Remediation Diesel Contaminated Soil By Enhanced Persulfate

Petroleum is used for many areas and as the one of the main products of the world energy supply.Contamination of soils by petroleum hydrocarbons is a serious and common problem all over the world due to leaks or another reasons.Chemical oxidation become one of the popular technology owe to low cost and short remediation period.In this study,activated persulfate and enhanced persulfate are used to remediate petroleum hydrocarbon contaminated soil.The degradation rate,kinetics,mechanism and effected soil properties by remediation were studied,the main research results as followed:?1?The single activator activated persulfate results were showed,the dosage of Na₂S₂O₈was 15 mmol in per 100 g petroleum hydrocarbon contaminated soil,when the Na₂S₂O₈:Fe²⁺molar ratio was 5:1,the petroleum degradation rate was 41.1%.And the petroleum degradation rate was 48.48%when the Na₂S₂O₈:Fe⁰ molar ratio was 5:1.The petroleum degradation rate of hydrogen peroxide activated persulfate was 40.3%when the hydrogen peroxide added was 10 ml.When the NaOH:Na₂S₂O₈ molar ratio was 5:1,the petroleum degradation rate was 48.48%and pH was 10.31.When the CaO₂:Na₂S₂O₈ molar ratio was5:1,the petroleum degradation rate was 35.93%.The petroleum degradation rate of2Na₂CO₃?3H₂O₂ activated Na₂S₂O₈ was 39.9%when the 2Na₂CO₃?3H₂O₂:Na₂S₂O₈ molar ratio was 1:5.?2?High concentration hydrogen peroxide was conducive to degradation of petroleum hydrocarbon in the Fe²⁺-H₂O₂-Na₂S₂O₈ remediation system,and the one-time addition of remediation reagents was superior to multiple additions.In addition,the petroleum hydrocarbon degradation in the Fe²⁺-H₂O₂-Na₂S₂O₈ remediation system followed the pseudo-first-order kinetic model.The petroleum hydrocarbon of the soil in the Fe²⁺-H₂O₂-Na₂S₂O₈ remediation system were oxidatively degraded by hydroxyl radical and persulfate radical,the remediation reagent had the strong synergistic effects among Fe²⁺,H₂O₂ and persulfate,and chain initial reaction,oxidative degradation reaction,intermediate products generation reaction,radical scavenging reaction coexisted in the Fe²⁺-H₂O₂-Na₂S₂O₈remediation system.The Fe²⁺-H₂O₂-Na₂S₂O₈ remediation system was enhanced by surfactants and chelating agents,and its treatment efficiency was as followed:citric acid>SDBS>?-cyclodextrin>glucose>SDS>TW-80.The degradation of petroleum hydrocarbon was 57.26%when the dosage of citric acid was 5 mmol,the soil was acidic,and the mass fraction of soil organic matter was 1.80%in the Fe²⁺-H₂O₂-Na₂S₂O₈-CA remediation system.?3?The degradation of petroleum hydrocarbon in the Fe⁰-H₂O₂-Na₂S₂O₈ remediation system followed the pseudo-first-order kinetic model,and hydroxyl radical and persulfate radical were coexisted in the system,and the remediation reagent had the strong synergistic effects among Fe⁰,H₂O₂ and persulfate.In addition,the hydroxyl radical was predominated in the remediation system.The petroleum hydrocarbon degradation of Fe²⁺-H₂O₂-Na₂S₂O₈-CA remediation system was superior to the Fe⁰-H₂O₂-Na₂S₂O₈ remediation system.The degradation of petroleum hydrocarbon was 55.48%when the dosage of SDBS was 0.5 mmol in the Fe⁰-H₂O₂-Na₂S₂O₈ remediation system.?4?The different addition order of citric acid,ferrous sulfate heptahydrate,hydrogen peroxide and persulfate had a small effect on the degradation of petroleum hydrocarbon,and the addition order of persulfate-citric acid-Fe²⁺-hydrogen peroxide remediation system petroleum hydrocarbon degradation was superior to another three addition orders.The degradation of petroleum hydrocarbon was effected by the number of added reagents,the degradation of diesel contaminated soil was 66.16%and the site-contaminated soil was61.22%when the number of added reagents was three times.The degradation of petroleum hydrocarbon in diesel contaminated soil and site-contaminated soil were gradual increased with the increasing number of the added remediation reagents,but its had the less effect on the degradation rate.The effective cation exchange capacity,the electrical conductivity and the content of Fe,S and other elements were increased with the number of added remediation reagents increased.But the pH was gradually decreased with the number of added remediation reagents increased.The germination rate of radish,cabbage,and corn seeds was almost unaffected with the number of added remediation reagents increased,but the capsicum seeds were affected.Besides,the roots and stems became shorter with the remediation reagents addition number increased,and which effected the growth of plants and damage the soil quality.In summary,the enhanced persulfate had the higher degradation of petroleum hydrocarbon than activated persulfate.In addition,the increased number of remediation reagents addition had little effected on the degradation of petroleum hydrocarbon,but the soil properties were affected,and the soil quality was damaged.Subsequent research can be carried by chemical oxidation pre-treatment of petroleum hydrocarbon contaminated soil,and then it was combined with bioremediation to reduce the effected on soil quality.