The role of anatase impurity in the leaching of Cd(II) from contaminated kaolinite
The role of anatase impurity in the leaching of Cd(II) from contaminated kaolinite
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DOI：
10.1016/j.jece.2018.102851
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发表时间：
2019-02
影响因子：
7.7
通讯作者：
Tasuma Suzuki;Kisyo Nakase;Satoshi Kakoyama;Junko Takamuro;Miyu Okita;Masakazu Niinae
中科院分区：
文献类型：
--
作者：
Tasuma Suzuki;Kisyo Nakase;Satoshi Kakoyama;Junko Takamuro;Miyu Okita;Masakazu Niinae
本研究的目的是加强对Cd（II）的污染高岭石的浸出机制的理解，重点是对镉杂质的作用。从滴定和批量镉（II）吸附实验获得的实验数据进行了分析，使用表面络合模型与离子交换反应。锐钛矿对Cd（II）的吸附能力显著高于高岭石和针铁矿（α-FeOOH），且以内球络合物形成为主。在酸性和近中性条件下，高岭石吸附Cd（II）主要通过外层络合物的形成，而外层和内层络合物的形成是重要的，在较高的pH值。结合常数从建模分析得到，然后被用来预测污染的高岭石中的Cd（II）的浸出程度与不同含量的镉杂质在pH 4.0-7.0。实验数据和模型预测一致表明，镉（II）的浸出减少，增加镉含量，这一趋势在酸性条件下更为显着。结果表明，高岭石中Cd（II）的含量是影响其在酸雨中浸出程度的一个重要因素。
This study was performed to enhance the understanding of the Cd(II) leaching mechanism from contaminated kaolinite with a focus on the role of anatase impurities. Experimental data obtained from titration and batch Cd(II) adsorption experiments were analyzed using a surface complexation model coupled with ion exchange reaction. Anatase showed significantly higher Cd(II) adsorption capability than those of kaolinite and goethite (α-FeOOH), with inner-sphere complex formation as the dominant adsorption mechanism. Under acidic and near-neutral conditions, kaolinite absorbs Cd(II) mainly via outer-sphere complex formation, while both outer-sphere and inner-sphere complex formation are important at higher pH. Binding constants obtained from modeling analyses were then used to predict the leaching extent of Cd(II) from contaminated kaolinite with different contents of anatase impurity at pH 4.0–7.0. The experimental data and model predictions consistently showed that the leaching of Cd(II) decreased with increasing anatase content and this trend was more significant under acidic conditions. These results showed that the content of anatase impurity is a factor controlling the leaching extent of Cd(II) from kaolinite when exposed to acid rain.