Mussel-Inspired Dual-Superlyophobic Biomass Membranes for Selective Oil/Water Separation

Dual-superlyophobic membranes that exhibit underwater superoleophobicity and underoil superhydrophobicity concurrently have gained considerable attention for oil/water separation. To effectively treat oily wastewater, consistent efforts have been made to develop fast and simple methodologies with low cost, environmentally friendly materials. Here, the dual-superlyophobic membranes are obtained based on one-step tailored growth of mussel-inspired polydopamine (PDA) nanoparticles on the surfaces of biomass membranes. The results demonstrate that the universal adhesion of PDA allows the modification of biomass fibers of different surface hydrophobicity. The oxidation polymerization of dopamine leads to the rapid growth of PDA nanostructures, which form stable coatings of high roughness instead of homogeneous conformal coatings generated in the conventional synthesis of PDA. The amphiphilic nature of PDA and the rough surfaces imparted by the PDA nanostructures collectively lead to dual-superlyophobic properties. Membranes of the coated biomass fibers prewetted by either water or oil become impermeable to the counterpart liquids, giving rise to efficient oil-water separation in a broad spectrum of mixtures. In particular, the membranes derived from cotton or kapok fibers show oil/water separation efficiencies of above 99.98%, fluxes ranging from 4000 to 22 200 L m(-2) h(-1), and robust performance for regeneration and repeated uses.