A visible light-driven floatable cyclized polyacrylonitrile-based aerogel (CPAN@ZnO-Ag) photocatalyst for sustainable wastewater purification

Abstract

Photocatalysis as an advanced oxidation technology is often used for wastewater treatment, whereas the sustainable photocatalysis is inhibited by the water-induced light attenuation for solar energy utilization efficiency and the insufficient oxygen in water. In this work, CPAN aerogel was used as a substrate. Ag nanoparticles were loaded on the surface of ZnO as inorganic catalysts (ZnO-Ag), and then ZnO-Ag was evenly dispersed in the three-dimensional network structure of CPAN aerogel. In the floatable CPAN@ZnO-Ag photocatalyst, CPAN with the aerogel architecture could continuously transfer pollutants upward to the photocatalyst surface through porous channels of the aerogel, utilizing light and oxygen efficiently. The coupling of ZnO-Ag with CPAN formed a heterojunction in the composite, which improved the carrier separation efficiency of floatable CPAN@ZnO-Ag. Ag as an electron bridge promoted the formation of the Z-Scheme heterojunction, which further improved the performance of photocatalytic removal of pollutants. The results showed that the maximum removal rate of Congo red (CR, 10 mg/L, 50 mL) by CPAN@ZnO-Ag was 98.47 % within 90 min. In particular, without any desorption procedure, the CPAN@ZnO-Ag could achieve continuous and efficient photocatalytic degradation within 450 min through continuous 5 cycles of CR feeding. What’s more, the CPAN@ZnO-Ag also exhibited the versatility to remove antibiotics, heavy metal ions and toxic phenols from water. This work presented a strategy to ingeniously design a floatable aerogel photocatalyst for sustainable photocatalytic treatment of actual wastewater, achieving efficient use of solar energy and energy conservation.