Citrate-Stabilized Amorphous Calcium Phosphate Nanoparticles as an Effective Adsorbent for Defluorination

Amorphous calcium phosphate (ACP), one of the most important calcium–phosphorus compounds, is widely used in dentistry, orthopedics, and medicine, but is rarely reported for fluoride removal from water. In view of this, sodium citrate-stabilized amorphous calcium phosphate (Cit-ACP) and Cit-ACP calc...

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Bibliographic Details
Main Authors: Ruojiao Su, Miaomiao Wang, Yuwei Jiang, Shuang Zhang, Junjun Tan
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Nanomaterials
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Online Access:https://www.mdpi.com/2079-4991/15/8/621
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Summary:Amorphous calcium phosphate (ACP), one of the most important calcium–phosphorus compounds, is widely used in dentistry, orthopedics, and medicine, but is rarely reported for fluoride removal from water. In view of this, sodium citrate-stabilized amorphous calcium phosphate (Cit-ACP) and Cit-ACP calcinated at different temperatures were successfully prepared for fluoride removal. The results showed that the adsorption data of the Cit-ACP sample could be well described by the Langmuir model, and the adsorption kinetic followed the pseudo-second-order model. The maximum adsorption capacity was 27.48 mg/g at pH 7.0 when the fluoride concentration is 100 mg/L. The thermodynamic parameters suggested that the adsorption of fluoride was a spontaneous endothermic process. The XRD, XPS, and Zeta potential analysis of the Cit-ACP sample before and after fluoride removal revealed that, owing to the core–shell structure of the Cit-ACP nanoparticles, the fluoride ions in solution and the calcium ions in shell layer of the Cit-ACP nanoparticles co-promoted the transformation of the core of the Cit-ACP nanoparticles into fluorapatite. Given the simplicity of its preparation and effectiveness of its fluoride removal properties, Cit-ACP would be a potentially economical, efficient, and biocompatible adsorbent for fluoride removal.
ISSN:2079-4991