A charged superhydrophilic-oleophobic anti-fouling sponges for rapid separation of O/W emulsions

Abstract

The crude oil spillage and large-scale industrial release of oily effluents has led to significant ecological degradation and resource wastage. Traditional superwetting materials encounter intractable challenges for treating surfactant-stabilized oil–water emulsions, including trade-off effect of permeation flux and separation efficiency, and low emulsion processing life. These issues considerably impede advancements in oil–water separation industry. In order to enhance the demulsification durability of materials while ensuring high separation efficiency and flux, this work doped perfluorooctanoic acid (PFOA) onto the modified sponge surface with superhydrophilic charged surface, and a unique in-air superhydrophilic-oleophobic sponge was prepared. This special surface allows rapid water phase permeation yet offers remarkably more stable oleophobicity compared with traditional underwater oleophobic materials when processing a large amount of emulsions. The intrinsic oleophobicity endows the sponge outstanding fouling resistance and greatly increases the one-cycle emulsion treatment amount up to 1695 L·m−2. Moreover, the sponge's inherent long permeation channels and surface charge maintain a high separation efficiency of over 97 %. The large pores of the sponges and superhydrophilic surface provide a high permeation flux exceeding 40,000 L·m−2·h−1. The sponge with high separation efficiency, flux, and capacity marks a significant advancement, offering a promising strategy for superwetting material applications in oil-in-water emulsion separation fields.