Iron-Tuned Depth-Dependent P Transformation on Calcium Carbonate Coprecipitates: The Impact of Fe and P Loadings

文献类型： 外文期刊

第一作者： Liu, Jin

作者： Liu, Jin;Zhou, Junfeng;Zhao, Yuhang;Xu, Jun;Chen, Tianwen;Sui, Peng;Chen, Yuanquan;Sun, Meili;Yang, Jianjun;Zhu, Mengqiang;Shakouri, Mohsen;Zheng, Lei

作者机构：

关键词： molecular speciation; X-ray absorption spectroscopy; phosphorus bioavailability; surface precipitation; nucleation

期刊名称：ENVIRONMENTAL SCIENCE & TECHNOLOGY （ 影响因子：11.3； 五年影响因子：12.4 ）

ISSN： 0013-936X

年卷期： 2025 年 59 卷 29 期

页码：

收录情况： SCI

摘要： The incorporation of iron (Fe) into calcium carbonate coprecipitates (CCCs) to form Fe-incorporated CCC (CCCFe) widely occurred in CCC-enriched soils and sediments. However, the molecular mechanism of phosphate (P) immobilization on CCCFe remains largely unknown. In this study, batch experiments were conducted to investigate the immobilization mechanisms of P on CCCFe with low and high Fe loadings (CCCFel vs CCCFeh) using P K-edge X-ray absorption near-edge structure (XANES) spectroscopy with surface-sensitive total electron yield (P-XANESTEY) and bulk-sensitive fluorescence yield (P-XANESFLY) modes. Results indicated that the high Fe loading inhibited calcite formation but favored vaterite production in the CCC and enhanced its P retention capacity. Hydroxyapatite (HAP) dominated over ferrihydrite-associated P (Fe-P) in the bulk of P sorbed on the CCCFeh, but amorphous calcium phosphate (ACP) dominated over HAP for the CCC, suggesting Fe-induced transformation of the ACP to the HAP. Furthermore, the P-XANESTEY analysis indicated brushite primarily formed on the surface of the P sorbed on the CCCFeh at high P loading. Consistently, the spherical aberration-corrected scanning transmission electron microscopy analysis directly revealed ferrihydrite coating on the CCC and the presence of Ca-P and Fe-P associations. This study provides new molecular-level insights into Fe-tuned depth-dependent transformation of P on the CCC, thus benefiting P management in the CCC-enriched environmental settings.

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