Department of Chemical Engineering, Guangdong Industry Technical College, Guangzhou, People's Republic of China.
College of Materials and Energy, South China Agricultural University, Guangzhou, People's Republic of China.
Environ Technol. 2019 Dec;40(28):3668-3677. doi: 10.1080/09593330.2018.1484523. Epub 2018 Jun 8.
Dicalcium phosphate was prepared by ethylenediaminetetraacetic acid as a calcium chelating agent, and further explored to remove the fluoride ions from aqueous solution. The as-prepared samples main existed in the monetite phase from the result of XRD. The dried sample consisted of small nanoparticles and displayed irregular particles with a size of ca. 3 μm due to the agglomeration. The fluoride removal ability was evaluated by batch adsorption experiments. The as-prepared adsorbent exhibited the enhanced fluoride removal behaviour with the maximum adsorption capacity of 66.72 mg/g from the Langmuir isotherm model, which was higher than that of other previously reported calcium phosphate. The adsorbent could be utilized in the wide pH range of 3-10. The adsorption kinetics could be better described by the pseudo-second-order model than first-second-order model. The co-existing anions had a negligible influence on the fluoride adsorption. The investigation of adsorption mechanism suggested that the chemical reaction and/or dissolution - precipitation mechanism should be dominant in the fluoride adsorption process, accompanying with electronic interaction and ions exchange, which enhanced the fluoride removal performance.
磷酸二钙是由乙二胺四乙酸作为钙螯合剂制备的，并进一步探索用于从水溶液中去除氟离子。从 XRD 的结果来看，所制备的样品主要以单水磷酸氢钙的形式存在。干燥后的样品由小纳米颗粒组成，并由于团聚而呈现出不规则的颗粒，尺寸约为 3μm。通过批量吸附实验评估了氟离子去除能力。从 Langmuir 等温模型可知，所制备的吸附剂表现出增强的氟离子去除行为，最大吸附容量为 66.72mg/g，高于其他先前报道的磷酸钙。该吸附剂可在 pH 值为 3-10 的较宽范围内使用。吸附动力学更符合准二级模型，而不是一级二级模型。共存阴离子对氟离子吸附的影响可以忽略不计。吸附机理的研究表明，化学反应和/或溶解-沉淀机理应该在氟离子吸附过程中起主要作用，同时伴随着电子相互作用和离子交换，从而增强了氟离子的去除性能。
