Study On Efficiency Of Chelating Agents And Their Separation For Heavy Metals?Fluorine In Soils

Hunan Province, As the world's "home of non-ferrous metal", many years of mining makes the soil polluted by heavy metals. It is important that find out an effective way to repair contaminated soil. This study choose contaminated soil in Hunan province, Chenzhou and Hengyang city, As the research object. The choice of 6 kinds of chelating agents on soil pollutant wAs extracted according to the principle below:their extraction efficiency, biological toxicity, and whether they are eAsy separation. In order to select the suitable extractant, provide reAsonable method for further removal of heavy metals in soil, arsenic and fluorine.In the selected two sample soils, major form of heavy metals is the organic and sulfide bound forms. In soil samples S, heavy mental Pb, Zn, Cu and Cd mainly in the form of the organic and sulfide bound, accounted for 64.91%,38.52%,56.35% and 23.18% of the total. In acidic soil samples W, Zn and Cu are organic and sulfide bound, respectively accounted for 37.45% and 46.55% of the total. The main form of Cd is exchangeable and carbonate bound, which accounts for 45.25% of the total. The species distribution of Pb is uniform. In the selected two sample soils, major form of As is the residual form.According to extraction test to select 6 kinds of chelating agent, the chelating agent have a certain effect on the extraction of soil in the pollution of heavy metals and arsenic, fluoride ion. Citric acid hAs high extraction ability on Pb and Zn, Cysteine, on As and F have better effect of extraction, although EDTA is weak in Zn extraction effect, but it hAs trong ability of extracting on Pb, Cu, Cd, As and F. The synthesis result shows that the EDTA for both the weakly alkaline soil or acidic soil, is the best extraction in these 6 chelating agents.For the acidic soil, EDTA not only strong on the extraction ability, and the extraction also eAsily separate. So for the acidic soil EDTA is the best choice. But for the weak alkaline soil, though EDTA and citric acid hAs high extraction ability, but their extraction are not so eAsy to separate. While cysteine not only hAs high extraction ability, and the extraction also eAsy to be separated, therefore cysteine may be a better choice for the weak alkaline soil.