Interaction Between Colloids And Pahs In Coking Contaminated Soil

In the soil environment,the interaction between polycyclic aromatic hydrocarbons(PAHs)and colloids has an important impact on their migration,transformation,fate and environmental hazards in the soil and groundwater environment.In this paper,the stability of colloidal suspension in the presence of different pH,valence cations and valence anions,the adsorption characteristics of PAHs by colloidal dosage,adsorption time and temperature,and the correlation between PAHs migration and colloids in contaminated soils under different pH conditions were studied.The results show that Colloidal stability of coking contaminated soils is slightly lower than that of non-contaminated soils,The critical concentration of colloid agglomeration increases with the increase of pH value of colloid solution,decreases with the increase of cationic valence in colloid solution,and increases with the increase of anionic valence in colloid solution.When the dosage of soil colloid was 30 mg,the adsorption of anthracene and phenanthrene by colloid reached equilibrium.The adsorption of anthracene and phenanthrene by colloids in coking contaminated soil conforms to a quasi-second-order kinetic model,indicating that chemical adsorption is the main adsorption on the kinetic level,and the adsorption equilibrium time is240 min and 120 min,respectively.Adsorption of anthracene and phenanthrene by coking contaminated soil colloids conforms to Langmuir and Freundlich isothermal adsorption models,and the range of R~2 varies from 0.92 to 0.99.This indicates that the adsorption surface of anthracene and phenanthrene by colloids is monolayer adsorption,and multiple adsorption sites act simultaneously.Each adsorption site shows different free energy and total residue of sites.The adsorption of anthracene and phenanthrene by coking contaminated soil colloids is 18.578KJ/mol and 19.451 KJ/mol,respectively.The adsorption of anthracene and phenanthrene by coking contaminated soil colloids is an endothermic,disordered and non-spontaneous process,and the adsorption of anthracene and phenanthrene by coking contaminated soil colloids is0.053 and 0.058 KJ/(mol·K),respectively.The thermodynamic parameters of anthracene and phenanthrene adsorption by coking contaminated soil colloidsΔH were 18.578 and 19.451KJ/mol,andΔS were 0.053 and 0.058 KJ/(mol·K).The adsorption thermodynamic parametersΔG were negative,which means the adsorption of anthracene and phenanthrene by coking contaminated soil colloids was an endothermic,disordered and non-spontaneous process.Colloids and PAHs had the strongest ability to penetrate the soil column when the pH value was6,and the weakest when the pH value was 4.When the pH value was 8 and 9,the penetration ability of colloids and PAHs was lagged behind that of leachate.With the increase of leachate volume,the concentration of colloids and PAHs first increases and then decreases,and finally the leachate concentration tended to be stable.Colloids and PAHs and various PAHs showed very significant positive correlation.The correlation coefficient ranged from 0.605 to 0.984.The research results have certain theoretical significance for the remediation and risk assessment of organic contaminated soil.