Related Experiment Video
Updated: Dec 18, 2025

Single-throughput Complementary High-resolution Analytical Techniques for Characterizing Complex Natural Organic Matter Mixtures
Published on: January 7, 2019
Coupled Manganese Redox Cycling and Organic Carbon Degradation on Mineral Surfaces
Dong Ma1,2, Juan Wu1,2, Peng Yang1
1Department of Ecosystem Science and Management, University of Wyoming, Laramie, Wyoming 82071, United States.
Abstract:
Minerals, natural organic matter (NOM), and divalent manganese (Mn(II)) often coexist in suboxic/oxic environment. Multiple adsorption and oxidation processes occur in this ternary system, which are coupled to affect the fate of both OM and Mn therein and alter their chemical reactivity toward metals and other pollutants. However, the details about the coupling are poorly known although much has been gained for the binary systems. We determined the mutual influence of surface-catalyzed Mn(II) oxidation and humic acid (HA) adsorption and oxidation in a Fe(III) oxide (goethite)-HA-Mn(II) system at pH 5-8. The presence of Mn(II) substantially increased HA adsorption whereas HA greatly impaired the extent and rate of Mn(II) oxidation by O2 on goethite surfaces. The impacts were more pronounced at higher pH. Mn(II) oxidation produced β-MnOOH, γ-MnOOH, and Mn3O4 which in turn oxidized HA, producing small organic acids. The presence of HA markedly altered the composition of Mn(II) oxidation products by inhibiting the formation of β-MnOOH while favoring the production of γ-MnOOH and Mn(II) adsorbed on the HA-mineral assemblage. Nonconducting γ-Al2O3 exhibited similar but weaker effects than semiconducting goethite in the above processes. Our results suggest that similar to Mn-oxidizing microorganisms, mineral surfaces can drive the coupling of the Mn redox cycle with NOM oxidative degradation under suboxic/oxic and circumneutral/alkaline conditions.
More Related Videos
06:53Author Spotlight: Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks
Published on: June 9, 2023
09:45Laboratory Simulation of an IronII-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria
Published on: July 24, 2016
Related Concept Videos
Oxidation and Reduction of Organic Molecules
The removal of an electron from a molecule, results in a...
Microbial Nutrition
Radical Oxidation of Allylic and Benzylic Alcohols
Metabolism of Chemolithotrophs
Redox Equilibria: Overview
Carbon-dioxide Fixation