Ratio Of Manganese Research Articles

Magnesium-manganese oxides for high temperature thermochemical energy storage

Abstract The reactive stability and energy density of magnesium-manganese oxides for high-temperature thermochemical energy storage have been investigated. Three variations of material with molar ratios of manganese to magnesium of 2/3, 1/1, and 2/1 were prepared using solid-state reaction synthesis and were tested for thermochemical reactive stability and energy storage capability. Results show that oxygen released and absorbed (standard cm3 g−1) by the materials remains unchanged over 20 cycles when cycled between 1200 and 1500 °C under an oxygen partial pressure (PO2) of 0.2 atm, indicating excellent reactive stability at high temperatures. Additional confirmation of reactive stability was obtained through testing over 10 energy storage cycles between 1000 and 1500 °C. The energy density of the material between 1000 and 1500 °C was determined through a combination of acid-solution calorimetry and drop calorimetry. The total volumetric energy densities (chemical, phase change, and sensible) obtained for samples of Mn/Mg of 2/3, 1/1, and 2/1 cycled between 1000 and 1500 °C are 1596, 1626 and 1654 MJ m-3, respectively.

Iron nutrition in low chill peach for improving yield and fruit quality

Foliar fertilization and microbe supplemented iron (Fe) bioavailability can fulfill iron demand of plants. An experiment was performed to examine the effect of Psuedomonas fluorescens along with foliar spray ferrous sulfate on low-chill peach plants suffering from iron deficiency. Number of leaves per shoot, leaf area, chlorophyl content, Fe: Mn ratio of leaves, fruit yield and fruit physico-chemical parameters were recorded. The results showed a significant increase in leaves chlorophyl content, iron: manganese ratio of leaves, fruit yield, fruit length, fruit breadth, total soluble solids (T.S.S) and T.S.S and acid ratio with the inoculation of Pseudomonas fluorescens as well as foliar spray of ferrous sulfate, whereas, acidity of fruit pulp was decreased. Significantly higher number of leaves per shoot was also noted with foliar spray of ferrous sulfate. Pseudomonas fluorescens inoculation along with foliar spray of ferrous sulfate significantly increased leaves chlorophyl content, fruit length, T.S.S and T.S.S : acid ratio of fruit pulp.

Preparation of MnCo/MCM-41 catalysts with high performance for chlorobenzene combustion

MCM-41 was synthesized by a soft template technique. The specific surface area and pore volume of the MCM-41 were 805.9 m2/g and 0.795 cm3/g, respectively. MCM-41-supported manganese and cobalt oxide catalysts were prepared by an impregnation method. The energy dispersive X-ray spectroscopy clearly confirmed the existence of Mn, Co, and O, which indicated the successful loading of the active components on the surface of MCM-41. The structure and function of the catalysts were changed by modulating the molar ratio of manganese to cobalt. The 10%MnCo(6:1)/MCM-41 (Mn/Co molar ratio is 6:1) catalyst displayed the best catalytic activity according to the activity evaluation experiments, and chlorobenzene (1000 ppm) was totally decomposed at 270 °C. The high activity correlated with a high dispersion of the oxides and was attributed to the exposure of more active sites, which was demonstrated by X-ray diffraction and high-resolution transmission electron microscopy. The strong interactions between MnO2, Co3O4, MnCoOx, and MCM-41 indicated that cobalt promoted the redox cycles of the manganese system. The bimetal-oxide-based catalyst showed better catalytic activity than that of the single metal oxide catalysts, which was further confirmed by H2 temperature-programmed reduction. Chlorobenzene temperature-programmed desorption results showed that 10%MnCo(6:1)/MCM-41 had higher adsorption strength for chlorobenzene than that of single metal catalysts. And stronger adsorption was beneficial for combustion of chlorobenzene. Furthermore, 10%MnCo(6:1)/MCM-41 was not deactivated during a continuous reaction for 1000 h at 260 °C and displayed good resistance to water and benzene, which indicated that the catalyst could be used in a wide range of applications.

Systematic Doping of Cobalt into Layered Manganese Oxide Sheets Substantially Enhances Water Oxidation Catalysis.

The effect on the electrocatalytic oxygen evolution reaction (OER) of cobalt incorporation into the metal oxide sheets of the layered manganese oxide birnessite was investigated. Birnessite and cobalt-doped birnessite were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and conductivity measurements. A cobalt:manganese ratio of 1:2 resulted in the most active catalyst for the OER. In particular, the overpotential (η) for the OER was 420 mV, significantly lower than the η = 780 mV associated with birnessite in the absence of Co. Furthermore, the Tafel slope for Co/birnessite was 81 mV/dec, in comparison to a Tafel slope of greater than 200 mV/dec for birnessite. For chemical water oxidation catalysis, an 8-fold turnover number (TON) was achieved (h = 70 mmol of O2/mol of metal). Density functional theory (DFT) calculations predict that cobalt modification of birnessite resulted in a raising of the valence band edge and occupation of that edge by holes with enhanced mobility during catalysis. Inclusion of extra cobalt beyond the ideal 1:2 ratio was detrimental to catalysis due to disruption of the layered structure of the birnessite phase.

ТЕРМОДИНАМИЧЕСКОЕ МОДЕЛИРОВАНИЕ ПРОЦЕССА ВОССТАНОВЛЕНИЯ МЕТАЛЛОВ ИЗ ТИТАНОМАГНЕТИТОВЫХ КОНЦЕНТРАТОВ СУРОЯМСКОГО МЕСТОРОЖДЕНИЯ

According to the P1 category, the forecast resources of the Suroyam ore deposit exceed 2.2 bn tones of titanomagnetite ore. This is an analog of the Kachkanarsk ore deposit in Sverdlovsk region. The major element in this ore is iron which content reaches about 16.5%. The other elements which are possible for extraction are titanium, vanadium and phosphorus. The processing of the concentrate is expected to be carried out by using the ITmk3 technology. In this paper the thermodynamic analysis was performed using the Terra software allowing estimation of the effect of temperature on parameters of processes occurring in the system metal-slag-gas. The effect of temperature on metal composition was analyzed. It was found that in the temperature range 500–800 °C the metal phase was comprised of iron, manganese, sulfur and carbon. With temperature increase to 800 °C and above vanadium, phosphorus, titanium and silicon were reduced to metal phase. The content of vanadium reached maximum at temperature 1100 °C, phosphorus at 1250 °C, whereas the content of titanium and silicon increased with the temperature enhancement. The effect of temperature on the composition of the slag phase was observed. It was found that in the temperature range 500–1100 °C the FeO content decreased from 65% to 0%. This led to an increase in the relative proportion of other oxides (SiO2, Al2O3, CaO, MgO and etc.). The proportion of P2O5 reached maximum at temperature 1000 °C, TiO2 – 1250 °C, SiO2 – 1350 °C, respectively. The coefficients of recovery of elements from the charge material to the metal were determined. It was found that with enhancement of temperature, the recovery ratio of iron, manganese, vanadium, phosphorus, titanium and silicon increased, whereas sulfur decreased. In the temperature range 1350–400 °C the coefficient of the extraction of iron, manganese, vanadium, phosphorus was 1, titanium 0.4–0.6, silicon 0.02–0.07 and sulfur 0.75–0.79.

A green preparation of Mn-based product with high purity from low-grade rhodochrosite

The low-grade rhodochrosite, the main resources for exploitation and applications in China, contains multiple elements such as iron, silicon, calcium and magnesium. So the conventional preparation of manganese sulphate and manganese oxide with high purity from electrolytic product is characterized by long production-cycle, high-resource input and high-pollution discharge. In our work, a sustainable preparation approach of high pure MnSO4 solution and Mn3O4 was studied by employing low-grade rhodochrosite (13.86%) as raw material. The repeated leaching of rhodochrosite with sulphuric acid was proposed in view of the same ion effect, in order to improve the solubility of Mn2+ and inhibit the dissolution of the impurities Ca2+ and Mg2+. With the aid of theoretical calculation, BaF2 was chosen to remove Ca2+ and Mg2+ completely in the process of purifying. The results showed that the impurities such as Ca2+, Mg2+, Na+ were decreased to less than 20ppm, and the Ni- and Fe- impurities were decreased to less than 1ppm, which meets the standards of high pure reagent for energy and electronic materials. The extraction ratio and the recovery ratio of manganese reached 94.3% and 92.7%, respectively. Moreover, the high pure Mn3O4 was one-step synthesized via the oxidation of MnSO4 solution with the ratios of OH-/Mn2+=2 and Mn2+/H2O2=1.03, and the recovery rate of manganese reaches 99%.

Relative association of Rubisco with manganese and magnesium as a regulatory mechanism in plants

Rubisco, the enzyme that constitutes as much as half of the protein in a leaf, initiates either the photorespiratory pathway that supplies reductant for the assimilation of nitrate into amino acids or the C3 carbon fixation pathway that generates carbohydrates. The relative rates of these two pathways depend both on the relative extent to which O2 and CO2 occupies the active site of Rubisco and on whether manganese or magnesium is bound to the enzyme. This study quantified the activities of manganese and magnesium in isolated tobacco chloroplasts and the thermodynamics of binding of these metals to Rubisco purified from tobacco or a bacterium. In tobacco chloroplasts, manganese was less active than magnesium, but Rubisco purified from tobacco had a higher affinity for manganese. The activity of each metal in the chloroplast was similar in magnitude to the affinity of tobacco Rubisco for each. This indicates that, in tobacco chloroplasts, Rubisco associates almost equally with both metals and rapidly exchanges one metal for the other. Binding of magnesium was similar in Rubisco from tobacco and a bacterium, whereas binding of manganese differed greatly between the Rubisco from these species. Moreover, the ratio of leaf manganese to magnesium in C3 plants increased as atmospheric CO2 increased. These results suggest that Rubisco has evolved to improve the energy transfers between photorespiration and nitrate assimilation and that plants regulate manganese and magnesium activities in the chloroplast to mitigate detrimental changes in their nitrogen/carbon balance as atmospheric CO2 varies.

Plasma Treatment Enhanced Magnetic Properties in Manganese Doped Titanium Nitride Thin Films

The ferromagnetic manganese doped TiN films were grown by plasma assisted molecular beam epitaxy on MgO(001) substrates. The nitrogen concentration and the ratio of manganese at Ti lattice sites increase after the plasma annealing post treatment. TiN(002) peak shifts toward low angle direction and TiN(111) peak disappears after the post treatment. The lattice expansion and peak shift are mainly ascribed to the reduction of nitrogen vacancies in films. The magnetism was suppressed in as-prepared sample due to the pinning effect of the nitrogen vacancies at defect sites or interface. The magnetism can be activated by the plasma implantation along with nitrogen vacancies reduce. The decrease of nitrogen vacancies leads to the enhancement of ferromagnetism.

Maternal and Cord Blood Manganese Concentrations and Early Childhood Neurodevelopment among Residents near a Mining-Impacted Superfund Site.

Background:Environmental manganese exposure has been associated with adverse neurodevelopmental outcomes among school-aged children; yet, few studies have evaluated prenatal exposure.Objectives:Our study examines associations between prenatal manganese concentrations and placental transfer of manganese with neurodevelopment in 224 2-y-old children residing near the Tar Creek Superfund Site.Methods:We collected maternal and cord blood at delivery, measured manganese using inductively coupled plasma mass spectrometry, and assessed neurodevelopment using the Bayley Scales of Infant Development-II. Associations between manganese and mental (MDI) and psychomotor (PDI) development indices were estimated in multivariable models. Placental transfer, approximated by cord/maternal manganese ratio, cord/total manganese ratio (), and by joint classification according to high or low (above or below median) maternal and cord manganese, was evaluated as a predictor of neurodevelopment.Results:Median levels [interquartile ranges (IQR)] of manganese in maternal and cord blood, respectively, were 24.0 (19.5–29.7) and . Adjusting for lead, arsenic, and other potential confounders, an IQR increase in maternal manganese was associated with (95% CI: , ) points on MDI and (95% CI: , ) points on PDI. Cord manganese concentrations were not associated with neurodevelopment scores. Cord/maternal and cord/total manganese ratios were positively associated with MDI [cord/maternal: ; cord/total: ] and PDI (cord/maternal: ; cord/total: ). Compared to mother–child pairs with low maternal and cord manganese, associations with neurodevelopment scores were negative for pairs with either high maternal, high cord, or high maternal and cord manganese.Conclusions:Maternal blood manganese concentrations were negatively associated with early childhood neurodevelopment scores in our study. Findings highlight the importance of understanding maternal exposures during pregnancy and factors influencing placental transfer. https://doi.org/10.1289/EHP925

Synthesis of Hexagonal FeMnP Thin Films from a Single-Source Molecular Precursor.

The first heterobimetallic phosphide thin film containing iron, manganese, and phosphorus, derived from the single-source precursor FeMn(CO)8 (μ-PH2 ), has been prepared using a home-built metal-organic chemical vapor deposition apparatus. The thin film contains the same ratio of iron, manganese, and phosphorus as the initial precursor. The film becomes oxidized when deposited on a quartz substrate, whereas the film deposited on an alumina substrate provides a more homogeneous product. Powder X-ray diffraction confirms the formation of a metastable, hexagonal FeMnP phase that was previously only observed at temperatures above 1200 °C. Selected area electron diffraction on single crystals isolated from the films was indexed to the hexagonal phase. The effective moment of the films (μeff =3.68 μB ) matches the previously reported theoretical value for the metastable hexagonal phase, whereas the more stable orthorhombic phase is known to be antiferromagnetic. These results not only demonstrate the successful synthesis of a bimetallic, ternary thin film from a single-source precursor, but also the first low temperature approach to the hexagonal phase of FeMnP.

Removal of elemental mercury by Ce-Mn co-modified activated carbon catalyst

A series of CeO2 modified and Ce-Mn co-modified activated carbons (AC) were prepared for the gas-phase elemental mercury (Hg0) removal experiment under N2 atmosphere. The loading of CeO2 ranged from1wt.% to 7wt.%, and the mass ratio of manganese to cerium was 0.7. The BET results indicated that the big surface area and pore volume benefited the physical adsorption of Hg0. The XPS results indicated the existence of the Ce3+/Ce4+ redox couple and multiple valence state Mn ions, and Ce4+ and Mn4+ species released lattice oxygen to promote the Hg0 oxidation. The experimental results showed the 3wt.% CeO2-Mn(0.7)/AC was the optimal sample at 120°C.

Preparation of High Purity Manganese Sulphate from Low-Grade Rhodochrosite

In our work, the preparation technique of high pure manganese sulfate directly from low-grade rhodochrosite ore (MnCO 3 ) was studied and improved intensively, including the effective leaching process and the short purifying process. Based on the same ion effect, the repeated leaching of rhodochrosite with sulfuric acid is proposed to improve the solubility of Mn 2+ and inhibit the dissolution of the impurities Ca 2+ and Mg 2+ . Moreover, the repeated leaching process could make full use of rhodochrosite and lower the dosage of sulfuric acidas raw material. With the aid of theoretical calculation, Ba(OH) 2 was chose to adjust the pH value of manganese sulfate solution, and BaF 2 to remove Ca 2+ and Mg 2+ completely in the process of purifying. The results demonstrate that the extraction ratio and the recovery ratio of manganese reached 94.3% and 92.7%, respectively, which shows the prospect of industrial application. In manganese sulfate production, the heavy metal impurities have been decreased to less than 1ppm. Moreover, the content of calcium, magnesium and sodium has been decreased to less than 20ppm, which meets the standards of high pure reagent for energy and electronic materials. Our study enlightens an approach to the sustainable application of low-grade rhodochrosite.

A Novel Process for Simultaneous Extraction of Iron, Vanadium, Manganese, Chromium, and Titanium from Vanadium Slag by Molten Salt Electrolysis

Disposal of slags from alloy steelmaking is a serious problem as the toxic metals in the slag such as chromium and vanadium can be leached out. Recovery of the valuable metals needs an effective, economically viable method with a minimum number of unit processes. In the present work, a novel process for simultaneous recovery of iron, vanadium, titanium, chromium, and manganese from vanadium slag is proposed including the chlorination of vanadium slag in molten salt and electrolysis of the salt bath. The optimal conditions for the chlorination are an AlCl3–slag mass ratio of 1.5:1 and a salt bath composition (NaCl–KCl)–AlCl3 mass ratio of 1.66:1, at 900 °C for 8 h. The chlorination ratio of iron, vanadium, chromium, and manganese can reach 90.3%, 76.5%, 81.9%, and 97.3%, respectively, and the titanium volatilization ratio was 79.9%. Metal chlorides in molten salts are electrolyzed at 900 °C with graphite electrodes. Valuable metals (Fe, V, Cr, Mn) were deposited on the cathode in terms of alloy or metal of...

Simultaneous leaching of low grade bismuthinite and pyrolusite ores in hydrochloric acid medium

A simultaneous leaching process to extract both bismuth and manganese by one-step leaching in hydrochloric acid solution is proposed in this paper. Thermodynamic investigations of the Eh–pH diagram of both Mn–H2O and Bi–S–Cl–H2O systems showed that the equilibrium potentials of MnO2/Mn2+ couple were much higher than that of Bi2S3/Bi(III) couple. The electrochemical experiments presented the electrochemical reactions of bismuthinite and pyrolusite. Most suitable operating leach parameters were established as follows: liquid-to-solid ratio (mL/g), 5:1; initial hydrochloric acid concentration, 4mol/L; leaching temperature, 70°C; ore ratio (measured by the mole ratio of manganese and sulfur, n(Mn)/n(S)), 1.4/1; leaching time, 2h; and agitation speed, 500rpm. Leaching efficiency of 96.6% and 97.1% for bismuth and manganese were obtained, respectively, under the optimum experimental conditions.

Low-temperature direct synthesis of layered m-LiMnO2 for lithium-ion battery applications

Layered monoclinic LiMnO2 is a potential low-cost alternative to LiCoO2 cathode for lithium-ion batteries. However, its application is limited partly because it cannot be synthesized easily. In this work, we successfully synthesized phase-pure layered LiMnO2 in a one-step low-temperature process using electrolytic manganese dioxide (EMD) as the manganese precursor at 450 °C in Ar atmosphere by a carbothermal reduction method. The initial carbon to manganese ratio has to be optimized to remove impurities. The particle size of the material is between 40 and 60 nm. The synthesized sample shows an initial reversible capacity of about 180 mAh g−1. The synthesis method is further applied to make boron-doped samples, which significantly enhanced the stability of the material, especially at high temperature. The boron-doped samples maintain a capacity of 150 mAh g−1 for 100 cycles and give a capacity of about 100 mAh g−1 at a current of 1000 mA g−1 (equivalent to 10C rate). The ability to directly synthesize the material at low temperature is crucial because it allows further improvement of material performances through methods such as surface coating and the use of electrolyte additives to reduce surface reaction and Mn-dissolution.

Assessing the Biological Stability of a Terpene-Based Advanced Biofuel and Its Relationship to the Corrosion of Carbon Steel

Energy-dense terpene biofuels have recently been recognized as renewable alternatives for high-density petroleum-derived fuels. While the physicochemical properties of terpene dimer fuel (TDF) have been well-documented, the propensity of these mixtures to undergo biodegradation and exacerbate the corrosion of the fuel infrastructure remains unknown. Coastal seawater/sediment incubations were amended with TDF or a blend of petroleum-derived hydrocarbons and incubated under strict anaerobic conditions. In some incubations, a model hydrocarbon-degrading sulfate-reducing bacterium (Desulfoglaeba alkanexedens, strain ALDC) was inoculated as a positive control. No increase in sulfate reduction or corrosion was observed in long-term experiments (300 days) relative to TDF-free controls when only seawater/sediment served as the inoculum. However, inoculation with the positive control organism and a mixture of C6–C12 n-alkanes increased both the sulfate reduction rate (95.2 ± 5.2 μM/day) and general corrosion, as determined by both coupon weight loss (27.9 ± 1.6 mg) and the number of pits (495 ± 62). The ratio of manganese (Mn)/weight loss (0.34) in incubations exhibiting coupon pitting was lower than those (0.53–0.68) showing only generalized coupon corrosion. Despite no indication for TDF biodegradation under all test conditions, the detection of a suite of alkylsuccinate metabolites attested to the anaerobic metabolism of the suite of n-alkanes when strain ALDC and the hydrocarbons served as amendments. These findings suggest that TDF is resistant to biodegradation and will not exacerbate the corrosion of carbon steel. If used in combination with petroleum hydrocarbons, the degree of metal corrosion would be that expected as a result of labile fuel components. However, the relatively recalcitrant nature of TDF might pose other risks if released to the environment and, thus, warrants further study.

Crystal Structure and Characterization of La1-xBixMnO3+δ

The La1-x Bi x MnO3+ δ (x=0.0-0.5) solid solutions were synthesized using three different methods: solid-state synthesis, citrate-nitrate combustion synthesis and mechanochemical activation. All obtained compositions crystallize in a rhombohedral perovskite structure, independent of the synthesis method. Two ranges with linear temperature dependence of the unit cell parameters have been observed during in-situ heating X-ray powder diffraction experiments. The transition between the two ranges occurs at 730°C and is explained by chemical expansion at high temperatures. The chemical compatibility between the obtained solid solutions and bismuth-containing electrolytes (Bi4V1.7Fe0.3O11, Bi13Mo5O34 and Bi3Nb0.8W0.2O7.1) was studied. Interaction between these materials has been observed at temperatures higher than 600°С. X-ray diffraction data collected at room temperature confirm that the La1-xBixMnO3+ δ solid solutions form in the whole range of the investigated bismuth concentrations independent of the synthesis method. All samples crystallize in a rhombohedral perovskite structure with a trigonal unit cell (S.G. R-3c). For a detailed microstructural characterization by transmission electron microscopy, the La0.8Bi0.2MnO3.15 composition obtained using the solid-state synthesis was chosen. All obtained diffraction patterns can be indexed in a trigonal unit cell with a=5.5300(1) Å, c=13.382(1) Å. An analysis of systematically absent reflections revealed the presence of two types of crystals. Extinction conditions for the fist type coincide with those obtained from XRD (hkl: -h+k+l=3n; h-hl: h+l=3n, l=2n; hhl: l=3n; 00l: l=6n), indicating two possible space groups: R-3c and R3c. A second type of crystals obeys the same extinction rules except for the 00l reflections for which l=3n and h-hl reflections for which l¹2n, pointing towards the following possible space groups: R3, R-3, R32, R3m, R-3m. The formation of two different types of crystallites with trigonal crystal symmetry has been observed in perovskite systems before and explained by the presence or absence of antiphase octahedral tilting about the [111] axis of the cubic perovskite sub-lattice. It is worth to mention that the X-ray powder diffraction pattern of this sample displays asymmetric line broadening of peaks, which can point towards the presence of an additional structurally related compound. A loss of oxygen was observed in the TG curves of La1-xBixMnO3+ δ (x=0.0-0.5; Δх=0.1) samples at temperatures >700°С, supporting the previously discussed results. TG/DSC curves of La0.9Bi0.1MnO3+ δ are shown in Figure 4. The loss of mass was found to be 0.6%. The excess of oxygen in La1-xBixMnO3+ δ (x=0.0-0.5; Δх=0.1) was determined using redox titration. The value of the oxygen nonstoichiometry (δ) was found to be positive and equal to 0.15 at all concentrations of dopant, which can be explained by the identical oxidation states of La3+ and Bi3+. To determine the concentration of metal atoms in the obtained solid solutions, surfaces and fractures of pellets have been studied using EDS and AAS. The elemental content of 15–20 crystallites of La1-xBixMnO3+ δ (x=0.1, 0.2) compositions was studied by EDS analysis inside the scanning electron microscope. It was found to be La0.9(1)Bi0.07(4)Mn0.9(7) and La0.9(8)Bi0.1(6)Mn0.9(6) for x = 0.1 and 0.2, respectively. The obtained results showed a slightly inhomogeneous cation distribution and a lower manganese concentration compared to the nominal value for both the bulk and the surface of the pellets. AAS measurements gave similar results for all synthesized solid solutions, showing the manganese content to be 0.9, and thus indicating that all obtained solid solutions lie in the homogeneity region of lanthanum manganite with a small manganese deficiency. Taking into account the obtained values of manganese deficiency and oxygen nonstoichiometry, the chemical formula of the solid solutions can be rewritten as La1-xBixMn1-yO[(3+(1-y) )/2] (where VMn is the average oxidation state of manganese). For example, for the La0.9Bi0.1MnO3+ δ compound with δ=0.15 and y=0.1, the average oxidation state of manganese (VMn) will be equal to 3.67. Thus, the ratio of manganese in different oxidation states (Mn4+/Mn3+) in the studied solid solutions is equal to 2, which means that 67% of the manganese cations in these compounds have oxidation state +4. This fact is probably the reason why we observe the formation of solid solutions with a rhombohedrally distorted perovskite structure already at room temperature. A study of the chemical compatibility between La1-x Bi x MnO3+ δ (x=0.0-0.5; Δх=0.1) solid solutions and bismuth-containing electrolytes shows that depending on the chemical nature of the electrolyte material, the formation of additional phases begins at different temperatures: at T³700°С for the studied niobate, at T³600°С for the studied vanadate and at T³500°С for the studied molybdate. The work was financially supported by Russian Fund of Fundamental Research, grant 14-03-92605.

Reusable Mn-Doped ZnS Magnetic Nanocomposite for Photodegradation of Textile Dyes

Magnetic nanoparticles of manganese doped ZnS has been synthesized with different molar ratios of manganese and zinc by co-precipitation method. Structure of the prepared nanocomposite was investigated using FT-IR, XRD, TEM and VSM. The most excellent photodegradation efficiency of Reactive Blue 198 (RB198) was observed with the molar ratio of Mn-doped ZnS/Fe3O4 and it was 1:1 in which molar percentage of Mn2+ was 9%. The experiments of dye degradation were carried out under visible light and UV radiation. Results shown that the degradation efficiency of RB198 was up to 100% at the concentration of 200 ppm for 10 minutes when the amount of catalyst was 0.2g/l. Additionally, the effect of various parameters including initial concentration, illumination time and pH to the photodegradation efficiency of dye was also carried out. More interestingly, the reusable experiments showed that the nanocomposited exhibited high photodegradation capacity after three cycles and can be recycled conveniently from water with the assist of an external magnet because of its exceptional properties.

TRANSFORMATIONAL CONVERSIONS OF MANGANESE HYDROXIDES FROM FERROMANGANESE DEPOSITS OF THE WORLD OCEAN UNDER THE INFLUENCE OF TEMPERATURE

The paper is aimed at investigation and characterization as well as at crystal-chemical interpretation of products of thermo conversions of manganese hydroxides from ferromanganese deposits from different areas in the World Ocean. The results of research which are represented in this paper give notions about features of crystal-chemical conversions of manganese minerals with different types of crystal structure, different chemical composition and genesis when they are heated. This allows to generate new diagnostic criteria of these minerals and valuation of such type of mineral resources. Such common minerals, in marine and oceanic nodules, as vernadite, birnessite, buzerit I, mixed-layer asbolan– buzerit, todorokit and pyrolusite, were selected for further research. The samples were taken in certain way to have one mineral phase of manganese hydroxide which is represented by two preparations: one of which is with high ratio of iron and manganese, and the other one with low ratio, and with different quantities of nickel, cobalt and copper. To study changes of mineral composition of ferromanganese deposits the samples were heated in consecutive order in the range of temperatures 20-9000С. The mineral composition of initial samples and the products of annealing was determined by means of x-ray diffraction. Transformations of manganese hydroxides under the influence of high temperatures are as follows: if iron is a dominant component in the initial sample, hematite and yakobsite will be formed; if manganese content will be increased in the initial sample then hematite is absent in the products of annealing and along with yakobsite such mineral as biksbiit appears. Later on, with incensement of manganese content in the initial sample such mineral as gausmanite appears in the products of annealing which corresponds to the area of disruption of miscibility in the system. Along with farther incensement of the ratio between iron and manganese, such mineral as yakobsite cannot be formed anymore and the quantity of gausmanite increases. Initial mineralogical composition of the sample determines the character of conversions of crystal lattice up to 7000C. The composition of the final products of annealing depends first of all on the ratio Mn/Fe in the sample. Thus, the trend of transformation of manganese hydroxides from marine and oceanic ferromanganese deposits under the influence of heating depicts commonality of their structure. Under the influence of temperature on manganese-oxygen octahedrons only the way of connection between layers and bands and their order can be changed. The scheme of transformational conversions of manganese hydroxides is suggested in the paper.

Preparation of Nickel and Manganese Dioxide by Co-Precipitation and its Electrochemical Capacitive Properties

The precursor nickel and manganese carbonates were synthesized by co-precipitation with sodium carbonate as precipitant, and then nickel and manganese oxides were gained after calcination. The phase and morphology of the synthesized product were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM), and the electrochemical characterization was performed using cyclic voltammetry (CV), galvanostatic charge–discharge tests (GCD) and electrochemical impedance spectroscopy (EIS) in a 6mol/L KOH aqueous solution electrolyte. The result showed that the products were the mixture of nickel and manganese oxides and solid solution. nanoparticles and spherical particles were gained by controlling the molar ratio of nickel and manganese. All of the samples exhibited typical Faradic redox capacitance. The specific capacitance was different with the change of nickel and manganese molar ratio. The specific capacitance (Cs) reached 130F/g at 1A/g when the ratio was 2:1.