Research On Remediation Of Lead And Arsenic Contaminated Soil With Iron Based Oxides

Soil heavy metal can directly threaten human health through food chains,therefore,soil remediation technology has become a research hotspot in the area of remediating heavy metal contaminated soil.Iron-based oxides is a relatively better material for remediating heavy metal contaminated soil for its high efficient and low cost.Therefore,it is of great significante to study the iron oxides for the remediation of soil heavy metal pollution.FeOOH,α-Fe₂O₃ and Fe₃O₄ were prepared and the phase composition,specific surface area and pore characteristic were also analyzed.And the removal of lead ions and arsenic ions in solution were researched.In addition laboratory experiments and field remediation experiments were carried.The results showed as follows:1)Characterization showed that the iron-based oxides prepared in the laboratory were FeOOH,α-Fe₂O₃ and Fe₃O₄,respectively,and the morphology was flake,curl and complete spherical shape.In order to sudy the adsorbent for the lead and arsenic adsorption efficiency of the five materials（FeOOH,α-Fe₂O₃,Fe₃O₄,ore Fe₂O₃ and ore Fe₃O₄）were studied.The results showed that FeOOH had the best lead removal effects.And FeOOH,α-Fe₂O₃ and Fe₃O₄ had a better arsenic removal effects and their removal rest all reached 95%.FeOOH and Fe₃O₄ had the best arsenic removal effects,and their removal rates were higher than 99%,which can reduce the content of arsenic to less than 0.01 mg/L.2)The laboratory experiments showed that Fe₃O₄ have good immobilization effect on lead and FeOOH have good immobilization effect on arsenic.When the addition amount of Fe₃O₄ was 3%,and at pH 4,the residue state of lead in the soil sample increase the most.3)The field remediation experiments showed that the application of 160g,180g and 250g AC,ore Fe₂O₃ and ore Fe₃O_4,the contents of lead increased and the effect was different on arsenic,respectively.The content of lead and arsenic decreased after the application of Fe₃O₄ was 5 g,10 g and 15 g respectively.The lead content decreased by 10.71%,16.11%and 20.92%,respectively.And the arsenic content was reduced by 1.83%,4.42%and 12.28%,respectively.When the applied amount is fixed at 250 g,the ratio of AC,ore Fe₂O₃ and ore Fe₃O₄ is changed.The lead content after remediation were lower than before.F1（AC:ore Fe₂O₃=2:1）,F2（AC:ore Fe₃O₄=2:1）,F5（ore Fe₃O₄:AC=2:1）and F6（ore Fe₃O₄:ore Fe₂O₃=2:1）treated soil,arsenic content were decreased,and the arsenic content increased with the soil treated with F3（ore Fe₂O₃:AC=2:1）and F4（ore Fe₂O₃:ore Fe₃O₄=2:1）.