含氧水溶液中δ-MnO_(2)对非晶态Cr(OH)_(3)的化学氧化:影响因素和作用机理  

Chemical oxidation of amorphous Cr(OH)_(3) in oxygen-containing aqueous solution:influencing factors and mechanisms

作　　者：曾其玲 刘元元[1,2] 罗程钟[3] 黄婉怡 王涛[1,2] 邹晴荣[1,2] 曹军 ZENG Qiling;LIU Yuanyuan;LUO Chengzhong;HUANG Wanyi;WANG Tao;ZOU Qingrong;CAO Jun(Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environment of Ministry of Education,Chongqing,400044,China;College of Environment and Ecology,Chongqing University,Chongqing,400044,China;Chongqing Solid Waste Management Center,Chongqing,400017,China)

机构地区：[1]重庆大学三峡库区生态环境教育部重点实验室,重庆400044 [2]重庆大学环境与生态学院,重庆400044 [3]重庆市固体废物管理中心,重庆400017

出　　处：《环境化学》2022年第5期1684-1692,共9页Environmental Chemistry

基　　金：国家自然科学基金(51778084);重庆市生态环境局科研项目(2019-128)资助。

摘　　要：对六价铬污染水体和土壤修复常采用化学还原方法,但是当前研究对还原产物非晶态Cr(OH)_(3)的再氧化过程以及环境酸碱性、有机质等因素对该过程的影响仍有较多分歧.本研究通过批试验,观测了含氧水溶液体系中非晶态Cr(OH)_(3)的长期稳定性及pH和溶解性有机质(Dissolved organic matter,DOM)对δ-MnO_(2)氧化非晶态Cr(OH)_(3)的影响.研究结果表明,在含氧水溶液中,Cr(OH)_(3)具有较好的长期稳定性;δ-MnO_(2)会显著增大Cr(OH)_(3)的氧化量,Cr(Ⅵ)生成量从0.03mg·L^(-1)增大为0.83 mg·L^(-1).环境酸碱性可显著影响δ-MnO_(2)对Cr(OH)_(3)的氧化行为,碱性条件下Cr(Ⅵ)生成量更大.当pH=8,反应365 d时,总Cr(Ⅵ)浓度可达0.83 mg·L^(-1);pH=6时,反应365 d时,总Cr(Ⅵ)浓度为0.15 mg·L^(-1).弱酸条件(pH=6)下生成的Cr(Ⅵ)以溶解态和固相结合态存在;弱碱条件(pH=8)下δ-MnO_(2)氧化Cr(OH)_(3)生成的Cr(Ⅵ)主要以溶解态存在.DOM对δ-MnO_(2)氧化Cr(OH)_(3)的影响在弱酸条件(pH=6)下不显著;弱碱条件(pH=8)下,低浓度DOM(1 mg·L^(-1))对δ-MnO_(2)氧化Cr(OH)_(3)的影响不显著,高浓度DOM(10 mg·L^(-1))可显著增大Cr(OH)_(3)的氧化量.Chemical reduction methods are generally used to remediate hexavalent chromiumcontaminated water and soil,but the reoxidation process of amorphous Cr(OH)_(3)—the main reduction product—and the effects of pH,organic matter remain unclear.This study investigated the long-term stability of amorphous Cr(OH)_(3) and the effects of pH and dissolved organic matter(DOM)on the oxidation of amorphous Cr(OH)_(3) byδ-MnO_(2) in an oxygen-containing aqueous solution system through batch experiments.The results showed that Cr(OH)_(3) had long-term stability in an oxygencontaining aqueous solution.δ-MnO_(2) significantly increased the oxidation of Cr(OH)_(3),and the amount of generated Cr(Ⅵ)increased from 0.03 to 0.83 mg·L^(-1).pH significantly affected the oxidation of Cr(OH)_(3) byδ-MnO_(2),and more Cr(Ⅵ)was produced under alkaline conditions than acidic conditions.When the reaction time reached 365 d,the total Cr(Ⅵ)concentration reached 0.83 mg·L^(-1) at pH=8,whereas the total Cr(Ⅵ)concentration was 0.15 mg·L^(-1) at pH=6.At a weakly acidic pH(pH=6),the generated Cr(Ⅵ)mainly existed as dissolved ions and solid-binding species,whereas at a weakly alkaline pH(pH=8),the generated Cr(Ⅵ)mainly existed as dissolved ions.DOM had an insignificant effect on the oxidation of Cr(OH)_(3) byδ-MnO_(2) under weakly acidic(pH=6)conditions.Under weakly alkaline(pH=8)conditions,the effect of DOM on the oxidation of Cr(OH)_(3) byδ-MnO_(2) was not significant at a low concentration of 1 mg·L^(-1);however,a high DOM concentration of 10 mg·L^(-1) significantly increased the oxidation of Cr(OH)_(3).

关 键 词：氢氧化铬 二氧化锰 化学氧化 pH值 溶解性有机质 

分 类 号：X505[环境科学与工程—环境工程]