炭石灰体系对于土壤中Cd赋存形态的影响

Effect of char-lime system on the speciation of cadmium in the soil

研究了熟石灰与活性炭组成的炭石灰体系用于固定土壤中Cd的可行性,考察了熟石灰/活性炭配比及炭石灰用量、土壤有机质和pH等对固定过程中镉赋存形态的影响,并初步探讨了固定机理和耐酸冲击负荷能力.研究结果表明,随着炭石灰的用量以及炭石灰中熟石灰用量的增加,交换态Cd均逐渐减少,同时碳酸盐结合态、铁锰氧化物结合态Cd增加.土壤有机质含量及pH值的增加,有利于提高炭石灰对交换态Cd的固定效率,降低土壤中交换态镉的含量,同时碳酸盐结合态、铁锰氧化物结合态和有机质结合态Cd含量增加.FTIR分析表明炭石灰主要通过化学沉淀、络合和物理吸附等方式固定土壤中的镉.初步的研究结果表明经炭石灰化学固定后的土壤对酸性高的降水具有较强的耐受性.

In this paper, the feasibility of solidification of Cd in soil by char-lime system which was made up of certain proportion of activated carbon and hydrated lime was studied. The effects of proportion of hydrated lime and activated carbon, the dosage of char-lime, soil organic matter content and pH value on the species of cadmium were examined. The solidifying mechanism and its resistance to acidic impact was also observed. The results showed that the exchangeable state of Cd was gradually reduced with the increase of the char-lime dosage and hydrated lime in it, while the carbonate-bound and the Fe-Mn oxides bound Cd increased. The increase of soil organic matter content and pH value was in favor of increasing the solidifying lime system on exchangeable state of Cd, and the carbonate-bound, the Fe-Mn oxides boun efficiency of char- d and the organic matter bound Cd increased. FI＇IR analysis showed that the solidifying mechanism of char-lime mainly was chemical precipitation, complexation and physical adsorption. At the same time, preliminary results showed that after chemical solidification by char-lime, the soil had a strong tolerance to acidic precipitation.