by membranes. It is expected that this work will provide new prospects for designing anti-oil-fouling membranes and applying in practical oil/water separation.