Using Fenton Reagents To Remove The Polycyclic Aromatic Hydrocarbons In Soils

Accompanied with the rapid development of industry and agriculture in our country,many kinds of toxic waste gas,water and solid have been discharged into enviornments.Some toxic chemicals would eventually enter into soils through air deposition,water irrigation,and landfill leaching,resulting in the serious soil pollution.Polycyclic aromatic hydrocarbons(PAHs)are a group of persistent organic pollutants with high toxicity.They have been found with high concentrations in soil.On April 17th,2014,China government issued that 1.4%of soils in China were found with excessive PAHs.How to remediate the PAH-contaminated soil has become a worldwide concern.Fenton's reagent has been proven to be effective on oxidizability of many organic pollutants.In this work,we seek to remove the PAH-bound residues in soil using Fenton's reagent oxidation technology.The Fenton's reagent package was prepared and applied to remove the PAHs in contaminated soil.The main results are as follows:(1)The removal of PAH-bound residues in soil was studied using Fenton oxidation technique.This paper takes several PAHs(naphthalene,acenaphthylene,anthracene and fluorene)in collecting polluted soil as the object to research the effect of Fenton reagent oxidation degradation in PAH-bound residues.The reaction is influenced by the concentration of H2O2,pH,reaction time,the addition of Fe2+ and the rate of water and soil.These experimental conditions were optimized in this paper.The results showed that:Fenton reagent could be great effective in the oxidative degradation of PAH-bound residues in soil.Based on the concentration of 12%H2O2,pH of 3.0 and 1:20 ratio of iron,when the reaction time is 24 h in the dark,four kinds of PAH-bound residues in soil with binding state residual effect got best and the removal rates of PAHs in soil were up to 81%,95%,100%and 62%.Ibid.,when set several other factors constant,Fe ions addition rate of 1:30 was the best conditions,removal rate of four kinds of PAHs reached 92%,27%,97%,100%;the concentration of 10%H2O2 was another best conditions,four kinds of PAH-bound residues removal rate were as high as 93%,44%,95%,100%;pH 3.0-5.0 was another best conditions,removal rate can reach 89%,58%,65%,99%respectively;when the ratio of soil and water was 3:1.6 g/mL,optimum removal rate were 82%,63%,95%,100%respectively.(2)The paper developed Fenton reagent oxidation removal of PAHs in soil,and test the actual effect of the treatment of PAHs contaminated soil.Based on the experimental data on the hydrogen peroxide to premium(30%),28%FeSO4 solution and 10%oxalic acid have been obtained,this paper aim at several PAHs contained by a collection of contaminated soil.It researched Fenton reagent oxidation degradation effects on several kinds of PAHs pollution in soil.In order to apply in engineering more conveniently,it was scheduled the acid and FeSO4 particles to deal with 1 g polluted soil in a reagent package,as Pack 1.It dealt with 1 g polluted soil samples with acid,K2C2O4 and FeSO4 particles in a reagent package for Pack 2.Similarly,H2O2 packed in another package,as Pack 3.And then it looked for each reaction condition optimization factors.The results show that:H2O2 is a very important factor of Fenton reagent oxidation to the degradation of PAHs.What's more,it can get great synergistic effect by joining K2C2O4 in Fenton's system.And with the time prolonged,the degradation effect is more obvious in 24 h.Optimum reaction conditions optimized experimentally as follows:the degradation rate of 4 PAHs can reach the maximum when 10%oxalic acid is added into 135 ?L,Fe2+/C2O42-ratio is 1/3,the target concentration of hydrogen peroxide is 11%and the reaction time is 48h.Finally concluded several optimization combination reagent package.(3)The paper applied three kinds of reagent packs which have been found in the actual contaminated soil samples with different qualities.The reagent packs inlcuded the highest efficiency kit,which condition was FeSO4:K2C2O4=1:3,11%H2O2,1:8 iron ions added ratio;the bound optimization conditions of 11%H2O2,1:8 iron added ratio;relatively cheap reagent kit was FeSO4:K2C2O4=3:1,11%H2O2,1:8 of iron ions added ratio.They all had very good degradation effect.For example,when dealing with 60 g contaminated soil,several kinds of PAHs(naphthalene,acenaphthene,acenaphthylene,anthracene,fluorine,phenanthrene)removal rate got 40%,70%,52%,50%,63%,75%respectively.The other group of rules is similar,the removal rate in different quality groups are the same,but the minimum removal rate in 40%-50%.