Multifunctional materials with controllable superwettability for oil–water separation and removal of pollutants: Design, emerging applications, and challenges

The water pollution problem caused by large‐scale industrial activity is becoming increasingly serious, which not only poses a major threat to the ecosystem and human health but also seriously impedes the green and sustainable development of modern society. It is urgent to efficiently purify stubborn wastewater containing oils and other pollutants to eliminate their harm to human and environment. Therefore, it is desirable to develop multifunctional materials that can simultaneously remove oil and various pollutants or microorganisms by filtration or absorption methods to meet the practical demand for highly effective purification of wastewater with complex components. This paper summarizes the latest research progress on the “oil removal” and “water removal” materials capable of purifying complex oily wastewater and their applications in adsorption, photocatalytic degradation, antibacterial, magnetic recovery, and others. The producing routes of multifunctional materials by constructing variable wettability surfaces and introducing functional components were summarized, and the mechanism of multifunctional materials in removing oil and various pollutants was discussed. On the basis of summarizing the types, compositions, and conventional separation technologies of oil‐bearing wastewater, the preparation methods and applications of the widely concerned convertible materials with complex wettability are also introduced, and the challenges and future development trends of efficient multifunctional oil–water separation and pollutant purification materials are proposed. It is expected to provide a reference for the development of more high‐performance multifunctional purification materials. The research progress on the multifunctional separation materials and their applications was summarized, and the future development prospect was proposed.