Crystallinity and dissolution-recrystallization mechanism controlled As(V) retention by calcium phosphate

Yao Yan; Xun Cao; Jun Li; Hanxiao Zhang; Yongqiang Yang; Fanrong Chen; Runliang Zhu; Dong Liu; Tim White; Shijun Wu

doi:10.1016/j.jhazmat.2024.136517

Crystallinity and dissolution-recrystallization mechanism controlled As(V) retention by calcium phosphate

J Hazard Mater. 2024 Nov 14:481:136517. doi: 10.1016/j.jhazmat.2024.136517. Online ahead of print.

Authors

Yao Yan¹, Xun Cao², Jun Li¹, Hanxiao Zhang¹, Yongqiang Yang³, Fanrong Chen³, Runliang Zhu³, Dong Liu⁴, Tim White⁵, Shijun Wu⁶

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; Guangdong Provincial Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, 808 Tianyuan Road, 510650 Guangzhou, China.
⁵ School of Materials Science & Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore. Electronic address: [email protected].
⁶ 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: [email protected].

PMID: 39561542
DOI: 10.1016/j.jhazmat.2024.136517

Abstract

Retention of toxic metals/metalloids like arsenic via mineral-water interaction plays a crucial role in the environmental behavior of pollutants. However, the influence of mineral crystallinity on the retention of toxic elements, the evolution of liquid composition, and the interaction mechanism are poorly understood. This study investigated the interaction between As(V) and calcium phosphate (CaP) under oxic conditions with varying crystallinities, particularly amorphous CaP (ACP), across varying As(V) concentrations and pH conditions. Results revealed that the amorphous phase substantially influenced As(V) fate, with the As(V) retention potential of ACP and poorly crystalline hydroxylapatite (HAP) being 13.65 and 12.61 times higher than highly crystalline HAP, respectively. As(V) retention involves the dissolution of ACP and the recrystallization of As(V)-substituted HAP, correlated with three distinct ACP transformation stages during recrystallization. The lower pH (7.5) facilitated ACP dissolution, and the elevated Ca²⁺ concentration enhanced the volume of CaP recrystallization. Conversely, higher pH levels (8.0, 8.5, and 9.0) promoted a higher degree of recrystallization, evidenced by reduced residual Ca²⁺ levels after 48 hrs (post-crystallization stage). Meanwhile, As-bearing CaP forms with greater competition between PO₄^3- and AsO₄^3- at higher initial As(V) concentrations than lower ones. Additionally, lattice distortion, increases in species of surface bond groups, and reduced crystallinity were observed in the As(V)-bearing CaP product. Overall, this study underscores the pivotal role of ACP and its poorly crystalline counterparts in arsenic retention through the dissolution-recrystallization mechanism.

Keywords: Amorphous calcium phosphate (ACP); Arsenate As(V) immobilization; Dissolution-recrystallization process; Hydroxylapatite (HAP); Mineral crystallinity.