Removal of Co²⁺ from aqueous solutions by hydroxyapatite

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• 作者：I. Smič ; iklas ; S. Dimović ; I. Pleć ; aš ; and M. Mitrić
• 关键词：Hydroxyapatite ; Cobalt removal ; Equilibrium isotherm ; Kinetics ; pH ; Desorption
• 刊名：Water Research
• 出版年：2006
• 期刊代码：57_00431354
• 类别：civ
• 出版时间：July 2006
• 卷：40
• 期：12
• 页码：2267-2274
• 文件大小：322 K

摘要

A study on the removal of cobalt ions from aqueous solutions by synthetic hydroxyapatite was conducted in batch conditions. The influence of different sorption parameters, such as: initial metal concentration, equilibration time, solution pH and presence of EDTA on the amount of Co²⁺ sorbed was studied and discussed. The sorption process followed pseudo-second-order kinetics with necessary time of 24 h to reach equilibrium. Cobalt uptake was quantitatively evaluated using the Langmuir and Dubinin–Kaganer–Radushkevich (DKR) model. The Langmuir adsorption isotherm constant corresponding to adsorption capacity, Xm, was found to be 20.92 mg/g. Sorption of Co²⁺ is constant in the initial pH range 4–8, because HAP surface buffers these solutions to the constant final pH value of 5.1. In the presence of EDTA, sorption of Co²⁺ decreases due to formation of complex with lower sorption affinities. Cobalt desorption depends on the composition of the extracting solution. The desorbed amount of cobalt decreased continuously with increasing pH, and increased with increasing Ca²⁺ concentration in leaching solution.