Study On Remediation Of Petroleum Contaminated Soil By Synergistic Activation Of Sodium Persulfate By Surfactant

In the petroleum industry,crude oil or petroleum products enter the soil environment for various reasons,endangering soil ecological security and human health.How to repair oil polluted soil efficiently has become a research hotspot.More and more attention has been paid to the remediation of petroleum polluted soil by activated persulfate oxidation.However,petroleum pollutants are hydrophobic and adsorbed easily on soil,which makes it difficult to achieve good remediation effect.Surfactants can promote the migration of pollutants from soil to water phase and increase the removal rate of petroleum.In this study,based on the activated sodium persulfate（Na₂S₂O₈）remediation,the feasibility of surfactant enhanced remediation of oil-contaminated soil and the optimization of reaction conditions were investigated.The study on the remediation of petroleum-contaminated soil by activated Na₂S₂O₈showed that the petroleum removal rates of Fe²⁺,Ca O,Fe²⁺/Ca O,Fe₃O₄,and Fe⁰ activated Na₂S₂O₈ were 39.26%,57.79%,61.25%,62.63%,and 71.04%,respectively.Compared with Fe²⁺and Ca O activation,Fe²⁺/Ca O activation has a better repair effect,and Fe₃O₄ and Fe⁰heterogeneous systems show better catalytic performance than Fe²⁺,Ca O and Fe²⁺/Ca O homogeneous systems.Kinetic studies show that except Fe²⁺activation,other activation modes are more consistent with second-order reaction kinetics model.The activation of Ca O and Fe₃O₄ had great influence on the soil color,which made the soil white and black,respectively.The soil was nearly neutral after the activation of Fe²⁺/Ca O and Fe⁰.Fourier transform infrared spectroscopy（FTIR）showed that the structures of C-H and C-O of petroleum pollutants were destroyed after oxidation.Scanning electron microsc（SEM）showed that the soil morphology changed obviously after restoration,and the changes of the morphology of Fe²⁺/Ca O,Fe₃O₄and Fe⁰ activated soil were more obvious.X-ray diffraction（XRD）analysis showed that activator and Na₂S₂O₈ caused the change of soil phase composition.Surfactant enhanced repair studies have shown that the enhancement effect of Sodium dodecylbenzene sulfonate（SDBS）was the best,followed by Sodium dodecyl sulfate（SDS）,and Cetyltrimethylammonium bromide（CTAB）showed inhibitory effect.SDBS enhancement was not applicable in Ca O activation restoration system,and the enhancement effect on Fe²⁺/Ca O and Fe⁰ was the best.The highest oil removal rates were 81.91%and 87.16%,respectively,when the reaction conditions were further optimized.Adding SDBS had little effect on soil p H and color.SDBS enhanced Ca O activation by FTIR analysis showed that there were more surfactants in the soil.SEM showed that SDBS had a great influence on the surface morphology of Fe²⁺/Ca O,Fe⁰ and Fe₃O₄ activation.After 30 days of SDBS enhanced activation of Fe²⁺/Ca O and Fe⁰,soil microbial activity was greater than that of unrepaired soil,and CO₂ release was 2 and 1.51 times of that of unrepaired soil,respectively.