@article {doi:10.1021/acs.est.5b04319,
	title = {Homogeneous and Heterogeneous (Fex, Cr1{\textendash}x)(OH)3 Precipitation: Implications for Cr Sequestration},
	journal = {Environmental Science \&amp; Technology},
	volume = {50},
	number = {4},
	year = {2016},
	note = {PMID: 26765070},
	pages = {1741-1749},
	abstract = {The formation of (Fe, Cr)(OH)3 nanoparticles determines the fate of aqueous Cr in many aquatic environments. Using small-angle X-ray scattering, precipitation rates of (Fe, Cr)(OH)3 nanoparticles in solution and on quartz were quantified from 0.1 mM Fe(III) solutions containing 0{\textendash}0.25 mM Cr(III) at pH = 3.7 {\textpm} 0.2. Concentration ratio of aqueous Cr(III)/Fe(III) controlled the chemical composition (x) of (Fex, Cr1{\textendash}x)(OH)3 precipitates, solutions{\textquoteright} supersaturation with respect to precipitates, and the surface charge of quartz. Therefore, the aqueous Cr(III)/Fe(III) ratio affected homogeneous (in solution) and heterogeneous (on quartz) precipitation rates of (Fex, Cr1{\textendash}x)(OH)3 through different mechanisms. The sequestration mechanisms of Cr(III) in precipitates were also investigated. In solutions with high aqueous Cr(III)/Fe(III) ratios, surface enrichment of Cr(III) on the precipitates occurred, resulting in slower particle growth in solutions. From solutions with 0{\textendash}0.1 mM Cr(III), the particles on quartz grew from 2 to 4 nm within 1 h. Interestingly, from solution with 0.25 mM Cr(III), particles of two distinct sizes (2 and 6 nm) formed on quartz, and their sizes remained unchanged throughout the reaction. Our study provided new insights on homogeneous and heterogeneous precipitation of (Fex, Cr1{\textendash}x)(OH)3 nanoparticles, which can help determine the fate of Cr in aquatic environments.},
	doi = {10.1021/acs.est.5b04319},
	url = {https://doi.org/10.1021/acs.est.5b04319},
	author = {Chong Dai and Zuo, Xiaobing and Bo Cao and Yandi* Hu}
}
