@article {40167,
	title = {Low-Molecular-Weight Organics Regulate the Composition and Stability of Calcium/Lead Phosphate Coprecipitates: Implications for Lead Remediation},
	journal = {Environmental Science \&amp; Technology},
	volume = {59},
	year = {2025},
	pages = {23519-23529},
	abstract = {Calcium phosphate is widely used for the remediation of lead-contaminated sites, where calcium/lead phosphate coprecipitates (Ca/Pb CoPs) form. This research investigated such coprecipitation with model low-molecular-weight organics (LMWOs), produced in the rhizosphere with representative functional groups, which were found to regulate both the composition (Ca/Pb and C/Pb ratios) and stability (aggregation and transformation) of Ca/Pb CoPs. The strong complexation ability of {\textendash}SH in\&nbsp;l-cysteine with aqueous Ca2+/Pb2+\&nbsp;ions inhibited coprecipitation to a great extent. Meanwhile, coprecipitates with lysine containing both {\textendash}NH2\&nbsp;and {\textendash}COOH had a higher Ca/Pb ratio than those with citrate containing only {\textendash}COOH, probably due to the elevated local supersaturation caused by both {\textendash}NH2\&nbsp;and {\textendash}COOH in lysine that attracted phosphate ions and cations, promoting Ca doping in CoPs. Also, the strong binding of both {\textendash}NH2\&nbsp;and {\textendash}COOH with coprecipitates resulted in a higher C/Pb ratio for the CoPs with lysine than citrate. The oriented aggregation of nano-CoPs formed needle-shaped hydroxylpyromorphite crystals without organics. Unexpectedly, lysine/citrate disrupted and\&nbsp;l-cysteine promoted such oriented aggregation, resulting in inhibited and promoted crystallinity, respectively. This study provided new mechanistic insights on LMWO effects on Ca/Pb CoP formation and their stability and can help understand Pb speciation and availability in the rhizosphere.},
	url = {https://pubs.acs.org/doi/abs/10.1021/acs.est.5c10391},
	author = {Jiang, Xulin and Juntao Zhao and Zhou, Zehao and Liu, Chuan and Jianhong Huang and Yandi* Hu}
}
