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Efficient removal of Cr(VI) by a 3D Z-scheme TiO2-ZnxCd1-xS graphene aerogel via synergy of adsorption and photocatalysis under visible light

Author:
Qianwei Liang, Xin Chen, Ruina Liu, Ke Xu, Hanjin Luo
Source:
Journal of environmental sciences (China) 2023 v.124 pp. 360-370
ISSN:
1001-0742
Subject:
adsorption, aerogels, graphene, graphene oxide, irradiation, light, photocatalysis, photocatalysts, synergism, virulence, wavelengths, China
Abstract:
Efficient and robust photocatalysts for environmental pollutants removal with outstanding stability have great significance. Herein, we report a kind of three dimensional (3D) photocatalyst presented as Z-scheme heterojunction, which combining TiO₂ and ZnₓCd₁₋ₓS with graphene aerogel to contrast TiO₂-ZnₓCd₁₋ₓS graphene aerogel (TSGA, x=0.5) through a moderate hydrothermal process. The as-prepared Z-scheme TSGA was used to remove aqueous Cr(VI) via a synergistic effect of adsorption and visible light photocatalysis. The adsorption equilibrium can be reached about 40 min, then after about 30 min irradiation under visible light (wavelength (λ) > 420 nm) the removal rate of Cr(VI) almost reached 100%, which is much better than the performance of pristine TiO₂ and Zn₀.₅Cd₀.₅S, as well as TiO₂ graphene aerogel (TGA) and Zn₀.₅Cd₀.₅S graphene aerogel (SGA). The virulent Cr(VI) was reduced to Cr(III) with hypotoxicity after photocatalysis on TSGA, meanwhile the as-synthesized TSGA presented a good stability and reusability. The reduced graphene oxide (rGO) sheets between TiO₂ and Zn₀.₅Cd₀.₅S played a role as charge transfer mediator, promoting the photoinduced electrons transfer and photocatalysis ability of TSGA was enhanced significantly. Hence, such photocatalyst exhibits a potential application on removing heavy metals with high efficiency and stability from polluted aqueous environment.
Agid:
7664498