硫化亚铁改性生物炭对水中Cr(Ⅵ)的去除机理研究  

Removal and mechanism study of Cr(Ⅵ)in water by sludge biochar-supported nano-ferrous sulfide

作　　者：吕思璐 刘天 王旭[1] 左开霞 谢燕华[1,2] LYU Si-lu;LIU Tian;WANG Xu;ZUO Kai-xia;XIE Yan-hua(College of Ecology and Environment,Chengdu University of Technology,Chengdu 610059,China;State Key Laboratory of Geohazard Prevention and Geoenvironment Protection,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]成都理工大学生态环境学院,四川成都610059 [2]成都理工大学地质灾害防治与地质环境保护国家重点实验室,四川成都610059

出　　处：《中国环境科学》2023年第8期3935-3945,共11页China Environmental Science

基　　金：国家自然科学基金资助项目(41977170)。

摘　　要：本研究采用Fe^(3+)和S^(2-)共浸渍剩余污泥后,热解制备硫化亚铁/生物炭复合材料(MBC),考察了MBC的制备条件及其对Cr(Ⅵ)的去除效果,并采用SEM、TEM、XRD和XPS等对材料进行表征,探讨去除机理.结果表明:选择污泥作为热解碳源和载体,掺入Fe^(3+)和S^(2-)后,可在较低的热解温度(500℃)下制备出性能优良的除Cr(Ⅵ)材料;酸性条件有利于MBC对Cr(Ⅵ)的去除,当pH值为2~4时,2.5g/L的MBC对浓度为50mg/L以下的Cr(Ⅵ)去除率高达99%以上;MBC+NaOH(pH=7.8)组合工艺可彻底将溶液中的总Fe和总Cr去除,反应后生成的沉淀较紧实,出水无色透明.表征结果表明,纳米硫化亚铁及氧化铁颗粒成功负载于污泥生物炭上,并以半透明膜的形式包覆在材料表面;复合材料中的Fe^(2+)、Sn^(2-)和C=O均可作为电子供体将大部分Cr(Ⅵ)还原,并形成C-O-Cr、C=O-Cr等络合物,剩余少量Cr(Ⅵ)可通过吸附作用被去除,即MBC对Cr(Ⅵ)的去除机制主要为化学还原、静电吸附和络合作用,且还原过程起着关键作用.In this study,sludge biochar loaded with nano-sized ferrous sulfide(MBC)was prepared by pyrolyzing the sludge impregnated with Fe^(3+)and S^(2-)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 Fe^(3+)and S^(2-)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.Fe^(2+),Sn^(2-)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.

关 键 词：六价铬Cr(Ⅵ) 污泥生物炭 硫化亚铁 化学还原 

分 类 号：X703.1[环境科学与工程—环境工程]