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Despite the widespread presence of hydrogen peroxide (H2O2) in surface water and groundwater systems, little is known about the impact of environmental levels of H2O2 on the redox activity of minerals. Here we demonstrate that environmental concentrations of H2O2 can alter the reactivity of birnessite-type manganese oxide, an earth-abundant functional material, and decrease its oxidative activity in natural systems across a wide range of pH values (4–8). The H2O2-induced reductive dissolution generates Mn(II) that will re-bind to MnO2 surfaces, thereby affecting the surface charge of MnO2. Competition of Bisphenol A (BPA), used as a target compound here, and Mn(II) to interact with reactive surface sites may cause suppression of the oxidative ability of MnO2. This suppressive effect becomes more effective in the presence of oxyanions such as phosphate or silicate at concentrations comparable to those encountered in natural waters. Unlike nitrate, adsorption of phosphate or silicate onto birnessite increased in the presence of Mn(II) added or generated through H2O2-induced reduction of MnO2. This suggests that naturally occurring anions and H2O2 may have synergetic effects on the reactivity of birnessite-type manganese oxide at a range of environmentally relevant H2O2 amounts. As layered structure manganese oxides play a key role in the global carbon cycle as well as pollutant dynamics, the impact of environmental levels of hydrogen peroxide (H2O2/MnO2 molar ratio ≤ 0.3) should be considered in environmental fate and transport models. [ABSTRACT FROM AUTHOR]

ABSTRACT The technical viability of enhancing oil recovery (EOR) using polymer flooding has been verified. Through correcting the unfavorable mobility ratio, polymer flooding could significantly improve the macroscopic sweep efficiency of waterflooding, which makes it attractive in middle to high permeability reservoirs. However, as the depletion of these easy-to-produce resources, the interests of oil industry will be diverted to low permeability reservoirs and polymer flooding is believed to be one of the key methods for this type of reservoir. To meet this technological tendency, the current work investigated the applicability of an anti-salinity polymer (KYPAM) in low permeability sandstone reservoirs. The interactions between polymer and sandstone surface including static adsorption and dynamic retention were addressed. Static adsorption data proved that the adsorptive behavior of this anti-salinity polymer was closely related to molecular weight and concentration. The quantity of the detained KYPAM polymer in the sandstone core rapidly increased once the permeability dropped below 38 mD. High molecular weight KYPAM experienced noticeable retention compared with low molecular weight polymers resulting from the large hydrodynamic size. Due to polymer retention, the permeability of the sandstone core was significantly influenced particularly for the low permeability cores. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44487. [ABSTRACT FROM AUTHOR]

In this paper, the degradation of three endocrine-disrupting chemicals (EDCs): bisphenol A (BPA), 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) by manganite (γ-MnOOH) activated peroxymonosulfate (PMS) was investigated. Preliminary optimisation experiments showed that complete degradation of the three EDCs was achieved after 30 min of reaction using 0.1 g L -1 of γ-MnOOH and 2 mM of PMS. The degradation rate constants were determined to be 0.20, 0.22 and 0.15 min -1 for BPA, E2 and EE2, respectively. Combining radical scavenging approaches, Electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) analyses, we revealed for the first time that about 40% of EDCs degradation can be attributed to heterogeneous electron transfer reaction involving freshly generated Mn(IV), and 60% to sulfate radical degradation pathway. The influence of various inorganic ions on the γ-MnOOH/PMS system indicated that removal efficiency was slightly affected by chloride and carbonate ions, while nitrate and nitrite ions had negligible impacts. The application of γ-MnOOH/PMS system in real sewage treatment plant water (STPW) showed that degradation rate constants of EDCs decreased to 0.035-0.048 min -1 and complete degradation of the three EDCs after 45 min. This study provides new insights into the reactivity of combined γ-MnOOH and PMS, and opens new ways for the application of Mn-bearing species in wastewater treatment technologies., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Despite the widespread presence of hydrogen peroxide (H 2 O 2 ) in surface water and groundwater systems, little is known about the impact of environmental levels of H 2 O 2 on the redox activity of minerals. Here we demonstrate that environmental concentrations of H 2 O 2 can alter the reactivity of birnessite-type manganese oxide, an earth-abundant functional material, and decrease its oxidative activity in natural systems across a wide range of pH values (4-8). The H 2 O 2 -induced reductive dissolution generates Mn(II) that will re-bind to MnO 2 surfaces, thereby affecting the surface charge of MnO 2 . Competition of Bisphenol A (BPA), used as a target compound here, and Mn(II) to interact with reactive surface sites may cause suppression of the oxidative ability of MnO 2 . This suppressive effect becomes more effective in the presence of oxyanions such as phosphate or silicate at concentrations comparable to those encountered in natural waters. Unlike nitrate, adsorption of phosphate or silicate onto birnessite increased in the presence of Mn(II) added or generated through H 2 O 2 -induced reduction of MnO 2 . This suggests that naturally occurring anions and H 2 O 2 may have synergetic effects on the reactivity of birnessite-type manganese oxide at a range of environmentally relevant H 2 O 2 amounts. As layered structure manganese oxides play a key role in the global carbon cycle as well as pollutant dynamics, the impact of environmental levels of hydrogen peroxide (H 2 O 2 /MnO 2 molar ratio ≤ 0.3) should be considered in environmental fate and transport models.

Manganese oxides have been proposed as promising geomedia to remove trace organic contaminants in both natural soils and artificial infiltration systems. Although MnO x -based redox processes have been largely investigated, little is known on the effects of water flow and dissolved Mn II on manganese-mediated redox reactions in saturated porous media. Here, we have demonstrated that the reactive transport of a widely used quinolone antibiotic, pipemidic acid (PIP), in MnO 2 -coated sand (MCS) columns is altered by the presence of dissolved Mn II , generated in situ as reduced ions or present in inflow solution. Decreasing the flow rate or flow interruption facilitated oxidation reactions and generated redox byproducts (Mn II and PIP ox ). However, preloading of MCS columns with dissolved Mn II led to suppressed reactivity with PIP. When PIP and Mn II are simultaneously injected, competition between PIP and Mn II for binding at the edge sites takes place during the initial kinetic phase of reaction, while at a later breakthrough time Mn II will occupy both edge and vacancy sites due to the continuous supply of Mn II . We also developed a reactive transport model that accounts for adsorption kinetics to predict changes in transport behavior of antibiotics in the presence of different doses of dissolved Mn II . This work has strong implications for an accurate assessment of the reactivity of manganese oxides used as engineered geomedia for quinolone remediation and in developing transport models of antibiotics in natural systems.