Rational design of materials interface at nanoscale towards intelligent oil–water separation

Abstract

Oil-water separation is critically important for the water treatment of oily wastewater or oil-spill accidents. The oil contamination in water not only induces severe water pollution but also threatens human beings’ health and all living species in the ecological system. To address this challenge, different nanoscale fabrication methods have been applied in endowing biomimetic porous materials, which provides a promising solution for oily-water remediation. In this review, we present the state-of-the-art developments on the rational material interface design on special wettability for the intelligent separation immiscible/emulsified oil-water mixture. Mechanism understanding towards oil-water separation is firstly described, following with the summary of separation solutions for traditional oil-water mixture and special oil-water emulsion enabled by the self-amplified wettability due to nanostructures. Guided by the basic theory, rational interface design at nanoscale on various porous materials with special wettability towards superhydrophobicity-superoleophilicity, superhydrophilicity-superoleophobicity, and superhydrophilicity-underwater superoleophobicity is discussed in details. Although the above nanoscale fabrication strategies are able to address most of current challenges, intelligent superwetting materials developed to meet special oil-water separation demands and to further promote the separation efficiency are also reviewed for various special application demands. Finally, challenges and the future perspectives on the development of more efficient oil-water separation materials and devices by nanoscale control are provided. It is expected that the biomimetic porous materials with nanoscale interface engineering will overcome the current challenges of oil-water emulsion separation, realizing in practical applications in the near future with continuous efforts in this field.