Formation Of MnO Research Articles

Complete oxidation of CO and propene as model component of diesel exhaust and VOC using manganese oxide supported on octahedral (AlO63−)-Ce3+

The complete oxidation of CO and propene as a model components of diesel engine exhaust and VOC have been investigated on a series of Ce doped MnOx/Al2O3 catalysts. The optimized MnOx/Al2O3 doped with 0.05 mol Ce showed higher CO and propene oxidation activity at 200 °C and 215 °C, respectively. The physicochemical properties of catalysts were analyzed by using XRD, RAMAN, NMR, H2-TPR, HRTEM and XPS techniques. The formation of Mn3O4 and Mn4+ species were observed on the catalyst surface. 27Al solid-state NMR showed the formation of octahedral [AlO63−]-Ce3+ species. These species were responsible for the donation of oxygen required for CO and propene oxidation. The adsorbed oxygen and oxygen vacancies were formed on the catalyst surface due to the synergistic interaction between Mn, Ce, and Al. The HRTEM results showed formation of well dispersed Mn over Ce-O-Al, and facilitated the proton abstraction required to activate the hydrocarbon. The mechanistic and kinetic aspects of CO and propene oxidation on catalyst surfaces have been reported in detail.

Catalytic Ozonation for Effective Degradation of Coal Chemical Biochemical Tail Water by Mn/Ce@RM Catalyst

An Mn/Ce@red mud (RM) catalyst was prepared from RM via a doping–calcination method. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were used to characterize the surface morphology, crystal morphology, and elemental composition of the Mn/Ce@RM catalyst, respectively. In addition, preparation and catalytic ozonation conditions were optimized, and the mechanism of catalytic ozonation was discussed. Lastly, a fuzzy analytic hierarchy process (FAHP) was adopted to evaluate the degradation of coal chemical biochemical tail water. The best preparation conditions for the Mn/Ce@RM catalyst were found to be as follows: (1) active component loading of 3%, (2) Mn/Ce doping ratio of 2:1, (3) calcination temperature of 550 °C, (4) calcination time of 240 min, and (5) fly ash floating bead doping of 10%. The chemical oxygen demand (COD) removal rate was 76.58% under this preparation condition. The characterization results suggested that the pore structure of the optimized Mn/Ce@RM catalyst was significantly improved. Mn and Ce were successfully loaded on the catalyst in the form of MnO2 and CeO2. The best operating conditions in the study were as follows: (1) reaction time of 80 min, (2) initial pH of 9, (3) ozone dosage of 2.0 g/h, (4) catalyst dosage of 62.5 g/L, and (5) COD removal rate of 84.96%. Mechanism analysis results showed that hydroxyl radicals (•OH) played a leading role in degrading organics in the biochemical tail water, and adsorption of RM and direct oxidation of ozone played a secondary role. FAHP was established on the basis of environmental impact, economic benefit, and energy consumption. Comprehensive evaluation by FAHP demonstrated that D3 (with an ozone dosage of 2.0 g/H, a catalyst dosage of 62.5 g/L, initial pH of 9, reaction time of 80 min, and a COD removal rate of 84.96%) was the best operating condition.

Modulating residual ammonium in MnO2 for high-rate aqueous zinc-ion batteries.

Manganese dioxide (MnO2), as a promising cathode candidate, has attracted great attention in aqueous zinc ion batteries (ZIBs). However, the undesirable dissolution of Mn2+ and the sluggish kinetic reaction are still two challenges to overcome before achieving good cycling stability and high-rate performance of ZIBs. Herein, β-MnO2 with chemically residual NH4+ (NMO) was successfully fabricated by controlling the washing condition and utilized as a cathode in a ZIB. Interestingly, NH4+, as a layer pillar in the tunnel structure of NMO, could enhance its conductivity by changing the chemical structure, contributing to accelerating the kinetics of the charge carrier. Moreover, the residual NH4+ in NMO could stabilize the chemical microstructure through the cationic electrostatic shielding effect and the formation of Mn-O⋯H bonds in NMO, promoting the reversible and successive insertion/extraction of H+/Zn2+ in the ZIB. As a result, the Zn/NMO battery exhibits excellent rate performance (up to 8.0 A g-1) and cycling stability (10 000 cycles). This work will pave the way for the design of cathode materials with nonmetallic doping for high-performance ZIB systems.

The effect of MnO<SUB align="right">2 concentration on the formation of MnO<SUB align="right">2/ZnO thin films with bifunctional thermal insulation and photocatalytic self-cleaning performance

This study focuses on fabricating manganese dioxide/zinc oxide (MnO2/ZnO) thin films using a two-stage chemical bath deposition (CBD) technique. The concentration effect of MnO2 thin film for the second stage deposition will be optimised and selected based on their thermal conductivity behaviour. It was found out that the wettability showed an increase in the contact angle (CA) after the addition of ZnO, with the highest CA of 14.5°C for 12% of ZnO. The same sample also demonstrated commendable thermal performance after reaching a constant temperature of 35.9°C in 65 minutes compared to the uncoated glass substrate. All thin films indicated low photocatalytic activity, where the best sample (12% of ZnO loading) yielded only 6% degradation efficiency of 10 mgL-1 malachite green (MG) as a model pollutant within 90 minutes. The porosity and agglomeration gradually increased following second stage deposition and ZnO introduction.

A new approach in the one-step synthesis of α-MnO2 via a modified solution combustion procedure.

Manganese oxides were synthesized systematically via the solution combustion procedure using two kinds of fuels, namely glycine and urea. The influences of the type of fuel and the fuel ratio were deeply investigated to explain the phase evolution and morphology of the product. The synthesized nanostructured powder was characterized by X-ray diffraction, particle size analysis, and FESEM. Furthermore, the thermodynamic aspects of all the synthesis reactions were studied by the calculation of the adiabatic temperature. Various manganese oxides, such as MnO, Mn3O4, Mn2O3, and MnO2, were obtained by varying the fuel ratio from 0.15 to 2. It was found that decreasing the fuel ratio promoted the formation of MnO2 by declining the combustion temperature and reductive conditions of the system. However, α-MnO2 could be simply achieved by adding KNO3 in a modified solution combustion process under fuel-lean conditions. Further heat treatment of the product was found to increase the crystallinity of the α-MnO2 nanoparticles.

A simple strategy to tune α-MnO2 and enhance VOC oxidation via precipitation rate control

Manganese dioxide (MnO2) has been widely used in environmental catalysis. The precipitation method is commonly used for preparing MnO2 in industrial applications, but always leads to unsatisfactory removal efficiency due to the intense precipitation rates of the metal precursors. Herein, a simple strategy was designed to control the precipitation rate. On the basis of 2MnO4− (aq) + 2NH4＋ (aq) = N2 (g) + 2MnO2 (s) + 4H2O (l), the precipitation rate was well regulated by the release of NH4+ in solution. Different precipitants with various release rates of NH4+ (i.e. urea, ammonium carbonate, and sodium bicarbonate) were investigated. The lower precipitate rate obtained by urea is favorable for the formation of nanoparticle-like MnO2 with larger surface area and stronger catalytic activity than the nanorods and bulk MnO2 obtained with ammonium carbonate and sodium bicarbonate, respectively. The precipitate rate could be further optimized by changing the amount of urea to obtain the optimal MnO2 catalysts, which were efficiently applied in the complete catalytic oxidation of VOC, mineralizing 100% of 1000 ppm of ethyl acetate into CO2 at 200 °C under a high GHSV of 78,000 h−1. Various characterization methods combined to reveal that the morphology, surface Mn4+ /Mn3+ ratio, surface oxygen species and low-temperature reducibility determined the excellent catalytic performance. This work provides a new strategy for tuning MnO2 and enhancing VOC elimination via improved precipitation methods.

Ultrasonication pretreatment assisted rapid co-assembly of cellulose nanocrystal and metal ion for multifunctional application

Co-assembly of metal ion and cellulose nanocrystals (CNC) is a promising strategy to fabricate novel iridescent CNC materials with advanced applications. By combining ultrasonication pretreatment and vacuum-assisted self-assembly (VASA) technique, a facile and rapid strategy is proposed to prepare the Mn2+-doped carboxylated CNC (C-CNC) iridescent films with multifunctional application. The ultrasonication pretreatment temporarily disassembles the aggregates of C-CNC nanorods caused by the electrostatic interaction between negative charged C-CNC and Mn2+. The subsequent VASA process accelerates the self-assembly of chiral liquid crystals prior to the re-agglomeration of C-CNC by the bridge effect of Mn2+. Furthermore, the as-prepared Mn2+/CNC film exhibits a rapid and visible color change in ammonia atmosphere along with the formation of MnO2. The reversible change can be realized by the stimulation of reducing agent. The derived MnO2/C-CNC composite film displays efficient removal of methylene blue dye in aqueous solution by both of adsorption and degradation procedure.

Hydrothermal growth of pompon-like manganese oxide microspheres with embedded nickel ions as single-atom catalysts for urea oxidation

]Manganese oxides (δ-MnO2) with pompon-like microspheres and non-spherical shaped particles were hydrothermally grown on Ni foam substrates in the presence and absence of a structure-directing agent (ammonium fluoride), respectively. The intercalated K+ ions in the layer-structured MnO2 were exchanged by the dissolved nickel ions from Ni foam during hydrothermal synthesis, leading to the formation of MnO2 with embedded nickel ions (labeled as Ni foam@Ni-MnO2). The dominated oxidation state of nickel ions in MnO2 was found to be trivalent (Ni3+), making Ni foam@Ni-MnO2 a promising catalyst electrode for direct and indirect urea oxidation reactions (UORs). Ni foam@Ni-MnO2 exhibited large electroactive surface area and high oxidation state of nickel-ion catalyst for adsorption of urea molecule and the successive cleavage of urea. Pompon-like microspheres with ultrathin nanosheets offered abundant pore channels to facilitate the spread of urea molecules and products in the UOR process. Electrochemical impedance spectroscopy revealed that Ni foam@Ni-MnO2 with pompon-like microspheres has lower direct UOR impedance and indirect UOR impedance in the regeneration of active Ni3+ catalyst than Ni foam. Thus, Ni foam@Ni-MnO2 displayed greater current density and smaller onset potential than bare Ni foam in catalyzing UOR.

Simultaneous Size- and Phase-Controlled Synthesis of Metal Oxide Nanocrystals through Esterification Reactions

Here, we report on the synthesis of metal oxide (manganese oxide) nanocrystals with simultaneous size- and phase-controlled manners through thermal decomposition of metal oleate. Bulk manganese oxide powders were applied as precursors, which react with oleic acid to yield manganese oleate at elevated temperature. In the presence of long-chain alkyl alcohols, these as-formed manganese oleates would react with alcohol to yield esters, which consequently leads to manganese hydroxide (oxide) (MnO or Mn3O4) nanocrystals. In this way, the size of manganese oxide nanocrystals can be tuned by different amounts of alkyl alcohols. Furthermore, the phase of manganese oxide nanocrystals can also be simultaneously controlled, where a small amount and large amount of alkyl alcohols lead to the formation of MnO and Mn3O4 phase, respectively. These high-quality manganese oxide nanocrystals are able to self-assemble into ordered nanocrystal superlattices.

Green Three-Step Electrodeposition of Mn+3 Rich Layered δ-Phase MnO2 Nanofibers on Silicon and Epitaxial Graphene-Silicon Carbide Heterostructures

Mixed valence manganese oxides (MnOx) have attracted significant research interest in recent years due to the easily reversible redox reactions between manganese oxidation states (Mn+2, Mn+3, and Mn+4)1 which enable applications in catalysis2, energy storage3, and gas sensing4. Of the manganese oxides manganese dioxide (MnO2) has been of particular interest due to its wide variety of synthesized structural polymorphs ((β)1x1 tunnel5, (α)1x2 tunnel5 (γ) spinel5, (δ) layered5) which allow for enhanced control over the available surface area and reactive properties of MnO2. Among these structural polymorphs, the α and δ phases exhibit mixed-valence character with Mn+3 defects being found throughout the crystal structure5. Mn+3 defects have been found to increase the catalytic activity of MnO2 making its presence desirable6. Hexagonal δ-MnO2, in particular, contains a large number of Mn+3 ions as the interlayer contains Mn+2/+3 ions to neutralize the layer charge from Mn+3 lattice defects7. However, the controlled synthesis of hexagonal δ-MnO2 has proven challenging and often relies on the use of harsh chemicals1, high temperatures1, and long reaction times1. These methods also rely on permanganate salts1 as the manganese precursor, which leads to the formation of monoclinic δ-MnO2 and significantly reduces the number of Mn+3 defects in the crystal lattice. In this work, we present the green facile synthesis of high Mn+3 content hexagonal δ-MnO2 via electrodeposition on both silicon(Si) and epitaxial graphene/silicon carbide(EG/SiC) substrates. The electrodeposition was carried out in a three-electrode electrochemical cell with an Ag/AgCl reference electrode, a Pt counter electrode, and the substrate (Si or EG/SiC) as the working electrode utilizing a 100mM manganese acetate solution. The electrodeposition process contained three steps, an initial pulse at the oxidation potential to seed the surface with oxygen, a second pulse at the reduction potential to deposit manganese on the surface, and a third pulse at the oxidation potential to oxidize the deposited manganese, with the potentials determined by cyclic voltammetry. The resulting δ-MnO2 thin films were then characterized through Raman spectroscopy, X-Ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy(AFM) to determine its crystalline phase and surface morphology. Raman spectroscopy(Fig. 1) confirmed the formation of MnO2 on both substrates due to the presence of Raman peaks between 650-640cm-1,8 575-585cm-1,8, and 490-510cm-1,8, which are associated with the Mn-O symmetric stretching bond8, the Mn-O stretching bond in the basal plane8, and Mn-O stretching bond in the [MnO6] octehedra8. The formation of the δ phase is confirmed by the presence of a weak peak at 130cm-1,2 consistent with the literature. The observed 9cm-1 redshift of the 490-510cm-1,6 between Si and SiC substrates is associated with the weakening Mn-O stretching bond on Si, which combined with the strengthening of the peak at 600-620cm-1 indicates that the growth on Si contains a higher rate of Mn+3defects2,8. XPS corroborated this result and indicated that the manganese in the δ-MnO2 deposited on EG/SiC had an average oxidation state of 3.3. The AFM images indicated that the surface was made up of nanofibrous nanoparticles, with the deposition on Si exhibiting significantly larger nanofibers (Fig 2.). SEM confirmed this (Fig. 3) and indicated that the deposition on EG/SiC was made up of microplates ~40umx40um in size, which was not observed in the deposition on Si. We believe this variation in surface morphology is due to interactions between SiC and MnO2, which are not present when δ-MnO2 is grown on Si. The reactivity of the deposited δ-MnO2 was then tested by depositing 4 Ti/Au (30nm/120nm) contacts on the δ-MnO2/EG/SiC heterostructures to form a simple gas sensor, which was tested against 5ppm NO2, 5ppm NH3, 1000ppm IPA, and 1000ppm methanol. The sensor displayed a remarkably fast response/ recovery time of 3.8s/2.2s to NH3 and 3.4/6.0s to NO2(Fig. 4), demonstrating the high reactive potential of the δ-MnO2 thin films. This reactivity demonstrates that our electrodeposited δ-MnO2 provides a good candidate for use in other applications of MnO2 such as energy storage and catalysis.

High electrochemical performance of spinel Mn3O4 over Co3O4 nanocrystals

Manganese and Cobalt oxide (Mn3O4 and Co3O4) nanocrystals are prepared via a simple and low cost combustion synthesis. The structural studies using XRD, Raman Spectroscopy and Fourier Transform Infrared Spectroscopy reveal that, the formation of Mn3O4 in tetragonal structure with I41/amd (141) space group and Co3O4 in cubic structure with Fd3m (227) space group. The average crystallite size of nanocrystals are estimated using Debye Scherrer formula and found to be 14 and 22 nm for Mn3O4 and Co3O4, respectively. The SEM images of as-prepared Mn3O4 and Co3O4 nanocrystals show the irregular shape of grains and uniform spherical grains with an average grain size of 100 and 120 nm. The binding energy peaks of Manganese, Cobalt and Oxygen from EDS and XPS spectra show the chemical purity of the samples. The optical band gap of Mn3O4 and Co3O4 nanocrystals are 2.93 and 2.50 eV respectively. The magnetic properties of Mn3O4 and Co3O4 nanocrystals prove a strong ferromagnetic nature at 5 K temperature. The electrochemical investigations of the samples demonstrate that the Mn3O4 nanocrystals exhibited a high specific capacitance of 417 F g−1 at a current density of 0.5 A g−1 with almost 100% coloumbic efficiency after 600 cycles and good cyclic stability up to 10,000 cycles. The poor electrochemical behavior of spinel Co3O4 proves that Mn3O4 nanocrystals are good electrodes for electrochemical capacitors due to greater mass transport of electrolyte ions into the Mn3O4 electrode.

Purification of the Acidic Vanadium-Bearing Solution with a Novel Approach of Chemical Precipitation

Calcified roasting followed by dilute sulfuric acid leaching is a promising process for cleaner vanadium extraction from converter vanadium slag. However, some impurities, like Ca, Mg, Mn, Si and Al, also transfer into the leaching solution, accompanying V during the dilute sulfuric acid leaching, leading to the product of vanadium pentoxide prepared from this acidic vanadium-bearing solution, inferior to the product from the traditional process of sodium roasting and water leaching. A chemical precipitation method was firstly proposed to purify this acidic vanadium-bearing solution with a new prepared remover of MnNH4F3, which combines neutralization and fluoride precipitation into one operational step to remove impurities of Ca2+, Mg 2+, Al3+ and Si4+ in an acidic pH range, simultaneously. Effecting factors involved in the purification process were investigated. It was found that removals of Ca, Mg and Al were all over 95% and around 55% of Si was removed as well at stirring speed of 200 rpm, adding coefficient of 1.6, temperature of 50 °C, reaction time of 30 min and pH of 4.50 ± 0.05, while the loss of vanadium was kept lower than 5%, which was attributed to the reason that the purification reactions mainly proceeded on the surface of the remover. Adding flocculant of polyacrylamide was conductive to accelerating sedimentation of the precipitate and reducing the loss of vanadium. Meanwhile, the filter aid of diatomaceous could improve the filtration performance of the slurry. Ammonium persulfate could effectively oxidize and separate Mn2+ in the form of MnO2 from the vanadium-bearing solution which had been treated by MnNH4F3, but performed less selectivity over Mn2+, and the loss of vanadium was unacceptable. The product of vanadium pentoxide prepared from the purified vanadium-containing solution satisfied the requirements for the standard of grade 98.

Dynamic structural evolution of oxygen vacancies in lithium rich layered composites cathodes for Li-ion batteries

Understanding structural evolution in lithium-rich layered oxidized composites (LLO) is fundamental to design improved cathode materials for rechargeable lithium-ion batteries (LIBs). In particular, retrieving quantitative structural parameters are essential factors to unveil the hidden phases or atomic orderings affecting the properties of LIBs. The oxygen-vacancies heterogeneity is revealed in 0.5Li2MnO3·0.5LiNi1/3Co1/3Mn1/3O2 (LR-NCM) during de-lithiation process via rigid structural refinements. Through the in-situ/ex-situ X-ray absorption spectroscopy (XAS) in synergy with first principles calculations, the dynamic structural (and electronic) evolution of oxygen vacancies is confirmed to be in the form of MnO2 (represents vacancy site) for Li2MnO3 component. With the formation of oxygen vacancies in Li2MnO3 component, the oxygen-vacancy-bearing structure MnO2 also play significant supporting role on its parent structure without obvious Mn ions activity. This result offers new perspectives on synergistic improvement in the electronic and structural evolution, which is the key to design high energy density cathode materials for next-generation lithium ion batteries.

High temperature characteristics and phase compositions of Cu/Mn multilayers with the different average thickness prepared by electrodeposition

Four different Cu/Mn multilayers are prepared on ferritic stainless steel 430 by direct current deposition, and the electrodeposition behavior of Cu and Mn is studied by chronopotentiometry and cyclic voltammetry. After oxidation at 750 °C for 500 h, the discontinuous Si oxides are formed in the vicinity of substrate/Cr2O3 oxide interface, Cu diffuses outward faster than Mn in CuMn compound oxides, and oxide compositions of designed samples are discussed based on the Cu-Mn-O phase diagram. The Cu-Mn compound oxide coatings do not effectively block outward diffusion of Fe, but effectively block Cr. The ASR value of the sample with the ratio of Cu/Mn about 1 is the lowest among all the samples, though its thickness of oxide layer (~15 µm) is in the middle of all samples. Besides Cr2O3 and SiO2, the formation of Mn3O4 and Fe2O3 oxides with low conductivity lead to the high ASR.

Biosynthesis of manganese oxide nanoparticles using Urginea sanguinea and their effects on cytotoxicity and antioxidant activity

Urginea sanguinea, a detoxifier utilised in African herbal medicine, contains toxic cardiac glycosides that are considered to have anticancer properties. In this study, manganese oxide nanoparticles (MnOxNPs) were synthesised using Urginea sanguinea and its isolates, a homoisoflavone (urgineanin E) and a mixture of bufadienolides (proscillaridin A, scillaren A and 5α-4,5-dihydroscillaren A), and their cytotoxic effects and antioxidant activities were investigated. The presence of absorption peaks between 262 nm and 272 nm using ultraviolet-visible spectroscopy, and Mn-O-Mn vibrations in the infrared spectrum confirmed the formation of MnO x NPs. Images from high-resolution transmission electron microscopy and scanning electron microscopy revealed interconnected spheroidal shapes with nanorods for MnO x NPs (extract), and ultrathin nanosheets assembled as nanoflowers for MnO x NPs (urgineanin E) and MnO x NPs (bufadienolides). The synthesised nanoparticles were evaluated for their anticancer properties using the MTT assay. The cytotoxic effects of MnOxNPs against A549 and HepG2 cancer cell lines increased with increasing concentration with no significant cytotoxicity towards HEK293 normal cells. MnOxNPs were found to exhibit moderate free radical scavenging activity. This warrants further research into the use of manganese oxide nanoparticles synthesised with medicinal plants and active compounds as anticancer agents.

Carbon Nanotube–Manganese oxide nanorods hybrid composites for high-performance supercapacitor materials

In the present work, multiwall carbon nanotubes (CNTs) were used as a reducing agent for the preparation of CNT-MnO2 nanocomposites by varying the amount of potassium permanganate (KMnO4). The chemical compositions of the as-synthesized materials were analyzed using X-ray diffraction, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy, which showed the formation of MnO2 in the CNT-MnO2 nanocomposites. The electrochemical properties of the CNT-MnO2 nanocomposites were thoroughly investigated through cyclic voltammetry, charge–discharge, and impedance studies. The CNT-MnO2-25 nanocomposites appeared with the highest specific capacitance of 674Fg−1 at a current density of 2Ag−1; they also displayed an excellent capacitance retention of ∼110% even after the completion of 5000 continuous charge–discharge cycles at 10Ag−1.

A Metal‐Segregation Approach to Generate CoMn Alloy for Enhanced Photothermal Conversion of Syngas to Light Olefins

As a promoter, Mn is widely used in Fischer–Tropsch synthesis (FTS) such as in the form of MnO, but few studies have focused on the effect of CoMn alloy on catalytic performance of FTS. Herein, a catalyst of CoMn alloy–loaded MnO is synthesized by a one‐step wet‐chemical method. The metallic Mn is formed through a segregation process from MnO support, which is induced by Co that is decomposed from Co‐contained precursor; then, the two metals form an alloy in the following growing process. In photothermocatalytic FTS, the optimized catalyst delivers good selectivity for light olefins (27.0% with the ratio of olefins to paraffins = 3.2); meanwhile, low CO2 selectivity (22.6%) ensures the effective use of carbon resources. Characterizations, including X‐ray photoelectron spectroscopy, high‐resolution transmission electron microscopy, and energy dispersive X‐ray mapping, reveal that the catalysts comprise CoMn alloy on MnO support. The formed CoMn alloy is the key for promoting the generation of light olefins. This study demonstrates a novel catalyst of CoMn alloy–loaded MnO for the production of light olefins via CO hydrogenation, which attains a value‐added solar‐to‐chemical energy conversion.

Understanding the chemistry of manganese fertilizers and glyphosate mixtures by using synchrotron X-ray spectrometry

The spraying of tank mixtures with manganese (Mn) and glyphosate is a practical alternative to alleviate nutritional deficiency while controlling weeds. Thereby, this study investigates the chemical interactions between glyphosate and commercial sources of Mn, such as MnSO4, Mn–phosphite, Mn–EDTA, Mn–glycine, and MnCO3. Nearly 30% of the Mn supplied as MnSO4 and Mn–glycine precipitated with glyphosate, yielding a Mn:glyphosate solid complex with molar ratio of nearly 2:1, both presenting similar chemical environment. XANES analysis of the supernatants indicate no formation of Mn–glyphosate soluble complexes. The use of Mn–EDTA as well as the maintenance of the mixture pH below 2.5 prevented precipitation, while pH above 7 caused the formation of MnO(OH). In conclusion, the Mn source and the pH of the mixtures matter. The absence of Mn–glyphosate soluble complexes suggests that dissolved Mn and glyphosate are still able to accomplish their functions, however, the precipitation significantly decreases their active availability.

One‐step Preparation of Conducting Polymer/Metal Oxide Doped RGO Trinary Composite for Supercapacitor Applications

AbstractA naive one‐pot strategy developed to prepare high‐performance trinary based material as an energy storage material for supercapacitor. Herein, we have systematically studied and established an effortless and proficient synthetic method to formulate reduced graphene oxide (rGO)/polyaniline (PANI)/manganese dioxide (MnO2) (RPM) trinary material in one‐step without any additional oxidizing/polymerizing agent and acidic condition. The approach of “one arrow two targets” have employed to synthesize trinary based nanocomposite. For the first time, we have synthesized this trinary material in one step. Initially, in‐situ synthesized carbonic acid was consumed as a reducing agent to reduce the graphene oxide (GO) as well as it provided acidic condition for the formation of MnO2 and polymerization of aniline. Secondarily, MnO2 particles synthesized from KMnO4 precursor, which acted as an oxidizing agent to polymerize aniline in the presence of carbonic acid. The material reflected the electrical double layer capacitance as well as pseudocapacitance of RGO and PANI/MnO2. The material exhibited the maximum specific capacitance, 592 F/g at 1 A/g current density corresponds to excessive specific energy and specific power 66.6 Wh/kg, 1800 W/kg, respectively. This familiar route of direct production of graphene with the synergism of PANI‐MnO2 on carbon can be useful for large‐scale fabrication of nano‐carbon material for diverse applications including energy storage application.

Recycling of discarded coin cells for recovery of metal values

Lithium-metal primary batteries, widely used in portable electronics, contain lithium, manganese, and carbon, which can be recycled to conserve resources and prevent environmental damage. This study investigates the thermal response of active material under ambient conditions and its effects on manganese dissolution in organic acid. Thus, spent lithium metal batteries were manually dismantled, the lithium they contain was dissolved in a mixture of distilled water and isobutyl alcohol, and the steel and active cathode material were mechanically separated. The thermal exposure of active material comprising MnO2 and C resulted in carbothermal reduction with products Mn3O4 and MnO. The composition of product at optimum condition (800 °C, 30 min) comprises 60 wt% Mn, 21.5 wt% O, and 18.5 wt% C in the form of MnO, Mn3O4, and C. Manganese extraction increased significantly on thermal treatment, yielding 81% at optimum condition. Therefore, thermal treatment for the indigenous reduction of MnO2, followed by leaching in an organic acid, is proposed for lithium and manganese value recovery from spent coin cells. The activation energy for thermal dissociation of active material has been identified as 20.96 kJ/ mol, and mass balance for the process followed has also been investigated.