| Bean dregs are a common production waste with wide source and low price and have a good application prospect in the treatment of heavy metals in soil on account of rich surface oxygen containing functional groups and relatively developed pore structure they have. In this experiment, bean dregs were as raw materials while their modified materials were prepared by acidification and alkalization treatment. Analyzed the physical and chemical properties of bean dregs and modified materials, studied the leaching ability of cadmium in Cd contaminated soil of bean dregs and modified materials, researched the removal effect of cadmium in water in different conditions of soil bean dregs and modified materials with the leaching experiment of cadmium contaminated soil, the adsorption experiment of cadmium in solution, the soil culture experiment and the pot experiment. Not only the effects of cadmium on bioavailability but the availability of heavy metals and the effect of basic nutrients in soil have been revealed or studied in this experiment. The main research results are as follows:(1)In terms of leaching of bean dregs studied at different concentrations, pH, leaching time on the cadmium leaching effect, bean dregs obtained when the concentration rises, the leaching rate rise, but when bean dregs concentration to 5g/mL or so to reach equilibrium, then the leaching rate of 9.42%. As the solution pH increased leaching rate of decline in the rate of leaching at pH 3 highest reaches 17.92% with the start of oscillation, leaching rate increased with time, when the oscillation to 2h, rinsed balance, leaching rate of 10.48% at this time.(2) In terms of water absorption of chromium to explore the impact on the concentration of cadmium in solution, the solution pH, shaking time and the concentration of cadmium adsorption material, when the solution cadmium concentration exceeds a certain concentration, alkali-modified material in solution are three kinds of material removal in the highest, and when the solution concentration of 500mg/L adsorption capacity reached 37.43g/kg. When the pH is 4, three kinds of material adsorption reached equilibrium, and as the best adsorption rate was 98.06%. At the same time with the adsorbent adsorption rate rise increased concentration equilibrium is reached, when the concentration of lOg/L, as the highest adsorption rate reached 97.36%.Three kinds of materials in about 2 hours adsorption reached equilibrium, as is best and the adsorption rate was 98.8%. The adsorption kinetic equation fitting, quasi-second-order kinetic model could well fit results.(3) By soil culture experiments as acid-modified material administration will reduce the soil pH, while three kinds of materials can effectively increase soil CEC content, wherein the base material is modified best. Bean dregs and materials can reduced soil exchangeable cadmium content, at 30 days the best base is modified material,33.9% lower than CK; incubated for 60 days as it is the best,37.4% lower than CK. And for the soil nutrients, each material have played a positive role in varying degrees.(4) Bean dregs and modified materials can reduce the plant rhizosphere soil cadmium activity, its effect a significant degree of material and add volume. Cadmium content of soil available minimum processing, supplemented with 10% of bean dregs, lower than CK of 0.31mg/kg. Plant cadmium minimum processing, supplemented with 2.5% of bean dregs, the cadmium content in plants is lower than CK of 1.07mg/kg. |
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