Phase evolution and arsenic immobilization of arsenate-bearing amorphous calcium phosphate

Yao Yan; Yanan Fang; Vivek Verma; Jun Li; Yong Wang; Yongqiang Yang; Fanrong Chen; Runliang Zhu; Shijun Wu; Thomas J N Hooper; Tim White

doi:10.1016/j.jhazmat.2023.130973

Phase evolution and arsenic immobilization of arsenate-bearing amorphous calcium phosphate

J Hazard Mater. 2023 Apr 15:448:130973. doi: 10.1016/j.jhazmat.2023.130973. Epub 2023 Feb 8.

Authors

Yao Yan¹, Yanan Fang², Vivek Verma², Jun Li¹, Yong Wang², Yongqiang Yang³, Fanrong Chen³, Runliang Zhu³, Shijun Wu⁴, Thomas J N Hooper², Tim White⁵

Affiliations

¹ CAS Key Laboratory of Mineralogy and Metallogeny & Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 511 Kehua Street, 510640 Guangzhou, China; CAS Center for Excellence in Deep Earth Science, 511 Kehua Street, 510640 Guangzhou, China; University of Chinese Academy of Sciences, 19 Yuquan Road, 100049 Beijing, China.
² School of Materials Science & Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore.
³ CAS Key Laboratory of Mineralogy and Metallogeny & Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 511 Kehua Street, 510640 Guangzhou, China; CAS Center for Excellence in Deep Earth Science, 511 Kehua Street, 510640 Guangzhou, China.
⁴ CAS Key Laboratory of Mineralogy and Metallogeny & Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 511 Kehua Street, 510640 Guangzhou, China; CAS Center for Excellence in Deep Earth Science, 511 Kehua Street, 510640 Guangzhou, China. Electronic address: wus@gig.ac.cn.
⁵ School of Materials Science & Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore. Electronic address: tjwhite@ntu.edu.sg.

PMID: 36860081
DOI: 10.1016/j.jhazmat.2023.130973

Abstract

The formation of As(V) substituted hydroxylapatite (HAP) has a vital influence on the fate of As(V) in the environment. However, despite growing evidence showing that HAP crystallizes in vivo and in vitro with amorphous calcium phosphate (ACP) as a precursor, a knowledge gap exists concerning the transformation from arsenate-bearing ACP (AsACP) to arsenate-bearing HAP (AsHAP). Here we synthesized AsACP nano-particles with varied As contents and investigated the arsenic incorporation during their phase evolution. The phase evolution results showed that the transformation process of AsACP to AsHAP could be divided into three Stages. A higher As(V) loading significantly delayed the transformation of AsACP, increased the distortion degree, and decreased the crystallinity of AsHAP. NMR result showed that the PO₄^3- tetrahedral is geometrically preserved when PO₄^3- is substituted by AsO₄^3-. From AsACP to AsHAP, the As-substitution led to the transformation inhibition and As(V) immobilization.

Keywords: Amorphous calcium phosphate; Arsenic substitution; Hydroxylapatite; Phase evolution.