添加羟基磷灰石对土壤铅吸附与解吸特性的影响

采用羟基磷灰石对四种不同类型的土壤进行铅的吸附-解吸试验.结果表明:四种土壤对铅的吸附均可用Langmuir和Freundlich方程进行描述,土壤中加入羟基磷灰石明显增加了土壤对铅的吸附量和吸附亲和力,同时降低了土壤中铅的解吸百分数,在偏酸性的红壤上表现更为明显,其最大吸附量增加28%.羟基磷灰石对铅吸附的反应机理可能与磷灰石溶解后与铅形成磷酸盐沉淀及其对铅的表面吸附作用有关.土壤对铅的吸附量及吸附亲和力与土壤的有机质、阳离子交换量及粘粒含量有显著正相关,而与土壤砂粒的含量呈负相关.

EFFECTS OF HYDROXYLAPATITE ON THE SORPTION AND DESORPTION OF LEAD IN VARIOUS CHINESE SOILS

Sorption and desorption of Pb by different type of Chinese soils after treated with hydroxylapatite(HA) were studied.The results indicated that the adsorption of Pb~(2 ) by the soils obeyed the Langmuir and(Freundlich) equation,the sorption maximum(b,lg K_f)and the affinity characteristics(k,1/n) of Pb by the soils (increased) greatly in the treated soils as compared with the control,while the percentage of Pb release decreased significantly,especially in the red soil with a increment of 28% of sorption maximum.The mechanism of HA on Pb sorption and desorption may concern the solution of hydroxylapatite and whereafter the(precipitation) of Pb with phosphate compounds and the surface adsorption of Pb on the phosphate minerals etc.The content of organic matter,capacity of exchangeable cations and the content of clay in the soils have positive effects with the maximumsorption capacity and the sorption affinity of Pb by the soils,while the content of sand in the soils had the reverse effects.