The adsorption behavior of niobium (V) on kaolin clay and kaolinite
The adsorption behavior of niobium (V) on kaolin clay and kaolinite
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DOI：
10.1016/j.clay.2023.106866
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发表时间：
2023-04
影响因子：
5.6
通讯作者：
Tingting Yang;Ning Wang;Hannian Gu
中科院分区：
文献类型：
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作者：
Tingting Yang;Ning Wang;Hannian Gu
高岭土中的铌通常存在于含钛矿物中，如金红石和锐钛矿。然而，某些高岭土的低含钛矿物含量不足以解释高铌含量。因此，人们普遍认为铌是被粘土矿物吸附的。然而，铌(V)在粘土矿物上的吸附行为尚不完全清楚。本研究采用草酸铌溶液对高岭土（Kclay）和纯高岭石（Kaol）进行了一系列的间歇吸附实验。考察了接触时间、初始铌(V)浓度、溶液pH和温度对吸附的影响。结果表明，在相同的条件下，Kclay的吸附能力比Kaol高。铌(V)在Kclay和Kaol上的吸附与pH值有关，在pH值为2 ~ 4时，两者的吸附量均呈下降趋势。铌(V)在Kclay和kol上的吸附行为符合伪二阶模型。Kclay吸附等温线较适合Freundlich吸附等温线模型，而Langmuir吸附等温线模型较适合Kaol吸附等温线模型。Kclay和Kaol的Langmuir最大吸附量分别为5.42和2.25 mg/g。这些结果表明，铌(V)可以被高岭土和高岭石吸附。
Niobium (Nb) in kaolin clay usually occurs in the Ti-bearing minerals, such as rutile and anatase. However, the low Ti-bearing minerals contents for some kaolin clay rocks were insufficient to explain the high Nb concentrations. Thus, Nb was widely considered to be adsorbed by clay minerals. However, the adsorption behavior of niobium (V) on clay minerals has not been fully understood. In this study, a series of batch adsorption experiments were carried out on kaolin clay (Kclay) and pure kaolinite (Kaol) using niobium oxalate solutions. The effects of contact time, initial niobium (V) concentration, solution pH, and temperature on the adsorption were investigated. The results showed that Kclay exhibited a higher adsorption capacity than Kaol under the same conditions. The niobium (V) adsorptions on Kclay and Kaol were pH-dependent, and both of them showed declining adsorption capacities from pH 2 to 4. The adsorption behaviors of niobium (V) on Kclay and Kaol conformed to the pseudo-second-order model. The adsorption isotherm of Kclay was a better fit with the Freundlich isotherm model, while the Langmuir isotherm model was a better fit for Kaol. The Langmuir maximum adsorption amount of Kclay and Kaol were 5.42 and 2.25 mg/g, respectively. These results demonstrated that niobium (V) can be adsorbed by kaolin clay and kaolinite.