CNTs-COOH@TA nanoparticles and chitosan hydrogel regulated PVDF composite fiber membranes with efficient oil-in-water emulsion and dye wastewater separation characters

The global water pollution problem is increasingly severe, and the wastewater separation technology has received high attention. Polyvinylidene fluoride (PVDF) fiber membranes have a great potential in wastewater treatment. However, its large pore size and high porosity lead to low retention rate and high contamination, which make it impossible to reuse. In this study, it was assumed that the modified nanoparticles CNTs-COOH@TA were prepared by modifying CNTs with tannic acid (TA) through π-π conjugation, and were used as the support layer of the PVDF matrix by electrostatic spinning. The chitosan hydrogel was tightly bound to the PVDF-CNTs-COOH@TA nanofiber support through hydrogen bonding and electrostatic interaction to confer the strong hydrophilicity on the surface of the composite fiber membranes, and the composite PVDF-CNTs-COOH@TA-CS membranes should have excellent performance in PVDF water treatment. The PVDF-CNTs-COOH@TA-CS composite fiber membrane should have high hydrophilicity, high retention rate and reusability. Compared to other separation membranes, the composite membranes achieved effective separation of the oil-in-water emulsion and the dye wastewater while maintaining the rapid permeation of the aqueous phase. The pure water flux of the optimum CS3 composite membrane was 1907.8 Lm -2 h -1 bar -1 , which could completely separate oil-in-water emulsion and retain more than 90% of dyes. In addition, the flux recovery rate (FRR) of the CS3 composite membrane was still more than 86.8% after five cycles, and which had a good antifouling ability. The maximum tensile strength of CS3 increased by 279.7% over PVDF fiber membrane. This innovative approach based on synergistic modification of natural materials provides new ideas for the development of efficient and environmentally friendly wastewater treatment technologies.