活化过硫酸盐对2-巯基苯并噻唑污染含水层的氧化修复效果与机理  

Performance and mechanisms of the oxidation of 2-mercaptobenzothiazolecontaminated aquifer using activated persulfate

作　　者：其布日 徐淼鑫 于博明 孙建芳 夏涛 QI Buri;XU Miaoxin;YU Boming;SUN Jianfang;XIA Tao(School of Chemistry,Chemical Engineering and Life Sciences,Wuhan University of Technology,Wuhan 430070)

机构地区：[1]武汉理工大学化学化工与生命科学学院,武汉430070

出　　处：《环境科学学报》2023年第5期196-205,共10页Acta Scientiae Circumstantiae

基　　金：武汉理工大学自主创新研究基金项目(No.2021IVA074)。

摘　　要：利用活化过硫酸盐(Persulfate,PS)对模拟含水层中的2-巯基苯并噻唑(2-Mercaptobenzothiazole,MBT)进行了原位氧化降解实验研究,并考察了多种不同条件下的处理效果,明确了介质含量、地下水组分、修复试剂投加量及环境条件等因素的影响.同时,采用多种分析手段对MBT降解产物进行了识别和定量并进行了物料衡算,初步探讨了地下水中MBT原位降解的机理.结果表明,在MBT初始浓度为0.12 mmol·L^(-1)、PS浓度为1.0~1.3 mmol·L^(-1)、Fe^(2+)浓度为0.05~0.4 mmol·L^(-1)、多孔介质(粗砂)量为10~50 g、pH为3~9且温度为25~50℃的条件下,反应6 h后MBT去除率达到90%以上,Fe^(2+)/PS体系可以在模拟的地下环境中有效降解MBT.模拟含水层多孔介质对MBT具有一定的吸附作用,适度增加PS和Fe^(2+)剂量均能有效提高MBT去除速率.初始pH值越高,MBT去除率越低;反应温度越高,MBT去除率越高.地下水中的Cl-对去除效果影响甚微,而HCO3-却具有显著的抑制作用.MBT分子最终矿化度为54%,降解后水中主要离子产物为SO_(4)^(2-)和NO_(2)^(-),主要有机产物为苯并噻唑(Benzothiazole,BTH)和2-羟基苯并噻唑(2-Hydroxybenzothiazole,OBT).Fe^(2+)/PS原位降解体系中既存在着自由基氧化途径也存在着直接氧化途径.PS活化产生的SO_(4)^(·-)和HO⋅主要攻击2-位C原子上的—SH取代基,使MBT氧化为BTH和OBT同时产生SO_(4)^(2-),再经过一系列降解步骤最终实现矿化.The in-situ oxidative degradation of 2-mercaptobenzothiazole(MBT)in simulated aquifers wasstudied experimentally using activated persulfate(PS).The treatment efficiencies under various conditions were investigated,and the influence of factors such as media content,groundwater components,remediation reagent dosage,and environmental conditions were clarified.At the same time,various analytical methods were used to identify and quantify MBT degradation products.Based on the mass balance calculation,the mechanism of in-situ degradation of MBT in groundwater was preliminarily discussed.The results showed that when the initial concentration of MBT was 0.12 mmol·L^(-1),the concentration of PS was 1.0~1.3 mmol·L^(-1),the concentration of Fe^(2+)was 0.05~0.4 mmol·L^(-1),the amount of porous medium(coarse sand)was 10~50 g,the pH was 3~9 and the temperature was 25~50℃,the MBT degradation ratio reached more than 90%after 6 h of reaction,and the Fe^(2+)/PS system could effectively decompose MBT in the simulated underground environment.The porous media of the simulated aquifer could adsorb MBT in some way,and moderate increase in the dosage of PS and Fe^(2+)could effectively improve the degradation rate of MBT.The higher the initial pH value,the lower the MBT degradation rate;the higher the reaction temperature,the higher the MBT degradation rate.Cl-in groundwater had little effect on the degradation,but HCO3-had a significant inhibitory effect.The final mineralization degree of MBT molecule was 43%.The main ionic products in water were SO_(4)^(2-)and NO_(2)^(-),and the main organic products were benzothiazole(BTH)and 2-hydroxybenzothiazole(OBT).Both the radical oxidation pathway and the direct oxidation pathway existed in the Fe^(2+)/PS insitu degradation system.The SO_(4)^(·-)and HO⋅generated by PS activation mainly attacked the—SH substituent on the 2-C atom,causing the oxidation of MBT into BTH and OBT and generation of SO_(4)^(2-),and finally achieving mineralization through a series of degradation steps.

关 键 词：2-巯基苯并噻唑(MBT) 地下水 原位化学氧化 多孔介质 硫酸根自由基 

分 类 号：X523[环境科学与工程—环境工程]