摘要
为揭示重非水相污染物(DNAPL)氧化修复中多相渗流−化学反应−相演变耦合过程的物理化学机理,利用新兴的微流控技术开展了高锰酸钾(KMnO_(4))氧化修复三氯乙烯(TCE)的实验.结果表明:当浓度3g/L以上的KMnO_(4)氧化TCE时,二氧化锰(MnO_(2))固相产物会在流道深度方向上产生“固体墙”,后续MnO_(4)^(−)只能缓慢渗入墙内对TCE进行氧化,此时MnO_(4)^(−)成为限制性因素并转化为Mn^(2+),而Mn^(2+)扩散出墙外后再次被氧化为MnO_(2)固相,形成一个负反馈系统并造成修复效率急剧降低.当3g/L以下的KMnO_(4)氧化TCE时,MnO_(2)固相产物附着在流道壁面上,后续MnO_(4)^(−)可以和TCE持续反应并生成MnO_(2),KMnO_(4)溶液−DNAPL界面不断后退且修复效率较高.当加入磷酸氢盐后,MnO_(2)固相产物被显著抑制从而提高了修复效率,且1~2g/L是孔隙尺度TCE修复的理想KMnO_(4)浓度.
To elucidate pore-scale mechanisms governing the coupled process of multiphase flow,chemical reactions,and phase transformations during the oxidation remediation of dense non-aqueous phase liquids(DNAPLs),we conducted 48microfluidic experiments to investigate the trichloroethylene(TCE)oxidation by potassium permanganate(KMnO_(4)).The results show that when KMnO_(4) concentration exceeded 3g/L,the manganese dioxide(MnO_(2))solid products during TCE oxidation formed a"solid wall",which hindered the contact between MnO_(4)^(−)and TCE.Under such conditions,the residual TCE oxidation proceeded only via the slow penetration of KMnO_(4) solution through the MnO_(2) wall,where limited MnO_(4)^(−)was converted to Mn^(2+).As Mn^(2+)diffused out of the MnO_(2) wall,it was re-oxidized to MnO_(2) solid phase,creating a negative feedback loop and significantly reducing remediation efficiency.At KMnO_(4) concentrations below 3g/L,the MnO_(2) solid products were able to attach to the channel surfaces,permitting continuous reaction between MnO_(4)^(−)and TCE,thereby resulting in a higher remediation efficiency.The introduction of phosphate significantly suppressed the formation of MnO_(2) solid products and improved remediation efficiency,with an optimal KMnO_(4) concentration for TCE remediation determined to be 1~2g/L.
作者
王泽君
杨志兵
胡冉
陈益峰
WANG Ze-jun;YANG Zhi-bing;HU Ran;CHEN Yi-Feng(State Key Laboratory of Water Resources Engineering and Management,Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering of the Ministry of Education,School of Water Resources and Hydropower Engineering,Wuhan University,Wuhan 430072,China)
出处
《中国环境科学》
EI
CAS
CSCD
北大核心
2024年第8期4530-4538,共9页
China Environmental Science
基金
国家自然科学基金资助项目(41877203,42377066)。
关键词
非水相液体
氧化修复
多相渗流
三氯乙烯
微流控
DNAPL
oxidative remediation
multiphase flow
trichloroethylene
microfluidics
