Novel manganese cycling at very low ionic strengths in the Columbia River Estuary

Jones, Matthew R.; Tebo, Bradley M.

doi:10.1016/j.watres.2021.117801

Cited by 13 publications

(8 citation statements)

References 92 publications

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“…Due to a high specific surface area, Tebo et al reported that BioMnO x can adsorb Mn(II) and then convert Mn(II) to MnO x through chemical/biological catalytic oxidation. 12,38,41 According to the EDX analysis of the BioMnO x cake layer surface, the Mn element and the O element in the BioMnO x cake layer were in good accordance with the ratio of 1:1.88 (Figure S6a). Combined with XRD analysis of BioMnO x particles, the main manganese oxide in the BioMnO x cake layer might be MnO 2 (detailed JCPDS card comparison results are shown in Figure S6b).…”

Section: Resultsmentioning

confidence: 78%

Exploring the Growth Pattern and Hydraulic Resistance of BioMnO_x Cake Layer under Different Fluxes in Ultrafiltration Processes

Wang,

Hu,

Zhou

et al. 2023

ACS EST Eng.

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Biogenic manganese oxides (BioMnOx) are known to self-catalyze Mn(II) oxidation and are unfavorable in conventional ultrafiltration (UF) processes for Mn(II)-containing water purification because they can accumulate on membrane surfaces and cause severe cake fouling. However, recent studies based on gravity-driven membrane (GDM) have found that the fouling resistance of the BioMnOx cake layer is surprisingly low under low flux conditions (several L m–2 h–1), but the underlying mechanism is not clear. Therefore, in this study, we investigated the formation and hydraulic resistances of the naturally formed BioMnOx cake layers at various fluxes (5, 10, 15, and 20 L m–2 h–1). The results showed that the BioMnOx could form a heterogeneous cake layer with many mounds, and these BioMnOx cake layers could remove nearly 100% of 2 mg L–1 Mn(II) after 34, 49, 55, and 64 days of dead-end filtration at fluxes of 5, 10, 15, and 20 L m–2 h–1, respectively. The hydraulic resistance of the BioMnOx cake layer rapidly increased at high fluxes of 10, 15, and 20 L m–2 h–1, while it remained very low (<5 × 1012 m–1) at a low flux of 5 L m–2 h–1. In-situ optical coherence tomography (OCT) observation revealed that at low flux, the BioMnOx mounds of the cake layer had a higher height–width ratio and lower coverage and thus more porous structures. We attributed this structure to the unique growth pattern of BioMnOx at low fluxes. Specifically, because the advection velocity of Mn(II) was low at low fluxes, new BioMnOx was mainly grown in the upper parts of the cake layer with enough time for Mn(II) diffusion and oxidation. Then, the upper parts depleted Mn(II), and consequently, the lower parts maintained a high porosity with few formations of BioMnOx at their confined pores.

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Section: Resultsmentioning

confidence: 78%

Exploring the Growth Pattern and Hydraulic Resistance of BioMnO_x Cake Layer under Different Fluxes in Ultrafiltration Processes

Wang,

Hu,

Zhou

et al. 2023

ACS EST Eng.

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“…During the CaCl 2 wash steps, Mn was below detection in the extracted supernatant solutions, which indicates retention of Mn(II) on the MnOx or MOMAC solid by either relocation to vacancy sites or adsorption to other surface sites rather than released into solution . In either case, sharp changes to the ionic strength and cation composition of the washing solution can cause changes in sorption (on AC in the case of MOMAC) or incorporation of metals into the MnOx interlayers. , The removal of interlayer cations such as Mn(II) to solution following washes with ultrapure water may have also contributed to the structural disorder observed with XRD. In addition to Mn(II) released through disproportionation of Mn(III), these washes may have also released Mn(II) diffused into AC pores during equilibration, which may account for the higher concentrations of Mn in solution from the CaCl 2 and ultrapure water washes of MOMAC samples compared to homogeneous MnOx.…”

Section: Discussionmentioning

confidence: 99%

Characterization of Manganese Oxide Modified Activated Carbon for Remediation of Redox-Sensitive Contaminants

Meraz

Traina

Beutel

et al. 2023

ACS Earth Space Chem.

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Manganese oxide modified activated carbon (MOMAC) was synthesized as a novel in situ sediment and soil amendment for treatment of redox-sensitive contaminants, such as mercury (Hg), through buffering of reduction−oxidation (redox) potential and sorption. This study characterized MOMAC synthesis products at three different Mn concentrations on activated carbon (AC) surfaces and compared them with homogeneously precipitated Mn oxide (MnOx) and unmodified AC for properties influencing redox buffering and sorption capacity. Bulk spectroscopic analyses (XAS and XPS), XRD, and electron microscopy showed that homogeneous MnOx matched the local structure of vernadite (δ-Mn(IV)O 2 ), while MOMAC formed aggregates on the AC surface composed mostly of vernadite with fractions of manganite (γ-Mn(III)OOH) (17−46%) and sorbed Mn(II) (11−21%). Higher bulk surface area and lower Mn average oxidation state were associated with MOMAC and are attributed to the reduction of Mn(IV) by Mn(II) adsorbed on AC or diffused into AC pores. Cation exchange reactions of Na + and Ca 2+ also contributed to Mn oxidation state changes by driving disproportionation of Mn(III) to Mn(II) and Mn(IV). In batch slurry experiments with and without Hg-contaminated sediment from Oak Ridge National Laboratory (TN, U.S.A.), addition of MOMAC and MnOx resulted in higher solution redox potential and lower pH compared to AC and no-amendment controls. MnOx poised solution redox at higher potential than MOMAC, but MOMAC was more effective at sorbing Hg released by the oxidation of sediment HgS(s), Hg 0 , and/or organic-associated Hg. By combining redox buffering with sorption, MOMAC is a promising in situ amendment that may efficiently target redox-sensitive contaminants in aquatic sediments.

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“…The reduction should take place above pH 4 to minimise iodine volatilisation, nitrite interference and precipitation of humic-like organics, which all occur at a lower pH. It was found that a final concentration of 7 mM hydroxylamine hydrochloride (NH 2 OH-HCl), commonly used in trace metal analysis [60,61], reduced inorganic iodine in both seawater and Di-H 2 O (Table 5) while maintaining a suitable sample pH. Following the addition of NH 2 OH-HCl to 7 mM, the pH decreased in DiH 2 O from pH 5.71 to 4.12, and in seawater from pH NIST 7.7 to pH NIST 5.7.…”

Section: Iodatementioning

confidence: 99%

Environmental iodine speciation quantification in seawater and snow using ion exchange chromatography and UV spectrophotometric detection

Jones

Chance

Dadić

et al. 2023

Analytica Chimica Acta

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Novel manganese cycling at very low ionic strengths in the Columbia River Estuary

Cited by 13 publications

References 92 publications

Exploring the Growth Pattern and Hydraulic Resistance of BioMnO_x Cake Layer under Different Fluxes in Ultrafiltration Processes

Exploring the Growth Pattern and Hydraulic Resistance of BioMnO_x Cake Layer under Different Fluxes in Ultrafiltration Processes

Characterization of Manganese Oxide Modified Activated Carbon for Remediation of Redox-Sensitive Contaminants

Environmental iodine speciation quantification in seawater and snow using ion exchange chromatography and UV spectrophotometric detection

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Novel manganese cycling at very low ionic strengths in the Columbia River Estuary

Cited by 13 publications

References 92 publications

Exploring the Growth Pattern and Hydraulic Resistance of BioMnOx Cake Layer under Different Fluxes in Ultrafiltration Processes

Exploring the Growth Pattern and Hydraulic Resistance of BioMnOx Cake Layer under Different Fluxes in Ultrafiltration Processes

Characterization of Manganese Oxide Modified Activated Carbon for Remediation of Redox-Sensitive Contaminants

Environmental iodine speciation quantification in seawater and snow using ion exchange chromatography and UV spectrophotometric detection

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Product

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Exploring the Growth Pattern and Hydraulic Resistance of BioMnO_x Cake Layer under Different Fluxes in Ultrafiltration Processes

Exploring the Growth Pattern and Hydraulic Resistance of BioMnO_x Cake Layer under Different Fluxes in Ultrafiltration Processes