Self-assembly graphene oxide membrane embedded with CPU@PAA@TiO2 for enhancing the dyes separation and photocatalytic self-cleaning performance

Abstract

Low separation efficiency and poor reusability have become the most important factors restricting the development of membranes in water purification. Herein, a photocatalytic self-cleaning graphene oxide (GO) membrane with a unique intercalated structure of CPU@PAA@TiO2 (CPU: CNS@PDA@UiO-66-NH2, PAA: polyacrylic acid, CNS: carbon nanospheres, PDA: polydopamine) was prepared by simple vacuum filtration self-assembly. The water channels formed by photocatalysis nano-filler CPU@PAA@TiO2 and the dense laminated structure of GO layer existed in the membrane at the same time. The core-shell CPU has a larger photocatalytic area than UiO-66-NH2. Moreover, the crosslinking modification of CPU, PAA, and TiO2 leads to an excellent water flux, dye separation performance, and photocatalytic activity of composite membranes. The water flux of GO/CPU/PAA/TiO2 membrane was 230.48 L ∙ m−2∙ h−1∙ bar−1, and the flux of three dyes was over 220 L ∙ m−2∙ h−1∙ bar−1 while the removal rates were over 99.5%. After 120 min of visible light irradiation, the GO/CPU/PAA/TiO2 membrane exhibited an enhanced degradation (94.21%) for methylene blue because of the suitable band-gap alignment and synergistic effect between CPU and TiO2. In addition, the GO/CPU/PAA/TiO2 membrane exhibited excellent acid/alkaline-stability and reusability in dye filtration and photocatalytic performance. The results indicated that the GO/CPU/PAA/TiO2 membrane has great potential in water purification and photocatalytic self-cleaning.