Solar-driven pH-responsive oil-water separation membranes for effective oil-water emulsion separation

Oil spills and industrial wastewater discharge have inflicted severe damage upon the ecological environment and human health. Therefore, the development of an environmentally friendly and pollution-free membrane material for oil-water separation is imperative. This study presents the development of a novel oil-water separation material (PP-PPy-pHR) that is environmentally benign and capable of switching between wetting properties. The material was synthesised by dopamine modification, treatment with a pH-responsive polymer and the use of a high-efficiency photothermal layer composed of self-assembled polypyrrole (PPy), and it not only separates incompatible oil-water mixtures but also efficiently separates oil-water emulsions under different pH conditions. Due to the good photothermal effect of PPy, the evaporation rate of PP-PPy-pHR composite membrane loaded with PPy was 3.95 times higher than that of pure water for oily wastewater. In addition, the PPy-pHR composite membrane exhibited excellent durability and high stability in extremely acidic and alkaline solutions, showing remarkable potential for oil-water separation applications. The membrane (PP-PPy-pHR) prepared in this paper automatically switches the wettability according to the change of pH to separate oil water emulsions. It has great potential for intelligent response in oil water separation.