Tremendous effect of oxygen vacancy defects on the oxidation of arsenite to arsenate on cryptomelane-type manganese oxide

Hou, Jingtao; Luo, Jie; Hu, Zhongqiu; Li, Yuanzhi; Mao, Mingyang; Song, Shaoxian; Liao, Qingling; Li, Qingzhu

doi:10.1016/j.cej.2016.07.072

Cited by 44 publications

(30 citation statements)

References 49 publications

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“…The average oxidation state (AOS) results were obtained from formula (3), and the ΔE s was doublet binding-energy peaks for Mn 3s (Fig. 5b) (Hou et al 2016). The AOS of OMS-2-0.7 was 3.40 which is much lower than OMS-2-0.3 (3.88).…”

Section: Fig 4 H 2 -Tpr Results Of the Catalystsmentioning

confidence: 97%

“…It is known that when Mn 3+ is contained in the framework, oxygen vacancies would be formed on manganese dioxide. Maintaining electrostatic balance was the reason which concluded the following process (2) (Hou et al 2016;Jia et al 2016a, b). According to this process, we calculate that OMS-2-0.7 had a surface oxygen vacancy content of 19%.…”

Section: Chemical States Of Surface Elementsmentioning

confidence: 99%

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Highly active OMS-2 for catalytic ozone decomposition under humid conditions

et al. 2019

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Four kinds of cryptomelane-type octahedral molecular sieve (OMS)-2-X (the X represents the molar ratio of KMnO 4 / MnAc 2) were prepared as catalytic materials for ozone decomposition through a one-step hydrothermal reaction of KMnO 4 and MnAc 2 , by changing their molar ratios. These samples were characterized by N 2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), temperature programmed reduction by H 2 (H 2-TPR) and X-ray photoelectron spectroscopy (XPS). Among them, the OMS-2-0.7 sample showed the best O 3 conversion of 92% under high relative humidity (RH) of 90% and gas hourly space velocity of 585,000 h −1. This was accordingly thought as a possible way for purifying ozone-containing waste gases under high RH atmospheres. The efficiency of ozone decomposition of the prepared OMS-2-X sample was found to be related to specific surface area, particle size, surface oxygen vacancies, and Mn 3+ cation amounts. The one-step hydrothermal synthesis was shown to be a simple method to prepare the considerably active OMS-2 solids for ozone decomposition.

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Section: Fig 4 H 2 -Tpr Results Of the Catalystsmentioning

confidence: 97%

Section: Chemical States Of Surface Elementsmentioning

confidence: 99%

Highly active OMS-2 for catalytic ozone decomposition under humid conditions

et al. 2019

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“…Manganese oxide (MnO x ) has received more and more attentions in water treatment (Allard, Gutierrez, Fontaine, Croue, & Gallard, 2017;Chen, Wang, Zhang, Wu, & Wang, 2018;Post, 1999), focusing mainly on two respects. One is the removal of heavy metals, such as As 5+ (Driehaus, Seith, & Jekel, 1995;Hou et al, 2016), Pb 2+ (Chen et al, 2017;Wan et al, 2016;Wang et al, 2015), and Cr 6+ (Landrot, Gindervogel, Livi, Fitts, & Sparks, 2012;Tang, Webb, Estes, & Hansel, 2014), and the other is to remove the organic matters, for example, phenols (Selig, Keinath, & Weber, 2003;Ulrich & Stone, 1989), anilines (Laha & Luthy, 1990;Park, Dec, Kim, & Bollag, 1999), low-molecular-weight acids (Xyla et al, 1992), and pesticide (Šťastný et al, 2016). Our previous research has found that MnO x film coated on silica sands in aerobic filter had strong catalytic activity for ammonium removal (Cheng, Huang, Sun, & Shi, 2017;Guo, Huang, Wen, & Cao, 2017;Zhang, Huang, et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Removing ammonium from underground water by strengthening Mn(III) generation through electrochemical reduction

Shi

et al. 2019

Water Environment Research

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Manganese oxide has been found to be an active catalyst for ammonium oxidation. This work presented an innovative electrochemical system to improve the removal efficiency of ammonium by strengthening the generation of Mn(III). In this system, the manganese oxide coating activated carbon (MnOx/AC) particles were used as the cathode of a fuel cell (MnOx/AC‐Ca). Compared to the conventional method using MnOx in a nonelectrochemical system (MnOx/AC‐Control), the ammonium removal efficiency was doubled in the MnOx/AC‐Ca system. Conversely, when using MnOx as the anode of a fuel cell (MnOx/AC‐An), the ammonium removal efficiency was lower than that in the MnOx/AC‐Control system. XPS results showed that Mn(III) in the MnOx/AC‐Ca system was obviously higher than that in the MnOx/AC‐Control system. Conversely, more Mn(IV), which was less active than Mn(III) for NH4+-N removal, was detected in the MnOx/AC‐An system. The possible pathway for the ammonium removal by MnOx was that Mn(III) reacted with NH4+-N and produced Mn2+. These Mn2+ were then reoxidized into new active MnOx under the self‐catalysis of MnOx, resulting in a continuous ammonium removal. Moreover, nitrite, the intermediate product of ammonium oxidation, can be oxidized by MnOx, thus helping the ammonium oxidation process. Practitioner points Mn(III) was generated by using MnOx as the cathode of fuel cells. Ammonium removal efficiency went up with the content of Mn(III) in MnOx. Mechanism of the NH4+-N removal by MnOx was discussed.

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“…Although both synthetic Fe-Mn binary oxides and Fe and Mn enriched samples present highly efficient removal of As(III), their As(III) oxidation kinetic rates are very slow, i. e., As(III) can be completely oxidized to As(V) only after 8 h (Zhang et al, 2007) and 50 h (Deschamps et al, 2005), respectively. It is well known that widespread coexisting ions, such as phosphate, readily bind to manganese oxide surface active sites, and these may hinder As(III) adsorption and subsequently impede their oxidation (Hou et al, 2017(Hou et al, , 2016Lafferty et al, 2010). Therefore, it is of scientific and technological importance to seek a novel approach to improving As(III) oxidation rate on manganese oxides by reducing the adverse effects of coexisting ions.…”

Section: Introductionmentioning

confidence: 99%

“…Cryptomelane-type manganese oxide (OMS-2) possesses a 2 × 2 tunnel structure formed by edge-and corner-shared MnO6 octahedra, and has attracted interest due to its ability to oxidize As(III) (Hou et al, 2016;Li et al, 2010;Wang et al, 2012). Since K + ions are similar to the dimensions of 2 × 2 tunnel structures, they have been used as an ideal template for synthetizing manganese oxide with 2 × 2 tunnel structures in the laboratory (Liu et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Enhanced oxidation of arsenite to arsenate using tunable K+ concentration in the OMS-2 tunnel

Hou

Sha

Hartley

et al. 2018

Environmental Pollution

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Cryptomelane-type octahedral molecular sieve manganese oxide (OMS-2) possesses high redox potential and has attracted much interest in its application for oxidation arsenite (As(III)) species of arsenic to arsenate (As(V)) to decrease arsenic toxicity and promote total arsenic removal. However, coexisting ions such as As(V) and phosphate are ubiquitous and readily bond to manganese oxide surface, consequently passivating surface active sites of manganese oxide and reducing As(III) oxidation. In this study, we present a novel strategy to significantly promote As(III) oxidation activity of OMS-2 by tuning K concentration in the tunnel. Batch experimental results reveal that increasing K concentration in the tunnel of OMS-2 not only considerably improved As(III) oxidation kinetics rate from 0.027 to 0.102 min, but also reduced adverse effect of competitive ion on As(III) oxidation. The origin of K concentration effect on As(III) oxidation was investigated through As(V) and phosphate adsorption kinetics, detection of Mn release in solution, surface charge characteristics, and density functional theory (DFT) calculations. Experimental results and theoretical calculations confirm that by increasing K concentration in the OMS-2 tunnel not only does it improve arsenic adsorption on K doped OMS-2, but also accelerates two electrons transfers from As(III) to each bonded Mn atom on OMS-2 surface, thus considerably improving As(III) oxidation kinetics rate, which is responsible for counteracting the adverse adsorption effects by coexisting ions.

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Tremendous effect of oxygen vacancy defects on the oxidation of arsenite to arsenate on cryptomelane-type manganese oxide

Cited by 44 publications

References 49 publications

Highly active OMS-2 for catalytic ozone decomposition under humid conditions

Highly active OMS-2 for catalytic ozone decomposition under humid conditions

Removing ammonium from underground water by strengthening Mn(III) generation through electrochemical reduction

Enhanced oxidation of arsenite to arsenate using tunable K+ concentration in the OMS-2 tunnel

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