Study Of Modified Biochar On Thestabilization Of Heavy Metals Lead And Copper Contamintes Soil

In recent years,soil heavy metal contamination events happened frequently,heavy metal pollution in soil seriously affects food safety and land utilization,which may cause harm to human health through the food chain.In this study,two repair agent--biochar?BO?and biochar/supported iron-manganese oxide?FMBO?were used as amendments for the stabilization remediation of Pb and Cu contaminated agricultural field in Xibu village of Yangling district.Through a series of characterization analysis of the two repair agents,preliminary discussion of its possible repair mechanism.The effects of the amendments on soil pH,heavy metals distribution,pakchoi growth and the heavy metal concentratio,and chlorophyll content of pakchoi were studied to evaluated the restorative effects on the remediation of heavy metal-contaminated agricultural soil with pot experiment,and the correlations between the factors are analyzed to discuss the remediation mechanism primary.The main results were as follows:1.The biochar is mixed with the aqueous solution of ferrous sulfate and manganese chloride,and the iron-manganese oxide modified biochar is prepared by the redox co-precipitation method under the action of potassium permanganate.The surface structure of modified biochar was researched based on BET,Zeta,FTIR.Zeta potential analysis shows that the isoelectric point of the modified biochar changes;The surface of modified biochar has particle aggregation,makes the specific surface area increased from 0.8805m2/g to383.2137m2/g;According to the infrared spectrum analysis,the modified biochar showed an absorption peak at 3400 cm^-1formed by O-H deformation vibration.2.The addition of two repair agents to some extent increased the pH of the soil.In Pb contaminated soils,soil pH increased the most during treatment of 5%BO,3%BO on the15th,30th days of the growth of pakchoi compared with the blank treatment;On the 45th day of the pakchoi growth,except for 3%FMBO,5%BO,the soil pH was lower than the blank treatment in other treatments.In the Cu contaminated soil,soil pH increased most in the treatments of 1%FMBO,5%FMBO,and 5%BO at the 15th,30th,and 45th days of the pakchoi growth compared with the blank treatment.3.With the exception of individual treatments,the addition of two remediation agents significantly reduced the content of the more hazardous carbonate bound state in Pb and Cu contaminated soils and converted them into more stable forms.In Pb contaminated soil,the3%FMBO,5%FMBO,and 5%FMBO treatments had the best effect on reducing carbonate-bound Pb in the 15th,30th,and 45th days of pakchoi growth compared to the blank treatment.99.09%,98.23%,98.98%,and mainly converted to iron-manganese oxide bound state,organic bound state and residue state,iron-manganese oxide bound state and organic combined state Pb;In the Cu contaminated soil,on the 15th,30th,and 45th days of the pakchoi growth,compared with the blank treatment,the three-time FMBO treatment had the best effect of reducing carbonate-bound Cu at 5%FMBO,which was reduced by 32.89%,27.23%,46.53%,and all mainly converted to iron manganese oxide bound and organically bound Cu.In the correlation analysis,it was found that on the 15th,30th,and 45th days of the pakchoi growth,with the exception of a few results,there were significant negative correlations between the carbonate-bound heavy metals Pb,Cu and soil pH in other treatments.The correlations indirectly prove that the increase of soil pH promotes the transformation of lead and copper in the soil from an unstable and highly active form to a stable and low-activity form.4.In Pb and Cu contaminated soils,the addition of two remediation agents significantly reduced the absorption of Pb and Cu by pakchoi and promoted the growth of pakchoi to a certain extent.In Pb contaminated soil,on the 15th,30th,and 45th days of the growth of pakchoi,compared with the blank treatment,3%BO,5%BO,and 3%BO have the best growth potential;In the Cu contaminated soil,in the 15th,30th,and 45th days of the pakchoi growth,compared with the blank treatment,the 3%BO,3%BO,and 1%BO treatment had the best growing trend.The addition of two kinds of repair agents promoted the synthesis of chlorophyll in pakchoi and inhibited the toxic effects of Pb and Cu on pakchoi.