Insights into Cr(VI) removal mechanism in water by facile one-step pyrolysis prepared coal gangue-biochar composite

• Published in: Chemosphere (Oxford) 2022-07, Vol.299, p.134334-134334, Article 134334
• Main Authors: Zhao, Ruohan, Wang, Bing, Zhang, Xueyang, Lee, Xinqing, Chen, Miao, Feng, Qianwei, Chen, Shiwan
• Format: Article
• Language: English
• Subjects: Adsorption; Chromium; Site energy analysis; Solid waste; Wastewater treatment
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2022.134334

The acceleration of industrialization has increased the discharge of chromium-containing wastewater, posing serious threat to the eco-environment and human health. To remove Cr(VI) in wastewater and improve resource utilization of solid waste, coal gangue and rape straw were initially used to prepare coal gangue-rape straw biochar (CG-RS) composite. The effects of pyrolysis temperatures, solution pH, coexisting ions of Cr(VI) adsorption were investigated. Different adsorption models combined with site energy analysis were used to explore the adsorption behaviors and mechanisms. The results showed higher pyrolysis temperature (600 °C) prepared CG-RS had a larger adsorption capacity (9.2 mg/g) for Cr(VI) (pH = 5.0). Analysis of XPS indicated that CG-RS successfully loaded with Fe–O and Al–O functional groups, which mainly participated in the reduction of Cr(VI). Site energy analysis further proved that reduction and surface complexation were the main adsorption mechanisms. This study shows an effective removal of Cr(VI) by CG-RS, providing a new way for resource utilization of solid waste. [Display omitted] •CG-RS was prepared by coal gangue co-pyrolysis with rape straw for Cr(VI) removal.•CG-RS prepared at high pyrolysis temperature has maximum adsorption capacity (9.2 mg/g).•CG-RS successfully loaded with Fe–O, Ca–O and Al–O functional groups.•Reduction and surface complexation are the main mechanisms.