Sustainable and durable superwetting textiles coated with polydopamine for oil/water separation

Abstract

The industrial revolution and the frequent crude oil spills have caused tremendous contamination of the natural water resources with oily waste. Superwetting textiles have been proposed as advanced functional materials for selective oil separation from oily wastewater. Superwetting textiles have been fabricated by engineering smart coatings that allow for the modified textile's optimal surface roughness and chemical composition. During the past decade, polydopamine (PDA) has been proposed as a sustainable, biodegradable, and biomimetic coating for the fabrication of superwetting textiles with superhydrophobic and/or underwater superoleophobic properties. PDA coatings offer advantages including a simple coating procedure in a wide pH range, use of various organic/inorganic oxidants, high adhesion strength to various substrates, increased surface roughness of the coated substrates, and diverse post-functionalization via different ionic/covalent interactions. Thus, bioinspired, sustainable and durable superwetting textiles have been designed and fabricated by controlling the surface roughness and the surface energy of the PDA-coated textiles. This review highlights the recent advances in fabricating superwetting PDA-coated textiles for the separation of various oil/water mixtures. Two classes of superwetting textiles are discussed, including superhydrophobic (SHB) and superhydrophilic/underwater superoleophobic (SHL/UWSOB) PDA-coated textiles. In each case, the discussion focuses on the fabrication methods, coating procedures, separation performance, recyclability, and enhanced mechanical and chemical durability due to the synergistic effect of the deposited and/or functionalized PDA coating. The discussion includes the separation of emulsified mixtures, current challenges, proposed solutions, and future perspectives of PDA-coated textiles for practical and large-scale oil/water separations.