Remediation Of Heavy Metals Contaminated By Lead And Cadmium By Natural Organic Acids And Surfactants

At present,soil heavy metal pollution is becoming more and more serious,and remediation of soil heavy metals has become an important subject.The advantages of chemical leaching and remediation technology are low cost and quick effect.But the single eluent is selective for heavy metals and is not suitable for contaminated soil.In response to this limitation,this paper designed natural organic acids,surfactants,and natural organic acids-eluent to repair Pb and Cd in soil.The adsorption kinetics of Pb and Cd removal by different eluents was studied.(1)A study on the remediation of Pb and Cd in soil by elution of natural organic acid under different conditions was carried out.The experimental results showed that natural organic acids could remove Pb and Cd from soil with increasing concentration in a certain range.The factor of time experiment shows that the removal effect of Pb and Cd in a certain time range will increase with the increase of time,and when it reaches a certain time,it will reach the equilibrium state.The experiments of liquid-solid ratio showed that the effects of natural organic acids on the remediation of heavy metals in soil were related to the types of heavy metals.The kinetic experiments show that the model is more consistent with the first-order kinetic model.(2)A study on the remediation of Pb and Cd in soil by surfactant leaching under different conditions was carried out.The experimental results show that the removal efficiency of Pb and Cd increases with the concentration increase in a certain concentration range.When a certain concentration is reached,the adsorption equilibrium is reached,and the removal efficiency of Pb and Cd is no longer changed.Time factors show that surfactants are selective for heavy metal remediation in soil.The liquid-solid ratio factor indicates that the two surfactants have different responses to the liquid-solid ratio factors due to different interaction mechanism.The kinetic analysis shows that the adsorption of Pb by CTAB and DBSS is more in accordance with the second-order kinetic model,and the adsorption of Cd is more consistent with the first-order kinetic model.(3)Study on the remediation of Pb and Cd in soil by leaching of natural organic acids and surfactants under different conditions.The concentration factor experimentshowed that the removal effect of complex eluent on Pb was: CA-CTAB >MA-CTAB > CA-DBSS > TA-DBSS > TA-CTAB > MA-DBSS.Cd removal efficiency: CA-CTAB > MA-CTAB > TA-CTAB > TA-DBSS > CA-DBSS >MA-DBSS.The experimental results of time factors show that the heavy metals in the soil can be remedied by the compound eluent,which can be divided into two stages: the rapid reaction stage and the adsorption equilibrium stage.The liquid-solid ratio factors showed that the removal rate of heavy metals increased with the increase of liquid-solid ratio in a certain range,and the removal rate of heavy metals decreased with the increase of liquid-solid ratio when the liquid-solid ratio exceeded a certain range.Kinetic studies show that the six formulated eluents are more consistent with the first-order kinetic model.