Remediation Of Diesel-contaminated Soil Using Coated Nano Zero Valent Iron/Sodium Peroxydisulfate System

The advanced oxidation technology based on sulfate radicals?SO·₄^-?has good prospects in the soil remediation due to its high stability and oxidation ability.However,traditional methods in activating may meet some shortages in practical applications.In this study,the coated nano zero valent iron?nZVI?was chosen to activating persulfate?PS?.Then,batch experiments were conducted to evaluate the feasibility of remediating diesel-contaminated soil using persulfate activated by T-n ZVI.Various controlling factors including different persulfate and ion concentrations,different activators(Fe²⁺,nZVI and T-nZVI)were considered.The main research contents and conclusions are as foloows:?1?The dispersing agents?CMC,PAA,Guar gum,Tween20?used in the study all can improve the performance of stability and migration capability of n ZVI.?2?Persulfate oxidation is capable of treating diesel contaminated soil.Higher persulfate and ion concentrations resulted in higher diesel degradation rates within the applied PS/Fe molar ratios.?3?A two-stage diesel degradation was observed in the batch experiments.Decreased diesel degrading rates and efficiencies during the second stage might be due to:?1?consumption of ferrous ion,?2?more complicated structures in the residual components of diesel,?3?adsorption of diesel onto organic matters and micropores in soil.?4?The maximum degradation efficiency of diesel?10000 mg/Kg?was 78% within 90 days in the T-nZVI system.Compared with the nZVI system,the degradation efficiency of diesel was better in the T-nZVI system,while the advantage is not obvious.?5?The main mechanism of T-nZVI activating persulfate is: under acidic or near neutral conditions,Fe²⁺ slowly released from T-nZVI,Fe²⁺ activating persulfate and producing SO·₄^-.