Reusable Underwater Superoleophobic Polyacrylamide Membranes for Effective Oil‐Water Separation and Dye Removal

Abstract Water contamination by oily wastes continues to rise with industrialization and pose a threat to marine ecosystem and public health. Water repellent special wettability membranes have been fabricated for oil removal. These superhydrophobic membranes have been fabricated utilizing hazardous chemicals such as fluorinated compounds, which again have shown toxicity. In contrast, environmentally friendly separation membranes are required for oily wastewater treatment. In this regard, we fabricated underwater superoleophobic membrane based on β‐cyclodextrin and acrylamide for efficient and effective water‐oil separation. Acrylamide polymeric membrane was prepared by free radical co‐polymerisation by incorporating acrylic acid and β‐cyclodextrin as monomer via crosslinking with N,N‐methylene bis‐acrylamide. FT‐IR and PXRD used for characterizing the prepared hydrogel and studied for morphological analysis by FE‐SEM. The oil and water wetting characterization of gels were evaluated, in ambient and submerged conditions. The dried gel showed gradual decrease of contact angle for both oil and water indicating liquid absorption with time. However, in completely water wetted state hydrogel was superoleophobic with a very high oil contact angle of ≥170°. The pre‐wetted hydrogel efficiently and effectively separated oil/water mixtures with ~99 % separation efficiency. Additionally, its effectiveness was monitored over several days of continuous separation operation. Interestingly, the hydrogel was also able to remove dye from water. The underwater superoleophobic acrylamide‐β‐cyclodextrin hydrogel demonstrated high oil recovery efficiency and indicated the potential for repeated oil‐water separation process.