Remediation Of Saponin And EDTA On Copper And Lead Contaminated Lou Soil

Soils is the most important and the most basic comprehensive natural resources of thehuman beings as one of the essential constituent parts of the ecological environment system.Large amount of pollutants containing heavy metal have been entered into the soils by manyways along with the progress of society and economy in China, resulting in increasinglyserious problem in heavy metal contaminated soils. The Comprehensive Prevention Planningof Heavy Metal Pollution, as the first12th Five-year plan(2010-2015)were published in2011,is to strengthen the heavy metal pollution prevention, and curb resolutely the occurrence ofsoil heavy metal pollution.Soil leaching is an efficient and complete technology to remediate the heavy metal inpollution soils by combining physical method and chemical method using appropriate eluant.Soil leaching process is affected by factors such as soil property, contaminant characters,leaching liquid types and operation styles. Selecting effective eluant is the key of all thefactors affecting the soil leaching efficiency. EDTA as strong chelating agents is widely used.Saponin, a plant-derived biosurfactant, has been paid more attention for its goodbiodegradation and compatibility in rencent years.In this paper, Cu and Pb was choosen to representative, batch shaking tests and soilcolumn leaching methods were performed, chelating agent EDTA and biosurfactant Saponinwere choosen to research the leaching effect and leaching kinetic characteristics of Cu and Pbin single contamination Lou soil and mixed contamination Lou soil. After selecting theoptimal test parameters(concentration of Saponin and EDTA, pH value and concact time andleaching times，EDTA/Saponin concentration ratio), compared the leaching results of Cu andPb by soil column in single contaminated Lou soil and mixed contaminated Lou soil.Compared the morphological variation of Cu and Pb before and after leaching, providing ascientific basis for pollution control of heavy metal of the calcareous contaminated Lou soil.(1) The kinetics of leaching Cu and Pb in contaminated Lou soil using biosurfactantSoponin showed that leaching rate of Cu and Pb was slow, it reached leaching equilibriumabout after leaching240minutes. The leaching percent of Cu using1%soponin in singlecontaminated Lou soil and mixed contaminated Lou soil were8.25%and7.12%respectively; The leaching percent of Pb in single contaminated Lou soil and contaminated Lou soil were5.56%and6.03%respectively. The leaching results of Cu and Pb in each single contaminatedLou soil were higher than in mixed contaminated Lou soil by comparing the max leachingpercent of Cu and Pb. Two constant rate equations and pseudo-second-order equation were wellfit the experimental data.（2）The equilibrium research of leaching Cu and Pb in contaminated Lou soil usingbiosurfactant Soponin showed that optimal conditions of Soponin solutions are the solutionconcentration5%, pH5.00、contacting time240min and no background electrolyte; Theresults of the4times cumulative leaching indicated Soponin is effective to remove Cu and Pbfrom contamination Lou soil.（3）It has stimulative effect for shaking leaching Cu and Pb in contaminated Lou soilwith concentration of Soponin5%, combinating the concentration of EDTA0.0005mol/L and0.001mol/L, and leaching percent of Pb in contaminated Lou soil is higher than leachingpercent of Cu. The leaching effect of Cu and Pb was inhibited when the concentration ofEDTA was above0.005mol/L。（4）The cumulative leaching amount of Cu and Pb in contaminated Lou soil columnwas increased gradually with the cumulative eluant volume increased using EDTA、Soponinand EDTA combinating Soponin. It has stimulative effect for leaching Cu using EDTAcombinating Soponin in single contaminated Lou soil and mixed contaminated Lou soil. Theleaching percent of Pb using EDTA combinating Soponin is a little less than using EDTAsingle. The leaching percent of Cu in single contaminated Lou soil and mixed contaminated Lousoil using EDTA combining soponin were23.59%and21.57%respectively, and the leachingpercent of Pb were27.59%and24.92%respectively.（5）The fractionation results after Sposito sequential extraction showed that Soponin,EDTA, and EDTA combinating Soponin can effectively remove Carbonate, Organic, Sulfideresidual fraction of heavy metal in contaminated Lou soil. The results showed EDTAcombinating Soponin could activate heavy metals in contaminated Lou soil, and then, thecombinating eluant being as fortifier to facilitate transporting effectively the heavy metal fromcontaminated Lou soil to hyperaccumulator plants, as a result, the contaminated Lou soil waspurified.