Enhanced Electrokinetic Remediation Of Copper And Lead Contaminated Soil By Combining Steel Slag Permeable Reactive Barrier

In recent years,China's economy has developed rapidly,but the industrial structure and industrial layout have not been significantly improved.The level of pollution control and industrial production technology has not been significantly improved.However,the enterprises related to heavy metals in the country are constantly increasing,and the emissions of heavy metals are also increasing.Heavy metals accumulate in the soil,once the heavy metals exceed the standard,they will affect the normal growth of plants,enter the bodies of animals by food chain,and thus threaten people's health eventually.In this paper,the simulated contaminated soil(copper and lead)was taken as the research object,and the indoor model remediation.test of the copper and lead contaminated soil was carried out by combining the steel slag permeable reactive barrier(PRB)and four different types of electrolyte solutions(KCl,HAc,AC and PASP)through electrodynamic remediation technology,study the remediation effect of steel slag as an adsorbent on copper and lead contaminated soil under different electrolyte conditions.details as follows:(1)This article first systematically studied the selected steel 'slag and discussed its feasibility as a PRB material in electrokinetic remediation technology.Therefore,this paper analyzes the surface morphology and composition of steel slag and conducts a toxic leaching experiment.An isothermal static adsorption test was conducted to study the adsorption effect and adsorption law of copper and lead ions by steel slag.The results show that the surface of the steel slag is rough,has a large specific surface area,and is alkaline in water.In the extreme environment of strong acids and alkalis,the steel slag will release a small amount of heavy metals,but it is far below the standard threshold.The steel slag has a strong adsorption capacity for copper and lead in water.The adsorption reaction is fast and the adsorption capacity is large.Both the Langmuir model and the Freundlich model have good fitting accuracy.The fitting results indicate that the steel slag adsorbs copper and lead solutions It approaches 25.6mg/g and 70.6mg/g.(2)In this paper,0.1M KCl,0.1M HAc,0.1M CA and 1%PASP are used as electrolytes to conduct electrodynamic remediation experiments on Cu contaminated soil.The pH value of the soil,the removal rate of pollutants,the current energy consumption and heavy metal morphology in soil were discussed.The results show that when the remediation is completed,the four groups of electrodynamic remediation experiments show that the soil pH value is increasing from the anode to the cathode.When the KCl solution is used as the electrolyte,the pH value of each area of the soil changes the most,and the pH value in each region of the soil changed the least when CA solution was used as the electrolyte.In the initial stage of electrodynamic remediation,Cu will accumulate near the anode and then be gradually removed.When 0.1M CA and 1%PASP solution is used as the electrolyte,the removal effect is better,the removal rate is 50.8 and 40.2%,and the energy consumption is 0.553 KWh and 0.359KWh.Compared with KCl solution and HAc solution,CA and PASP solutions have lower specific energy consumption and higher removal efficiency.When the remediation is completed,the removal rate of water-soluble copper is the highest among the five heavy metal forms,and the removal effect of oxidizable and residual copper is not ideal.In the acidic environment,the removal rate of exchangeable copper can be improved.When CA and PASP solutions are used as electrolytes,the removal of reducible copper can be promoted.Therefore,CA and PASP are very powerful electrodynamic remediation electrolytes with broad application prospects.(3)In this paper,using steel slag as the PRB material,through the EK-PRB system remediation indoor model test,the effect of combined remediation technology on soil pH,pollutant removal rate,current consumption and the form of heavy metals in the soil when the remediation is completed is studied.The results show that in the EK-PRB remediation test,the acid-pretreated steel slag can absorb the OH' generated by the cathode to avoid the pH value of the soil near the cathode not being affected by the catholyte.When the remediation is completed,the soil pH near the cathode of the joint remediation test Values between 5.5 and 6.0 have been effectively reduced.Compared with the electrodynamic remediation technology alone,the combined remediation technology can reduce the accumulation of heavy metals,and reduce the accumulation range of heavy metals,promote the removal of heavy metals in the soil,the removal effect has also increased by 22%to 56%.The current value of the EK-PRB remediation test also began to decline earlier,and a better ion migration effect was obtained.Through energy consumption analysis,it can be found that EK-PRB remediation has better energy utilization efficiency under the same external conditions.The unit energy consumption W' is less than the individual electrodynamic remediation test,and W' drops by 10.1%? 46.1%.Compared with the electrodynamic remediation technology alone,the EK-PRB remediation technology removes more reducible copper,its removal rate is increased by 7%? 21%,and the exchangeable copper removal rate is increased by 9.5?32.1%.(4)The degree of binding of Cu and Pb in the soil and the organic matter in the soil is different,resulting in different forms of Cu and Pb in the soil.Comparing the forms of copper and lead in the initial soil,it can be seen that the proportion of water-soluble and oxidizable lead in total lead is significantly more than copper,while the exchangeable,reducible and residue lead accounts for less than total lead.