针铁矿硫化过程对Cr(Ⅵ)还原的影响与机理  

Effect and mechanism of sulfurization process of goethite on Cr(Ⅵ)reduction

作　　者：崔雅云 朱琳 盖楠 杜江坤 CUI Yayun;ZHU Lin;GAI Nan;DU Jiangkun(School of Environmental Studies,China University of Geosciences(Wuhan),Wuhan 430078,China;National Research Center for Geo-analysis,Beijing 100037,China)

机构地区：[1]中国地质大学(武汉)环境学院,湖北武汉430078 [2]国家地质实验测试中心,北京100037

出　　处：《安全与环境工程》2024年第4期236-243,共8页Safety and Environmental Engineering

基　　金：国家重点研发计划政府间国际科技创新合作重点专项项目(2021YFE0106600);国家重点研发计划项目(2019YFC1805105)。

摘　　要：Cr(Ⅵ)在自然界中的迁移转化与铁(氢)氧化物的吸附、氧化还原过程有着紧密的联系。选取针铁矿作为研究对象,探究其硫化过程对Cr(Ⅵ)还原的影响与机理。结果表明:针铁矿/Na2S/Cr(Ⅵ)体系还原Cr(Ⅵ)的作用机理为体系中的S(-Ⅱ)提供电子并促进电子转移,将针铁矿结构中的Fe(Ⅲ)还原为Fe(Ⅱ)吸附态;Fe(Ⅱ)和S(-Ⅱ)均作为还原剂,将Cr(Ⅵ)还原成Cr(Ⅲ),最终形成Cr(Ⅲ)-Fe(Ⅲ)氢氧化物共沉淀物被吸附在矿物的表面;Cr(Ⅵ)的去除效果随着Na2S投加量的增加而增加,在p H值为6时Cr(Ⅵ)的去除效果最好;NO_(3)^(-)、SO_(4)^(2-)、PO_(4)^(3-)、CO_(3)^(2-)对Cr(Ⅵ)的去除率均有不同程度的抑制作用,其中PO43-对Cr(Ⅵ)的去除影响相对最大。The migration and transformation of Cr(Ⅵ)in nature are closely related to the adsorption and redox processes of iron(hydrogen)oxides.This study selected goethite as the object to investigate the effect and mechanism of its sulphidation process on the reduction of Cr(Ⅵ).The results show that the mechanism of Cr(Ⅵ)reduction by goethite/Na_(2)S/Cr(Ⅵ)system is to provide electrons for S(-Ⅱ)in the system and promotes electron transfer,reducing Fe(Ⅲ)in goetnite structure to adsorbed Fe(Ⅱ).Both Fe(Ⅱ)and S(-Ⅱ)act as reducing agents to reduce Cr(Ⅵ)to Cr(Ⅲ),ultimately forming Cr(Ⅲ)-Fe(Ⅲ)hydroxide co-precipitates adsorbed on the mineral surface.The removal efficiency of Cr(Ⅵ)increases with the increasing dosage of Na_(2)S,with the best removal efficiency of Cr(Ⅵ)at pH=6.NO_(3)^(-)、SO_(4)^(2-)、PO_(4)^(3-)、and CO_(3)^(2-)all exhibit varying degrees of inhibitory effects on the removal of Cr(Ⅵ),among which PO_(4)^(3-)has the relatively largest impact on the removal of Cr(Ⅵ).

关 键 词：针铁矿 Cr(Ⅵ) 硫化作用 Fe(Ⅱ)/Fe(Ⅲ)循环 

分 类 号：X703[环境科学与工程—环境工程]