Mn Hydroxides Research Articles

Manganese accumulation and solid-phase speciation in a 3.5 m thick mud sequence from the estuary of an acidic and Mn-rich creek, northern Baltic Sea

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 3.5m 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 3.5m long sediment core is two depth intervals (60–155cm and 181–230cm) where there are strong fine-scale variations in Mn concentrations with peaks episodically reaching up to 10–25gkg−1 and 6.7–12gkg−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 (1M NH4-acetate at pH6), which is frequently employed to dissolve carbonate. We ascribe this discrepancy to only partial dissolution of rhodochrosite in the weakly acidic (pH=6) NH4-acetate leach.

Near shore groundwater acidification during and after a hydrological drought in the Lower Lakes, South Australia

An extreme hydrological drought in the Lower Lakes of the Murray–Darling Basin (Ramsar listed site) resulted in exposure of large areas of lake bed (25% of pre-drought lake area), containing the reduced iron (Fe) sulfide mineral pyrite. The pyrite oxidised and the resulting acidification (pH<4) posed risks of acid and metals entering shallow groundwater and potentially discharging to the remaining lake water body. Piezometer transects were installed at four locations and monitoring of the groundwater levels and quality was undertaken for six years from 2009 (drought) to 2014 (4years post-reinundation). Acidic (pH3–5) groundwater was recorded at three of the four piezometer locations and included sites close to the lake water. The acidic groundwater (0.5–2m below lake bed) at these sites is likely to have originated from the transport of acid from the upper oxidised sediment layer formed during the drought. High soluble metal (Fe, Al, Mn) levels were also recorded at acidic locations. Acidic shallow groundwater has persisted at many sites for over 4years following reinundation post-drought, and is likely due to slow diffusion and limited sulfate reduction. Increases in dissolved Fe and Mn with decreases in redox potential suggest that reductive dissolution of Fe and Mn hydrous oxides and Fe oxy-hydroxysulfate minerals (e.g. jarosite) occurred post-drought. Groundwater hydraulic head gradients were low, indicating there was limited potential for groundwater to discharge to the lake. The hydraulic gradients at all locations were dynamic with complex relationships along the near-shore environment. The results highlight the long lasting and severe effects on groundwater that can occur following hydrological drought in aquatic environments with sulfidic sediments.

RARE EARTH ELEMENTS USED AS FINGERPRINTS OF DIFFERENTIATED SEDIMENT SOURCES IN THE RIA DE AVEIRO (PORTUGAL)

This work focuses on the distribution and the controlling factors of rare earth element (REE) total concentrations and fractionation patterns in fine sediment fractions of 53 samples collected along the main channels of the Ria de Aveiro, a northern Portuguese coastal lagoon. Total and available concentrations and residual phases of REE and total concentrations in three chemically partitioned fractions (S1 - adsorbed by clay and co-precipitated with carbonates; S2 - adsorbed by organic matter; S3 - adsorbed by amorphous Mn hydroxides) are analysed. These data are joinly analysed with physicochemical, textural and mineralogical and other geochemical data. Sediment samples mainly consisted of phyllosilicates, quartz, plagioclase and K–feldspars. Cerium (Ce) is the most abundant REE in the residual phase and displays the lowest total available percentage, whereas Yttrium (Y) is the most available. The highest total concentration and residual concentration (R) of Ce, Lanthanum (La), Scandium (Sc) and Y are mostly related to fine grained sediments, suggesting that their distributions are conditioned by lagoon hydrodynamics. The dissimilar distribution of REE-S1, REE-S2 and REES3 indicates differentiated sedimentary processes. The enrichment of REE-S2 and REE-S3 is related essentially to biogeochemical processes inside the lagoon. The REE-S1, as well as Ce-S1/Sc-R, trace sediments supplied from the northern areas suplyed mostly by the Douro River outflow and from the Antuã River. In the past, the sediments suplyed by the Douro River through the litoral drift contributed to the formation of the lagoon islands. Thus the relatatively high Ce-S1/Sc-R values inside the lagoon allowed the identification of: sediments supplied from the litoral drift and deposited near the lagoon mouth, erosional processes of the lagoonal islands and sediments supplied by the Antuã River. This work demonstrates that the available concentrations of rare earth elements can be considered as important tools for investigating sediment sources and dispersion in a coastal system. doi: 10.12957/jse.2016.21444

Layered Co–Mn hydroxide nanoflakes grown on carbon cloth as binder-free flexible electrodes for supercapacitors

The layered Co–Mn hydroxide nanoflakes grown on carbon cloth (CC) have been successfully fabricated via a facile solvothermal method in a mixed solvent of water and methanol. The structure and morphology of final products could be readily tuned in a wide range by tuning volume ratios of methanol and water. The electrochemical measurements revealed that layered Co–Mn hydroxide nanoflakes grown on CC, exhibit a high-specific capacitance and remarkable cycling stability, which is of great importance for their practical applications in high-performance supercapacitor. Moreover, the specific capacitances of layered hydroxides would be enhanced with the expansion of interlayer spacing.

Electro-Surface Properties of Metal Oxides and Hydroxides in Water Solutions

The results of the determination of zero-charge points pH0 and isoelectric potentials (ζ-potential) in water solutions for some oxides and hydroxides used in the production of ceramic and glass as well as different material compositions are presented. A mechanism is proposed for the formation of the charge of metal oxides and hydroxides depending on the pH of the medium. The effect of the pH of the medium on the dispersion characteristics of hydroxides is shown for the example of the Ni(II), Cu(II), and Mn(II) hydroxides.

Influence of Soil Components on Sorption of Atrazine under Aerobic and Anoxic Conditions

The adsorption of atrazine onto untreated and soils when oxides and hydroxides of Fe, Mn, and organic matter have been reduced was studied under aerobic and anoxic conditions. The Freundlich model appeared to fit the isotherm data better than the Langmuir model, while second-order reaction rates were best fit for atrazine in the aqueous phase. Simple regression analysis indicated that the Fe content of the geosorbents is the most important primary factor controlling the sorption processes of atrazine (r2 = 0.947). Similar sorption capacity of atrazine by geosorbents but different isotherm nonlinearity indicated different sorption domains due to structural modifications and hydrophobicity. The sample treated to significantly remove organic carbon exhibited the greatest organic carbon–normalized sorption capacity. There existed apparent sorption–desorption hysteresis for each sorbent–sorbate system with desorption being more significant under anoxic conditions. The study suggests that, in remediation exercise, in situ redox barriers such as Fe2+-enriched zones can be created by stimulation of Fe3+ through chemical reduction. This study observed that soil predominated by Fe and with low OC content is probably a more effective sorbent for atrazine, implying that atrazine applied to such soils is less likely to leach into groundwater.

Early diagenesis and clay mineral adsorption as driving factors of metal pollution in sediments: the case of Aveiro Lagoon (Portugal).

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.

Ammonia-free coprecipitation synthesis of a Ni–Co–Mn hydroxide precursor for high-performance battery cathode materials

The ammonia-free coprecipitation process using citric acid as a new chelating agent successfully produced a micro-sized spherical Ni0.5Co0.2Mn0.3(OH)2 precursor and a well-performed cathode active material LiNi0.5Co0.2Mn0.3O2 for Li-ion batteries.

Plasma-grown graphene petals templating Ni–Co–Mn hydroxide nanoneedles for high-rate and long-cycle-life pseudocapacitive electrodes

Ni–Co–Mn triple hydroxide (NCMTH) nanoneedles were coated on plasma-grown graphitic petals (GPs) by a facile one-step hydrothermal method for high-rate and long-cycle-life pseudocapacitive electrodes.

An Investigation on the Influence of EAF Slag Particle Size on AMD Neutralization Behavior in Static and Dynamic Slag Leaching Systems

Steel slag, which contains basic oxides capable of generating high levels of alkalinity, may be used in leaching beds or leaching channels to neutralize acid mine drainage (AMD). In the present study, electric arc furnace (EAF) slag from the Pasargad Steel Complex was used to investigate the influence of slag particle size on AMD treatment. Three slag samples with different particle size distributions (coarse, mixed, fine) were prepared. Slag composition, pH variation, level of alkalinity, and specific surface area were measured and the surfaces of the slag particles was examined by scanning electron microscopy. In both dynamic and static leaching tests, there proved to be three stages: an initial high pH, alkalinity digestion-exhaustion, and low pH. Depletion of fine particles and precipitation of Fe, Al, and Mn hydroxides on particle surfaces were critical factors in how the alkalinity in the slag was exhausted during the second stage. SEM images suggest that metal precipitates prevented the AMD from reaching the slag surface and hence its neutralization potential was reduced. We also found that finely-ground slag produced a higher initial pH in the leachate but that after 60 leaching cycles, the pH value dropped below that of the coarse slag. A mixed sample demonstrated an initial high pH and a moderate pH after the 60th cycle, which verified greater potential for long-term alkalinity generation than the well-sorted slag.

Mechanism of selenite removal by a mixed adsorbent based on Fe-Mn hydrous oxides studied using X-ray absorption spectroscopy.

Selenium cycling in the environment is greatly controlled by various minerals, including Mn and Fe hydrous oxides. At the same time, such hydrous oxides are the main inorganic ion exchangers suitable (on the basis of their chemical nature) to sorb (toxic) anions, separating them from water solutions. The mechanism of selenite adsorption by the new mixed adsorbent composed of a few (amorphous and crystalline) phases [maghemite, MnCO3, and X-ray amorphous Fe(III) and Mn(III) hydrous oxides] was studied by extended X-ray absorption fine structure (EXAFS) spectroscopy [supported by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) data]. The complexity of the porous adsorbent, especially the presence of the amorphous phases of Fe(III) and Mn(III) hydrous oxides, is the main reason for its high selenite removal performance demonstrated by batch and column adsorption studies shown in the previous work. Selenite was bound to the material via inner-sphere complexation (via oxygen) to the adsorption sites of the amorphous Fe(III) and Mn(III) oxides. This anion was attracted via bidentate binuclear corner-sharing coordination between SeO3(2-) trigonal pyramids and both FeO6 and MnO6 octahedra; however, the adsorption sites of Fe(III) hydrous oxides played a leading role in selenite removal. The contribution of the adsorption sites of Mn(III) oxide increased as the pH decreased from 8 to 6. Because most minerals have a complex structure (they are seldom based on individual substances) of various crystallinity, this work is equally relevant to environmental science and environmental technology because it shows how various solid phases control cycling of chemical elements in the environment.

Arsenic distribution and hydrochemical factors in urban groundwater, Foshan City, South China

The distribution of arsenic (As) in shallow groundwater of eastern Chancheng District in Foshan City as a function of season and water table was investigated, and the influence of hydrochemical factors on the As distribution was discussed. The groundwater samples were collected from 20 sites in dry season and 9 sites in wet season. As concentrations in 20% groundwater samples exceeded value of the WHO guideline (10 μg/L), and the highest As concentration of 23.5 μg/L occurred in dry season. It is observed that groundwater As concentration decreased with the increase of depth of water table in dry season, and were generally higher in wet season than that in dry season, indicating that ground surface As might be one of the main sources for shallow groundwater As in study area, especially in wet season. Groundwater As concentration in study area had significantly positive correlation with the concentration of Fe, Mn, NH4, F, and COD, and was positively correlated to pH, but negatively correlated to Eh and K, indicating that reductive dissolution of Fe and Mn (oxy)hydroxides might be one of the main control mechanisms for groundwater As mobilization, while pH and F also played an important role in controlling the groundwater As mobilization in study area.

Geochemical aspects of accumulation of macroelements in the subcolloidal fraction of bottom sediments at the Razdol’naya River-Amur Bay cross-section (the Sea of Japan)

The concentration of Si, Al, Mg, K, Ca, Na, Sr, and Ba in the subcolloidal fraction of sediments at the Razdol’naya River-Amur Bay cross-section is determined using the atomic emission spectroscopy method. Computed is the mean content of studied elements in the soil and river bottom sediments (to the mixing zone). Revealed are river bottom sediments with the high concentration of macroelements corresponding to the zone of mixing of fresh river water and salt sea water. It is demonstrated that the additional accumulation of macroelements (Ca, Na, and Sr) in these sediments is associated with the formation of hydroxides of Fe and Mn and processes of sorption (Mg, Ca, Na, K, Sr, and Ba) on clay minerals (hydromica and smectites).

ChemInform Abstract: One‐Step Bulk Synthesis of Stable, Near Unit‐Cell Sized Oxide Nanoparticles and Nanoparticle Blends Using KO2.

AbstractBulk quantities of nm‐sized oxides or hydroxides of Mg, Y, Ti, Mn, Fe, Co, Ni, Cu, Zn, Sn, Tl, Pb, and Ce, and nanoparticulate blends of the lithium cathode material LiCoO2, the multiferroic compound BiMnO3+δ, and the superconducting YBa2Cu3O7‐γ are prepared from aqueous solutions of sulfates, chlorides, acetates, or nitrates and a 2‐fold molar excess of KO2 (pH 7, &lt;90% yields).

Uranium release from sediment to groundwater: Influence of water chemistry and insights into release mechanisms

Uranium (U) contamination in groundwater often results from natural geochemical processes such as mineral dissolution and desorption of adsorbed U from mineral surface. Although U adsorption and U mineral dissolution have been extensively studied, current knowledge of minerals and water chemistry conditions that control U release in uncontaminated soil and aquifers is still limited. Identification of these minerals and the knowledge of how water chemistry conditions influence U release is critical to better understand, predict, and manage geogenic U contamination in soil and groundwater. The objective of this study is to determine the extent and mechanisms of U release from a heterogeneous natural sediment under water chemistry conditions relevant to natural soil water and groundwater. A sediment sample was collected and characterized by XRD, SEM-EDX and extraction methods, and examined using laboratory leaching experiments. Our results show that Fe–Mn (oxy)hydroxides and silicate minerals are the major U hosting minerals, and a substantial fraction of U exists as adsorbed ions on minerals. We also found that U release is controlled by a number of interactive processes including dissolution of U-bearing minerals, U desorption from mineral surface, formation of aqueous U complexes, and reductive precipitation of U. Results from this study shed light on the important geochemical reactions that need be considered for developing a conceptual model that predicts U contamination in subsurface environment.

One-step bulk synthesis of stable, near unit-cell sized oxide nanoparticles and nanoparticle blends using KO2.

Presented here is a novel one-step synthesis of oxide or hydroxide nanoparticles using, for the first time, potassium superoxide (KO2). This work demonstrates that the reaction of KO2 with different salt solutions produces grams of stable, near unit-cell sized nanoparticles. This new synthetic technique is applied to representative elements from across the periodic table to rapidly produce nanometer sized oxides or hydroxides of Mg, Al, Y, Ti, Mn, Fe, Co, Ni, Cu, Zn, Sn, Tl, Pb, and Ce. This technique is also used to produce blends of nanoparticles, demonstrating the ability to prepare complex materials such as nanoparticulate blends of a lithium cathode material (LiCoO2), the multiferroic compound (BiMnO(3+δ)), and the superconducting YBa2Cu3O(7-γ).

Meromictic Lakes as On-Field Laboratories for Microbial Fuel Cells

In this contribution, a meromictic lake situated in the north of Italy is descripted from a physico-chemical point of view. The characteristics of this lake makes the application of microbial fuelcells (MFC) technology a challenging task. Many are the particularities that produce a unique environment for microbial fuelcells:A) Conformation of the lake basin: the glacial origin of the lake, together with the steep walls of the basin and the depth of 120 m, creates the conditions for the evolution of a meromicticcondition (Fig 1). A first layer of water (about 50 m) is continuously recirculated and oxygenated; a second layer finds the depletion of oxygen; a third layer is constituted of stationary water.B) Water analyses: analysis of the water composition at various depths reveals stratifications of different metals, especially of manganese.C) Physico-chemical variations: based on home-built sensors, oxygen, pH, sulphide, conductivity, and temperature profiles were obtained, demonstrating the unique correlations between these parameters (Fig. 2).D) compositionof the rocks around the lake: carbonatic dolomite mineral, with small percentages of manganese, is susceptible to leaching and acidic dissolution. For the first time, the presence of a well-defined zone appearing as a “white cloud” was revealed near the interfacial region of the oxygen depletion. This cloud is rich in Mn. A mechanism is herein proposed for the white cloud formation by means of analysis of Mn lacustral concentrations as well as of redox and pH variations. This phenomenon is referred to the first chemical dissolution of the rocks by the slightly acidic monimolimion zone. Mn(II) solution diffuses upwards and meets the zone of oxygen depletion, where pH increases. Mn(OH)2 (white hydroxide) starts to floculate, and buildup of the Mn salts takes place. Moving downwards, the hydroxide meets again the acidic zone, thus dissolving. Moving upwards, the white hydroxide encounters oxygen and an higher redox potential. At these pH (about 8), transformation of Mn(OH)2 to Mn3O4is quick and produces a reddish-brown powder, easy to precipitate. From time to time, hydrodynamics and convective diffusion lead to mixing of the water of the differen layers, and the brown color is visible even on the surface of the lake.The presence of these layers, characterized by different chemistry, pH and redox potential (more than 500 mV of potential difference), might be exploited to achieve electrical current generation and Mn depollution of the waters. The role of microrganism in the cycling of manganese is now under investigation aiming to the experiemntation of bio-electrochemical systems. The electrolysis catalyzed by bacteria naturally present in the lake is able to produce large amounts of Mn2O3 from Mn(II) hydroxide. A lab-scale experiment demonstrates that this process is viable. As-produced Mn2O3precipitates on the electrode surface in a non-insulating porous layer, with the final result of collecting Mn and clear the water from the white cloud effect.In this scenario, microbial fuel cells (MFC) might produce power by utilizing the microbial capacity of catalyzing the oxygen reduction at the cathode, and the Mn(OH)2 oxidation at the anode. Another type of MFC might develop power by reduction of Mn2O3.Furthermore, microbial electrolysis cells (MEC) could produce valuable products.In our opinion, the white cloud layer is a product of long-term building up of the Mn(II) concentration, and the process of water clarification may be achieved by a non-intrusive, long-term, application of the bacterial catalyzed electrochemical systems described. Fig. 1: Scheme of a typical meromictic lake, with the three main characteristic stratifications: mixolimion, chemocline, and monimolimion and Depth-profiles of the Idro lake, by sensor probes: A) redox potential; B) sulphide pontentiometric signal; C) temperature; D) O2 content.

Effects on Ni and Cd speciation in sewage sludge during composting and co-composting with steel slag

Sewage sludge and industrial steel slag (SS) pose threats of serious pollution to the environment. The experiments aimed to improve the stabilizing effects of heavy metal Ni and Cd morphology in composting sludge. The total Ni and Cd species distribution and chemical forms in the compost sewage sludge were investigated with the use of compost and co-compost with SS, including degradation. The carbon/nitrogen ratio of piles was regulated with the use of sawdust prior to batch aerobic composting experiments. Results indicated that the co-composting with SS and organic matter humification can contribute to the formation of Fe and Mn hydroxides and that the humus colloid significantly changed Ni and Cd species distribution. The decreased content of Ni and Cd in an unstable state inhibited their biological activity. Conclusions were drawn that an SS amount equal to 7% of the dry sludge mass was optimal value to guarantee the lowest amount of Cd in an unstable state, whereas the amount was 14% for Ni.

Kizilcaören ore-bearing complex with carbonatites (northwestern Anatolia, Turkey): Formation time and mineralogy of rocks

The results of isotope-geochronological and mineralogical studies of the rocks making up the Kizilcaoren fluorite-barite-REE deposit, northwestern Anatolia, Turkey are discussed in the paper. The ore is a constituent of the subvolcanic complex localized in a large fault zone. The complex combines (from earlier to later rocks): (1) phonolite and trachyte stocks, (2) carbonatite and carbonate-silicate dikelike bodies; and (3) fluorite-barite-bastnaesite ore in the form of thick homogeneous veins and cement in breccia. The K-Ar dating of silicate igneous rocks and carbonatites shows that they were formed in the Chattian Age of the Oligocene 25–24 Ma ago. Mineralogical observations show that the ore is the youngest constituent in the rock complex. Supergene alteration deeply transformed ore-bearing rocks, in particular, resulting in leaching of primary minerals, presumably Ca-Mn-Fe carbonates, and in cementation of the residual bastnaesitefluorite framework by Fe and Mn hydroxides. Most of the studied rocks contain pyrochlore, LREE fluorocarbonates, Nb-bearing rutile, Fe-Mg micas, and K-feldspar. The genetic features of the deposit have been considered. In general, the ore-bearing rock complex is compared in the set of rocks and their mineralogy and geochemistry with deposits of the Gallinas Mountains in the United States, the Arshan and Khalyuta deposits in the western Transbaikalia region, and Mushugai-Khuduk deposit in Mongolia. The Kizilcaoren deposit represents a variant of postmagmatic mineralization closely related to carbonatite magmatism associated with alkaline and subalkaline intermediate rocks.

Electrodeposition of Heterogeneous Mn-Bi Thin Films from a Sulfate-Nitrate Bath: Nucleation Mechanism and Morphology

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.