高盐强酸性地下水中复合苯系污染物原位芬顿氧化实验研究

In-situ Fenton oxidation experiment of compound benzene pollutants in high salt and strong acid groundwater

在原位氧化过程中,实际场地地下水和含水介质的物化特征是影响氧化效果的重要因素,而目前对此影响的研究较少。以某场地实际高盐强酸性复合苯系污染地下水为研究对象,以地下水中2-硝基-4-甲氧基苯胺(2-nitro-4-methoxyaniline,2-N)和3-硝基-4-甲氧基苯胺(3-nitro-4-methoxyaniline,3-N)为特征污染物,探究芬顿(Fenton)试剂原位氧化特征,并研究液相环境因素(初始H2O2浓度、初始Fe2+浓度、初始pH值、初始醋酸(Acetic acid,HAc)浓度、初始SO4^(2-)浓度)以及含水层介质对Fenton法去除2-N和3-N的影响。结果显示:(1)Fenton法去除2-N和3-N效果显著,且在初始液相条件为c(H2O2)=7 mmol/L、c(Fe^(2+))=4 mmol/L、pH=4、c(HAc)=0 mg/L和c(SO4^(2-))=0 mmol/L时去除效果最佳;(2)各因素对Fenton法氧化2-N和3-N的影响不同,加入H_(2)O_(2)和Fe^(2+)使2-N和3-N去除率上升,增大HAc浓度使2-N和3-N去除率下降;(3)含水层介质对2-N和3-N具有一定吸附性,且对3-N的吸附性强于2-N,二者在本实验中最大吸附态占比分别为29%和42%,而吸附态的存在会抑制Fenton法对2-N和3-N的去除;(4)矿物分析结果显示介质含有少量黄铁矿,在硫酸环境下,介质腐蚀溶解释放Fe^(2+),在达到一定浓度后,无需额外添加Fe^(2+)即可完成Fenton反应进而去除2-N和3-N。

In the process of in-situ oxidation,the physical and chemical characteristics of actual ground water and water-bearing media are the important factors affecting the oxidation effect,but there are few specific studies on this effect at present.The actual high-salt and strong-acid compound benzene contaminated groundwater in a certain site is used as the research object,and 2-nitro-4-methoxyaniline(2-N)and 3-nitro-4-methoxyaniline(3-N)in groundwater are characteristic pollutants.The in-situ oxidation characteristics of Fenton’s reagent are explored,and the liquid environmental factors(initial H2O2 concentration,initial Fe2+concentration,initial pH value,initial acetic acid(HAc)concentration,initial SO4^(2-)concentration)and aquifer media on the removal of 2-N and 3-N by Fenton method are examined.The results show that(1)the Fenton method has a significant effect on removal of 2-N and 3-N,and when the initial liquid phase conditions are c(H2O2)=7 mmol/L,c(Fe^(2+))=4 mmol/L,pH=4,c(HAc)=0 mg/L and c(SO4^(2-))=0 mmol/L,the removal effect is the best.(2)Each factor affects the oxidation of 2-N and 3-N by the Fenton method.The effect of the addition of H_(2)O_(2) and Fe2+increases the removal rate of 2-N and 3-N.Increase in the concentration of HAc decreases the removal rate of 2-N and 3-N.(3)The groundwater medium has a strong effect on 2-N and 3-N,and the adsorption of 3-N is stronger than that of 2-N.In this experiment,the two largest adsorption states accounte for 29%and 42%,respectively.The existence of the adsorption state will inhibit the Fenton method to 2-N.(4)The mineral analysis results show that the medium contains a small amount of pyrite.In a sulfuric acid environment,the medium corrodes and dissolves to release Fe^(2+).Therefore,the Fenton reaction can be completed without additional Fe2+to remove 2-N and 3-N.