Ionic‐liquid grafted poly(vinylidene fluoride) with pH responsiveness using as water treatment separation membranes for multi‐dye retention and adsorption

Abstract The rapid development of the world economy and industry brings us a higher standard of living and also causes severe water pollution at the same time. Herein, pH‐responsive 1‐allyl‐3‐methylimidazole acetate grafted poly(vinylidene fluoride) membranes (PVDF‐g‐IL) were prepared by high‐energy electron irradiation grafting and non‐solvent‐induced microphase separation technology. The corresponding pH‐responsive membranes can be used to separate dye wastewater with different charges by converting the positive and negative nature of the membrane surface charge. Moreover, the grafted 1‐allyl‐3‐methylimidazole acetate offers a reversible wettability switching ability in different acidic and alkaline environments. The results showed that membrane porosity and average pore size become more prominent, and the pure water flux increases from 121 to 622 Lm −2 h −1 . The functionalized membranes exhibited excellent filtration performance of cationic and anionic dyes wastewater by transforming the positive and negative surface charge. The optimum PVDF‐g‐IL membrane displayed a nearly 100% rejection and flux recovery rate. Furthermore, PVDF‐g‐IL membranes exhibited both adsorption and desorption properties for dyes with high adsorption and desorption rates at different pH values. The present research provides a practical and straightforward preparation method of pH‐responsive PVDF‐g‐IL membranes and can apply in the field of dye wastewater purification.