Na0.44Mn02 as a cathode material for aqueous sodium-ion batteries

The application of rechargeable batteries is growing significantly and it became the nlost important field for largescale electric energy storage. While lithiuln-ion batteries (LIBs) have great commercial success, due to their large energy and power density, their application was limited because of the availability of lithiunl and its high cost. Sodiunl-ion batteries (SIBs) can be a promissing alternative due to the huge availability of sodium, its low price and similar intercalating electrochelnistry to LIBs. Among various Na-ion battery materials, low-cost and tunnel-type, Na0.44Mn02 (NMO) was regarded as one of the most pronlising cathode materials for sodium-ion batteries, because of its high theoretical specific capacity (122 rnA h g1) and good cyclability [2]. In this work, for the synthesis of NMO powder, rapid glycine-nitrate nlethod (GNM) was used, which, on the basis of the literature review, has not been used to synthesize this material so far

Synthesis, characterization and electrochemical properties of Na0.44MnO2 in NaNO3 and LiNO3 aqueous solution

Na0.44MnO2 synthesized by glycine-nitrate method (GNM) was described in this paper and it was characterized by X-ray powder diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). Electrochemical performances of Na0.44MnO2 were studied by cycling voltammetry (CV) at various scan rates in NaNO3 and LiNO3 aqueous solutions in order to compare the intercalation/deintercalation kinetics of Li+ and Na+ ions. The initial discharge capacity was found to be 27.1 and 27.44 in the aqueous solution of NaNO3 and LiNO3, respectively, and after 30 cycles its values increased for 12% in both electrolytes

Mineralogical Characterization of the Grot Lead and Zinc Mine Tailings from Aspects of Their Further Use as Raw Material

The possibility of using waste tailings produced by flotation in the lead and zinc mine of Grot, Serbia as a potential source of secondary mineral raw materials was examined. The aim of the research was primarily to carry out a detailed characterization in order to determine the dominant minerals, and, for the first time, to trace the changes occurring in the unit cells of the minerals present in that deposit. There was also a need to determine the exact proportions of the present mineral phases for their further application and utilization as natural resources in environmental protection. Samples were taken from three different sections of tailings: the crest of dam (JKB), outlet pipe of the flotation facility (JOF) and hydrocyclone overflow (JHC). Granulometric separation was performed to facilitate the extraction of certain minerals from waste. The results showed that all samples mainly contained quartz, clinochlore, calcite, albite, pyrite and biotite, but their ratios in each sample varied significantly. After characterization, samples were separated into different fractions and their mineralogical compositions were determined. Depending on the fraction, the mineralogical compositions also changed. Mineralogy and geochemical analysis indicate that waste tailings can be used as a secondary mineral raw materials source applicable in various industries

Synthesis and characterisation of ZnO synthesized by glycine-nitrate combustion process

One of the ways to get rid of toxic organic compounds that industries release into natural waters is photocatalysis of the decomposition of organic compounds on the surface of heterogenous photocatalysts such as zinc oxide. Zinc oxide is a semiconductor that interacts with UV and near-UV visible light by generating electron-hole pairs which decompose organic molecules. Therefore it is useful to explore different ways of synthesizing zinc oxide and to test quality and quantity of organic decomposition photocatalysis so as to enable the commercial use of the material. Zinc oxide is also a respectable material for use as a photoelectrocatalyst in water oxidation, for example, which can be useful for generating oxygen while using natural sunlight - a clean and abundant energy source. In this project nanocrystalline zinc oxide was synthesized by glycin-nitrate combustion process and the powder was annealed on temperatures of 400 °C and 500 °C. Obtained particles where characterized in detail using X-ray powder diffraction (XRPD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, field emission scanning microscopy (FESEM), photoluminescence spectroscopy (PL) and diffuse reflectance spectroscopy (DRS). The results show that obtained samples are nanocrystalline wurtzite zinc oxide, with particle diameters of 33 nm (annealed at 400 °C) ad 48 nm (annealed at 500 °C). Both samples show significant amount of various crystal defects. Zinc oxide band gap of the samples are determined to be lower than the band gap of the bulk zinc oxide. Photoelectrocatalytic properties were investigated via electrochemical methods: linear voltammetry (LV), chronoamperometry (CA) and impedance spectroscopy (EIS). The results show that material is photostable and reactive to the light. Water oxidation is enhanced by exposing to sunlight. Finally, photocatalytic properties are tested with determining kinetic parameters of phenole and methyl blue decomposition. Zinc oxide nanoparticles are efficient photocatalysts, although sample annealed at 500 °C shows better properties than sample annealed at 400 °C

Structure and photocatalytic properties of sol-gel synthesized pseudobrookite

Fe2TiO5 nanopartcles were synthesized by modified sol-gel method with aid of Fe(NO3)3 9H2O and Ti(OC3H7)4 as starting reagents, oxalic acid as chilate agent and cetyltrimethylammonium bromide as surfactant. The aim of this study was to asses the photocatalytic degradaton of the antibiotic Oxytetracycline (OTC) using visible light irradiation. As prepared nanoparticles were characterized by XRD, BET, FESEM and UV-vis DRS. The optimal operating conditions of oxytetracycline photocatalytic degradation were achived by changing the pH of the solution and changing the concentration of photocatalyst

Photocatalytic degradation of methylene blue and oxytetracycline via sol-gel synthesized pseudobrookite

Fe2TiO5 nanoparticles were synthesized by modified sol-gel method using Fe(NO3)3×9H2O and Ti(OC3H7)4 as starting reagents, oxalic acid as chilate agent and cetyltrimethylammonium bromide as surfactant. The aim of this study was to asses the photocatalytic degradaton of water pollutants, methylene blue and the antibiotic Oxytetracycline (OTC) using natural sunlight irradiation. As prepared nanoparticles were characterized by XRD, BET, FESEM and UV-vis DRS. The optimal operating conditions of photocatalytic degradation of water pollutants were achived by changing the pH of the solution and changing the concentration of photocatalyst

Geopolymer materials based on the electric arc furnace slag

The remelting of iron and steel scrap in the electric arc furnaces generates the non-hazardous waste – electric arc furnace slag (EAFS), which can be disposed of to appropriate landfills. Currently, this slag found its application in conventional concrete production to improve its mechanical, chemical and physical properties, as an additive to asphalt base mixture and in cement production. In this study we have investigated the effect of alkaline dosage on the strength and thermal resistance of EAFS based geopolymers. The results have shown that these materials are mainly amorphous with some crystal phases remained from the undisolved EAFS such as larnite, gehlenite, wuestite, monticellite, calcite. Compressive strength of these materials is strongly influenced by the alkaline dosage. An increase of NaOH concentration in the interval of 7-10 M leads to the increase of geopolymer’s strength. The maximal compressive strength of EAFS based geopolymer was obtained using the 10 M NaOH. Further increase of alkaline dosage to the value of 13 M NaOH results in the slight decrease of the geopolymer strength. Additionally, depending on the synthesis parameters, EAFS based geopolymers exhibit improved durability in high temperature environments in comparison with conventional cement based materials. All investigated samples exhibit a shrinkage which is attributed to the change of porosity. The mass loss due to the loss of water was also observed. This research was supported by a Ministry of Science of Montenegro under the contract No 01-460

Sorption of Cu2+ and Co2+ from aqueous solutions onto sepiolite: an equilibrium, kinetic and thermodynamic study

The efficiency of natural sepiolite for the removal of Cu2+ and Co2+ from aqueous solution was determined using the batch method. The sorption experiments were performed as a function of the initial metal concentration, the equilibration time and temperature. Thermodynamic parameters, such as enthalpy, free energy and entropy, were calculated from the temperature dependent sorption isotherms and these values showed that the sorption of the investigated metals onto sepiolite was endothermic. The pseudo-second order kinetic model provides the best correlation of the experimental kinetic data

Alkali Activated Slag as Adsorbents for Cu2+ Removal from Wastewaters

The removal of heavy metals from wastewaters is presently a global imperative primarily due to their well-known toxic nature and detrimental effects on the environment, and more importantly, on human health. Currently, special attention is paid to the use of novel slag based materials – alkali activated slag (AAS) as potential novel adsorbents. Our previous studies have shown that electric arc furnace slag (EAFS) can be successfully used as a precursor for the production of AAS. Generally, alkaline activation involves a chemical reaction between solid aluminosilicate materials and a highly alkaline activator. The alkali activation mechanism of slag involves the dissolution of slag in a highly alkaline, which is followed by the condensation and hardening processes. Dependent on the pH and type of alkaline activator, calcium (alumina) silicate hydrate or C–(A)–S–H gel has been identified as a reaction product of slag alkali activation. The objective of this research was to investigate the removal of Cu2+ from aquatic solution using alkali activated slag (AAS) obtained by alkaline activation of EAFS

Synthesis and characterisation of ZnO synthesized by glycine-nitrate combustion process

One of the ways to get rid of toxic organic compounds that industries release into natural waters is photocatalysis of the decomposition of organic compounds on the surface of heterogenous photocatalysts such as zinc oxide. Zinc oxide is a semiconductor that interacts with UV and near-UV visible light by generating electron-hole pairs which decompose organic molecules. Therefore it is useful to explore different ways of synthesizing zinc oxide and to test quality and quantity of organic decomposition photocatalysis so as to enable the commercial use of the material. Zinc oxide is also a respectable material for use as a photoelectrocatalyst in water oxidation, for example, which can be useful for generating oxygen while using natural sunlight - a clean and abundant energy source. In this project nanocrystalline zinc oxide was synthesized by glycin-nitrate combustion process and the powder was annealed on temperatures of 400 °C and 500 °C. Obtained particles where characterized in detail using X-ray powder diffraction (XRPD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, field emission scanning microscopy (FESEM), photoluminescence spectroscopy (PL) and diffuse reflectance spectroscopy (DRS). The results show that obtained samples are nanocrystalline wurtzite zinc oxide, with particle diameters of 33 nm (annealed at 400 °C) ad 48 nm (annealed at 500 °C). Both samples show significant amount of various crystal defects. Zinc oxide band gap of the samples are determined to be lower than the band gap of the bulk zinc oxide. Photoelectrocatalytic properties were investigated via electrochemical methods: linear voltammetry (LV), chronoamperometry (CA) and impedance spectroscopy (EIS). The results show that material is photostable and reactive to the light. Water oxidation is enhanced by exposing to sunlight. Finally, photocatalytic properties are tested with determining kinetic parameters of phenole and methyl blue decomposition. Zinc oxide nanoparticles are efficient photocatalysts, although sample annealed at 500 °C shows better properties than sample annealed at 400 °C