pH-responsive fiber membrane with high flux and photocatalytic performance for oily wastewater

Membrane separation technology is widely used in separating oily wastewater, where pH-responsive membranes can cope with different conditions of oil-water separation. However, it is limited by membrane contamination during application. A multifunctional oil-water separation membrane (HATP@CN) with photocatalytic performance and pH response was prepared. The wettability of the membrane can be switched by adjusting the pH quickly, which has hydrophobicity when pH <= 7 and hydrophilicity when pH > 7, and it has stable pH responsiveness. The separation effect of membrane on different kinds of oil-water mixtures under different response conditions was explored. The results showed that the separation efficiency of HATP@CN on heavy oil/water mixture and light oil/water mixture was higher than 96.3 % and 99.2 %, respectively, and the separation flux was higher than 6800 L<middle dot>m(-2)<middle dot>h(-1) and 10000 L<middle dot>m(-2)<middle dot>h(-1), respectively. After 50 cycles of separation, HATP@CN still had good separation effects. At the same time, it can also separate water-in-oil emulsion and oil-in-water emulsion. The loading of TiO2 endows the membrane with excellent photocatalytic performance, which has a high degradation ability of over 90 % within 6 min for various dye solutions. Even in dynamic filtration and separation, MB can be rapidly degraded to realize water purification. This study provided an effective strategy for applying membranes in complex oil-water separation.