NOM-Induced Dissolution of CrxFe1-x(OH)3Precipitates and Formation of Cr(III)-NOM-Fe Colloids under Oxic and Anoxic Conditions

Li，Binrui1; Zhang，Shaojian2; Liao，Peng2; Liu，Peng3; Ye，Zhihang3; Liu，Chongxuan1

2022

10.1021/acsearthspacechem.2c00255

ACS Earth and Space Chemistry   Impact Factor & Quartile

2472-3452

2472-3452

Mixed Cr(III)-Fe(III) (hydr)oxides (CrxFe1-x(OH)3) are common reduction products of Cr(VI) that have long been considered as the sink of Cr in subsurface environments. While current field and laboratory studies have demonstrated that natural organic matter (NOMox) can dissolve CrxFe1-x(OH)3 under oxic conditions, much less is known regarding the dissolution of CrxFe1-x(OH)3 by reduced NOM (NOMred) and geochemical behaviors of released Cr(III) under anoxic conditions, which limited our ability to completely predict the cycle of Cr. This study provided new knowledge regarding the simultaneous dissolution of CrxFe1-x(OH)3 and formation of Cr(III)-NOM-Fe colloids by NOMox and NOMred under oxic and anoxic conditions. We showed that NOM dissolved CrxFe1-x(OH)3 via ligand-promoted dissolution under oxic conditions and reductive dissolution under anoxic conditions, releasing aqueous Cr(III) and Fe(III/II). Size fractionization results showed that the aqueous Cr(III) and Fe observed at high NOM concentration were Cr(III)-NOM-Fe colloids (ca. 3-450 nm). Dynamic light scattering results further revealed that the colloids had a particle size ranging from 79 to 167 nm and strongly negative surface charges (-40-17 mV). Cryogenic X-ray photoelectron spectroscopy and X-ray absorption fine structure measurements further indicated a close association of NOM with Cr and Fe within the particle structure. This study provides insights into the fate of CrxFe1-x(OH)3 in redox-dynamics and organic-rich environments, which is critical for evaluating the long-Term stability of Cr remediation sites.

colloid characterization Cr(III)-NOM-Fe colloids CrxFe1-x(OH)3precipitates ligand-promoted dissolution NOM reductive dissolution

SCI

English

First ; Corresponding

[42177237] ; [2017ZT07Z479] ; [2022-217] ; [20214028]

Chemistry ; Geochemistry & Geophysics

Chemistry, Multidisciplinary ; Geochemistry & Geophysics

WOS:000891585800001

AMER CHEMICAL SOC

2-s2.0-85143400425

Scopus

1.State Environ. Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control,School of Environmental Science and Engineering,Southern University of Science and Technology,Shenzhen,518055,China
2.State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang,550081,China
3.School of Environment,China University of Geosciences,Wuhan,388 Lumo Road,430074,China

Li，Binrui,Zhang，Shaojian,Liao，Peng,et al. NOM-Induced Dissolution of CrxFe1-x(OH)3Precipitates and Formation of Cr(III)-NOM-Fe Colloids under Oxic and Anoxic Conditions[J]. ACS Earth and Space Chemistry,2022.

Li，Binrui,Zhang，Shaojian,Liao，Peng,Liu，Peng,Ye，Zhihang,&Liu，Chongxuan.(2022).NOM-Induced Dissolution of CrxFe1-x(OH)3Precipitates and Formation of Cr(III)-NOM-Fe Colloids under Oxic and Anoxic Conditions.ACS Earth and Space Chemistry.

Li，Binrui,et al."NOM-Induced Dissolution of CrxFe1-x(OH)3Precipitates and Formation of Cr(III)-NOM-Fe Colloids under Oxic and Anoxic Conditions".ACS Earth and Space Chemistry (2022).