Removal and mechanism study of Cr(VI) in water by sludge biochar-supported nano-ferrous sulfide
LYU Si-lu1, LIU Tian1, WANG Xu1, ZUO Kai-xia1, XIE Yan-hua1,2
1. College of Ecology and Environment, Chengdu University of Technology, Chengdu 610059, China; 2. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China
Abstract：In this study, sludge biochar loaded with nano-sized ferrous sulfide (MBC) was prepared by pyrolyzing the sludge impregnated with Fe3+ and S2- ions. The preparation conditions of MBC and its removal performance on Cr(Ⅵ) were investigated, and the composites before and after reaction were characterized by SEM, TEM, XRD and XPS to explore the removal mechanism. The results show that the pyrolysis temperature (500℃) was relatively low because the presence of Fe3+ and S2- ions. Acidic conditions were beneficial to the Cr(Ⅵ) removal. When the pH was 2~4 and the dosage of MBC was 2.5g/L, the removal rate of 50mg/L Cr(Ⅵ) can reach 99%. Furthermore, the combined process of MBC+NaOH (pH=7.8) can completely remove the total Fe and total Cr in the effluents. The precipitates generated from the combined process were very compact, and the effluents were colorless and transparent. The characterization results showed that nano-sized ferrous sulfide and iron oxide particles were successfully loaded on the sludge biochar and coated on the surface of the material in the form of semi-transparent film. Fe2+, Sn2- and C=O on the MBC could be acted as electron donors to reduce most of Cr(Ⅵ) to form the chelated compounds such as C-O-Cr, C=O-Cr etc. The residual Cr(Ⅵ) in solution can be also adsorbed by the composites. Therefore, the removal mechanism of Cr(Ⅵ) by MBC manly included chemical reduction, complexation, and adsorption, especially reduction played the key role.
吕思璐, 刘天, 王旭, 左开霞, 谢燕华. 硫化亚铁改性生物炭对水中Cr(Ⅵ)的去除机理研究[J]. 中国环境科学, 2023, 43(8): 3935-3945.
LYU Si-lu, LIU Tian, WANG Xu, ZUO Kai-xia, XIE Yan-hua. Removal and mechanism study of Cr(VI) in water by sludge biochar-supported nano-ferrous sulfide. CHINA ENVIRONMENTAL SCIENCECE, 2023, 43(8): 3935-3945.
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