Manganese Hydroxide Research Articles

Enhanced phosphate anion flux through single-ion, reverse-selective mixed-matrix cation exchange membrane

Phosphate recovery from wastewater is vital for both environmental sustainability and resource conservation, offering the dual benefit of reducing phosphate pollution while providing a valuable source of this essential nutrient. We previously reported an approach for synthesizing hydrous manganese oxide (HMO) nanoparticles within a polymeric cation-exchange membrane (CEM) to achieve a phosphate-selective mixed-matrix membrane (PhSMMM); however, the phosphate flux was lower than desired. Herein, we demonstrate a next-generation PhSMMM membrane with enhanced phosphate flux and selectivity. Experimental results confirm the successful incorporation of up to 28 wt% HMO nanoparticles into the polymeric CEM. The new PhSMMM exhibits a phosphate flux of 1.57 mmol∙m–2.hr–1 (an 8.5X enhancement), with selectivity over chloride, nitrate, and sulfate ions of 9, 11, and 104, respectively. This significant enhancement in phosphate flux marks a promising advancement in a sustainable solution for phosphate removal and recovery from wastewater.

Waste Zinc–Carbon Battery Recycling: Focus on Total Material Recovery

Currently, less attention is paid to zinc–carbon batteries, although they are still widely used and are among the major types of batteries collected and recycled. The recycling technologies currently in use do not allow the complete recovery of resources, are not self-sufficient and require additional financing. Therefore, this paper aims to study the possibility of complete recycling of waste zinc–carbon batteries and to suggest the practical use of the final products generated in the recycling process. The possibility of complex processing of spent zinc–carbon batteries using mechanical separation and processing of the battery’s components (steel case, zinc electrode, graphite electrode, polypropylene and paper insulators) is justified. The separation of spent electrolytes from other components of batteries with hydrochloric acid was studied. It was shown that the extraction of Zn2+ and NH4+ cations takes place following the addition of an equivalent amount of Na3PO4 solution and water-insoluble NH4ZnPO4 salt sedimentation. Waste agglomerate (mixture of MnO2, MnO(OH), and graphite) was regenerated to its initial composition (MnO2, graphite) at a temperature of 300–325 °C; manganese (III) hydroxide was oxidized to manganese (IV) dioxide. Thermal destruction of polypropylene and paper insulators with additional introduction of polyethylene into the primary mixture produced pyrolysis liquid, pyrocarbon and pyrolysis gas as products. The practical use of the products obtained and compliance with the environmental requirements of the suggested method of waste batteries recycling were shown.

Study on harmless treatment of electrolytic manganese residue by low temperature thermochemical method.

The Electrolytic Manganese Residue (EMR) is a by-product of the electrolytic manganese metal (EMM) industry, containing high concentrations of potential pollutants such as NH4+-N and soluble Mn2+. These components pose a serious threat to the ecological environment. To explore accurate, efficient, and harmless treatment methods for EMR, this study proposes a low-temperature thermochemical approach. The orthogonal experiment design investigates the effects of reaction temperature, reaction time, quicklime (CaO), sodium carbonate (Na2CO3), sodium phosphate (Na3PO4) (Reviewer #3), and water consumption on manganese solidified and ammonia removal from EMR. The results indicate that optimal conditions are a reaction temperature of 60 ℃ (Reviewer #3) and a reaction time of 10min. CaO precipitates Mn2+ as manganese hydroxide (Mn(OH)2) (Reviewer #3), achieving effective manganese solidified and ammonia removal. The addition of Na2CO3 causes Mn2+ to form manganesecarbonate (MnCO3) (Reviewer #3)precipitate, while Na3PO4 makes Mn2+ form Manganese phosphate trihydrate (Mn3(PO4)2·3H2O) (Reviewer #3). Increased water consumption enhances the interaction adequacy between ions. Under optimal conditions (CaO 10%, Na2CO3 1%, Na3PO4 0.5%, and 80% water consumption), the removal rate of ammonium ions reaches 98.5%, and the solidification rate of soluble Mn2+ is 99.9%. The order of influence on ammonium ion removal is CaO > water consumption > Na3PO4 > Na2CO3. Therefore, this study provides a new method for low-cost process disposal and efficient harmless treatment of EMR (Reviewer #3).

Synthesis, characterization and reactivity of a Mn(III)–hydroxido complex as a biomimetic model for lipoxygenase

Manganese hydroxido (Mn–OH) complexes supported by a tripodal N,N′,N″-[nitrilotris(ethane-2,1-diyl)]tris(P,P-diphenylphosphinic amido) ([poat]3−) ligand have been synthesized and characterized by spectroscopic techniques including UV–vis and electron paramagnetic resonance (EPR) spectroscopies. X-ray diffraction (XRD) methods were used to confirm the solid-state molecular structures of {Na2[MnIIpoat(OH)]}2 and {Na[MnIIIpoat(OH)]}2 as clusters that are linked by the electrostatic interactions between the sodium counterions and the oxygen atom of the ligated hydroxido unit and the phosphinic (P=O) amide groups of [poat]3−. Both clusters feature two independent monoanionic fragments in which each contains a trigonal bipyramidal Mn center that is comprised of three equatorial deprotonated amide nitrogen atoms, an apical tertiary amine, and an axial hydroxido ligand. XRD analyses of {Na[MnIIIpoat(OH)]}2 also showed an intramolecular hydrogen bonding interaction between the MnIII–OH unit and P=O group of [poat]3−. Crystalline {Na[MnIIIpoat(OH)]}2 remains as clusters with Na+---O interactions in solution and is unreactive toward external substrates. However, conductivity studies indicated that [MnIIIpoat(OH)]− generated in situ is monomeric and reactivity studies found that it is capable of cleaving C-H bonds, illustrating the importance of solution-phase speciation and its direct effect on chemical reactivity.Synopsis: Manganese–hydroxido complexes were synthesized to study the influence of H-bonds in the secondary coordination sphere and their effects on the oxidative cleavage of substrates containing C-H bonds.

Preparation of core-shell NiMnB/rGO composite electrodes and their application in hybrid supercapacitors

The rapid advancement of science and technology has led to the development of electronic devices that require higher energy storage capacities. Because of their greater energy as well as power density capabilities, hybrid supercapacitors offer an answer to the problems that result from the limitations of both supercapacitors and batteries when it comes to power densities and energy density. Borate ion-functionalized nickel manganese hydroxide nanoparticles (denoted as NiMnB) were prepared by a simple chemical reduction method, and novel complexes were obtained by growing NiMnB with a core-shell structure on reduced graphene oxide (rGO). The NiMnB inner core facilitates electron transport, while the borate/metal borate shell layer on the outer layer aids in OH- absorption. Additionally, rGO integrates the dispersed nanoparticles, resulting in a comprehensive conductive system. This design optimizes the electrochemical performance of NiMn-based electrodes. The specific capacitance of the NiMnB/rGO-16 electrode was 916 F g−1 when tested at a current density of 1 A g−1. NiMnB/rGO-16 was used as the positive electrode and activated carbon (AC) as the negative electrode assembled the hybrid supercapacitor. It showed strong cycling stability and an energy density of 50.2 Wh kg−1.

Taphonomy and paleohistology of a dinosaur rib from Marília Formation, Bauru Group, in the state of Minas Gerais, Brazil

The Bauru Group (Campanian–Maastrichtian) has one of the richest fossil records of Cretaceous in South America. All dinosaur fossils from this unit were assigned to Saurischia, most of them poorly preserved. We present the histological and taphonomic analysis of a dinosaur dorsal rib fragment from the Marília Formation in the western state of Minas Gerais. Thin sections were prepared to describe the microstructures of the bone tissue and the fossilization processes involved in preserving the specimen. An elemental analysis was also performed to verify the chemical composition of the fossil and rock matrix. Haversian bone was identified in the rib cortex, and no growth marks or an external fundamental system were found. The rib probably belonged to a saurischian dinosaur because of its plank shape and elliptical cross-section. Hypotheses regarding taphonomic processes were inferred. An extended period of subaerial exposure, followed by high-energy transport, was interpreted due to extensive fractures and signs of abrasion on the outer surface of the bone. Pyrite pseudomorphs (framboids) indicate that the bone was deposited in a reductive environment. After burial, the rapid precipitation of calcite and alkaline stability allowed the preservation of apatite during the recrystallization phase. The manganese hydroxides were deposited on apatite crystals during early diagenesis. We concluded that the fossil rib presented a common taphonomic bias identified among vertebrate fossils of the Bauru Group, which is associated with the exposure of the bones to arid and semiarid climates, their transport into the depositional environments and pedogenetic influence during fossil diagenesis.

The green reductive leaching of manganiferous iron ore and Mn3O4 nanoparticles production: Kinetic modeling and comparison of various reductants

BackgroundSecuring critical metals is crucial for the transition from fossil fuels to renewable energies. In this regard, extracting metals from various sources and low-grade ores can lead to the sustainable production of metals. Manganese, as a strategic metal, can play a significant role in achieving this goal. MethodsIn this study, various reductants such as oxalic acid, citric acid, ascorbic acid, acetic acid, tannic acid, hydrogen peroxide, iron (II) sulfate, sodium thiosulfate, and DL-malic acid were used to evaluate the feasibility and comparison on the manganiferous iron ore leaching. Significant findingsDL-malic acid was chosen as the main reductant to investigate other factors because it is novel (as a reductant), eco-friendly, cost-effective, accessible, and easily storable. Therefore, more detailed studies on the dissolution of manganiferous iron ore in the presence of DL-malic acid as the reductant were carried out considering different levels of temperature, particle size, acid concentrations, and leaching time. Increasing the temperature from 298 K to 348 K notably boosted the leaching recovery from 27.00 % to 70.11 %. It was observed that decreasing the ore particle size from -212 μm to -38 μm resulted in an enhancement of leaching recovery from 57.74 % to 70.11 %. Also, adding only 250 % stoichiometry of DL-malic acid notably increased the leaching recovery to 70.11 %, compared to just 5.32 % in a reductant-free medium. It should be noted that the concentration of sulfuric acid had a direct impact on leaching recovery, increasing by 28.28 % with a concentration of 0.5 M and by 93.08 % with a concentration of 4 M. In this research work, the kinetic of the leaching process was modeled using the modified shrinking core model (MSCM). The calculated activation energy was about 33 kJ/mole, which confirmed that the mixed mechanism controlled the reaction. Mn3O4 nanoparticles were synthesized using a pregnant leach solution (PLS) and through a multi-stage co-precipitation method. In this method, hydrogen peroxide was used to modify the manganese hydroxide phase as a more eco-friendly method than other heat treatment methods. The SEM and EDX analyses revealed an average particle size of 80 nm with spherical shapes and no impurities. The XRD pattern of the synthesized nanoparticles confirmed the Mn3O4 phase composition.

Влияние природных и антропогенных факторов на формирование микроэлементного состава буроземов острова Рейнеке

The role of natural and anthropogenic factors in the formation of the microelement composition of the brown soils of the Reinecke Island is considered. Analysis of the concentration coefficients of heavy metals in the island brown soils showed that during soil formation, active accumulation occurs in the surface horizons of Zn, Cu, Cd and Co. The research results indicate the prevailing influence of soil formation features on the content and distribution of heavy metals in areas remote from the coast. As we approach the coastal zone, beloved by tourists for recreation, the content of Zn, Cu, Cd increases significantly in the surface layer of the island's brown soils, which is probably due to the local anthropogenic impact that takes place there. The data on the profile distribution of heavy metals in the studied brown soils reflect the intensity of the processes of humus formation occurring in the profile of brown soils and indicate the affinity of Pb, Cd to organic complexes. This is confirmed by the presence of significant positive correlation coefficients between organic matter and Pb and Cd content. The role of physical indicators of borozems on the fixation of a number of heavy metals in their profile is also noted. Quantitative indicators of Cr and Ni content are most determined by the distribution of the silty fraction. High values of the correlation coefficient between pH, the sum of exchange bases and the Mn content may indicate the influence of acid-base properties on its accumulation in the soil profile. Manganese hydroxide plays an important role in fixing Co in the brown soils of the island. The correlation between Co and Mn is estimated as noticeable.

Features of the Tanalyk gold placer and its primary sources (the Baymak ore-placer cluster, Southern Urals)

The article presents the results of a study of the Tanalyk placer, which is part of the Baymak ore-placer cluster. It is shown that gold is predominantly bright yellow in color and has lump-shaped, wedge-shaped, plate-shaped and wire-rod-shaped forms. In terms of granulometric composition, it belongs to the large and medium class and is characterized mainly by medium roundness. The uniformity of morphological varieties of gold in different lithological and stratigraphic horizons indicates the inheritance of gold from ancient deposits to young ones.
 Placer gold is of high quality and has a fairly consistent composition; the main impurity here is silver, the content of which varies from 0.2 to 9%. The average fineness of gold in the placer in the following areas: Baymak pond – 938, Shurinsky log – 935, Aktash log – 943, Tanalyk (lines 1502-1559) – 917. Hypergene new formations on the surfaces of gold grains are represented by high-fineness rims. A common feature for gold of all size classes is the presence in the depressions and on their surface of films of iron and manganese hydroxides, crusts of fine-grained quartz, chlorite, and less commonly biotite, in which a large number of microparticles of very high-fine gold measuring 0.1–0.5 μm were found.
 The typomorphism of schlich gold, its composition and features of the internal structure indicate that the main source of gold was gold-quartz mineralization in the zones of wall-metasomatites of the Kul-Yurt-Tau gold-pyrite deposit, gold-polymetallic and gold-barite deposits Grafskoye, Troitsk and Novo-Troitsk. The junction points of diagonal neotectonically active lineaments with meridional magma- and ore-supplying faults form polychronic and polygenic through ore-concentrating structures. Dispersed gold occurrences in these structures are placer-forming and serve as the main source of the formation of large placers.

Нанопрайминг семян сои с применением марганецсодержащего нанокомпозита в арабиногалактановой матрице

The results of studies on the stimulation of soybean seed germination under the influence of nanopriming with a chemically synthesized nanocomposite (NC) based on manganese-containing nanoparticles and a water-soluble polysaccharide arabinogalactan are presented. The study was carried out on the phytopathosystem: soybean seeds Glycine max (L) – phytopathogenic bacterium Pectobacterium carotovorum. Phytopathogenic bacterium P. carotovorum causes the infectious disease soft rot in various plant species from vegetables to trees and shrubs. After nanopriming (treatment Mn(OH)2/AGs NC), seed germination, biometric characteristics (mass and length of the root and hypocotyl) and biochemical parameters of soybean seedlings (content of reactive oxygen species (ROS), activity of antioxidant enzymes, amount of lipid peroxidation products) were analyzed. It was shown that the infection of seeds with P. carotovorum led to a decrease in their germination, 50 % of the seeds did not germinate. In addition, seedlings obtained from infected seeds had reduced all biometric characteristics compared to the control. Infection of seeds with P. carotovorum showed an increase in the amount of ROS in root tissues and caused a significant increase in peroxidase activity in the roots of soybean seedlings. A significant increase in diene conjugates (DC) was noted in the tissues of the roots of the hypocotel in this variant. The nanocomposite of manganese hydroxide and sulfated arabinogalactan (Mn(OH)2/AGs NC, 4,8 % Mn) removed the negative effect of the phytopathogen P. carotovorum. Morphometric characteristics of seed sprouts after nanopriming were characterized by an increase in biomass compared to the control. Thus, after nanopriming with Mn(OH)2/AGs NC, the length and weight of the root in uninfected seeds increased. The most pronounced stimulating effect of nanopriming was expressed in sprouts obtained from infected seeds. The length weight of the hypocotyl and the length of the root in infected seeds significantly increased after nanopriming of infected seeds. The precursor NC – MnSO4×5H2O did not affect the germination and sprouting of seeds both infected with P. carotovorum and free from infection. Nanopriming of infected seeds reduced the formation of ROS in seedling tissues. It was found that after nanopriming, peroxidase activity increased significantly in soybean roots compared to the control. This effect can be explained by the antioxidant effect of Mn NPs. Nanopriming of infected seeds reduced the amount of DC in root tissues to the control level. Thus, the mechanisms of interaction of NC with the studied phytopathosystem are represented by an increase in seed germination under the influence of NC, stimulation of morphometric parameters of seedlings, as well as an effect on the components of the antioxidant system. The obtained results and our previous studies on the antibacterial effect of Mn(OH)2/AGs against phytopathogens Clavibacter sepedonicus demonstrate the great potential of using Mn(OH)2/AGs in practical agriculture, in particular for application in the field of stimulating plant growth and increasing their resistance to phytopathogens.

Нанопрайминг семян сои с применением марганецсодержащего нанокомпозита в арабиногалактановой матрице

The results of studies on the stimulation of soybean seed germination under the influence of nanopriming with a chemically synthesized nanocomposite (NC) based on manganese-containing nanoparticles and a water-soluble polysaccharide arabinogalactan are presented. The study was carried out on the phytopathosystem: soybean seeds Glycine max (L) – phytopathogenic bacterium Pectobacterium carotovorum. Phytopathogenic bacterium P. carotovorum causes the infectious disease soft rot in various plant species from vegetables to trees and shrubs. After nanopriming (treatment Mn(OH)2/AGs NC), seed germination, biometric characteristics (mass and length of the root and hypocotyl) and biochemical parameters of soybean seedlings (content of reactive oxygen species (ROS), activity of antioxidant enzymes, amount of lipid peroxidation products) were analyzed. It was shown that the infection of seeds with P. carotovorum led to a decrease in their germination, 50 % of the seeds did not germinate. In addition, seedlings obtained from infected seeds had reduced all biometric characteristics compared to the control. Infection of seeds with P. carotovorum showed an increase in the amount of ROS in root tissues and caused a significant increase in peroxidase activity in the roots of soybean seedlings. A significant increase in diene conjugates (DC) was noted in the tissues of the roots of the hypocotel in this variant. The nanocomposite of manganese hydroxide and sulfated arabinogalactan (Mn(OH)2/AGs NC, 4,8 % Mn) removed the negative effect of the phytopathogen P. carotovorum. Morphometric characteristics of seed sprouts after nanopriming were characterized by an increase in biomass compared to the control. Thus, after nanopriming with Mn(OH)2/AGs NC, the length and weight of the root in uninfected seeds increased. The most pronounced stimulating effect of nanopriming was expressed in sprouts obtained from infected seeds. The length weight of the hypocotyl and the length of the root in infected seeds significantly increased after nanopriming of infected seeds. The precursor NC – MnSO4×5H2O did not affect the germination and sprouting of seeds both infected with P. carotovorum and free from infection. Nanopriming of infected seeds reduced the formation of ROS in seedling tissues. It was found that after nanopriming, peroxidase activity increased significantly in soybean roots compared to the control. This effect can be explained by the antioxidant effect of Mn NPs. Nanopriming of infected seeds reduced the amount of DC in root tissues to the control level. Thus, the mechanisms of interaction of NC with the studied phytopathosystem are represented by an increase in seed germination under the influence of NC, stimulation of morphometric parameters of seedlings, as well as an effect on the components of the antioxidant system. The obtained results and our previous studies on the antibacterial effect of Mn(OH)2/AGs against phytopathogens Clavibacter sepedonicus demonstrate the great potential of using Mn(OH)2/AGs in practical agriculture, in particular for application in the field of stimulating plant growth and increasing their resistance to phytopathogens.

Impact of Sulfate Adsorption on Particle Morphology during the Precipitation of Ni-Rich Hydroxide Precursors for Li-Ion Battery Cathode Active Materials

Nickel-cobalt-manganese-hydroxides (NixCoyMnz(OH)2, with x+y+z = 1) are utilized as precursor for lithium-ion battery cathode active material (CAM). The physical properties and electrochemical performance of CAM are affected by the morphology, crystallinity and impurity content of the associated NixCoyMnz(OH)2 (with x+y+z = 1) employed for the CAM synthesis. To promote the mechanistic understanding of the NixCoyMnz(OH)2 (with x+y+z = 1) formation, the coprecipitation pH23 °C-value was systematically varied from 8.6–12.7 during the synthesis of Ni0.8Co0.1Mn0.1(OH)2, and the obtained powders were characterized by elemental analysis. A dependency of residual sulfur content and crystallinity of the obtained Ni0.8Co0.1Mn0.1(OH)2 on the pH-value in relation to the point-of-zero-charge (pzc) is revealed. This result is rationalized by a pH-dependent sulfate adsorption equilibrium. Furthermore, a suppression of the growth along the (001) plane of the crystallites due to sulfate adsorption is identified. This in turn governs the vertical primary particle size and thus the porosity of the secondary particles, which was verified by substituting the sulfate ion of the metal feed by nitrate or acetate. Adsorption/desorption experiments demonstrate the possibility to decouple secondary particle morphology and residual impurity content. The demonstrated relationships allow formulating design strategies to tailor the NixCoyMnz(OH)2 (with x+y+z = 1) morphology and its impurity content for CAM synthesis.

Ag-integrated mixed metallic Co-Fe-Ni-Mn hydroxide composite as advanced electrode for high-performance hybrid supercapacitors

Direct growth of redox-active noble metals and rational design of multifunctional electrochemical active materials play crucial roles in developing novel electrode materials for energy storage devices. In this regard, silver (Ag) has attracted great attention in the design of efficient electrodes. Inspired by the house/building process, which means electing the right land, it lays a strong foundation and building essential columns for a complex structure. Herein, we report the construction of multifaceted heterostructure cobalt-iron hydroxide (CFOH) nanowires (NWs)@nickel cobalt manganese hydroxides and/or hydrate (NCMOH) nanosheets (NSs) on the Ag-deposited nickel foam and carbon cloth (i.e., Ag/NF and Ag/CC) substrates. Moreover, the formation and charge storage mechanism of Ag are described, and these contribute to good conductive and redox chemistry features. The switching architectural integrity of metal and redox materials on metallic frames may significantly boost charge storage and rate performance with noticeable drop in resistance. The as-fabricated Ag@CFOH@NCMOH/NF electrode delivered superior areal capacity value of 2081.9 µA h cm−2 at 5 mA cm−2. Moreover, as-assembled hybrid cell based on NF (HC/NF) device exhibited remarkable areal capacity value of 1.82 mA h cm−2 at 5 mA cm−2 with excellent rate capability of 74.77% even at 70 mA cm−2 Furthermore, HC/NF device achieved maximum energy and power densities of 1.39 mW h cm−2 and 42.35 mW cm−2, respectively. To verify practical applicability, both devices were also tested to serve as a self-charging station for various portable electronic devices.

TITANOMAGNETITE CONCENTRATE PROCESSING BY SORPTION CONVERSION

A hydrometallurgical technology for processing titanomagnetite concentrate has been proposed and justified. It includes the decomposition of the concentrate in low-concentration sulfur-acidic solution in the presence of sulfonic cation exchanger in H+ form with the transfer of the main part of the metals of the titanomagnetite concentrate into the sorbent and obtaining a residue enriched with ilmenite, desorption of metals from the saturated sulfonic cation exchanger with a 5 M sodium chloride solution, fractional hydrolytic precipitation and separation of titanium hydroxide, vanadium-enriched iron hydroxide, pure hydroxide iron and mixtures of iron and manganese hydroxides, regeneration of sulfonic cation exchange resin. The optimal parameters for carrying out individual processes have been determined. The technology practically does not consume sulfuric acid and does not generate liquid waste.

Quantitative Distribution and Contamination Risk Assessment of Cu and Zn in Municipal Sewage Sludge

One of the methods of managing sewage sludge (SS) is its soil application. This possibility is promoted by the chemical composition rich in organic matter and nutrients. However, heavy metal contents in SS must meet respective permissible limits. Among the heavy metals in SS, Cu and Zn are found in the largest amount; thus, this study focuses on these elements. The main aim of the study is to investigate the quantitative distribution of metals in sequentially separated fractions of sewage sludge. Additionally, the potential risk of environmental contamination with heavy metals was assessed in the case of SS application for agricultural purposes. The relevant analyses were conducted on four different examples of municipal SS. Based on the total amounts as well as those determined in the SS fractions, the following indices were calculated: Igeo (geoaccumulation index), ICF, (individual contamination factor), and RAC (risk assessment code). The use of data from the sequential analysis as well as the calculated indices made it possible to assess the usefulness of SS in practice in terms of potential introduction of Cu and Zn into the environment with the sludge dose. It was found that total Cu (Cutot) and Zn (Zntot) did not exceed the permissible limits binding within respective Polish and international regulations. Regardless of the years of study and the analyzed SS, Cutot ranged from 260.9 to 393.5 mg·kg−1, and Zntot from 475.5 to 1153.1 mg·kg−1. The amounts of Cu and Zn were predominantly reducible (bound to iron and manganese hydroxides, Fr. II) and oxidizable complexes (bound to organic matter and sulfides, Fr. III). The average amounts of Cu in Fr. II ranged from 149.4 to 172.4 mg·kg−1, while those of Zn in Fr. II ranged from 370.9 to 754.6 mg·kg−1. Cu amounts in Fr. III were from 160.9 to 183 mg·kg−1 and Zn amounts in Fr. III were from 104.9 to 171.9 mg·kg−1. Total content of metals as well as TOC values strongly determined the quantitative level of both elements in the SS fractions. Generally, with the increase in the total amount of metals, their levels in the sludge fractions increased. In turn, the increase in TOC resulted in a decrease in the amounts of Cu and Zn in the sludge fractions. Calculated Igeo and ICF ratios showed high and very high SS contamination with Cu and Zn. Igeo values for Cu, regardless of the year of study and sludge sample, that ranged from 4.62 to 5.43 and for Zn from 3.41 to 4.86. At the same time, the ICF values for Cu ranged from 8.59–23.04, and for Zn 15.42–44.47. The RAC values indicated a low (Cu) and medium (Zn) risk of using SS in terms of the potential metal availability in the environment. The RAC values ranged from 1.46 to 4.40% for Cu and from 9.63 to 23.13% for Zn.

Tuning the surface chemistry of La0.6Sr0.4CoO3-δ perovskite via in-situ anchored chemical bonds for enhanced overall water splitting

Perovskites have garnered huge interest as electrocatalysts in water–oxidation. Despite their salient features, chemical instability of the perovskite oxide surfaces still limits their durability in electrochemical water–splitting. Here, we propose a simple strategy to increase the overall activity and stability of La0.6Sr0.4CoO3-δ (LSC) perovskite just by reconstructing its surface. Preeminent oxygen evolution (OER) and hydrogen evolution reaction (HER) catalysts, namely, nickel–iron oxyhydroxide (NiFe(OH)2 denoted as NiFe) and nickel–manganese hydroxide (NiMn(OH)2 denoted as NiMn) are in–situ anchored on LSC surface, respectively. The resulting composites greatly facilitate the electron mobility and deliver excellent activity towards OER and HER with low overpotentials of η = 250 mV at 10 mA cm−2 and η = 63 mV at 50 mA cm−2, respectively. The (LSC@NiFe‖LSC@NiMn) electrolyzer reached 10 mA cm−2 at a cell voltage of 1.57 V. We also validated the redistribution of electrons and oxygen, and the abundance of exposed active sites by incorporation of active hydroxides.

Nickel manganese hydroxide on hierarchically porous phenolic resin as a high-performance electrode material for supercapacitors

Novel electrode composite materials consisting of NiMn spherical double hydroxide coated on the phenolic resin (PR) were successfully synthesized using water bath and hydrothermal methods. Spherical Ni(OH)2 was generated using the water bath method and used as a template. A series of composite electrodes (PR@NiMn) were obtained by making adjustments to the amount of manganese acetate (Mn(CH3COO)2·4H2O) using a hydrothermal method. PR@NiMn SDH-1.5 exhibited excellent electrochemical performance and achieved a maximum specific capacitance of 559 F g−1, remaining at 93.2% of the initial capacity following 10,000 cycles. In addition, the symmetric cell based on PR@NiMn SDH-1.5 demonstrated a power density of 374 W kg−1 and an energy density of 24.1 Wh kg−1, indicating that it has potentially promising practical application prospects. This PR-based electrode material preparation strategy will provide new opportunities for the development of low-cost and efficient energy storage devices.

Особенности элементного химического состава магнитной фазы урбогорно-подзолистых почв промышленного города

A relevant environmental problem in cities is the increased concentration of some heavy metals in soils. Heavy metals come to the soil from natural and anthropogenic sources. Emissions from industry, transport, and fertilizers are anthropogenic sources. In the soil, heavy metals are bound by carrier phases: organic matter, clay minerals, sulfur compounds, oxides and hydroxides of iron and manganese. Highly magnetic iron-bearing minerals are concentrators of heavy metals in soils. The aim of the study is to characterize the features of the elemental chemical composition of the Urbic soils and its magnetic phase of the industrial city Gubakha, Perm region (Russia). We used the background soils, the clarke of the lithosphere, and the clarke of the soils of the world to assess the ecological-geochemical role of the magnetic phase in the accumulation of heavy metals. The magnetic phase is rich in Fe, Ni, Cu, Cr, and Zn. The Urbic Technosol Loamic, Skeletic of the city Gubakha is contaminated with Cu, Cr, Ni, and Zn. Ecological-geochemical monitoring of the soil cover by the method of ecological magnetism is relevant in the territory of the cities. Keywords: URBIC TECHNOSOL, TECHNOGENIC MAGNETIC PARTICLES, IRON, HEAVY METALS, XRD, ECOLOGICAL-GEOCHEMICAL ASSESSMENT, GUBAKHA, PERM REGION, URAL, RUSSIA

Особенности элементного химического состава магнитной фазы урбогорно-подзолистых почв промышленного города

A relevant environmental problem in cities is the increased concentration of some heavy metals in soils. Heavy metals come to the soil from natural and anthropogenic sources. Emissions from industry, transport, and fertilizers are anthropogenic sources. In the soil, heavy metals are bound by carrier phases: organic matter, clay minerals, sulfur compounds, oxides and hydroxides of iron and manganese. Highly magnetic iron-bearing minerals are concentrators of heavy metals in soils. The aim of the study is to characterize the features of the elemental chemical composition of the Urbic soils and its magnetic phase of the industrial city Gubakha, Perm region (Russia). We used the background soils, the clarke of the lithosphere, and the clarke of the soils of the world to assess the ecological-geochemical role of the magnetic phase in the accumulation of heavy metals. The magnetic phase is rich in Fe, Ni, Cu, Cr, and Zn. The Urbic Technosol Loamic, Skeletic of the city Gubakha is contaminated with Cu, Cr, Ni, and Zn. Ecological-geochemical monitoring of the soil cover by the method of ecological magnetism is relevant in the territory of the cities. Keywords: URBIC TECHNOSOL, TECHNOGENIC MAGNETIC PARTICLES, IRON, HEAVY METALS, XRD, ECOLOGICAL-GEOCHEMICAL ASSESSMENT, GUBAKHA, PERM REGION, URAL, RUSSIA

Comparative Analysis of Groundwater Quality near a Dumping Ground in Garchuk Area, Guwahati

Abstract: This project focuses on analyzing and comparing the water quality of a dumping ground, nearby residential area, and commercial area in Garchuk, Guwahati. Water samples were collected from these three locations using tube wells and various parameters were assessed to evaluate the water quality. The analysis included the measurement of Dissolved Oxygen (DO) and Biochemical Oxygen Demand (BOD). The Winkler method was employed for DO analysis, involving the oxidation of divalent manganese hydroxide precipitate by dissolved oxygen in the water sample. The BOD determination assessed the oxygen required for the biochemical degradation of organic material during a specified incubation period. Results from the DO analysis indicated varying levels of dissolved oxygen in the water samples collected from the dumping ground, residential site, and commercial site. BOD analysis revealed the oxygen utilization and degradation of organic material in the water samples after a 5-day incubation period. Additionally, the concentrations of heavy metals such as lead (Pb), arsenic (Ar), zinc (Zn), copper (Cu), and mercury (Hg) were analyzed in the groundwater samples. The results showed that some heavy metal concentrations were below the detectable limit, while others exhibited measurable levels. The findings of this study provide valuable insights into the water quality of the studied areas, indicating potential pollution levels and the effectiveness of waste treatment processes. These results contribute to better understanding and management of water resources in the Garchuk area, helping to protect the environment and public health.