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| Persistence and effectiveness of oxidants during the treatment of petroleum-contaminated soil by chemical oxidation with Na2S2O8 and H2O2 |
| Received:June 28, 2019 |
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| KeyWord:petroleum pollution;soil;in-situ remediation;chemical oxidation;persulfate |
| Author Name | Affiliation | | YANG Bing | College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, China
Institute of Industrial Hazardous Waste Disposal and Utilization, Southwest Petroleum University, Chengdu 610500, China | | CHEN Ke-ming | College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, China | | LI Qin-man | College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, China | | LIU Yu-cheng | College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, China
Institute of Industrial Hazardous Waste Disposal and Utilization, Southwest Petroleum University, Chengdu 610500, China |
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| Abstract: |
| Hydrogen peroxide(H2O2)and sodium persulfate(Na2S2O8)were used to treat petroleum-contaminated soil in laboratory experiments. The influences of different oxidants, fractional addition methods(1 or 3 times), and external addition of zero-valent iron(ZVI)on the degradation of total petroleum hydrocarbon(TPH)were investigated. The persistence of oxidants and the effectiveness of removing pollutants under different treatments were discussed. The results showed that H2O2 was not detected on the second day of the reaction, but the remaining amount of Na2S2O8 was 11, 35, and 60 mmol·L-1, respectively, after 10 days of reaction in treatments with initial oxidant concentration at 21, 63, and 105 mmol·L-1. After 10 days of reaction, the total removal rate of TPH in Na2S2O8 treatment was 12.41% and 14.21% higher than that in H2O2 treatment with the initial oxidant concentration at 63 mmol·L-1 and 105 mmol·L-(1 P<0.05), respectively. The decrease of Na2S2O8 and TPH residual concentration was extremely slow on the 4th to 10th day, indicating that the substances capable of activating Na2S2O8 were insufficient in the soil. Adding ZVI to Na2S2O8 treatment significantly promoted the total removal rate of TPH(P<0.05), and the degradation of TPH during days 4~10 increased by 8.46%, 8.49%, and 12.26%, respectively, with initial oxidant concentration at 21, 63, and 105 mmol·L-1. When H2O2 was added in three portions at 0, 24, and 48 h, with initial total oxidant concentration at 21, 63, and 105 mmol·L-1, TPH degradation rate rose by 17.26%, 25.43%, and 28.11%, respectively, after 10 days of reaction. GC-MS analysis of the organic components showed that the total peak area of petroleum hydrocarbons decreased by 56.64% and 57.60%, respectively, in treatments with H2O2 added in three portions and ZVI-activated Na2S2O8, and some long-chain alkanes were degraded to relatively "short-chain" alkane component. The overall results show that persistence of Na2S2O8 in petroleum-contaminated soil is superior to that of H2O2, but the effectiveness of Na2S2O8 in removing TPH decrease with the reaction time. The addition of ZVI improve the effectiveness of Na2S2O8 in removing TPH. Fractional addition of H2O2(added three times)increase the degradation rate of TPH in petroleum-contaminated soils. |
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