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.
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.
J Hazard Mater. 2021 Jun 15;412:125261. doi: 10.1016/j.jhazmat.2021.125261. Epub 2021 Jan 29.
Coprecipitation with calcium carbonate (CaCO) could decrease the bioavailability of arsenic (As). However, in a phosphate-rich environment, some CaCO will be converted to hydroxylapatite (HAP). Currently, the behavior of carbonate-bound As during conversion is unclear. Therefore, we prepared bio-induced CaCO in an As solution and converted it to HAP. The results showed that a high concentration of arsenate promoted vaterite precipitation and the conversion of CaCO to HAP. The dissolution data verified the low solubility of As in HAP, though its As-bearing CaCO precursor released up to 88.19% As during the conversion. Furthermore, HPLC-ICP-MS data showed partial oxidation of arsenite to arsenate, suggesting that CaCO and HAP's structure favored the incorporation of arsenate. Our results demonstrated that the stability of heavy metal-bearing CaCO should be considered, and the role of HAP in the immobilization of heavy metals such as As should not be overestimated.
共沉淀作用会使砷（As）的生物可利用性降低，碳酸钙（CaCO）会与砷结合。然而，在富磷环境中，部分 CaCO 会转化为羟磷灰石（HAP）。目前，在转化过程中，碳酸盐结合态 As 的行为尚不清楚。因此，我们在含砷溶液中制备了生物诱导的 CaCO，并将其转化为 HAP。结果表明，高浓度的砷酸盐会促进球霰石的沉淀和 CaCO 向 HAP 的转化。溶解数据验证了 HAP 中 As 的低溶解度，尽管其含 As 的 CaCO 前体在转化过程中释放了高达 88.19%的 As。此外，HPLC-ICP-MS 数据显示亚砷酸盐部分被氧化为砷酸盐，表明 CaCO 和 HAP 的结构有利于砷酸盐的掺入。我们的结果表明，应考虑含重金属的 CaCO 的稳定性，不应高估 HAP 在固定重金属（如 As）方面的作用。
