作　　者： ; ; ;

机构地区： 中山大学地球科学系

出　　处： 《矿物岩石地球化学通报》 2004年第4期305-309,共5页

摘　　要： 介质的pH值是影响羟基磷灰石(Hap)除镉行为最为复杂的因素之一,它决定了水溶液中Cd2+的赋存状态及Hap的溶解特性与表面性质等,而这些因素与Hap的除镉行为密切相关。实验研究表明,强酸(pH<3)条件下Cd2+的去除率随pH值的升高增加较快,但当pH≥3时这种增加变缓。在广泛的pH值范围内,Hap在含镉溶液和空白溶液中均表现为质子催化和非化学计量比的溶解机理。根据络合平衡计算,Cd2+在不同pH值时具有不同的型体及分布系数。Hap在空白溶液中的表面电动电势ζ为负值,且随pH值的增加其电负性增大。由此可知Hap除镉行为的作用机理是表面络合与表面电位吸附,而不存在溶解 沉淀作用。 pH is one of the most complicated factors which affect the removal of aqueous cadmium ion by hydroxyapatite (Hap), because it determines the speciation of cadmium ion, characteristics of Hap dissolution and properties of Hap surface, and all of which are nearly related to the removal of cadmium ion. Experiment results indicate that the removal efficiencies of cadmium increases as pH value increases, while the increase is more rapid under strong acid (pH<3) conditions. In a broad pH range, the dissolution mechanisms of Hap in aqueous cadmium and blank solution accord with non-stoichiometric dissolution and hydrogen catalytic model. From calculation of complexation balance, the speciation and its distribution coefficient of cadmium can be obtained at different pH value. The ζ potential of Hap in blank solution is negative, and the electronegative values increase as pH increases. On the basis of experiment analyses, we can conclude that the mechanisms of cadmium removal are surface-complexation and surface-potential-adsorption, and dissolution-precipitation does not exist.

关 键 词： 羟基磷灰石 镉离子 溶解特性 电位 机理

领　　域： [天文地球] [天文地球]