Department of Applied Sciences, Muroran Institute of Technology, 050-8585, Hokkaido, Japan.
Department of Applied Sciences, Muroran Institute of Technology, 050-8585, Hokkaido, Japan.
Chemosphere. 2022 Jan;287(Pt 3):132257. doi: 10.1016/j.chemosphere.2021.132257. Epub 2021 Sep 16.
Previous studies on cadmium adsorption of calcium carbonate have found that polymorph, and, crystallinity are influential factors for adsorbing cadmium ions. The predominant factor for cadmium adsorption has yet to be elucidated because these factors are linked. To overcome this, here each factor is investigated separately. First, atmospheric grinding prepared surf clam (aragonite phase) and scallop (calcite phase) shells with similar crystallite sizes and specific surface areas. Using adsorption isotherm models, kinetics, X-ray diffraction analysis, and TEM observations, both calcite and aragonite react with cadmium to form cadmium carbonate. The chemisorption follows the adsorption mechanism reported in the literature. Based on the Langmuir isotherm model fitting, the maximum adsorbed amount for the ground surf clam shells is 633.3 mg/g, while that for scallop shells is 195.8 mg/g. Then fine surf clam shell particles with a similar specific surface area, and with a relatively wide range of the aragonite ratio, and crystallite size are prepared via a combination of grinding and a subsequent calcination process. Our experiments where one explanatory variable is changed at a time demonstrate that the polymorph ratio and crystallite size of the ground shells play key roles in the chemisorption.
先前有关碳酸钙对镉吸附的研究发现，多晶型和结晶度是影响镉离子吸附的因素。由于这些因素相互关联，因此尚未阐明主要的吸附因素。为了克服这一问题，我们分别研究了这些因素。首先，通过大气研磨制备了具有相似晶粒尺寸和比表面积的栉孔扇贝（文石相）和海湾扇贝（方解石相）贝壳。通过吸附等温线模型、动力学、X 射线衍射分析和 TEM 观察，方解石和文石均与镉反应生成碳酸镉。化学吸附遵循文献中报道的吸附机制。基于 Langmuir 等温线模型拟合，研磨后的栉孔扇贝贝壳的最大吸附量为 633.3 mg/g，而海湾扇贝贝壳的最大吸附量为 195.8 mg/g。然后，通过研磨和随后的煅烧工艺制备了具有相似比表面积、相对较宽的文石比例和晶粒尺寸的细小栉孔扇贝贝壳颗粒。我们的实验表明，在一个解释变量发生变化的情况下，研磨贝壳的多晶型比例和晶粒尺寸在化学吸附中起着关键作用。
