期刊
MINERALS
卷 10, 期 8, 页码 -出版社
MDPI
DOI: 10.3390/min10080690
关键词
birnessite; Mn average oxidation state; redox potential; oxidative activity; removal of organic contaminants
资金
- National Natural Science Foundation of China [91751105, 41820104003, 41972318]
As the dominant manganese oxide mineral phase in terrestrial and aquatic environments, birnessite plays an important role in many biogeochemical processes. The coexistence of birnessite with aqueous Mn(2+)is commonly found in the subsurface environments undergoing Mn redox cycling. This study investigates the change in Mn average oxidation state (AOS) of birnessite after reaction with 0.1-0.4 mM Mn(2+)at pH 4.5-6.5, under conditions in which phase transformation of birnessite by Mn(2+)was not detectable. The amount of Mn(2+)uptake by birnessite and the equilibrium concentration of Mn(III) proportionally increased with the initial concentration of Mn2+. The Mn AOS of birnessite particles became 3.87, 3.75, 3.64, and 3.53, respectively, after reaction with 0.1, 0.2, 0.3, and 0.4 mM Mn(2+)at pH 5.5. Oxidation potentials (E-h) of birnessite with different AOS values were estimated using the equilibrium concentrations of hydroquinone oxidized by the birnessite samples, indicating thatE(h)was linearly proportional to AOS. The oxidation kinetics of bisphenol A (BPA), a model organic pollutant, by birnessite suggest that the logarithms of surface area-normalized pseudo-first-order initial rate constants (logk(SA)) for BPA degradation by birnessite were linearly correlated with theE(h)or AOS values of birnessite with AOS greater than 3.64.
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