基于除镉作用机理探讨的碳羟磷灰石溶解特性研究

碳羟磷灰石（CHap）在含镉溶液和空白溶液中溶解特性的对比实验结果表明：介质pH值是影响CHap溶解的重要因素，强酸务件下，溶解度最大；溶钙量和溶磷量的摩尔比均不是1、67；溶解初期阶段反应速度快，动力学过程复杂，后期阶段符合一级反应动力学特征，说明CHap溶解机理符合氢催化模型、非化学计量比溶解模型、多核模型，在含镉溶液中溶解时，还包括离子交换模型，即溶液中的镉离子与CHap中的钙离子发生交换作用。从溶解特性的角度推测：CHap除镉过程中存在有离子交换作用机理。

DISSOLUTION BEHAVIORS OF CARBONATE-HYDROXYAPTITE

The study of the removal mechanisms of aqueous Cadmium ion by carbonate-hydroxyapatite (CHap) demonstrated the dissolution behaviors of CHap in aqueous Cadmium-bearing and blank (Cadmium-non-bearing) solutions. Experimental results show that dissolution of CHap strongly depends on pH values of the solutions and the solubility reaches maximum under strong acid conditions. Meanwhile,the Ca/P molar ratios of CHap dissolved in Cd-bearing and blank solutions are not 1.67,in agreement with non-stoichiometric dissolution model. The dissolution of CHap in both solutions is a complicated non-homogeneous solid/liquid reaction,which can be described by two stages from kinetic point of view. At the first stage,reaction rate is so fast that its kinetic course is intricate,which requires further investigation. At the second stage,the rate of reaction becomes slow and the process of reaction accords with one-order reaction kinetic equation. The mechanisms of CHap dissolution in both aqueous Cd-bearing and blank solutions comply with hydrogen catalytic model,non-stoichiometric dissolution model and polynuclear model,but the dissolution of CHap in Cd-bearing solution also obeys ion-exchange model,indicating that Ca ions in Hap structure are exchanged by Cd ions in the solution.