Leaching Remediation Of Soil Co-contaminated By Heavy Metals And PAHs

Heavy metals are poor in mobility, and can’t be degraded by microorganism insoil; PAHs are hardly degraded by natural environment, and are carcinogenic,teratogenic, and mutagenic. What’s more, they all can be absorbed into our body byfood chain, which are very harmful to our health. Now, more and more governmentsare paying attention to remediate heavy metals and PAHs co-contaminated sites.Modified cyclodextrins are non-toxicity, higher biodegradability, low affinity ofsorption to the solid phase and so on. Due to organic compounds can be absorbed bythe low-polarity cavity of Carboxymethyl-β-cyclodextrin(CMCD), and the carboxylgroups of CMCD can complex the heavy metal ions outside the cavity, then it can beapplied to removal of heavy metals and organic compounds from co-contaminatesdsoil simultaneously. Now, it is very prevail to use CMCD to remediate heavy metalsand PAHs co-contaminated soil.We studied the interactions between heavy metal ions and PAHs when CMCDremediate heavy metals and PAHs co-contaminated soil by a set of experiments in thispaper. The results show that naphthalene and anthracene have no influence on themetal-CMCD interactions, and heavy metals make no contribution to the adsorptionof PAHs by CMCD, either. Results of experiments show that the apparent aqueoussolubility of Nap and Ant are linearly increased with the concentration of CMCD, inother words, it can greatly increase the solubility of naphthalene and anthracene, theirsolubility is enhanced almost18-and7-fold in10g/L CMCD. CMCD can chelatewith Cu2+, Cd2+, and Pb2+efficiently, and10g/L CMCD has the removal efficiency ofabout92%,89%and95%for Cu2+, Cd2+, and Pb2+of contaminated quartz sand.Lots of factors will affect efficiency of elution of heavy metals and PAHsco-contaminated soil by CMCD. Results of experiments show the removal efficiencyof Cd2+and anthracene are obviously increased with the concentration of CMCDincreasing, and if the concentration of CMCD reach10g/L, the removal efficiency ofCd2+can only increase a little; the removal efficiency of Cd2+and anthracene areslowly increased with the particle size of quartz sand increasing; the tempreture hasno influence on the removal efficiency of Cd2+, but it can improve the removalefficiency of anthracene a little bit; the pH of solution can improve the removal efficiency of Cd2+obviously, but it can’t affect the removal efficiency of anthracene.The micelle of rhamnolipid could combine with heavy metal ions, and it also canincrease the solubility of organic compounds obviously, then rhamnolipid can removalof heavy metals and organic compounds from co-contaminatesd soil simultaneously.Rhamnolipid is non-toxicity, higher biodegradability, no secondary pollution and soon.This paper investigated some key factors which could affect efficiency of elutionof heavy metals and PAHs co-contaminated soil by rhamnolipid. Results ofexperiments show the removal efficiency of Cd2+and anthracene are obviouslyincreased with the concentration of rhamnolipid increasing; the removal efficiency ofCd2+and anthracene are slowly increased with the particle size of quartz sandincreasing; the tempreture has no influence on the removal efficiency of Cd2+, but itcan improve the removal efficiency of anthracene a bit; the pH of solution couldimprove the removal efficiency of Cd2+and anthracene, but it strengthen the removalefficiency of Cd2+more obviously.