Construction and mechanistic insights of a novel ZnO functionalized rGO composite for efficient adsorption and reduction of Cr(VI)

• Published in: Environmental science and pollution research international 2024-05, Vol.31 (23), p.34607-34621
• Main Authors: He, Haixia, Cheng, Yanhui, Qiu, Siwei, Sun, Lei, Jin, Bohua, Yuan, Xiangjuan
• Format: Article
• Language: English
• Subjects: adsorbents; Adsorption; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Carboxylic acids; Chromium; Chromium - chemistry; Doping; Earth and Environmental Science; Ecotoxicology; Endothermic reactions; endothermy; Environment; Environmental Chemistry; Environmental Health; Graphene; graphene oxide; Graphite - chemistry; hot water treatment; Kinetics; Liquid phases; liquids; Nanoparticles; Research Article; Solid phases; Valence; Waste Water Technology; Water Management; Water Pollutants, Chemical - chemistry; Water Pollution Control; Water Purification - methods; X ray photoelectron spectroscopy; Zinc oxide; Zinc Oxide - chemistry
• ISSN: 1614-7499; 0944-1344; 1614-7499
• DOI: 10.1007/s11356-024-33585-3

A series of ZnO decorated reduced graphene oxide (rGO) (ZnrGO x ) with different doping ratios were synthesized by the alkaline hydrothermal method using graphene oxide (GO) and Zn(NO 3 ) 2 ·6H 2 O as precursors, and subsequently used for the adsorption study of Cr(VI) in water. The morphology, crystalline phase structure, and surface elemental properties of ZnrGO x composites were revealed by XRD, SEM, BET, FT-IR, and XPS characterizations. The results showed that ZnO nanoparticles can be clearly seen on the surface of layered rGO. Meanwhile, as the doping rate increased, the C = C double bonds were broken and more carboxylic acid groups formed in ZnrGO x . In addition, the ZnrGO 0.1 composite had the most excellent adsorption performance and good stability, and reusability. The adsorption removal rate of Cr(VI) can reach 99%, and the maximum adsorption amount of Cr(VI) was 68.9655 mg/g in 3 h. The isothermal and kinetic model simulations showed that Cr(VI) adsorption on ZnrGO 0.1 composite is a chemical adsorption process, spontaneous and endothermic. Based on the concentrations of different valence states of Cr in the solid and liquid phases, 40% of Cr(VI) was reduced to Cr(III) on the surface of ZnrGO 0.1 composite. Moreover, the adsorption-reduction mechanisms of Cr(VI) on ZnrGO 0.1 composite were further elucidated. The ZnrGO 0.1 composite manifested great potential as an efficient adsorbent for Cr(VI) removal. Graphical Abstract