Different Pathways for Cr(III) Oxidation: Implications for Cr(VI) Reoccurrence in Reduced Chromite Ore Processing Residue

Environmental Science & Technology, Journal Year: 2020, Volume and Issue: 54(19), P. 11971 - 11979

Published: Sept. 9, 2020

Hexavalent chromium contamination is a global environmental issue and usually reoccurs in alkaline reduced chromite ore processing residues (rCOPR). The oxidation of Cr(III) solids rCOPR one possible cause but as yet little studied. Herein, we investigated the Cr(OH)3, typical species rCOPR, at pH (9-11) with δ-MnO2 under oxic/anoxic conditions. Results revealed three pathways for oxic conditions: (1) by oxygen, (2) δ-MnO2, (3) catalytic Mn(II). Oxidations latter two were efficient, via Pathway 3 was continuous increased dramatically increasing pH. XANES data indicated feitknechtite (β-MnOOH) hausmannite (Mn3O4) reduction products substances. Additionally, kinetic model established to describe relative contributions each pathway specific time. simulation outcomes showed that Cr(VI) mainly formed 2 (>51%) over short time frame (10 days), whereas longer-term (365 predominated (>78%) an proportion These results suggest can be oxidized conditions even small amount manganese oxides, providing new perspectives on reoccurrence emphasizing risks environments.

Language: Английский

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A biogeochemical–hydrological framework for the role of redox-active compounds in aquatic systems

Nature Geoscience, Journal Year: 2021, Volume and Issue: 14(5), P. 264 - 272

Published: May 1, 2021

Language: Английский

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Stabilization of Arsenic Sulfide Sludge to Form Stable Johnbaumite by Alkaline-Oxidative Hydrothermal Treatment

ACS ES&T Engineering, Journal Year: 2024, Volume and Issue: 4(7), P. 1657 - 1667

Published: May 13, 2024

The arsenic sulfide sludge (ASS) generated from the treatment of acidic arsenic-containing wastewater by precipitation causes severe environmental pollution due to its potential release highly toxic As(III). This work describes an alkaline-oxidative hydrothermal method that converted ASS stable johnbaumite mineral (Ca5(AsO4)3(OH)) in which exists as less As(V). Under optimal reaction conditions, i.e., with H2O2 (ω = 3.3 wt %) and Ca(OH)2 (mCH/mASS 1:1) at pH 14.18 180 °C for 18 h, leaching was reduced 762.85 mg/L original down 0.04 hydrothermally treated product, far below 1.2 limit set Chinese standard GB 18598-2019. stabilization mainly involved three steps: (i) As(III) released into alkaline solution oxidized AsO43–, (ii) free AsO43– captured Ca2+ form Ca3(AsO4)2 Ca5(AsO4)3(OH), (iii) intermediate further under condition, eventually stably encapsulated lattice. study thus provided effective strategy safe disposal revealed mechanisms underlying via johnbaumite.

Language: Английский

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As(III) adsorption on Fe-Mn binary oxides: Are Fe and Mn oxides synergistic or antagonistic for arsenic removal?

Chemical Engineering Journal, Journal Year: 2020, Volume and Issue: 389, P. 124470 - 124470

Published: Feb. 16, 2020

Language: Английский

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Removal of Sb(V) from aqueous solutions using Fe-Mn binary oxides: The influence of iron oxides forms and the role of manganese oxides

Chemical Engineering Journal, Journal Year: 2018, Volume and Issue: 354, P. 577 - 588

Published: Aug. 11, 2018

Language: Английский

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Coupled Manganese Redox Cycling and Organic Carbon Degradation on Mineral Surfaces

Environmental Science & Technology, Journal Year: 2020, Volume and Issue: 54(14), P. 8801 - 8810

Published: June 17, 2020

Minerals, natural organic matter (NOM), and divalent manganese (Mn(II)) often coexist in suboxic/oxic environment. Multiple adsorption oxidation processes occur this ternary system, which are coupled to affect the fate of both OM Mn therein alter their chemical reactivity toward metals other pollutants. However, details about coupling poorly known although much has been gained for binary systems. We determined mutual influence surface-catalyzed Mn(II) humic acid (HA) a Fe(III) oxide (goethite)-HA-Mn(II) system at pH 5-8. The presence substantially increased HA whereas greatly impaired extent rate by O2 on goethite surfaces. impacts were more pronounced higher pH. produced β-MnOOH, γ-MnOOH, Mn3O4 turn oxidized HA, producing small acids. markedly altered composition products inhibiting formation β-MnOOH while favoring production γ-MnOOH adsorbed HA-mineral assemblage. Nonconducting γ-Al2O3 exhibited similar but weaker effects than semiconducting above processes. Our results suggest that Mn-oxidizing microorganisms, mineral surfaces can drive redox cycle with NOM oxidative degradation under circumneutral/alkaline conditions.

Language: Английский

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Arsenic remediation onto redox and photo-catalytic/electrocatalytic Mn-Al-Fe impregnated rGO: Sustainable aspects of sludge as supercapacitor

Chemical Engineering Journal, Journal Year: 2019, Volume and Issue: 390, P. 124000 - 124000

Published: Dec. 31, 2019

Language: Английский

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Coupled redox cycling of Fe and Mn in the environment: The complex interplay of solution species with Fe- and Mn-(oxyhydr)oxide crystallization and transformation

Earth-Science Reviews, Journal Year: 2022, Volume and Issue: 232, P. 104105 - 104105

Published: July 5, 2022

Language: Английский

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The key roles of Fe oxyhydroxides and humic substances during the transformation of exogenous arsenic in a redox-alternating acidic paddy soil

Water Research, Journal Year: 2023, Volume and Issue: 242, P. 120286 - 120286

Published: June 29, 2023

Language: Английский

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Micropore sites in ferrihydrite are responsible for its higher affinity towards As(III) relative to As(V)

Geochimica et Cosmochimica Acta, Journal Year: 2023, Volume and Issue: 348, P. 27 - 40

Published: March 7, 2023

Language: Английский

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