Experimental Study On In-situ Chemical Oxidation Remediation Of 1,2,4-Trichlorobenzene Pollution In Groundwater

Based on the cooperation project between Nanjing University and DuPont Company,the main pollutant in Nanjing Liuhe District was found to be 1,2,4-(1,2,4-TCB),so the 1,2,4-TCB is regarded as the target pollutant.Because in-situ chemical oxidation technology is commonly used remediation techniques,this study conducted lab tests to simulate groundwater 1,2,4-TCB in situ chemical oxidationremediation.The oxidation degradation of 1,2,4-TCB and the recovery of chloride ion after 1,2,4-TCB oxidation were studied by using Fenton reagent,sodium persulfate oxidizer and the mix of both two oxidants.The objective is to determine the minimum dosing amount of the required oxidants for the total degradation of the quantitative 1,2,4-TCB.The results show that:(1)when the ratio of 1,2,4-TCB to hydroxyl free mole is 1:2.85 in batch test,the 1,2,4-TCB removal rate reaches 96.8%and the chloride recovery reaches 92.4%;(2)When the ratio of free mole ratio of 1,2,4-TCB to sulfate root is 1:3.5,the TCB removal rate can reach 97.8%,and the recovery of chloride ion is 94.4%.Based on the quantitative 1,2,4-TCB in batch test,the minimum dosage of different oxidants was applied to the sand column experiments,simulating the groundwater environment,studying the influence of flow rate,medium size,and the type of oxidant on the 1,2,4-TCB in situ chemical oxidation remediation.The purpose is to provide reference for practical site application.Experimental results:(1)The sodium persulfate oxidation system and the double oxidation system are more suitable for 1,2,4-TCB in situ chemical oxidation technology than the Fenton reagent.(2)Except Fenton reagent,the removal rate of TCB by sodium persulfate and double oxidant was similar with the change of particle size in different flow rates.(3)Except Fenton reagent,in the flow range of 3ml/min to 9ml/min,with the increase in flow,the TCB removal rate increased with the reagents in the flow of 9ml/min to get the highest degradation efficiency.It can provide reference for the site application.