Effect Of Modified Lignite On Heavy Metals Transformation In The Calcareous Soils

The lignite were modified for preparing alkaline lignite, lignite calcification, sulfonated lignite, nitration lignite, lignite-based activated carbon, demineralized lignite, lignite-based humic acid, humic acid resin, humic acid graft copolymer, a total of nine kinds of lignite modified materials. Selection heavily polluted soils of Ji Yuan mine, with lignite and modified materials for heavy metal contaminated soil improvement, cultivated30 days, 60 days, 90 days, 120 days, collected soil samples and determinated the content of Pb, Cd. Soilcultivated after 120 days, extracted organic mineral complex of heavy metals soil, while selected three different desorbent, measured the content of heavy metals after soil improvement. The main conclusions were as follows:1. Pb in soil morphology of distribution: Fe-Mn oxide > carbonate fraction > residua l> strong organic fraction > weak organic fraction > exchangeable, Cd forms distribution: exchangeable > carbonate fraction, Fe-Mn oxide fraction > weak organic fraction > residual > strong organic fraction.2. After adding modified materials, with the period delaying, the content of Pb and Cdion exchangeable was decreased, the content of weak organic fraction, strong organic fraction, residual were increased; the content of Carbonate fraction and Fe-Mn oxide bound varied, alkalization, calcification, demineralization, activated carbon, resin, graft copolymer were increased, the content of lignite, humic acid, nitration, sulfonation treatment of Pb and Cd were decreased. When you added humic acid, nitration, sulfonation,you can get a better curing effect. When you add different amounts of modified materials, better curing effect of the added amount of 5%.3. After cultivating soilfor120 days, each treatment to extract three organic mineral complexes soil sample proportion accounted for G1> G0> G2, while G0 group modifier processing complex content below the blank, G1 and G2 group complexes were higher than the blank, after adding the modified materials, an increase content in G1 and G2 group complexes, the stability of soil aggregates structure, improve soil physical and chemical properties have an important role.4. After cultivating soil for 120 days, the content of exchangeable、carbonate fraction and Fe-Mn oxide in Pb and Cd were G0 group complexes > G1 group complexes > G2 group complexes for each treatment, the content of weak organic fraction、strong organic fraction and residual in Pb and Cd were the G2 group complexes > G1 group complexes > G0 group complex.5. Three desorbent desorption soil, the content of0.1M EDTA desorption of Pb and Cd higher than 0.1M HCl and 0.1M citric acid. With the increase of the amount of modified materials added three desorbent desorbed, the content of Pb, Cd decreased, the amount of Pb in the desorption process was less than the blank, and in addition to the resin, the graft copolymer treatment, the desorption amount was less than the other treatments blank, visible, after you add modified materials, the content of Pb and Cd that soil can be fixed were increased, and the effect of adding a fixed 5% modifier better.6. Compared with the blank, the treatment of humic acid, nitration, sulfonation increased the content of Pb and Cd which is difficulty to move in soil, and increased the content of G1 and G2 groups complex in soil, while they had a lower desorption amount, can better soil heavy metals of Pb and Cd fixed.