Facile synthesis of Cu-doped manganese oxide octahedral molecular sieve for the efficient degradation of sulfamethoxazole via peroxymonosulfate activation

Advanced processes for peroxymonosulfate(PMS)-based oxidation are efficient in eliminating toxic and refractory organic pol-lutants from sewage.The activation of electron-withdrawing HSO_(5)^(-)releases reactive species,including sulfate radical(·SO_(4)^(-)),hydroxyl radical(·OH),superoxide radical(·O_(2)^(-)),and singlet oxygen(1O_(2)),which can induce the degradation of organic contaminants.In this work,we synthesized a variety of M-OMS-2 nanorods(M=Co,Ni,Cu,Fe)by doping Co^(2+),Ni^(2+),Cu^(2+),or Fe^(3+)into manganese oxide oc-tahedral molecular sieve(OMS-2)to efficiently remove sulfamethoxazole(SMX)via PMS activation.The catalytic performance of M-OMS-2 in SMX elimination via PMS activation was assessed.The nanorods obtained in decreasing order of SMX removal rate were Cu-OMS-2(96.40%),Co-OMS-2(88.00%),Ni-OMS-2(87.20%),Fe-OMS-2(35.00%),and OMS-2(33.50%).Then,the kinetics and struc-ture-activity relationship of the M-OMS-2 nanorods during the elimination of SMX were investigated.The feasible mechanism underly-ing SMX degradation by the Cu-OMS-2/PMS system was further investigated with a quenching experiment,high-resolution mass spec-troscopy,and electron paramagnetic resonance.Results showed that SMX degradation efficiency was enhanced in seawater and tap water,demonstrating the potential application of Cu-OMS-2/PMS system in sewage treatment.

Preparation of Manganese Oxide and Its Adsorption Properties

The in-situ oxidation of manganese sulfate solution with H2O_(2),sodium hypochlorite,potassium permanganate and oxygen as oxidants was investigated by means of SEM,EDS,XRD,BET and infrared analysis,and the effects of different oxidants on the morphology,phase composition,surface properties and specific surface area of manganese oxides were investigated.The experimental results show that the diameter of manganese oxide particles prepared with H_(2)O_(2)is the smallest,about 50 nm,and the specific surface area is the largest,63.8764 m^(2)/g.It has the advantages of abundant surface hydroxyl groups,no introduction of other impurities and large adsorption potential.It is most suitable to be used as an oxidant for oxidizing manganese sulfate solution to prepare manganese oxide by in-situ oxidation.Nano manganese oxide prepard by H_(2)O_(2)in-situ oxidation method is used as adsorbent to adsorb cobalt and nickel impurities in manganese sulfate.When the reaction pH is 6,the reaction time is 30min and the amount of adsorbent is 1.0 g,the adsorption rates of cobalt and nickel impurities in 100ml manganese sulfate solution are 97.59%and 97.67%,respectively.The residual amounts of cobalt and nickel meet the industrial process standard of first-class products(Co,Ni w/%≤0.005)of high-purity manganese sulfate(Hg/t4823-2015)for batteries.The study plays a guiding role in the preparation and regulation of manganese oxide,and provides a new method with high efficiency,purity and adsorbent availability for the preparation of high-purity manganese sulfate solution.

Comparative structural and electrochemical properties of mixed P2/O′3-layered sodium nickel manganese oxide prepared by sol-gel and electrospinning methods:Effect of Na-excess content

The effect of Na-excess content in the precursor on the structural and electrochemical performances of sodium nickel manganese oxide(NNMO)prepared by sol-gel and electrospinning methods is investigated in this paper.X-ray diffraction results of the prepared NNMO without adding Na-excess content indicate sodium loss,while the mixed phase of P2/O′3-type layered NNMO presented after adding Na-excess content.Compared with the sol-gel method,the secondary phase of NiO is more suppressed by using the electrospinning method,which is further confirmed by field emission scanning electron microscope images.N_(2) adsorption-desorption isotherms show no remarkably difference in specific surface areas between different preparation methods and Na-excess contents.The analysis of X-ray absorption near edge structure indicates that the oxidation states of Ni and Mn are+2 and+4,respectively.For the electrochemical properties,superior electrochemical performance is observed in the NNMO electrode with a low Na-excess content of 5wt%.The highest specific capacitance is 36.07 F·g^(-1)at0.1 A·g^(-1)in the NNMO electrode prepared by using the sol-gel method.By contrast,the NNMO electrode prepared using the electrospinning method with decreased Na-excess content shows excellent cycling stability of 100%after charge-discharge measurements for 300 cycles.Therefore,controlling the Na excess in the precursor together with the preparation method is important for improving the electrochemical performance of Na-based electrode materials in supercapacitors.

Reductive leaching of manganese oxide ores using waste tea as reductant in sulfuric acid solution

Manganese oxide ores from Gabon and Xiangxi were leached with waste tea as reductant in dilute sulfuric acid solution. The effects of waste tea dosage, concentration of sulfuric acid, liquid-to-solid ratio, leaching temperature and reaction time on leaching process were explored. The leaching efficiency of Gabonese manganese oxide ore reached almost 100% under the optimal condition which was determined as follows： manganese oxide ore to waste tea mass ratio of 10：1, sulfuric acid concentration of 2.5 molFL, liquid-to-solid ratio of 7.5：1, leaching temperature of 368 K, time of 8 h. The leaching efficiency of Xiangxi manganese oxide ore reached 99.8% under the optimal condition which was determined as follows： manganese oxide ore to waste tea mass ratio of 10：1, sulfuric acid concentration of 1.7 mol/L, liquid-to-solid ratio of 7.5：1, leaching temperature of 368 K, time of 8 h. The leaching process followed the internal diffusion controlled kinetic model, and the apparent activation energies of Gabonese manganese oxide ore and Xiangxi manganese oxide ore were calculated to be 38.2 kJ/mol and 20.4 kJ/mol, respectively. The morphological changes and mineralogical forms of the ore before and after the chemical treatment were discussed with the support of XRD analysis and SEM analysis.

Manganese extraction by reduction-acid leaching from low-grade manganese oxide ores using CaS as reductant

The extraction of manganese from low-grade manganese oxide ores using Ca S derived from Ca SO4 as reductant was investigated. The effects of mass ratio of Ca S to ore, reduction temperature, reduction time, liquid to solid ratio（L/S ratio）, stirring speed, leaching temperature, leaching time and H2SO4 concentration on the leaching rates of Mn and Fe during the reduction–acid leaching process were discussed. The leaching rates of 96.47% for Mn and 19.24% for Fe were obtained under the optimized conditions of mass ratio of Ca S to manganese oxide ore 1：6.7, L/S ratio 5：1, stirring speed 300 r/min, reduction temperature of 95 °C for 2.0 h in the reduction process and leaching stirring speed of 200 r/min, H2SO4 concentration of 1.5 mol/L, leaching temperature of 80 °C for 5 min in the leaching process. In addition, this process can be employed in the recovery of manganese from various manganese oxide ores, and Mn leaching rate above 95% is obtained.

Carbon monoxide oxidation on copper manganese oxides prepared by selective etching with ammonia

A series of copper manganese oxides were prepared using a selective etching technique with various amounts of ammonia added during the co-precipitation process. The effect of the ammonia etching on the structure and catalytic properties of the copper manganese oxides was investigated using elemental analysis, nitrogen physisorption, X-ray powder diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, H2 temperature-programmed reduc- tion, and Oz temperature-programmed desorption combined with catalytic oxidation of CO. It was found that ammonia can selectively remove copper species from the copper manganese oxides, which correspondingly generates more defects in these oxides. An oxygen spillover from the man- ganese to the copper species was observed by H2 temperature-programmed desorption, indicating that ammonia etching enhanced the mobility of lattice oxygen species in these oxides. The Oz tem- perature-programmed desorption measurements further revealed that ammonia etching improved the ability of these oxides to release lattice oxygen. The improvement in redox properties of the copper manganese oxides following ammonia etching was associated with enhanced catalytic performance for CO oxidation.

Preparation of Manganese Oxide Hollow Spheres Using pH-responsive Microgels as Templates

Manganese oxide hollow spheres were prepared by a novel and facile approach using pH- responsive microgels as templates. The final products were thoroughly characterized with X-ray powder diffraction, thermogravimetric analysis, scanning electron microscopy, Fourier transform infrared, and transmission electron microscopy. The results reveal that the shell thickness of manganese oxide hollow spheres increased with the dosage of KMnO4, which implies that a controllable and feasible strategy for manganese oxide hollow spheres prepa- ration has been established. Further studies on the microgels template showed some of them had an irreversible swelling/deswelling transition due to the uneven cross-link extent. Based on the results, a probable formation mechanism for the hollow spheres was proposed.

Feasibility of flue-gas desulfurization by manganese oxides

For the purpose of effective and economic desulfurization of flue-gas, the predominance area diagram of the Mn-S-O system at different temperatures was constructed based on the thermodynamic data obtained from the literatures. It is seen from this figure that flue-gas desulfurization by manganese oxides is feasible from the thermodynamic point of view. Additionally, the most appropriate temperature range for flue-gas desulfurization is between 600 and 800 K, and the reaction is strongly exothermic to maintain the heat balance. The natural manganese ores encompass large tunnels that exhibit large surface areas and highly chemical activity, which can provide a high enough SO2 removing efficiency. From the superposition of the diagrams of Mn-S-O and Fe-S-O systems, it is found that there is a coexistent stability region of MnSO4 and Fe2O3, which provides the possibility of desulfurization by selective sulfation without ferric sulfate forming. A multi-stage desulfurization system has been discussed briefly.

Solvent-free selective oxidation of cyclohexane with molecular oxygen over manganese oxides:Effect of the calcination temperature

The effects of calcination temperature on the physicochemical properties of manganese oxide catalysts prepared by a precipitation method were assessed by X-ray diffraction,N2 adsorption-desorption,X-ray photoelectron spectroscopy,H2 temperature-programmed reduction,O2 temperature-programmed desorption,and thermogravimetry-differential analysis.The catalytic performance of each of these materials during the selective oxidation of cyclohexane with oxygen in a solvent-free system was subsequently examined.It was found that the MnOx-500 catalyst,calcined at 500 °C,consisted of a Mn2O3 phase in addition to Mn5O8 and Mn3O4 phases and possessed a low surface area.Unlike MnOx-500,the MnOx-400 catalyst prepared at 400 °C was composed solely of Mn3O4 and Mn5O8 and had a higher surface area.The pronounced catalytic activity of this latter material for the oxidation of cyclohexene was determined to result from numerous factors,including a higher concentration of surface adsorbed oxygen,greater quantities of the surface Mn4＋ ions that promote oxygen mobility and the extent of O2 adsorption and reducibility on the catalyst.The effects of various reaction conditions on the activity of the MnOx-400 during the oxidation of cyclohexane were also evaluated,such as the reaction temperature,reaction time,and initial oxygen pressure.Following a 4 h reaction at an initial O2 pressure of 0.5 MPa and 140 °C,an 8.0% cyclohexane conversion and 5.0% yield of cyclohexanol and cyclohexanone were achieved over the MnOx-400 catalyst.In contrast,employing MnOx-500 resulted in a 6.1% conversion of cyclohexane and 75% selectivity for cyclohexanol and cyclohexanone.After being recycled through 10 replicate uses,the catalytic activity of the MnOx-400 catalyst was unchanged,demonstrating its good stability.

Effect of Precipitation Method and Ce Doping on the Catalytic Activity of Copper Manganese Oxide Catalysts for CO Oxidation

The influence of Ce doping and the precipitation method on structural properties and the catalytic activity of copper manganese oxides for CO oxidation at ambient temperature have been investigated. The catalysts were characterized by means of the powder X-ray diffraction and N2 adsorption-desorption, the inductively coupled plasma atomic emission spectrometry, the temperature programmed reduction, diffuse reflectance UV-Vis spectra, and the X-ray photoelectron spectroscopy. It was found that after doping little amount of Ce in copper manganese oxide, CeO2 phase was highly dispersed and could prevent sintering and aggregating of the catalyst, the size of the catalytic material was decreased, the reducibility was enhanced, the specific surface area was increased and the formation of the active sites for the oxidation of CO was improved significantly. Therefore, the activity of the rare earth promoted catalyst was enhanced remarkably.

Removal of Uranium（Ⅵ） by Fixed Bed Ion-exchange Column Using Natural Zeolite Coated with Manganese Oxide

The adsorption of uranium(Ⅵ)on the manganese oxide coated zeolite(MOCZ)from aqueous solution was investigated in a fixed-bed column.The experiments were conducted to investigate the effects of bed height,flow rate,particle size,initial concentration of uranium(Ⅵ),initial pH,presence of salt and competitive ions.The U-uptake by MOCZ increased with initial uranium(Ⅵ)concentration and bed height,but decreased as the flow rate and particle size increased.In the presence of salt and competitive ions,the breakthrough time was shorter.The adsorption capacity reached a maximum at pH of 6.3.The Thomas model was applied to the experimental data to determine the characteristic parameters of the column for process design using linear regression.The breakthrough curves calculated from the model were in good agreement with the experimental data.The BDST model was used to study the influence of bed height on the adsorption of uranium(Ⅵ).Desorption of uranium(Ⅵ)in the MOCZ column was investigated.The column could be used for at least four adsorption-desorption cycles using 0.1mol.L-1 NaHCO3 solution as the elution.After desorption and regeneration with deionized water,MOCZ could be reused to adsorb uranium(Ⅵ)at a comparable capacity.Compared to raw zeolite,MOCZ showed better capacity for uranium(Ⅵ)removal.

Sulfur resource recovery based on electrolytic manganese residue calcination and manganese oxide ore desulfurization for the clean production of electrolytic manganese

An environmentally friendly and resource-conserving route to the clean production of electrolytic manganese was developed,in which the electrolytic manganese residue(EMR)was initially calcined for cement buffering;then the generated SO2-containing flue gas was managed using manganese oxide ore and anolyte(MOOA)desulfurization;at last,the desulfurized slurry was introduced to the electrolytic manganese production(EMP).Results showed that 4.0 wt%coke addition reduced the sulfur of calcined EMR to 0.9%,thereby satisfying the cement-buffer requirement.Pilot-scale desulfurization showed that about 7.5 vol%of high SO2 containing flue gas can be cleaned to less than 0.1 vol%through a five-stage countercurrent MOOA desulfurization.The desulfurized slurry had 42.44 g·L-Mn2+and 1.92 g·L-1 S2 O62-,which was suitable for electrowinning after purification,and the purity of manganese product was 99.93%,satisfy the National Standard of China YB/T051-2015.This new integrated technology fulfilled 99.7%of sulfur reutilization from the EMR and 94.1%was effectively used to the EMP.The MOOA desulfurization linked the EMP a closed cycle without any pollutant discharge,which promoted the cleaner production of EMP industry.

Catalytic performance enhancement by alloying Pd with Pt on ordered mesoporous manganese oxide for methane combustion

Ordered mesoporous Mn2O3 (meso‐Mn2O3) and meso‐Mn2O3‐supported Pd, Pt, and Pd‐Pt alloy x(PdyPt)/meso‐Mn2O3; x = (0.10?1.50) wt%; Pd/Pt molar ratio (y) = 4.9?5.1 nanocatalysts were prepared using KIT‐6‐templated and poly(vinyl alcohol)‐protected reduction methods, respectively.The meso‐Mn2O3 had a high surface area, i.e., 106 m2/g, and a cubic crystal structure. Noble‐metalnanoparticles (NPs) of size 2.1?2.8 nm were uniformly dispersed on the meso‐Mn2O3 surfaces. AlloyingPd with Pt enhanced the catalytic activity in methane combustion; 1.41(Pd5.1Pt)/meso‐Mn2O3gave the best performance; T10%, T50%, and T90% (the temperatures required for achieving methaneconversions of 10%, 50%, and 90%) were 265, 345, and 425 °C, respectively, at a space velocity of20000 mL/(g?h). The effects of SO2, CO2, H2O, and NO on methane combustion over1.41(Pd5.1Pt)/meso‐Mn2O3 were also examined. We conclude that the good catalytic performance of1.41(Pd5.1Pt)/meso‐Mn2O3 is associated with its high‐quality porous structure, high adsorbed oxygen species concentration, good low‐temperature reducibility, and strong interactions between Pd‐Pt alloy NPs and the meso‐Mn2O3 support.

Mechanism of Capacity Fading Caused by Mn(Ⅱ)Deposition on Anodes for Spinel Lithium Manganese Oxide Cell

The capacity fade of spinel lithium manganese oxide in lithium-ion batteries is a bottleneck challenge for the large-scale application.The traditional opinion is that Mn（Ⅱ） ions in the anode are reduced to the metallic manganese that helps for catalyzing electrolyte decomposition.This could poison and damage the solid electrolyte interface（SEI） film,leading to the the capacity fade in Li-ion batteries.We propose a new mechanism that Mn（Ⅱ） deposites at the anode hinders and/or blocks the intercalation/de-intercalation of lithium ions,which leads to the capacity fade in Li-ion batteries.Based on the new mechanism assumption,a kind of new structure with core-shell characteristic is designed to inhabit manganese ion dissolution,thus improving electrochemical cycle performance of the cell.By the way,this mechanism hypothesis is also supported by the results of these experiments.The LiMn2-xTixO4 shell layer enhances cathode resistance to corrosion attack and effectively suppresses dissolution of Mn,then improves battery cycle performance with LiMn_2O_4 cathode,even at high rate and elevated temperature.

Factors Affecting Cr(Ⅲ) Oxidation by Manganese Oxides

The high oxidation ability of manganese oxides or soils was used to study effects of pH and coatingon Cr(Ⅲ) oxidation. The results indicated that Cr(Ⅲ) oxidation peaked in pH 4.0-6.5. The amount andrate of Cr(Ⅲ) being oxidized by uncoated δ-MnO2 were larger than those by Fe oxide- or CaCO3-coatedone. Inorganic Cr(Ⅲ) was more easi1y oxidized by MnO2 than organic complex Cr(Ⅲ) due to differentsurface affinities. Precipitated Cr(Ⅲ) and adsorbed Cr(Ⅲ) might be transferred onto MnO2 surface andthen oxidized to Cr(VI).

Kinetics of reductive leaching of manganese oxide ore using cellulose as reductant

The kinetics of reductive leaching of manganese from a low-grade manganese oxide ore were studied using cellulose as reductant in dilute sulfuric acid medium.It was found that when the stirring speed was higher than 200 r/min,the effect of gas film diffusion on manganese extraction efficiency could be neglected,and the kinetic behavior was investigated under the condition of elimination of external diffusion influence on the leaching process.Effects of leaching temperature,mass ratio of cellulose and ore,and the sulfuric acid concentration on manganese extraction efficiency were discussed.The kinetic data were analyzed based on the shrinking core model,which indicated that the leaching process was dominated by both ash layer diffusion and chemical reaction at the initial stage,with the progress of leaching reaction,the rate-controlling step switched to the ash layer diffusion.It was also concluded that the sulfuric acid concentration had the most significant influence on the leaching rate,the reaction orders with respect to the sulfuric acid concentration were 2.102 in the first 60 min,and 3.642 in the later 90 min,while the reaction orders for mass ratio of cellulose and ore were 0.660 and 0.724,respectively.An Arrhenius relationship was used to relate the temperature to the rate of leaching,from which apparent activation energies were calculated to be 46.487 kJ/mol and 62.290 kJ/mol at the two stages,respectively.Finally,the overall leaching rate equations for the manganese dissolution reaction with cellulose in sulphuric acid solution were developed.The morphological changes and mineralogical forms of the ore before and after the chemical treatment were discussed with the support of SEM and XRD analyses.

Facile synthesis of hierarchically structured manganese oxides as anode for lithium-ion batteries

Developing high-performance lithium ion batteries(LIBs)using manganese oxides as anodes is attractive due to their high theoretical capacity and abundant resources.Herein,we report a facile synthesis of hierarchical spherical MnO2 containing coherent amorphous/crystalline domained by a simple yet effective redox precipitation reaction at room temperature.Further,flower-like CoMn2O4 constructed by single-crystalline spinel nanosheets has been fabricated using MnO2 as precursor.This mild methodology avoids undesired particle aggregation and loss of active surface area in conventional hydrothermal or solid-state processes.Moreover,both MnO2 and CoMn2O4 nanosheets manifest superior lithium-ion storage properties,rendering them promising applications in LIBs and other energy-related fields.

Critical role of corrosion inhibitors modified by silyl ether functional groups on electrochemical performances of lithium manganese oxides

Lithium manganese oxides(Li Mn2 O4, LMO) have attracted significant attention as important cathode materials for lithium-ion batteries(LIBs), which require fast charging based on their intrinsic electrochemical properties. However, these properties are limited by the rapid fading of cycling retention, particularly at high temperatures, because of the severe Mn corrosion triggered by the chemical reaction with fluoride(F-) species existing in the cell. To alleviate this issue, three types of silyl ether(Si–O)-functionalized task-specific additives are proposed, namely methoxytrimethylsilane, dimethoxydimethylsilane, and trimethoxymethylsilane. Ex-situ NMR analyses demonstrated that the Si-additives selectively scavenged the F-species as Si forms new chemical bonds with F via a nucleophilic substitution reaction due to the high binding affinity of Si with F-, thereby leading to a decrease in the F concentration in the cell. Furthermore, the addition of Si-additives in the electrolyte did not significantly affect the ionic conductivity or electrochemical stability of the electrolyte, indicating that these additives are compatible with conventional electrolytes. In addition, the cells cycled with Si-additives exhibited improved cycling retention at room temperature and 45 °C. Among these candidates, a combination of MTSi and the LMO cathode was found to be the most suitable choice in terms of cycling retention(71.0%), whereas the cell cycled with the standard electrolyte suffered from the fading of cycling retention triggered by Mn dissolution(64.4%). Additional ex-situ analyses of the cycled electrodes using SEM, TEM, EIS, XPS, and ICP-MS demonstrated that the use of Si-additives not only improved the surface stability of the LMO cathode but also that of the graphite anode, as the Si-additives prevent Mn corrosion. This inhibits the formation of cracks on the surface of the LMO cathode, facilitating the formation of a stable solid electrolyte interphase layer on the surface of the graphite anode. Therefore, Si-additives modified by Si–O functional groups can be effectively used to increase the overall electrochemical performance of the LMO cathode material.

Effects of carrier and Mn loading on supported manganese oxide catalysts for catalytic combustion of methane

Supported manganese oxide catalysts were prepared by incipient wetness impregnation method for methane catalytic combustion, and effects of the support （Al2O3, SiO2 and TiO2） and Mn loading were investigated. These catalysts were characterized with N2 adsorption, X-ray diffraction, X-ray photoelectron spectroscopy and temperature-programmed reduction techniques. Methane conversion varied in a large range depending on supports or Mn loading. Al2O3 supported 15% Mn catalyst exhibited better activity toward methane catalytic oxidation. The manganese state and oxygen species played an important role in the catalytic performance,

Mixed phase sodium manganese oxide as cathode for enhanced aqueous zinc-ion storage

Aqueous zinc-ion batteries have been regarded as a promising alternative to large-scale energy storage, due to associated low-cost, improved safety and environmental friendliness. However, a high-performance cathode material for both rate capability and specific capacity is still a challenge. One kind of the more promising candidates are sodium manganese oxide(NMO) materials, although they suffer from individual issues and need to be further improved. Herein, we present a novel mixed phase NMO material composed of nearly equal amounts of Na(0.55)Mn2O4 and Na(0.7)MnO(2.05). The structured configuration with particle size of 200–500 nm is found to be beneficial towards improving the ion diffusion rate during the charge/discharge process. Compared with Na(0.7)MnO(2.05) and Na(0.55)Mn2O4, the mixed phase NMO demonstrates an enhanced rate capability and excellent long-term cycling stability with a capacity retention of 83% after 800 cycles. More importantly, the system also delivers an impressive energy density and power density, as 378 W·h·kg^-1 at 68.7 W·kg^-1, or 172 W·h·kg^-1 at 1705 W·kg^-1. The superior electrochemical performance is ascribed to the fast Zn^2+ diffusion rate because of a large ratio of capacitive contribution(63.9% at 0.9 m V·s^-1). Thus, the mixed phase route provides a novel strategy to enhance electrochemical performance, enabling mixed phase NMO as very promising material towards large-scale energy-storage applications.