Fan Liu

Huazhong Agricultural University, Wu-han-shih, Hubei, China

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Publications (118)308.44 Total impact

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    ABSTRACT: The effects of particle size (5, 35 and 70nm) on the sorption of myo-inositol hexakisphosphate (IHP) and inorganic phosphate (KH2PO4, Pi) on γ-Al2O3 nanoparticles were investigated using batch sorption experiments, zeta potential measurements and solid-state nuclear magnetic resonance spectroscopy (NMR). The results show that the maximum sorption densities (μmolm(-2)) for IHP and Pi increase with decreasing γ-Al2O3 particle size. The sorption affinity of γ-Al2O3 for IHP and Pi generally increases with decreasing particle size, and the sorption affinity for IHP is approximately one order of magnitude greater than that for Pi. In our experimental time scale, surface complexation is the main mechanism for IHP and Pi sorption on large size γ-Al2O3. While an additional surface precipitation mechanism, indicated by solid-state (31)P and (27)Al NMR data, is partly responsible for the greater sorption density on very small size γ-Al2O3. Compared with Pi, the effect of particle size on the sorption of IHP is more pronounced. The results suggest a size-dependent surface reactivity of Al2O3 nanoparticles with Pi/IHP. The underlying mechanism will also be relevant for other small nanosize (hydr)oxide particles and is important for our understanding of the role of small nanoparticles in controlling the mobility and fate of organic and inorganic phosphates in the environment. Copyright © 2015 Elsevier Inc. All rights reserved.
    Journal of Colloid and Interface Science 08/2015; 451. DOI:10.1016/j.jcis.2015.03.045 · 3.55 Impact Factor
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    ABSTRACT: The relationships between the basic properties and trace elements in soil argillans and corresponding matrix soils were studied by sampling from the B horizons of 26 Alfisols in croplands of the subtropical area in Central China. The soil elements (K, Na, Ca, Mg, Mn, Co, Cu, Cr, Cd, Li, Mo, Ni, Pb, Ti, V, and Zn) were extracted by acid digestion and their contents were measured using inductively coupled plasma optical emission spectrometry (ICP-OES). The mean contents of clay and organic matter in the argillans were approximately 1.1 and 1.3 times greater than those in the matrix soils, respectively. The pH values and the contents of P2O5 and bases (K2O, Na2O, CaO, and MgO) in the argillans were higher than those in the corresponding matrix soils. Cu, Cd, Ti, and V were enriched in the argillans. Correlation coefficients and factor analyses showed that Co, Cu, Li, and Zn were bound with phyllosilicates and manganese oxides (Mn-oxides) in the argillans. Cr and Pb were mainly associated with iron oxides (Fe-oxides), while Ni was bound with Mn-oxides. Cd, Ti, and V were chiefly associated with phyllosilicates, but Cr and Mo were rarely enriched in the argillans. In contrast, in the matrix soils, Co and Zn were associated with organic matter and Fe-oxides, Cr existed in phyllosilicates, and Mo was bound to Fe-oxides. Cd, Ti, and V were associated with organic matter. The results of this study suggest that clays, organic matter, and minerals in the argillans dominate the illuviation of trace elements in Alfisols. Argillans might be the active interfaces of elemental exchange and nutrient supply in cropland soils in Central China.
    Pedosphere 06/2015; 25(3). DOI:10.1016/S1002-0160(15)30009-6 · 1.38 Impact Factor
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    ABSTRACT: Todorokite, formed from Mn(II) in supergene environments, can affect the transformation and migration of dissolvable sulfides in soils and water. In this work, todorokite was synthesized with different degrees of crystallinity, and the redox mechanism of dissolvable sulfide and todorokite was studied in both closed and open aqueous systems. The influences of pH, temperature, crystallinity, the amount of manganese oxides, and oxygen gas on S(2-) oxidation process were investigated. It is found that S(2-) was oxidized to S(0), SO3(2-), S2O3(2-) and SO4(2-), and about 90% of S(2-) was converted into S(0) in closed systems. The participation of oxygen facilitated the further oxidation of S(0) to S2O3(2-). S(0) and S2O3(2-) were formed with the conversion rates of S(2-) about 45.3% and 38.4% after 1h of reaction, respectively, and the conversion rate for S2O3(2-) increased as reaction prolonged for a longer period. In addition, todorokite was reduced to Mn(OH)2 in the presence of nitrogen gas, and its chemical stability increased when oxygen gas was admitted into the reaction system during the process. The oxidation rate of dissolvable sulfide followed a pseudo-first-order kinetic law in the initial stage (within 10min), and the initial oxidation rate constant of S(2-) increased with elevating temperature, increasing the quantity and decreasing crystallinity of todorokite. The initial oxidation rate of dissolvable sulfide decreased with continuous feeding of O2 into the test solution, possibly due to a decrease in active Mn(III) content in todorokite. The present work demonstrates the redox behaviors and kinetics of dissolvable sulfide and todorokite in aquatic environments. Copyright © 2015 Elsevier B.V. All rights reserved.
    Journal of Hazardous Materials 06/2015; 290. DOI:10.1016/j.jhazmat.2015.02.018 · 4.33 Impact Factor
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    ABSTRACT: In this manuscript, we report that a bacterial multicopper oxidase (MCO266) catalyzes Mn(II) oxidation on the cell surface, resulting in the surface deposition of Mn(III) and Mn(IV) oxides and the gradual formation of bulky oxide aggregates. These aggregates serve as nucleation centers for the formation of Mn oxide micronodules and Mn-rich sediments. A soil-borne Escherichia coli with high Mn(II)-oxidizing activity formed Mn(III)/Mn(IV) oxide deposit layers and aggregates under laboratory culture conditions. We engineered MCO266 onto the cell surfaces of both an activity-negative recipient and wild-type strains. The results confirmed that MCO266 governs Mn(II) oxidation and initiates the formation of deposits and aggregates. By contrast, a cell-free substrate, heat-killed strains, and intracellularly expressed or purified MCO266 failed to catalyze Mn(II) oxidation. However, purified MCO266 exhibited Mn(II)-oxidizing activity when combined with cell outer membrane component (COMC) fractions in vitro. We demonstrated that Mn(II) oxidation and aggregate formation occurred through an oxygen-dependent biotic transformation process that requires a certain minimum Mn(II) concentration. We propose an approximate electron transfer pathway in which MCO266 transfers only one electron to convert Mn(II) to Mn(III) and then cooperates with other COMC electron transporters to transfer the other electron required to oxidize Mn(III) to Mn(IV).
    Scientific Reports 06/2015; 5:10895. DOI:10.1038/srep10895 · 5.58 Impact Factor
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    ABSTRACT: Despite its presence in limited amounts, birnessite has a wide spread distribution and is often highly enriched in trace metals such as Co in diverse geological environments. This study investigated the effects of Co doping on the layer structure and properties of birnessites synthesized through the oxidation of Mn2 + by O2 under alkaline conditions, by using powder X-ray diffraction (XRD) and X-ray absorption spectroscopy (both XANES and EXAFS). The Co doped, high-pH birnessites are composed of platy crystals, and have lower crystallinity, larger specific surface areas (SSAs) and higher Mn average oxidation states (AOSs) than pure birnessite. Cobalt K-edge EXAFS analysis reveals that no CoOOH is formed, and ~ 76% of the total Co is located in the layers of the Co-doped birnessites. Careful examination of these Co-doped samples by XRD and EXAFS analyses demonstrates that the presence of Co during the synthesis of high-pH birnessite promotes the structural transition of the birnessite layer symmetry from orthogonal to hexagonal. This is due to the decrease in Mn(III) in the layers of the doped solids, leading to the attenuation of Jahn-Teller effect. The decrease in Mn(III) in the layers might be attributed to the substitution of Mn(III) by Co(III) in the layers. The competitive adsorption of Co2 +/3 + with Mn2 + might also decrease the oxidation of Mn2 + to Mn(III) and the subsequent migration of Mn(III) into the birnessite layers. The results provide new insights into the interaction mechanisms between transition metals and birnessite-like minerals, and improve our understanding of the abiotic oxidation of Mn2 + as well as the prevalence of birnessites with hexagonal symmetry in natural environments.
    Chemical Geology 06/2015; 410. DOI:10.1016/j.chemgeo.2015.05.015 · 3.48 Impact Factor
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    ABSTRACT: Cryptomelane is a reactive Mn oxide and has been used in removal of heavy metal from wastewaters. Co-doped cryptomelane was synthesized by refluxing at ambient pressure and characterized by powder X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and extended X-ray absorption fine structure spectroscopy, and its performances for removal of Pb2 + and Cr3 + from aqueous solutions were investigated. Co doping has a negligible effect on the structure and morphology of cryptomelane but increases the specific surface area and Mn average oxidation state. Mn and Co K-edge EXAFS analysis shows that Co barely affects the atomic coordination environments of Mn, and distances of edge- and corner-sharing Co–Me (MeCo, Mn) pairs are shorter than those of the corresponding Mn–Me pairs, implying the replacement of framework Mn(III) by Co(III). These Co-doped cryptomelanes can quickly oxidize Cr3 + to be HCrO4− and remove 45%–66% of the total Cr in the reaction systems by adsorption and fixation, and they have enhanced Pb2 + adsorption capacities. Thus these materials are promising adsorbents for heavy metal remediation. The results demonstrate the design and modification of environmental friendly Mn oxide materials and can help us understand the interaction mechanisms of transition metals with Mn oxides.
    Journal of Environmental Sciences 05/2015; 34. DOI:10.1016/j.jes.2015.02.006 · 1.92 Impact Factor
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    ABSTRACT: Although most reported biogenic Mn oxides are hexagonal birnessites, other types of biogenic Mn oxides also commonly occur in the environment. However, sorption characteristics and underlying mechanisms of the adsorption of heavy-metal ions on these biogenic Mn oxides are still rarely addressed. In this study, the sorption mechanisms of Cu(II) on a low valence biogenic Mn oxide, poorly crystallized bixbyite-like Mn2O3 (α-Mn2O3), were investigated. The maximum adsorption capacity of Cu(II) onto this biogenic Mn oxide at pH 6.00 was 796 mmol/kg (0.45 mol Cu mol(-1) Mn). The complex structure of adsorbed Cu(II) was constrained using Cu extended X-ray absorption fine structure (EXAFS) analysis, combined with structural parameters of the biogenic Mn oxide with alternately arranged regular and distorted MnO6 octahedra obtained through multiple-FEFF fitting of Mn EXAFS data. The sorbed Cu(II) was found to coordinate with the biogenic Mn oxide particle edges as inner-sphere complexes. At a relatively low Cu(2+) loading (233 mmol/kg, pH 6.00), Cu(II) adsorbed onto the biogenic Mn oxide with two types of coordinated complexes, i.e., (1) coordinated with one regular/distorted MnO6 octahedron as a monodentate-mononuclear complex and (2) with two adjacent MnO6 octahedra as a bidentate-binuclear complex. While, at a relatively high Cu(2+) loading (787 mmol/kg, pH 6.00), only one type of coordinated complex was constrained, the adsorbed Cu(II) coordinated with one regular/distorted MnO6 octahedron as a monodentate-mononuclear complex. This research extends further insight into the bacterial Mn(II) oxidation in the environment and serves as a good reference for understanding the interactions between metal ions and biogenic low valence Mn oxides, which are still poorly explored either theoretically or practically.
    Geochemical Transactions 05/2015; 16(1). DOI:10.1186/s12932-015-0020-6 · 2.65 Impact Factor
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    ABSTRACT: Fe-doped cryptomelanes were synthesized by refluxing at ambient pressure, followed by characterization with multiple techniques and test in photocatalytic degradation of phenol. The introduction of Fe(III) into the structure of cryptomelane results in a decrease in particle size and the contents of Mn and K(+), and an increase in the Mn average oxidation state (AOS), specific surface area and UV-vis light absorption ability. Mn and Fe K-edge extended X-ray absorption fine structure spectroscopy analysis indicates that some Fe(III) is incorporated into the framework of cryptomelane by replacing Mn(III) while the remaining Fe(3+) is adsorbed in the tunnel cavity. These Fe-doped cryptomelanes have significantly improved the photocatalytic degradation rate of phenol, with the sample of ∼3.04wt.% Fe doping being the most reactive and achieving a degradation rate of 36% higher than that of the un-doped one. The enhanced reactivity can be ascribed to the increase in the coherent scattering domain size of the crystals, Mn AOS and light absorption, as well as the presence of sufficient K(+) in the tunnel. The results imply that metal doping is an effective way to improve the performance of cryptomelane in pollutants removal and has the potential for modification of Mn oxide materials. Copyright © 2015. Published by Elsevier B.V.
    Journal of hazardous materials 04/2015; 296:221-229. DOI:10.1016/j.jhazmat.2015.04.055 · 4.33 Impact Factor
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    ABSTRACT: Nanostructured birnessite, promising candidate for supercapacitor electrode materials, shows greatly improved discharge capacity and cyclic stability with vanadium doping. The influence of vanadium doping on the physicochemical properties and supercapacitance performance of birnessite-type manganese oxides is investigated. Crystal structures, micromorphologies, bond lengths and chemical compositions of vanadium doped birnessites are characterized by XRD, SEM, XPS, TGA, and titration. The electrochemical properties are analyzed using galvanostatic charge-discharge test, cyclic voltammetry, and electrochemical impedance spectroscopy. The results exhibit that V/Mn molar ratio can reach 0.16:1 when Mn(IV) and K+ are partially substituted by V(V) in birnessite. The thickness of disk-shaped crystal, bond length of Mn-O1 and manganese average oxidation state decreases first and then increases with an increase in V/Mn molar ratio in synthesis system. Charge-transfer resistance decreases after doping vanadium, and increases with an increase in the content of vanadium in birnessite. Diffusion resistance increases first and then decreases due to the change of particle size and pore size distribution. The highest specific capacitance of 245 F g-1 is obtained with excellent cyclic stability for doped birnessite with V/Mn molar ratio of 0.14:1. Our study indicates that vanadium remarkably affects micromorphology, substructure, and electrochemical properties of manganese dioxides.
    Journal of Power Sources 02/2015; 277. DOI:10.1016/j.jpowsour.2014.12.004 · 5.21 Impact Factor
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    ABSTRACT: Vanadium(V)-doped hexagonal turbostratic birnessites were synthesized and characterized by multiple techniques and were used to remove Pb(2+) from aqueous solutions. With increasing V content, the V(V)-doped birnessites have significantly decreased crystallinity, i.e., the thickness of crystals in the c axis decreases from 9.8nm to ∼0.7nm, and the amount of vacancies slightly increases from 0.063 to 0.089. The specific surface areas of these samples increase after doping while the Mn average oxidation sates are almost constant. V has a valence of +5 and tetrahedral symmetry, and exists as oxyanions, including V6O16(2-), and VO4(3-) on birnessite edge sites by forming monodentate corning-sharing complexes. Pb LIII-edge extended X-ray absorption fine structure (EXAFS) spectra analysis shows that, at low V contents (V/Mn≤0.07) Pb(2+) mainly binds with birnessite on octahedral vacancy and especially edge sites whereas at higher V contents (V/Mn>0.07) more Pb(2+) associates with V oxyanions and form vanadinite [Pb5(VO4)3Cl]-like precipitates. With increasing V(V) content, the Pb(2+) binding affinity on the V-doped birnessites significantly increases, ascribing to both the formation of the vanadinite precipitates and decreased particle sizes of birnessite. These results are useful to design environmentally benign materials for treatment of metal-polluted water. Copyright © 2015 Elsevier B.V. All rights reserved.
    Journal of Hazardous Materials 02/2015; 288C. DOI:10.1016/j.jhazmat.2015.01.068 · 4.33 Impact Factor
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    ABSTRACT: Novel Ag3PO4 photocatalyst possesses high visible-light photocatalytic activity, but the large crystallite size and the photocorrosion severely limit its practical application. It is highly desirable to develop new Ag3PO4 photocatalytic systems with nanosized structure and good photocatalytic stability. In this work, we prepare new graphene-modified nanosized Ag3PO4 photocatalyst by in situ growth strategy in an organic solvent. The as-prepared nanosized Ag3PO4 particles–graphene composite exhibits enhanced visible-light photocatalytic activity and stability toward the degradation of methylene blue (MB) in aqueous solution compared with bare nanosized Ag3PO4 particles and conventional large-sized Ag3PO4 particles–graphene composite. This enhanced photocatalytic activity and stability arise from the positive synergetic effects of the nanosized Ag3PO4 particles and graphene sheets including an increase in the number of active adsorption sites, suppression of charge recombination, reducing the formation of Ag nanoparticles. This work shows a great potential of nanosized Ag3PO4 particles–graphene composite for environmental purification of organic pollutants.
    Applied Catalysis B Environmental 01/2015; 162:196–203. DOI:10.1016/j.apcatb.2014.06.051 · 6.01 Impact Factor
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    ABSTRACT: To obtain delta-MnO2 particles with a large specific surface area, MnO2 was synthesized in an ice-water bath using ascorbic acid (AA) to reduce KMnO4. At pH 3 and 5 and KMnO4/AA molar ratios of 8/1 and 10/1, nanoparticles of delta-MnO2 were produced. The specific surface areas (SSAs) of the samples ranged from 163 to 207 m(2)/g. The Mn average oxidation state of the samples ranged from 3.88 to 3.98 and increased with the KMnO4/AA ratio and pH. The adsorption of the samples with respect to metal ion revealed pseudo adsorption capacities of 3425 mmol Pb2+/kg and 1789 mmol Zn2+/kg. The decolorization behaviors of sample S10-5 (produced at pH 5 and KMnO4/AA molar ratios of 10/1) to methylene blue (MB) were compared at different pH values and temperatures. After 120 min at room temperature, 97% of the MB was adsorbed, and approximately 68% was oxidized. The adsorbed amount and the level of oxidation increased with increasing temperature and decreased with increasing pH.
    Materials Chemistry and Physics 12/2014; 148(3):1149-1156. DOI:10.1016/j.matchemphys.2014.09.037 · 2.13 Impact Factor
  • Annals of Microbiology 12/2014; 64(4):1-4. DOI:10.1007/s13213-014-0825-z · 1.04 Impact Factor
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    ABSTRACT: Although most reported biogenic Mn oxides are hexagonal birnessites, other types of biogenic Mn oxides also commonly occur in the environment. Compared to hexagonal birnessites, the sorption characteristics and the underlying mechanism of adsorption of heavy-metal ions to those of the other biogenic Mn oxides are still rarely addressed. A strain of Mn-oxidizing bacteria isolated from Claypani-Udic Argosols was identified as Bacillus with 16S rRNA sequencing analysis. The bacterial Mn(II) oxidation product is a poorly crystallized bixbyite-like Mn2O3 (α-Mn2O3). The maximum adsorption capacities of Zn(II) onto the biogenic Mn oxide at pH 6.00 and pH 4.00 were 663 mmol/kg and 629 mmol/kg, respectively. The complex structure of adsorbed Zn2 + was constrained using Zn EXAFS analysis, combined with structural parameters of the biogenic Mn oxide with alternately arranged regular and distorted MnO6 octahedra obtained through multiple-FEFF fitting of Mn EXAFS data. At a relatively low Zn2 + loading (100 mmol/kg, pH 6.00), Zn2 + adsorbed onto the biogenic Mn oxide with two types of tetrahedrally coordinated complexes, i.e. (1) coordinated with one regular/distorted MnO6 octahedron as a monodentate–mononuclear complex and (2) with two MnO6 octahedra (two regular, two distorted or a regular and a distorted) as a bidentate–binuclear complex. While, at a relatively high Zn2 + loading (556 mmol/kg, pH 4.00; 635 mmol/kg, pH 6.00), two types of octahedrally coordinated complexes are constrained, i.e. (1) coordinated with one regular/distorted MnO6 octahedron as a monodentate–mononuclear complex and (2) with one regular MnO6 octahedron as a bidentate mononuclear complex. This research extends further understanding on the formation of biogenic Mn oxides in the environment and the adsorption mechanism of heavy metals onto low-valence Mn oxides with distorted structures. The application of low valence biogenic Mn oxides to efficiently remove heavy metals from water is also shown to be promising.
    Chemical Geology 12/2014; 389:82–90. DOI:10.1016/j.chemgeo.2014.09.017 · 3.48 Impact Factor
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    ABSTRACT: Cryptomelane exhibits excellent photocatalytic activity for the degradation of organic pollutants. Incorporation of transition metals (TMs) into the structure of Mn oxides will cause changes to their substructure and physicochemical properties. However, the synergetic effects of incorporation of two kinds of metals have yet to be investigated. Here, cobalt and nickel co-doped cryptomelanes were synthesized with different molar ratios of Co/Ni, and characterized by powder X-ray diffraction, elemental analysis, N-2 physical adsorption and UV-Visible diffuse reflectance spectroscopy, and their photocatalytic performance for the degradation of phenol was investigated. These studies demonstrate that, doping of Co and Ni did not change the crystal structure of cryptomelane, but resulted in decreased crystallinity, and generally increased the specific surface area. Co(III) and Ni(II) were incorporated into cryptomelane and substituted for Mn(IV) and Mn(III), respectively, leading to a change in Mn average oxidation state. Compared with non-doped and singly doped samples, Co and Ni co-doped cryptomelanes have large increase in optical absorption properties and increase the rate of phenol degradation, i.e. the TOC removal rate was increased by 28-38%. Co and Ni co-doped cryptomelane has potential applications in the remediation of natural waters contaminated by organic pollutants.
    Materials Chemistry and Physics 12/2014; 148(3):783-789. DOI:10.1016/j.matchemphys.2014.08.049 · 2.13 Impact Factor
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    ABSTRACT: Cadmium sulfide and oxide hexagonal nanoplates were prepared by a facile ion-exchange strategy and crystal transformation process by using morphology-analogous cadmium oxyhydroxide as a precursor. The precursors of uniform Cd(OH)2 hexagonal nanoplates was first synthesized by a simple ethylenediaminetetraacetic acid disodium salt assisted hydrothermal method. Then, through ion-exchange reactions of the as-prepared Cd(OH)2 precursors with S2− anions, cubic-phase CdS was formed immediately on the surface of Cd(OH)2 nanoplates. The above intermediates could be further completely converted into CdS and CdO nanoplates without morphology changes through thermal treatment at 280 °C for 4 h under a sulfur atmosphere and under air, respectively. The photocatalytic activity of all samples was evaluated by the photocatalytic decolorization of an aqueous solution of methylene blue and photocatalytic hydrogen production under visible-light irradiation. The results show that the CdS hexagonal nanoplates exhibit high visible-light photocatalytic degradation properties and photocatalytic hydrogen production activity. The enhanced visible-light photocatalytic activity can be related to several factors, including a suitable band gap, phase structure, and morphology of the hexagonal nanoplates.
    ChemPlusChem 09/2014; DOI:10.1002/cplu.201402220 · 3.24 Impact Factor
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    ABSTRACT: Natural hexagonal birnessites are enriched in various transition metals (TMs). Many studies have examined the effects of single metal doping on the structures and properties of birnessites, but none focused on the simultaneous interaction mechanism of coprecipitation of two different TMs with birnessite. In this work Co and Ni co-doped hexagonal birnessites were synthesized and characterized by powder X-ray diffraction (XRD), elemental analysis, field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) spectroscopy to investigate the effects of co-doping on the structure and reactivity of birnessite and the crystal chemistry of Co and Ni. These co-doped birnessites have lower crystallinity, i.e., fewer manganese layers stacking in the c* direction, larger specific surface areas (SSAs) and increased Mn average oxidation states (AOSs) than the undoped birnessite, and Co exists in a valence of + 3. Co, Ni and Mn K-edge extended X-ray absorption fine structure spectroscopy (EXAFS) spectra demonstrate an increase in edge-sharing Ni-Me (Me = Ni, Co and Mn) distances in birnessite layers with the increase of the contents of dopants while Mn-Me distances first decrease and then increase while those of Co-Me pairs are nearly constant, coupled with first a decrease and then increase of the in-plane unit-cell parameter b. The effect of co-doping on the amounts of structural Mn and K+, numbers of [MnO6] layers stacked in c* axis, and SSAs, are larger than the effects of doping with Co alone, but less than singly Ni doping. In birnessites doped with both Co and Ni, ~ 74-79% of the total Co and ~ 23-39% of the total Ni are present within the manganese layers. Compared with the spatial distribution of TM in singly doped birnessites, the coexistence of Ni hinders incorporation of Co into the layers during birnessite crystallization; however, coprecipitation with Co has little effects, neither hindrance nor promotion, on the insertion of Ni into the layers. These results provide insight into the interaction mechanism between coexisting Co, Ni within layered Mn oxides. It further helps us to interpret the geochemical characteristics of multi metals incorporation into natural Mn oxides and their effects on the structures and physicochemical properties of these minerals.
    Chemical Geology 08/2014; 381. DOI:10.1016/j.chemgeo.2014.05.017 · 3.48 Impact Factor
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    ABSTRACT: The bacterial abundance and community composition in four types of soils and their associated Fe-Mn nodules from Queyu (QY) in Shandong Province, Zaoyang (ZY), Wuhan (WH) in Hubei Province and Guiyang (GY) in Hunan Province, China were investigated using real-time PCR, cloning and sequencing approaches. It was found that the bacterial 16S rRNA gene copy numbers in the soils were almost 3 magnitudes greater than those in their corresponding nodules and positively correlated with OM. The bacterial diversity as indicated by Simpson and Shannon indices, were significantly lower in the nodules than in the soils. Remarkable divergence in bacterial community structure was observed between the soils and the nodules, and the difference was the mainly explained by OM. In contrast, the differences within the soils and within the nodules were minor, suggesting significant habitat filtering for the bacterial community composition in the nodules. Acidobacteria was the most abundant group (accounting for 28.6%–51.6%) in soil bacterial community while nodule bacterial community was predominated by Proteobacteria (accounting for 62.8%– 90.5%). A number of clones closely related to well-known Mn-oxidizing, Fe-oxidizing and Fe-reducing bacteria within Proteobacteria were retrieved mainly from nodules.
    Geomicrobiology 08/2014; 31(7). DOI:10.1080/01490451.2013.854428 · 1.80 Impact Factor
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    ABSTRACT: LiMn2O4 cathode materials with high discharge capacity and good cyclic stability were prepared by a simple one-step hydrothermal treatment of KMnO4, aniline and LiOH solutions at 120-180 °C for 24 h. The aniline/KMnO4 molar ratio (R) and hydrothermal temperature exhibited an obvious influence on the component and phase structures of the resulting product. The precursor KMnO4 was firstly reduced to birnessite when R was less than 0.2:1 at 120-150 °C. Pure-phased LiMn2O4 was formed when R was 0.2:1, and the LiMn2O4 was further reduced to Mn3O4 when R was kept in the range of 0.2-0.3 at 120-150 °C. Moreover, LiMn2O4 was fabricated when R was 0.15:1 at 180 °C. Octahedron-like LiMn2O4 about 300 nm was prepared at 120 °C, and particle size decreased with an increase in hydrothermal temperature. Especially, LiMn2O4 synthesized at 150 °C exhibited the best electrochemical performance with the highest initial discharge capacity of 127.4 mAh g-1 and cycling capacity of 106.1 mAh g-1 after 100 cycles. The high discharge capacity and cycling stability of the as-prepared LiMn2O4 cathode for rechargeable lithium batteries were ascribed to the appropriate particle size and larger cell volume.
    ChemInform 07/2014; 31. DOI:10.1016/j.solidstatesciences.2014.02.015