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An electrode with multi electron surfaces facilitates more redox sites during charge storage reaction in the case of transition metal oxides used in supercapacitor application. Molybdenum (Mo) oxide and manganese (Mn) oxide have high theoretical capacitance; this study focused on depositing Mo–Mn together in a single mixed metal oxide. Here, Mo–Mn hydroxide was deposited on Ni-foam by a single-step hydrothermal method. The X-ray photoelectron spectroscopy confirms the presence of Mo and Mn in 4+ and 3+ oxidation states, respectively. The different size of Mo–Mn hydroxide microstructures was observed with varying deposition time. The porous cubes-like microstructure exhibited high areal capacitance of 88.6 mF cm−2 with energy density of 3.08 μWh·cm−2 at 125 μW cm−2 power density within a kinetic potential. This microcubes-like structures and activated carbon were used as positive and negative electrodes, respectively, to fabricate an asymmetric supercapacitor (ASS) device. The ASS device showed capacitance retention of 87% (∼5,000 cycles) and excellent Coulombic efficiency (96%) with energy density of 5.6 μWh·cm−2 at 1.12 mW cm−2 power density at 1.8 V potential. [ABSTRACT FROM AUTHOR]

A flower-like nickel-cobalt-manganese hydroxide (NiCoMn-OH) modified with two-dimensional Ti3C2 nanoflakes has been synthesized via simple one-step hydrothermal method. The NiCoMn-OH/Ti3C2 composite exhibits a high specific capacity of 670.3 C/g at a specific current of 1 A/g, higher than 614.6 C/g for NiCoMn-OHand 8.9 C/g for Ti3C2 at the same conditions. The improved electrochemical performance is due to that Ti3C2 is absorbed and distributed on the surface of NiCoMn-OHin its situ synthesis process and enhances its electro-activity. The hybrid supercapacitor based on NiCoMn-OH/Ti3C2 and RGO shows high specific capacity of 177.5 C/g at 0.5 A/g and 103.1 C/g at 10 A/g, retaining 93.28% of initial capacity after 5000 charge/discharge cycles at 7 A/g. The hybrid supercapacitor also displays extraordinary specific energy of 41.15 Wh/kg at a specific power of 375 W/kg and 21.46 Wh/kg even at 7.5 kW/kg. [ABSTRACT FROM AUTHOR]

We propose a simple and effective one-step hydrothermal strategy to prepare various nickel manganese layered double hydroxides (NiMn-LDHs) by changing the concentrations of NiCl2·6H2O and MnCl2·4H2O under a fixed molar ratio of Ni to Mn of 3:1. The SEM and TEM results indicate that the obtained NiMn-LDHs are composed of thin-layer nanosheets with well-improved dispersity. Furthermore, the NiMn-LDHs displayed by the XPS analysis contain multivalent Ni and Mn ions, in which the relative contents of Ni2+ and Mn3+ are increasing with the decrease of reactant concentration. When the concentration reduce to 0.0125 mol L−1, the optimal Ni1Mn1-LDH exhibits both the thin-layer nanosheets structure with average thickness of about 15 nm and the highest contents of Ni2+ and Mn3+. Applied as an electrode material for supercapacitors, the Ni1Mn1-LDH can deliver an excellent electrochemical performance with a maximum specific capacity of 624 C g−1 at a current density of 0.5 A g−1 and above 80% capacitance retention over 1000 cycles. The electrochemical performance of Ni1Mn1-LDH is further investigated by assembling two-electrode asymmetric supercapacitor with carbon spheres. The specific capacity is 106 C g−1 at 0.5 A g−1 and the capacitance retention is 75% over 1000 cycles. This work offers a facile way to tune simultaneously the nanostructure and multivalence of the NiMn-LDHs, and also provides a confirmation about the important affection of them on the enhanced capacitive performance for supercapacitor electrode.

Cobalt manganese hydroxides with well-defined nanowire morphology (CoMn-HW) is scalable fabricated by adjusting solution contents, Mn/Co ratio and alkaline species. To further improve the conductivity of CoMn-HW, GO is introduced during fabrication process and reduced to rGO according to the high temperature and alkali atmosphere. By optimizing the adding mass of rGO, CoMn-HW/rGO with sandwiched like structure is successfully synthesized for supercapacitor electrode. The composite delivers a high specific capacitance of 784 F g−1 at current density of 0.5 A g−1, good rate capability (84.2% capacitance retention after current density increase 10 times). Moreover, an asymmetric supercapacitor with CoMn-HW/rGO10 as the positive electrode and active carbon as the negative electrode, is assembled and delivers a maximum energy density of 38.3 Wh kg−1 and power density of 8000 W kg−1, representing its potential in energy storage and conversion systems. • Co, Mn-hydroxides with nanowire morphology is scalable fabricated. • CoMn-HW/rGO with sandwiched like structure is synthesized under optimal synthesis condition. • An asymmetric supercapacitor based on CoMn-HW/rGO and AC is assembled with high energy and power densities. [ABSTRACT FROM AUTHOR]

The Curiosity and Opportunity rovers have found depositions of manganese (Mn) (hydr)oxides within the veins of the sedimentary rocks at Gale and Endeavour craters. Since Mn is a redox sensitive element, revealing the chemical form of the Mn (hydr)oxide provides unique information on the redox state of the near‐surface/groundwater at the time of deposition. Here we report results of laboratory experiments that investigated scavenging patterns of trace metals (zinc, nickel, and chromium) on different Mn (hydr)oxides in order to constrain the chemical form of the Mn precipitates found on Mars. Our results show manganese dioxide (MnO2) scavenges zinc and nickel effectively but not for chromium. The agreement of this scavenging pattern with the observations strongly suggests that the Mn (hydr)oxides found on Mars are highly likely to be MnO2. To form MnO2, oxidizing aqueous environments are required (e.g., Eh > 0.5 V at pH ~ 8). The candidates of the oxidant include molecular oxygen, ozone, nitrates, and perchlorate acids; all of which are considered to be produced by photochemical processes. The presence of MnO2 veins in sediments suggests that such atmospheric high‐Eh oxidants may have been supplied to the subsurface, possibly through hydrological cycles activated by transient warming. Plain Language Summary: Early Mars is believed to have possessed an abundance of liquid water on its surface. The Mars rover Curiosity has found both complex organic matter and bio‐essential elements within the lake deposits at Gale crater. To further understand habitability on early Mars, knowledge of the redox states of the aqueous environments is essential because redox disequilibria in environments provide chemical energy to chemoautotrophic life. A key to constraining the redox states is the enrichment of "redox sensitive elements" within sediments. Manganese (Mn) is a redox‐sensitive element, changing its chemical form depending on the redox states. Curiosity and Mars Exploration Rover Opportunity have found Mn enrichments within the veins of ancient sediments on Mars; however, their chemical forms are poorly constrained. Here we constrain the chemical form of the Mn enrichments based on precipitation experiments. Our results suggest that the Mn enrichments on Mars were caused by deposition of MnO2, which requires highly oxidizing conditions in the aqueous environment at the time of deposition. The candidates of the oxidant include molecular oxygen, ozone, perchlorates, and nitrates. We suggest that these oxidants formed in the atmosphere and may have been supplied into reducing groundwater via hydrological cycles on early Mars. Key Points: Scavenging pattern of trace metals on Mn (hydr)oxides is investigated by precipitation experimentsThe scavenging pattern for MnO2 is consistent with the measurements of trace metals within Mn‐rich veins found on MarsTo form MnO2, high‐Eh oxidants formed in the atmosphere need to be supplied to groundwater on early Mars [ABSTRACT FROM AUTHOR]

The aerobic oxidative coupling of aniline is an effective process for producing aromatic azo compounds, which are widely used in the organic chemical industry. The development of heterogeneous catalysts for this reaction would be advantageous because of their recyclability and convenience in posttreatment. In this work, one-dimensional Mn(OH)2 nanostructure with various shapes were synthesized through the adjustment of various surfactants. The as-synthesized Mn(OH)2 nanobelts and nanowires showed superior catalytic activity in the activation of oxygen and aniline. Aromatic azo compounds with a variety of substituents were produced through the coupling of the corresponding anilines without additives under ambient conditions. [ABSTRACT FROM AUTHOR]

A new modification of Mn(OH)Cl was obtained under high‐pressure/high‐temperature conditions in a Walker‐type multianvil device. The pale pink, hygroscopic compound crystallizes in the orthorhombic space group Pnma (no. 62) with a = 602.90(4), b = 350.98(2), c = 1077.69(7) pm, and V = 228 × 106 pm3. The layered centrosymmetric structure consists of edge‐sharing Mn(OH)3Cl3 octahedra arranged in sheets parallel to the (001) plane. The comparatively long H···Cl distance of 275 pm suggests only weak hydrogen bonds between neighboring layers. Spin‐polarized scalar‐relativistic DFT+U calculations predict a non‐conducting magnetically ordered ground state with a band gap of at least 3.2 eV and an effective magnetic moment of 4.65 µB/f. u. The experimentally determined magnetic response of Mn(OH)Cl is paramagnetic in the range of 10–300 K. The estimated moment of 5.6 µB/f. u. indicates the high‐spin d5 configuration of manganese(II). We find hints for a long‐range magnetic ordering below 10 K. The compound γ‐Mn(OH)Cl was synthesized under high‐pressure/high‐temperature conditions. Single‐crystal X‐ray diffraction reveals a layered structure composed of edge‐sharing fac‐Mn(OH)3Cl3 octahedra arranged in sheets. Characterization by magnetization experiments were complemented by spin‐polarized scalar‐relativistic DFT+U calculations. [ABSTRACT FROM AUTHOR]

Relative stability between manganese hydroxide (H 2 O) 2 (OH) 4 Mn(IV) OH ( 1 ) and manganese oxo (H 2 O) 3 (OH) 3 Mn(IV) O ( 2 ) species were investigated by coupled cluster (CC) SD and SD(T), DMRG CASCI, CASSCF, CASPT2 and CASDFT methods. The DMRG CASCI and DMRG CASSCF based on thirteen active orbitals and thirteen active electrons {13, 13} CAS space indicted the greater stability of 2 than 1 . On the other hand, the relative stability between 1 and 2 was reversed by UCC SD, DLPNO-UCC SD, CASPT2 and CAS-DFT, indicating an important role of dynamical electron correlation corrections. Implications of present results are discussed to elucidate scope and applicability of hybrid DFT (HDFT) methods for 1 and 2 . [ABSTRACT FROM AUTHOR]

The development of new non-precious metal catalysts and understanding the origin of their activity for the hydrogen evolution reaction (HER) are essential for rationally designing highly active low-cost catalysts as alternatives to state-of-the-art precious metal catalysts. Herein, manganese oxide/hydroxide was demonstrated as a highly active electrocatalysts for the HER by fabricating MnO2 nanosheets coated with Cu2O nanowire arrays (Cu2O@MnO2 NW@NS) on Cu foam followed by an in situ chronopotentiometry (CP) treatment. It was discovered that the in situ transformation of Cu2O@MnO2 into Cu@Mn(OH)2 NW@NS by the CP treatment drastically boosted the catalytic activity for the HER due to an enhancement of its intrinsic activity. Together with the benefits from such three-dimensional (3D) core-shell arrays for exposing more accessible active sites and efficient mass and electron transfers, the resulting Cu@Mn(OH)2 NW@NS exhibited excellent HER activity and outstanding durability in terms of a low overpotential of 132 mV vs. RHE at 10 mA/cm2. Overall, we expect these findings to generate new opportunities for the exploration of other Mn-based nanomaterials as efficient electrocatalysts and enable further understanding of their catalytic processes. [ABSTRACT FROM AUTHOR]

In a boreal stream network, stream water concentrations of As, Co and Pb (filtered, <0.4 μm) of 10 nested streams were studied during two consecutive years in order to evaluate the influence of land cover on the temporal and spatial variability of metal concentrations and speciation. Mean concentrations of Co and Pb showed significant but contrasting relationship to landscape type, while As concentrations were not related to landscape type. Highest concentrations of Pb were found in the wetland dominated streams (>30% wetland), which was suggested to be controlled by atmospheric deposition in combination with high DOC release from the wetlands. For Co, the highest concentrations were found in the forest dominated sites (>98% forest), which were attributed to the weathering of minerogenic sources. Contrasting response to runoff events could also be related to landscape type; during the spring flood, decreasing concentrations of As, Co and Pb were observed in the wetland dominated catchments due to dilution, while increasing concentrations during spring flood were observed in the mixed catchments (2–30% wetland) and to some degree in the forested catchments, probably due to flushing of the organic-rich riparian sources. Further, metal speciation was calculated using the geochemical equilibrium model Visual MINTEQ. This suggests that dissolved inorganic species of As and Co dominated in headwater streams with low pH while DOC had a major influencing role for Pb. In the larger mixed streams where pH was higher and precipitation of e.g. colloidal Fe and Mn (hydr)oxides was favoured, the major influencing factor was instead adsorption to colloidal Fe for As and Pb, while association to organic matter and colloids of e.g. Mn influenced the concentrations of Co. We thus conclude that landscape type and the magnitude of the runoff events are of great importance for the spatial and temporal variations of As, Co and Pb in this boreal stream network. Projected climate change, with increasing runoff, may therefore influence riverine concentrations and fluxes differently, depending on the prevailing landscape type. [ABSTRACT FROM AUTHOR]

Oxidation of Mn(II) is an important process that controls the mobility and bioavailability of Mn, as well as the formation of Mn (oxyhydr)oxides in natural systems. It was found that the surfaces of minerals, such as iron (oxyhydr)oxides, can accelerate Mn(II) oxidation to a certain degree, but the underlying mechanism has not been clearly understood. This study explores the reaction pathways and mechanisms of Mn(II) oxidation on ferrihydrite surfaces at neutral pH, commonly found in natural environments, by comparisons with montmorillonite, amorphous Al(OH) 3 , goethite, and magnetite using macroscopic experiments and spectroscopic analyses. Results show that when Mn(II) concentrations are below 4 mM, macroscopic Mn(II) adsorption on the three iron (oxyhydr)oxide surfaces conforms well to the Langmuir equation, with ferrihydrite showing the highest adsorption capacity. With Mn(II) concentrations ranging within 6–24 mM, the adsorbed Mn(II) is mainly oxidized into manganite (γ-MnOOH) and/or feitknechtite (β-MnOOH) by dissolved O 2 , and Mn(II) removal on a unit mass basis in the presence of magnetite is the highest compared with ferrihydrite and goethite. Ferrihydrite, a semiconductor material, shows stronger catalytic ability for Mn(II) oxidation on the same surface area than insulator minerals ( i.e. , montmorillonite and amorphous Al(OH) 3 ). Additionally, the products of Mn(II) oxidation in the presence of semiconductor iron (oxyhydr)oxides ( i.e. , ferrihydrite, goethite, or magnetite) at the same Fe/Mn molar ratio include both manganite and a small amount of Mn(IV) minerals, and the Mn average oxidation states (Mn AOSs) of these products follow the order: magnetite > goethite > ferrihydrite. Magnetite and goethite, with relatively smaller SSAs and lower band gap energies, exhibit greater catalysis for Mn(II) oxidation than ferrihydrite at the same Fe/Mn ratio, which goes against the conventional interfacial effect and is related to the electrochemical properties. Thus, the Mn(II) catalytic oxidation by O 2 on ferrihydrite surfaces should include an electrochemical pathway, i.e. , electron transfer (ET) in the Mn(II)-Conduction Band (CB) Ferrihydrite -O 2 complexes, in addition to the conventional two interfacial catalytic pathways, i.e. , ET in the Mn(II)-Fe(II, III)-O 2 complexes and direct ET in the Mn(II)-O 2 complexes. These results reveal new implications for understanding the processes and mechanisms of Mn(II) oxidation on iron (oxyhydr)oxide surfaces and the abiotic formation of Mn (oxyhydr)oxides in surface environments. [ABSTRACT FROM AUTHOR]

In this study, nano-sized particles of manganese oxyhydroxide (MnO(OH)) are synthesized. Sorption properties of this material towards 90Sr and 137Cs radionuclides in the pH range from 2 to 9 at a temperature of 293.15 K solution are studied. The time of sorption achievement equilibrium in the radionuclide sorbent system depends on the nature of sorbed cation, but does not exceed 60 min. [ABSTRACT FROM AUTHOR]

Catalysts prepared by the modification of FIBAN K-4 and FIBAN X-1 fibrous ion exchangers with the hydroxides of iron and manganese were developed and tested in a water deoxygenation process. It was established that the samples obtained by the supporting of Fe(III) hydroxide onto the FIBAN X-1 ampholyte were most effective. The conclusion that the high activity of the catalytic system is caused by the formation of a mixed phase of Fe(II) and Fe(III) hydroxides of the spinel type containing mobile (weakly bound) lattice oxygen was made. A reaction scheme was proposed to explain the reaction mechanism. [ABSTRACT FROM AUTHOR]

MnOOH nanorods, which were prepared using a hydrothermal method, have been used for the first time as anode materials for sodium ion batteries. The as-prepared MnOOH nanorods with lengths of 1.2–3.7 μm and diameters of 60–90 nm delivered high performance of reversible electrochemical Na/Na+ storage such as an initial discharge capacity of 485.5 mA h g−1 at 80 mA g−1, a high initial Coulombic efficiency of 86.7% and a low average potential polarization of 0.36 V. Instrumental analyses with ex situ XRD, TEM and XPS show that the sodium storage mechanism in MnOOH can be related to the reversible formation of MnO and NaOH. This work demonstrates that cheap MnOOH nanorods are potential anode materials for SIBs. [ABSTRACT FROM AUTHOR]

In this study a total of 30 street dusts and 10 surface soils were collected in the central district of Tehran and analyzed for major potentially toxic metals. Street dust was found to be greatly enriched in Sb, Pb, Cu and Zn and moderately enriched in Cr, Mn, Mo and Ni. Contamination of Cu, Sb, Pb and Zn was clearly related to anthropogenic sources such as brake wear, tire dust, road abrasion and fossil fuel combustion. Spatial distribution of pollution load index in street dust suggested that industries located south-west of the city intensify street dust pollution. Microscopic studies revealed six dominant group of morphological structures in calculation of the exposurethe street dusts and surface soils, with respect to different geogenic and anthropogenic sources. The BCR (the European Community Bureau of Reference) sequential extraction results showed that Sb, Ni, Mo, As and Cr bonded to silicates and sulfide minerals were highly resistant to dissolution. In contrast, Zn, Cd, and Mn were mostly associated with the exchangeable phase and thus would be easily mobilized in the environment. Cu was the most abundant metal in the reducible fraction, indicating its adsorption to iron and manganese oxy-hydroxides. Pb was equally extracted from exchangeable and reducible fractions. Anthropogenic sources related to traffic apparently play a small role in Cr, Ni and Mo contamination and dispersed them as bioavailable forms but with reduced mobility and bioavailablity due to high potential of complexation and adsorption to organic matter and iron and manganese oxy-hydroxides. Calculated Hazard Index (HI) suggests ingestion as the most important pathway for the majority of PTMs in children and dermal contact as the main exposure route for Cr, Cd and Sb for adults. The HIs and fractionation pattern of elements revealed Pb as the sole element that bears potential health risk in street dust and surface soil. [ABSTRACT FROM AUTHOR]

We present experimental results on the sorption behavior of rare earth elements and yttrium (REY) on precipitating manganese (hydr)oxide in the presence of the biogenic siderophore desferrioxamine B (DFOB). In marked contrast to inorganic systems, where preferential adsorption of HREY and depletion of LREY is commonly observed in manganese (hydr)oxide precipitates, sorption of REY in presence of the DFOB siderophore leads to HREY-depleted and LREY-enriched patterns in the precipitates. Moreover, our data indicate that surface oxidation of Ce(III) to Ce(IV) during sorption onto manganese (hydr)oxides and the resulting development of a positive Ce anomaly, which are commonly observed in inorganic experiments, are prevented in the presence of DFOB. Instead, Ce(III) is oxidized to Ce(IV) but associated with the dissolved desferrioxamine B which forms complexes with Ce(IV), that are at least twenty orders of magnitude more stable than those with Ce(III) and REY(III). The overall result is the formation of a positive Ce anomaly in the solution and a negative Ce anomaly in the Mn (hydr)oxides. The distribution of the strictly trivalent REY and Eu(III) between the manganese (hydr)oxide phase and the remaining ambient solution mimics the distribution of published stability constants for complexes of REY(III) with DFOB, i.e. the heavy REY form more stable complexes with the ligand and hence are better shielded from sorption than the LREY. Surface complexation modeling corroborates our experimental results. Negative Ce anomalies in Mn precipitates have been described from biogenic Mn oxides. Our results provide experimental evidence for the development of negative Ce anomalies in abiogenic Mn (hydr)oxide precipitates and show that the presence of the widespread siderophore desferrioxamine B during mineral precipitation results in HREY-depleted Mn (hydr)oxides with negative Ce anomalies. [ABSTRACT FROM AUTHOR]

In sediments, manganese (Mn) is typically enriched in the form of authigenic Mn hydroxides at the water-sediment interface where intensive redox cycling of Mn occurs. Here we show, based on existing hydrochemical and geochemical (sediment core) data and new detailed chemical and mineralogical characterization of a 3.5 m long sediment core from a Boreal estuary, that the behavior of Mn can be profoundly different and more complex in estuarine settings receiving an abundance of terrestrial Mn. The most notable feature in the 3.5 m long sediment core is two depth intervals (60–155 cm and 181–230 cm) where there are strong fine-scale variations in Mn concentrations with peaks episodically reaching up to 10–25 g kg − 1 and 6.7–12 g kg − 1 , respectively. X-ray absorption spectroscopy and sequential chemical extraction show that Mn occurs mainly as authigenic rhodochrosite at these two depth intervals and is mainly surface-sorbed in other sections with relatively low and stable Mn concentrations. The data suggests that the strong fine-scale variations in Mn concentrations are a reflection of the extent of formation and settling of Mn hydroxides, the precursors of the authigenic rhodochrosite (and also of the surface-sorbed Mn), rather than Mn input to the estuary or redox-related Mn translocation within the sediment. There was agreement between the results of linear combination fitting of extended X-ray absorption fine structure data and a 7-step sequential chemical extraction (SCE) in terms of quantification of surface-sorbed Mn species, whereas the SCE experiment failed to fractionate a majority of rhodochrosite into SCE step-2 (1 M NH 4 -acetate at pH 6), which is frequently employed to dissolve carbonate. We ascribe this discrepancy to only partial dissolution of rhodochrosite in the weakly acidic (pH = 6) NH 4 -acetate leach. [ABSTRACT FROM AUTHOR]

The early nucleation stage of Mn (hydr)oxide on mineral surfaces is crucial to understand its occurrence and the cycling of nutrients in environmental systems. However, there are only limited studies on the heterogeneous nucleation of Mn(OH)2(s) as the initial stage of Mn (hydr)oxide precipitation. Here, we investigated the effect of pH on the initial nucleation of Mn(OH)2(s) on quartz. Under various pH conditions of 9.8, 9.9, and 10.1, we analyzed the structural matches between quartz and heterogeneously nucleated Mn(OH)2(s). The structural matches were calculated by measuring the lateral and vertical dimensions using grazing incidence small angle X-ray scattering and atomic force microscopy (AFM), respectively. We found that a poorer structural match occurred at a higher pH than at a lower pH. The faster nucleation under a higher pH condition accounted for the poorer structural match observed. By fitting the structural match using classical nucleation theory, we also calculated the interfacial energy between Mn(OH)2(s) and water: γnf = 71 ± 7 mJ/m². The calculated m values and γnf provided the variance of interfacial energy between quartz and Mn(OH)2(s): γsn = 262-272 mJ/m². This study provides new qualitative and quantitative information on heterogeneous nucleation on an environmentally abundant mineral surface, quartz, and it offers important underpinnings for understanding the fate and transport of trace ions in environmental systems. [ABSTRACT FROM AUTHOR]

In this paper, a detailed study of the influence of Mn2+ ions on quartz and hematite flotation (at pH 10.5 with starch/amine as depressor/collector) in the absence and presence of ethylenediaminetetraacetic acid (EDTA) is presented. By using zeta potential measurement and a careful analysis of manganese species present in water for dosages in which manganese hydroxide precipitated, we confirmed that the depression of both minerals by Mn2+ ions is due to the following: (i) the adsorption of Mn hydroxy complexes (Mn2(OH)3+ and Mn(OH)+); (ii) Mn2+ and mainly (iii) the precipitation of Mn(OH)2 on mineral surfaces. These effects hindered the adsorption of amine species on the surfaces of the minerals (quartz and hematite). EDTA was used to complex Mn2+ to restore the recoveries of both minerals. This was confirmed by the species distribution diagrams of Mn and EDTA-Mn in water. Conditioning with starch followed by amine at pH 10.5 enabled a selective separation of these minerals. [ABSTRACT FROM AUTHOR]

Presented here is the solvothermal preparation of two luminescent coordination polymers (L-CPs) based on the same mixed ligands, namely [Cd2(1,4-NDC)2(dppe)] ( 1) and [Mn3(OH)2(1,4-NDC)2(dppe)(H2O)] ( 2) (1,4-NDCH2=1,4-naphthalene dicarboxylic acid, dppe=1,3-di(4-pyridyl)propane). Both the title compounds feature a neutral three-dimensional (3D) network. Photoluminescence (PL) studies indicated that the compound 1 based on d10 Cd2+ exhibited dual emissions with tunable intensities that could result in direct white-light emission based on the intraligand charge transfer (LLCT); while the compound 2 showed a single band of yellow emission based on the charge transfer between the ligands and the metal ion (LMCT), due to the partially filled d-orbital of Mn2+ ion. The temperature-dependent powder X-ray diffraction patterns (PXRD) and PL spectra were further measured to identify their thermal stabilities. This work may provide a certain guiding significance for exploiting L-CPs based on different metal ions. [ABSTRACT FROM AUTHOR]

The REE contents (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) are determined by atomic emission spectroscopy in the subcolloidal fraction of bottom sediments in the Razdol'naya River-Amur Bay section. The mean contents of lanthanides in soils and river bottom sediments (before the mixing zone) are calculated. The increase in REE content and the fractioning in the series from light to middle and heavy REE in sediments of different estuary zones (river, water mixing, and marine), with the latter related to flocculation, sorption on iron and manganese hydroxides, clay minerals (hydromica, smectites), and lifetime accumulation of marine plankton, are dtermined. Via extraction of 0.5 N sodium hydroxide solution, the content of lanthanides associated with humic substances of subcolloidal fraction from the Amur Bay sediments are determined: 1.3 to 8.2% of La; 1.1 to 11% of Ce; and 0.3 to 1.5 of Gd. [ABSTRACT FROM AUTHOR]

The additive under assessment, manganese hydroxychloride, contains ≥ 45% manganese (Mn). Manganese hydroxychloride is a safe source of manganese for all target species when used up to the maximum level of total manganese in complete feed authorised in the EU ( Fish 100 (total) and Other species 150 (total) mg Mn/kg feedingstuffs). Manganese hydroxychloride would substitute for other manganese sources in feed. It does not differently affect tissue deposition compared to manganese sulphate. The Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concludes that the use of manganese hydroxychloride in animal nutrition is safe for the consumers, provided the maximum authorised manganese content in complete feed is respected. In the absence of specific data, the FEEDAP Panel cannot conclude on the safety for the user when handling the additive. The use of manganese hydroxychloride in animal nutrition for all animal species is not expected to pose a risk to the environment. Manganese hydroxychloride is considered a source of bioavailable manganese as indicated by a dose-dependent increase of manganese deposition in bone and liver based on two studies on chickens for fattening. The FEEDAP Panel concludes that the additive is efficacious in meeting the manganese requirements for all animal species/categories. [ABSTRACT FROM AUTHOR]

Hydrous manganese oxides are an important class of minerals that help regulate the geochemical redox cycle in near-surface environments and are also considered to be promising catalysts for energy applications such as the oxidation of water. A complete characterization of these minerals is required to better understand their catalytic and redox activity. In this contribution an empirical methodology using X-ray photoelectron spectroscopy (XPS) is developed to quantify the oxidation state of hydrous multivalent manganese oxides with an emphasis on birnessite, a layered structure that occurs commonly in soils but is also the oxidized endmember in biomimetic water-oxidation catalysts. The Mn 2p 3/2 , Mn 3p , and Mn 3s lines of near monovalent Mn(II), Mn(III), and Mn(IV) oxides were fit with component peaks; after the best fit was obtained the relative widths, heights and binding energies of the components were fixed. Unknown multivalent samples were fit such that binding energies, intensities, and peak-widths of each oxidation state, composed of a packet of correlated component peaks, were allowed to vary. Peak-widths were constrained to maintain the difference between the standards. Both average and individual mole fraction oxidation states for all three energy levels were strongly correlated, with close agreement between Mn 3s and Mn 3p analyses, whereas calculations based on the Mn 2p 3/2 spectra gave systematically more reduced results. Limited stoichiometric analyses were consistent with Mn 3p and Mn 3s . Further, evidence indicates the shape of the Mn 3p line was less sensitive to the bonding environment than that for Mn 2p . Consequently, fitting the Mn 3p and Mn 3s lines yielded robust quantification of oxidation states over a range of Mn (hydr)oxide phases. In contrast, a common method for determining oxidation states that utilizes the multiplet splitting of the Mn 3s line was found to be not appropriate for birnessites. [ABSTRACT FROM AUTHOR]

The crystal structure of brackebuschite, ideally Pb2Mn3+(VO4)2(OH) [dilead(II) manganese(III) vanadate(V) hydroxide], was redetermined based on singlecrystal X-ray diffraction data of a natural sample from the type locality Sierra de Cordoba, Argentina. Improving on previous results, anisotropic displacement parameters for all non-H atoms were refined and the H atom located, obtaining a significant improvement of accuracy and an unambiguous hydrogen-bonding scheme. Brackebuschite belongs to the brackebuschite group of minerals with general formula A2M(T1O4)(T2O4)(OH, H2O), with A = Pb2+, Ba, Ca, Sr; M = Cu2+, Zn, Fe2+, Fe3+, Mn3+, Al; T1 =As5+, P,V5+; and T2 = As5+, P, V5+, S6+. The crystal structure of brackebuschite is based on a cubic closest-packed array of O and Pb atoms with infinite chains of edge-sharing [Mn3+O6] octahedra located about inversion centres and decorated by two unique VO4 tetrahedra (each located on a special position 2e, site symmetry m). One type of VO4 tetrahedra is linked with the 1∞[MnO4/2O2/1] chain by one common vertex, alternating with H atoms along the chain, while the other type of VO4 tetrahedra link two adjacent octahedra by sharing two vertices with them and thereby participating in the formation of a three-membered Mn2V ring between the central atoms. The 1∞[Mn3+(VO4)2OH] chains run parallel to [010] and are held together by two types of irregular [PbOx] polyhedra (x = 8, 11), both located on special position 2e (site symmetry m). The magnitude of the libration component of the O atoms of the 1∞[Mn3+(VO4)2OH] chain increases linearly with the distance from the centerline of the chain, indicating a significant twisting to and fro of the chain along [010]. The hydroxy group bridges one Pb2+ cation with two Mn3+ cations and forms an almost linear hydrogen bond with a vanadate group of a neighbouring chain. The O···O distance of this interaction determined from the structure refinement agrees well with Raman spectroscopic data. [ABSTRACT FROM AUTHOR]

Sorbents based on xerogels of zirconium, aluminum and manganese oxyhydroxides. The actual problem of water supply in the world and in Ukraine, in particular, is a high level of pollution in water resources and an insufficient level of drinking water purification. With industrial wastewater, a significant amount of pollutants falls into water bodies, including suspended particles, sulfates, iron compounds, heavy metals, etc. Aim: The aim of this work is to determine the impact of aluminum and manganese ions additives on surface and sorption properties of zirconium oxyhydroxide based sorbents during their production process. Materials and Methods: The sorbents based on xerogels of zirconium, aluminum and manganese oxyhydroxides were prepared by sol-gel method during the hydrolysis of metal chlorides (zirconium oxychloride ZrOCl2, aluminum chloride AlCl3 and manganese chloride MnCl2) with carbamide. Results: The surface and sorption properties of sorbents based on xerogels of zirconium, aluminum and manganese oxyhydroxides were investigated. X-ray amorphous structure and evolved hydroxyl-hydrate cover mainly characterize the obtained xerogels. The composite sorbents based on xerogels of zirconium oxyhydroxide doped with aluminum oxyhydroxide (aS = 537 m2/g) and manganese oxyhydroxide (aS = 356 m2/g) have more developed specific surface area than single-component xerogels of zirconium oxyhydroxide (aS = 236 m2/g) and aluminum oxyhydroxide (aS = 327 m2/g). The sorbent based on the xerogel of zirconium and manganese oxyhydroxides have the maximum SO4 2--ions sorption capacity. It absorbs 1.5 times more SO4 2--ions than the industrial anion exchanger AN-221. The sorbents based on xerogels of zirconium oxyhydroxide has the sorption capacity of Fe3+-ions that is 1.5…2 times greater than the capacity of the industrial cation exchanger KU-2-8. The Na+-ions absorption capacity is 1.47…1.56 mmol/g for each sorbent. Conclusions: Based on these data, it can be concluded that the proposed method is effective to produce of sorbents based on xerogels of zirconium, aluminum and manganese oxyhydroxides for further use them to remove both polyvalent anions and heavy metals from aqueous solutions [ABSTRACT FROM AUTHOR]

Large conglomerate fragments up to 25 cm across were dredged off the submarine volcanic Vityaz Rise, Japan Sea in the 1600-1350 m depth range. These are the first ever that were recovered in this location. The fragments consist of pebble and gravel material that is cemented by manganese hydroxides. The cement is basal in type; the chemical composition is MMnO, where M = Na, Mg, K, Ca, Ba. The Mn/Fe ratio is 802. The upper part of the conglomerates is covered with a layered crust of the same hydroxides. A similar crust can be discerned within the conglomerate closer to the bottom of a sample. Some layers of the crusts are rich in NaCl, CaSO, F, Co, Cu. The crusts contain inclusions of grains that consist of Ag and intermetallic compounds based on Cu and Ni. The superimposed manganese mineralization is Quaternary. The metals originated, most likely, from gas-rich hydrothermal fluids. [ABSTRACT FROM AUTHOR]

This work aims to define the factors driving the accumulation of metals in the sediment of the lagoon of Aveiro (Portugal). The role of initial diagenetic processes in controlling trace metal retention in surface sediment is traced by mineralogy, magnetic susceptibility and geochemical analyses. Although several studies have focused on the metal distribution in this polihaline and anthropized coastal lagoon, most of them have been solely focused on the total metal concentrations. This study instead represents the first attempt to evaluate in a vast area of the Aveiro Lagoon the role of biogeochemical processes in metal availability and distribution in three extracted phases: exchangeable cations adsorbed by clay and elements co-precipitated with carbonates (S1), organic matter (S2) and amorphous Mn hydroxides (S3). According to the sediment guideline values, the sediment is polluted by, for instance, As and Hg in the inner area of the Murtosa Channel, Pb in the Espinheiro Channel, Aveiro City canals and Aveiro Harbour, and Zn in the northern area of the Ovar Channel. These sites are located near the source areas of pollutants and have the highest total available concentrations in each extracted phase. The total available concentrations of all toxic metals are however associated, firstly, with the production of amorphous Mn hydroxides in most of the areas and, secondly, with adsorption by organic compounds. The interplay of the different processes implies that not all of the sites near pollution sources have polluted surface sediment. The accumulation of metals depends on not only the pollution source but also the changing in the redox state of the sediments that may cause alterations in the sediment retention or releasing of redox-sensitive metals. Results of this work suggest that the biogeochemical processes may play a significant role in the increase of the pollutants in the sediment of the Aveiro Lagoon. [ABSTRACT FROM AUTHOR]

The Si–MnOOH composite electrode exhibits very stable cycling and excellent rate capability, such as 1200 mA h g−1 at 12 A g−1, and 700 mA h g−1 at 20 A g−1. The γ-MnOOH component significantly promotes the alloying/de-alloying reaction between Si and lithium. [ABSTRACT FROM AUTHOR]

The combination of analysis, multivariate treatment (PCA) and chemical speciation calculation confirmed the control of Fe, Mn, sulphide and organic matter on metals dynamics in coastal sediments (0–5 cm surface sediments and sediments cores) of Toulon Bay (NW Mediterranean). The temporal monitoring of the physic-chemical parameters as well as the dissolved/particulate minor (Fe/Mn) and trace elements (i.e. Ag, Cd, Co, Cu, Ni, Pb, Zn, …) concentrations in porewaters and sediments were assessed. Multivariate treatment revealed different behaviours for marine elements, terrestrial ones and contaminants. Seasonal variations of metals mobilization in porewater were observed, related to diagenesis activity. Element mobility was studied by selective extractions (ascorbate, acid and alkaline) on sediments. Thermodynamic simulation (PHREEQC) was performed to calculate the elemental dissolved speciation, the mineral saturation index and then to simulate the solid/liquid interaction through precipitation processes, studying the contrasted influence of dissolved organic matter and sulphide. [ABSTRACT FROM AUTHOR]

LiNiMnO samples with their particle sizes from micro to nano are synthesized via polyvinylpyrrolidone (PVP)-assisted coprecipitation of nickel and manganese hydroxide. Their morphology, structure, and performance as cathode of high-voltage lithium ion battery are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge/discharge test. The characterizations from SEM and XRD show that the particle size of the resulting LiNiMnO is tunable from micro to nano by controlling the concentrations of PVP for the formation of nickel and manganese hydroxide precursor. The results from CV, EIS, and charge/discharge test reveal that reducing the particle size of LiNiMnO results in its less interfacial resistance for lithium insertion/desertion process, leading to its improved rate capability. Meanwhile, the cyclic stability of LiNiMnO is also improved when its particle size is changed from micro to nano, but too smaller particle size is not beneficial to its cyclic stability, especially at elevated temperature. When evaluated in LiNiMnO/Li half cell, the resulting LiNiMnO samples of 800, 250, and 125 nm, in average, deliver a 20 C rate capacity of 40, 58, and 71 mAh g, while they exhibit a capacity retention of 79, 89, and 82 % after 250 cycles with 0.5 C rate at room temperature and 33, 77, and 64 % after 200 cycles with 1 C rate at 55 °C, respectively. This difference in capacity retention becomes more significant in LiNiMnO/graphite full cells due to the effect of graphite anode. [ABSTRACT FROM AUTHOR]

In this paper, we report a simple and controlled synthesis of novel MnOOH–graphene nanocomposites with a one-step facile hydrothermal method. It is template-free and easy to reproduce. Electrochemical properties are investigated in different media. The values of specific capacitance achieved are 112 F g −1 in 1 M Na 2 SO 4 and 165 F g −1 in 6 M KOH electrolyte, respectively. The assembly of multiple branched MnOOH and graphene flakes results in synergistic effects, forming new electron transfer channels to accelerate electron transfer and provide the pseudocapacitance to increase the overall capacitance. The novel composites have potential applications in the fields of supercapacitors, lithium battery and so on. [ABSTRACT FROM AUTHOR]

Cost-effective production of solar fuels requires robust and earth-abundant oxygen evolution reaction (OER) catalysts. Herein, we report that ultrathin nanoplates of cobalt--manganese layered double hydroxide (CoMn LDH) are a highly active and stable oxygen evolution catalyst. The catalyst was fabricated by a one-pot coprecipitation method at room temperature, and its turnover frequency (TOF) is more than 20 times higher than the TOFs of Co and Mn oxides and hydroxides, and 9 times higher than the TOF of a precious IrO2 catalyst. The activity of the catalyst was promoted by anodic conditioning, which was proposed to form amorphous regions and reactive Co(IV) species on the surface. The stability of the catalyst was demonstrated by continued electrolysis. [ABSTRACT FROM AUTHOR]

The effect of sodium thiosulfate (Na 2 S 2 O 3 ) on trace mercury removal from aqueous solution by in situ MnO x was investigated. Removal efficiency was studied at different molar ratios of Na 2 S 2 O 3 /Mn (0, 0.264, 0.593 and 1.582) and under changes in Mn dosage, reaction time and pH conditions. Additionally, the ionic strength and the mercury removal amount were examined to evaluate the efficiency of trace mercury removal. The results indicated that the presence of thiosulfate clearly improved removal of mercury from solution, and that increases in the ionic strength enhanced removal in a certain range of thiosulfate concentration. At neutral conditions, the mercury removal amount reached to maximum of 64 μg/mg. It is proposed that the ability of thiosulfate to reduce some MnO x to Mn 2+ as well as transfer the uncharged mercury species to a negatively charged species ( [ Hg ( S 2 O 3 ) 2 ] 2 − ) improved trace mercury removal. The mechanism analysis revealed that ternary complexes or large aggregations may be formed because of surface complexation or electrostatic attraction. [ABSTRACT FROM AUTHOR]

The palladium nanoparticle grafted manganese oxyhydroxide nanorod (MON) electrocatalyst has been synthesized and tested for the electrooxidation of ethylene glycol (EG) in an alkaline medium. The MON was prepared using the hydrothermal method and the Pd nanoparticles were coated on the MON using an in situ reduction method. The nanocatalyst thus prepared was characterized by powder X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy and electrochemical methods. The microscopic studies confirm the formation of MON and reveal that the Pd nanoparticles were grafted uniformly on the MON. In the voltammetric studies, the Pd/MON catalyst exhibited a six-fold improved peak current for ethylene glycol electrooxidation compared with the C/Pd. The EG electrooxidation reaction performances of the Pd/MON nanocatalyst in the alkaline solutions containing different quantities of EG were tested through cyclic voltammetry. The catalytic removal of the poisonous intermediates formed during electrooxidation of EG was explained. The present study shows that MON can act as an active support for the Pd nanocatalyst. [ABSTRACT FROM AUTHOR]

The article discusses a study that focuses on the geochemical problems related to formation of ferromanganese nodules composition and cobalt bearing crusts on the ocean bottom. Topics include impact of sea water hydrogen ion concentration variations on the concentration of dissolved oxygen, metal diagenetic mobilization process in the geochemical barrier sediment or water and increase in the adsorption of all metals with increased oxidation of manganese hydroxides.

Highlights: [•] Nanoarchitectures constructed with MnOOH nanorods and RGO were prepared via a one-pot approach. [•] The energy density of asymmetric supercapacitors made with the nanoarchitectures achieves 41.1Wh·kg−1 at 400W·kg−1. [•] The devices exhibit long cycle life of retaining 98.3% specific capacitance after cycling for 5000 times. [ABSTRACT FROM AUTHOR]

In this paper, we report on the nucleation and the growth of heterogeneous Mn-Bi thin films on Cu substrate from a mixed sulfate-nitrate bath using direct current plating. The electrolytic bath is characterized by the presence of ammonium sulfate which was used as complexing agent to avoid the precipitation of Mn hydroxides. Cyclic voltammetry and chronoamperometry measurements are used to study the reaction mechanisms of the Mn-Bi electrodeposition as a function of the ammonium sulfate concentration and the pH value: the optimized conditions for a stable bath are obtained for 2.5 mol. L-1 of ammonium sulfate and pH 2.3. The Scharifker and Hills (SH) model was used to analyze the current transients at the initial stage of deposition; it was revealed that Mn-Bi electrocrystallization process is governed by three-dimensional nucleation. But as the electrochemical deposition clearly involves the simultaneous presence of the proton cathodic reaction, another model developed by Palomar-Pardavé and co. was used to explain the nucleation mechanism and to describe the individual contribution of both the metallic ions and the proton reduction process. The morphology and chemical composition of the films were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The deposits have a cauliflower-shaped appearance with a heterogeneous distribution of manganese and bismuth. The energy dispersive spectroscopy analysis reveals the presence of manganese and bismuth peaks with almost the same relative intensities. The X-rays diffraction analysis shows characteristic peaks of manganese and bismuth. [ABSTRACT FROM AUTHOR]

The article discusses the study which focuses on the intranasal delivery of manganese hydroxide nanoparticles in brain structure. The use of the magnetic resonance imaging (MRI) in determining the neuronal transport of the brain is mentioned. The evaluation the olfactory bulb region is noted, along with the analysis of paramagnetic nanoparticles.

Single-crystal manganese oxyhydroxide (MnOOH) nanorods with high aspect ratios have been successfully prepared employing a simple hydrothermal route based on the redox between potassium permanganate (KMnO4) and polyvinyl pyrrolidone (PVP). By adjusting the reaction temperature, reaction time and the mass ratio of PVP/KMnO4, MnOOH nanorods with lengths up to 20 |im and diameters in the range of 100-400 nm could be facilely prepared in high yield. The as-prepared MnOOH nanorods were characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and Fourier transformed infrared spectroscopy. The formation mechanism of MnOOH nanorods was preliminarily discussed based on the Ostwald's ripening process. Furthermore, MnO2 and Mn2O3 nanorods with high aspect ratios were synthesised by calcination of MnOOH nanorods. [ABSTRACT FROM AUTHOR]

Highlights: [•] We report on the synthesis of phases in the Mn oxi-hidroxyde system in supercritical water. [•] Acetates were employed as precursors and only two high pressure pumps were used. [•] Synthesis conditions have been optimized concerning the flow rate and temperature. [•] Monodispersion and shape of nanoparticulated samples are characterized. [Copyright &y& Elsevier]

Abstract: Bermanite is a mixed valent hydrated hydroxy phosphate mineral. The mineral is reddish-brown and occurs in crystal aggregates and as lamellar masses. Bermanite is a common mineral in granitic pegmatites. The chemical composition of bermanite was obtained using EDS techniques. We have studied the molecular structure of bermanite using vibrational spectroscopy. The mineral is characterized by a Raman doublet at 991 and 999cm−1 attributed to the phosphate stretching mode of two non-equivalent phosphate units. Raman bands at 1071, 1117 and 1142cm−1 are assigned to the phosphate antisymmetric stretching modes. The hydroxyl stretching spectral region is complex with overlapping bands attributed to water and hydroxyl stretching vibrations. Vibrational spectroscopy proves most useful for the study of the mineral bermanite. [Copyright &y& Elsevier]

The structure and properties of nanodisperse manganese oxides obtained under conditions of an external electric field are studied using transmission and scanning electron microscopy, X-ray diffraction analysis, thermic analysis, and atom-emission spectroscopy. The influence of synthesis conditions on formation of structure and morphology of nanoparticles is studied. It is shown that effect of electric field on reaction media allows us to control the physicochemical properties and morphology of manganese oxide. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study was to investigate the influence of humic acid (HA) and salinity on adsorption of Hg on the amorphous and crystalline of iron and manganese hydroxides. The results show that the adsorption of Hg2+ on Fe and Mn hydroxides was inhibited in marine system due to the formation of stable, nonsorbing aqueous HgCl2 complexes in solution. Moreover, Cl− inhibited the Hg2+ adsorption more severely on amorphous than crystalline hydroxides. The addition of HA inhibited Hg2+ adsorption on Fe and Mn hydroxides in freshwater system might be attributed to the competition between Hg2+ and HA on adsorption to Fe and Mn hydroxides. In contrast, the addition of HA promoted Hg2+ adsorption on Fe and Mn hydroxides in the marine system, which might be due to the addition of humic acid resulted in the reaction between Cl− and HA, and therefore the reducing of Cl− promoted more Hg2+ on Fe and Mn hydroxides. In addition, the influence of HA on Hg2+ adsorption on Fe and Mn hydroxides are more visible for crystalline than amorphous hydroxides. [Copyright &y& Elsevier]

Single agent extractions of major and trace metals from soil samples were conducted by means of a rotary mixer and an ultrasonic bath with sonication times of 10, 20, 30, 40 and 50 min. The sequential extraction was undertaken according to the European Community Bureau of Reference. The obtained soil extracts were analyzed by inductively coupled plasma-optical emission spectrometry and according to the results, the rotary mixer-assisted extraction was more efficient in the case of alkaline earth elements. However, by use of ultrasound, several times higher amounts of matrix elements (Fe, Al and Mn) and heavy metals predominantly associated with Fe, Al and Mn oxyhydroxides were extracted. The increase of the sonication time failed to improve the extraction yields. The changes in the conductivity, pH, redox potential, particle size diameter and zeta potential of colloid particles with increasing sonication time were measured. The extraction mechanism and expressed selectivity of ultrasound is discussed and an explanation is suggested. [ABSTRACT FROM AUTHOR]

Manganese (hydr)oxides (MnO) is a powerful oxidant in the oxidation of As(III) in natural environment. Under some circumstances, Mn(II) can be oxidized to MnO which in turn accelerates the oxidation of As(III). However, to the best of our knowledge, little is known regarding how Mn(II) affects the oxidation of both the dissolved and the adsorbed As(III) in aquatic environments. In this study, effects of abiotic oxidation of Mn(II) on the oxidation of As(III) were investigated. Kinetic results as well as TEM and XRD analyses confirmed the formation of amorphous MnO after sorption of Mn(II) on hematite nano-particles under oxic conditions. Mn(II) was oxidized to Mn(III) and then to Mn(IV), and this process was dependent upon pH and Mn(II) concentrations. The newly formed MnO played an important role in the further oxidation of the dissolved and the adsorbed As(III) on hematite, and the oxidation rate of As(III) increased with the rising Mn(II) concentrations. As the adsorbed As(III) was oxidized to As(V), a fraction of As(V) was released into the solution, which increased the mobility of As. The present study reveals that abiotic oxidation of Mn(II) affects the oxidation of As(III) in aquatic environment. [ABSTRACT FROM AUTHOR]

A Li2MnSiO4 cathode material for lithium-ion batteries was prepared by a molten carbonate flux method. The preparation conditions such as gas atmospheres, heating temperatures and manganese sources were examined. Single phase Li2MnSiO4 was obtained at 500°C with two kinds of manganese sources (manganese oxalate dihydrate and manganese hydroxide), which was confirmed using high-resolution synchrotron X-ray diffraction (XRD). The Li2MnSiO4 prepared using manganese hydroxide has smaller particle size (100-300 nm) and higher specific surface areas (19.4 m² g-1) than those prepared using manganese oxalate dihydrate (200-600 nm, 12.5 m² g-1). Former sample showed higher discharge capacity (156 mAh g-1), initial efficiency (89%) and capacity retention (55% on 20th cycle) than latter one (92 mAh g-1, 69% and 37% on 20th cycle). [ABSTRACT FROM AUTHOR]

Abstract: The aims of the present study were to investigate the effects of mariculture activities on inorganic mercury (Hg2+) adsorption/desorption on sediments and the distributions of newly adsorbed Hg2+ on different chemical fractionations. The adsorption amount and binding energy of Hg2+ on mariculture sediment (MS) were significantly higher (p <0.05) than reference sediment (RS). This may be explained by the strong complexation role that exists between Hg2+ and organic matter (OM), which derived from unconsumed fish feed and fish metabolites. The reducible Hg2+ in MS was significantly lower (p <0.01) than RS, which may have been caused by the decreasing amount of iron and manganese hydroxide in MS, lead to the decrease of Hg2+ bound to them. On the contrary, the residual Hg2+ was significantly higher (p <0.01) in MS than RS, which suggests that newly adsorbed Hg2+ was more stable in MS than RS. [Copyright &y& Elsevier]