Hydrophobic Ionic Liquid-Doped Poly(3-hydroxybutirate) Membranes as Sustainable Systems for Efficient Dye Pollutant Removal and Photodegradation

Contamination of water bodies is one of the pressing issues of modern society. In this context, to achieve sustainable removal of pollutants from wastewater, the authors prepared hybrid membranes based on biomass-derived poly(3-hydroxybutirate) doped with hydrophobic imidazolium-based ionic liquids differing for the alkyl chain length. Membranes were easily prepared, without synthetic steps, and were characterized by surface roughness, hydrophobicity/hydrophilicity and morphology. Then, these materials were investigated for their ability to remove cationic, neutral and anionic dye pollutants from water. The materials showed fast and thorough removal of most dyes, particularly cationic and neutral ones. Adsorption process was investigated in terms of mechanism and kinetics determining the adsorption isotherms and rate. The best results were obtained for methyl violet with maximum adsorption capacity of 132 mg/g, and the performance of the systems proved comparable to the one of related systems reported in the literature. The best-performing membrane was reused nine times without significant loss in removal efficiency or intermediate washing. To minimize the waste generated by the adsorption process, the membranes were further doped with a photocatalyst like TiO2 and employed to degrade dyes in water solution, finding that they are effective and recyclable catalysts, especially toward cationic dyes.