Unreacted Oxidant Research Articles

Pristine NASICON Electrolyte: A High Ionic Conductivity and Enhanced Dendrite Resistance Through Zirconia (ZrO2) Impurity-free Solid-Electrolyte Design.

Sodium batteries are considered a promising candidate for large-scale grid storage at tropical climate zone, and solid-state sodium metal batteries have a strong proposition as high energy density battery. The main challenge is to develop ultra-pure solid-state ceramic electrolyte and compatible metal interface. Here, a scalable and energy-efficient synthesis strategy of sodium (Na) Super Ionic CONductor, Na1+xZr2SixP3-xO12(x = 2, NZSP) solid electrolyte, has been introduced with the complete removal of unreacted zirconium oxide (ZrO2) impurities. Additionally, the reaction mechanism for the formation of pure phase NZSP is reported for the first time. The NZSP prepared by utilizing the Zr precursor, i.e., tetragonal zirconium oxide (t-ZrO2) derived from the Zr(OH)4 gets quickly and completely consumed in the synthesis process leaving no unreacted monoclinic ZrO2 impurities. The synthesis process only needs a minimum stay of 4 h, which is three times less than the conventional synthesis method. The elimination of ZrO2 impurities results in a 2.5-fold reduction in grain boundary resistivity, showcasing a total ionic conductivity of 1.75 mS cm-1 at room temperature and a relative density of 98%. The prepared electrolyte demonstrates remarkable resistance to dendrite formation, as evidenced by a high critical current density value of 1.4mA cm-2.

Assembly of Zinc‐Single‐Site‐Containing Silica Nanoparticles to Supraparticle Powders with Destructibility to Serve as Filler and Vulcanization Activator in Rubbers

AbstractThe vulcanization process is widely used in industry for tire manufacturing. Therefore, zinc oxide is commonly utilized as an activator material, but unreacted zinc oxide remains in the final products and can be released into the environment with a significant impact. To reduce the amount of required zinc and to prevent leaching from tire material, zinc single site‐containing silica fillers are interesting candidates. In these materials, zinc sites are anchored on the surface of silica nanoparticles through their complexation with functionalized aminosilanes. Based on these, a novel powder sample is prepared via spray‐drying. The obtained supraparticles allow for a homogeneous distribution of the filler nanoparticles in the rubber matrix via their disintegration during the incorporation process. All synthesis steps are carried out in ethanol and water, respectively, at very mild temperatures to account for sustainability demands. As core of this study, the role of zinc ions and their amino‐complexation in nanoparticle dispersion stability and in supraparticle formation during spray‐drying is elucidated. Additionally, the superior performance of supraparticles as activator in rubber vulcanization is demonstrated. These show a higher curing efficiency, leading to lower curing time (−70%), higher torque values (+15%), and improved dynamic mechanical properties compared to the conventional ZnO activator.

Mill Scale - Biomass Pellet as a Charged Material for EAF Steelmaking

With an aim to utilize the local-based waste materials, this research investigated the production of mill scale - biomass pellet (MBP) as an alternative charged material for EAF steelmaking. Rubber tree bark (RTB) is one of the major biomasses in Thailand, consisting of carbon and hydrogen as the main compositions. The carbon derived from RTB was mixed with coal into five different ratios. Pure coal and RTB were employed for comparison. Seven carbonaceous samples were blended with mill scale at a C/O molar ratio of 1:1 to produce MBP, namely Coal, blend#1 – blend#5 and RTB. The reduction of MBP was investigated in a horizontal tube furnace under argon atmosphere at 1550°C for 15 and 30 minutes. The obtained products were iron droplets and residual black powder of unreacted oxides. Quantities of reduced iron from the MBP of blend#1 – blend#5 was about 58 – 61 wt% after 30 minutes, while it was 62 wt% and 57 wt% for coal and RTB, respectively. Degree of metallization (DOM) for blend#1 – blend#5 was between 78.1 – 81.7%, while it was 82.7% and 83.3% for coal and RTB. This research offers the possible method to utilize mill scale and RTB biomass toward circular economy.

Spectrophotometric determination of Montelukast Sodium in pure form and in its pharmaceutical formulations

A simple, sensitive and rapid spectrophotometric method for determination of Montelukast Sodium (MON) in both pure form and pharmaceutical formulations was developed. This method was based on the oxidation of the studied drug in presence of acidic medium by a known excess of (Potassium bromide: Potassium bromate) (KBr:KBrO3) and subsequent determination of unreacted oxidant by reacting it with Crystal Violet (CV) dye [4 [bis [4 (dimethylamino) phenyl] methylidene] cyclohexa-2,5-dien-1-ylidene]-dimethylazanium to produce blue product at λmax. 592 nm. The linearity range was found to be (5-50)µg/ml and molar absorptivity 1.5691×104 L/mol.cm, correlation coefficient 0.9993 and the limit of detection 0.209 µg/ml. This method was successfully applied for the determination of (MON) in tablet formulation.

Corchorus Olitorius-Mediated Green Synthesis and Characterization of Nickel and Manganese Ferrite Nanoparticles

Developing a method for preparing Ni and Mn ferrites was the main objective of this study due to the importance of these materials in high-frequency applications. These ferrites were made by assisting combustion with dried leaves of Corchorus olitorius and then heating them to 700 °C. Several methods, including FTIR, XRD, TEM, and SEM/EDX, were used to characterize these ferrites. The thermal behavior, surface and magnetic properties of the as-prepared materials were determined. The results revealed that the method used is cheap, economical, environmentally friendly and makes it easy to produce the studied ferrites. FTIR, XRD, TEM, and SEM/EDX analyses show the formation of nanocrystalline ferrites with brittle, spongy and spinel-type structures, having two main vibration bands located around 400 cm−1 and 600 cm−1. However, TG-DTG results display the thermal behavior of different materials which consisted of unreacted oxides, carbon and the corresponding ferrites in the range of 300 °C to 600 °C. Moreover, complete conversion of the unreacted oxides to the equivalent ferrite was achieved by increasing heat treatment from 600 °C to 1000 °C. Ferrites are heated at 700 °C, which reduces their surface area. The magnetic properties of different ferrites calcined at 700 °C were estimated using the VSM technique. The magnetism of Fe-based materials containing Ni and Mn is 12.189 emu/g and 25.988 emu/g, respectively. Moreover, the squareness and coercivity of Ni ferrite are greater than for Mn ferrite.

Synthesis of Ferroalloys via Mill Scale-Dross-Graphite Interaction: Implication for Industrial Wastes Upcycling

Mill scale and aluminum dross are the industrial wastes from steel and aluminum industries, which have high concentrations of Fe2O3 and Al2O3, respectively. This paper reports the conversion of reducible metal oxides in scale and dross into an alloy via carbothermic reduction at 1550 °C. Scale and dross were mixed with graphite into three different C/O molar ratios of 1, 1.5, and 2 to produce a pellet. The pellets were heated at 1550 °C for up to 6 h under an argon atmosphere. By this method, carbothermic reductions were found to proceed and formed Fe–Si–Al–C alloy that consists of Fe3Al and Fe3Si phases. The presence of Si in the alloy came from the reduction of SiO2 in aluminum dross. Levels of Al and Si in the alloy increase with increasing C/O molar ratios. However, the Si level in the alloy was found to stabilize since 3 h, while the Al level increases with increasing time up to 6 h. Unreacted oxides in the wastes had an insignificant effect on the ferroalloy formation. These results provide evidence for carbothermic reduction of the Fe2O3-Al2O3-SiO2 system at 1550 °C and show the novel method to upcycling aluminum dross and mill scale toward a circular economy.

Indirect Spectrophotometric Determination of Famotidine and Ciprofloxacin Hydrochloride in Pharmaceuticals Using N-Bromosuccinimde and Janus Green B Dye.

An indirect simple and sensitive spectrophotometric method has been developed for the determination of famotidine (FAM) and ciprofloxacin hydrochloride (CIP) in pure and pharmaceutical dosages. The method is based on the oxidation of FAM and CIP with known excess of N-Bromosuccinimde in acidic medium and subsequent occupation of unreacted oxidant in decolorization of Janus green B dye and measure the absorbance of residual dye at 618 nm. Calibration curves of residual Janus green B dye in the presence of FAM or CIP were rectilinear over the ranges 1.0-10.0 and 1.0-7.5 µg/ml with molar absorptivity 3.61×104 and 5.14×104 l.mol-1.cm-1 respectively. The accuracy (average recovery) was ranged between 99.68 and 100.23% and precision (RSD%) is less than 3.80%. The developed method was successfully applied for the determination of the studied drugs in their pharmaceutical preparations. The results obtained are in agreement with certified values of pharmaceutical preparations and also with standard addition procedure and standard method applied in state company for drugs industry and medical appliance,SDI.

Evidence of ammonia synthesis by bulk diffusion in cobalt molybdenum particles in a CLAS process

For the first time ammonia-synthesis-on-nitridation has been reported in CoMo during a chemical looping ammonia synthesis experiment. The observation lends evidence to the existence of a dynamic surface, a shrinking core and counter diffusion. The Mars-van Krevlen mechanism involving surface and bulk exchange has been established for the CoMo system under H2:N2 atmospheres was extended into the CLAS domain and complicated by the existence of an unreacted oxide core containing molybdenum bronzes, HxMoO3. This OH−1 diffuses outward as the core is stabilized by N−3, resulting in the observation of gas phase H2O and NH3 in the absence of gaseous H2.

Contribution of TiO2 and ZnO nanoparticles to the hydration of Portland cement and photocatalytic properties of High Performance Concrete

This paper aims to study the hydraulic and photocatalytic behavior of mixtures based on TiO2 and ZnO nanoparticles in cement pastes and High Performance Concretes (HPCs) for the self-cleaning application of building materials. The two nanoparticles were used to partially replace the cement of varying values from 0% to 3% by weight. Cement pastes were characterized by X-ray diffraction, X-Ray Fluorescence, Differential Scanning Calorimetry and Thermogravimetric analyzes to study their compatibility in the cement matrix. The addition of TiO2 in Portland cement resulted in better reactivity by the large presence of hydration products and the appearance of unreacted anatase titanium oxide which is responsible for the photocatalysis process. The cement pastes containing ZnO had clearly indicated the retarding effect of zinc in the hydration of Portland cement. The photocatalytic properties are determined by studying the efficiency of the degradation of nitrogen oxides (NOx) and by monitoring the discoloration of Rhodamine B under UV irradiation of HPC samples. The results showed that the introduction of titanium oxides in the HPCs exhibited a significant degradation efficiency compared to zinc oxide and the samples containing the later underwent greater discoloration of the red color coordinate (Rt).

Spectrophotometric Determination of Salbutamol Sulphate and Isoxsuprine Hydrochloride in Pharmaceutical Formulations

A simple, sensitive and accurate spectrophotometric method has been developed for the determination of salbutamol sulphate (SAB) and isoxsuprine hydrochloride (ISX) in pure and pharmaceutical dosage. The method involved oxidation of (SAB) and (ISX) with a known excess of N-bromosuccinamid in acidic medium, and subsequent occupation of unreacted oxidant in decolorization of Evans blue dye (EB). This, in the presence of SAB or ISX was rectilinear over the ranges 1.0-12.0, 1.0-11.0 µg/mL, with molar absorptivity 4.21×104 and 2.58×104 l.mol-1.cm-1 respectively. The developed method had been successfully applied for the determination of the studied drugs in their pharmaceutical dosage resulting in a good agreement with certified value and standard addition procedure.

Behaviour of SiO2 during a new process applied to nickel concentrate from matte separation at Kola MMC

Kola MMC has built a new nickel site that relies on chlorine leaching of nickel powder followed by electrowinning of nickel with insoluble anodes. After the new site had been commissioned, the operations of the refining facility saw changes, the electric anode furnaces were taken out of service, and a magnetic separation section was commissioned. The latter helps remove unreacted coal, metal oxides and other non-magnetic components from the tube kiln nickel powder thus ensuring its optimized quality. At the same time, once the electric furnaces had been removed from the process, it created the need for strict control over carbon and slag-forming constituent concentration in the nickel powder that goes to the chlorine leaching section. This paper looks at the history of the process behind the production of roasted nickel – the product of fluidized-bed furnaces – and describes the revamping stages witnessed by the Kola MMC site. The paper also analyzes certain features related to the current processing of nickel concentrates – from nickel matte separation to the production of nickel metal powder. The latter is further sent for chlorine leaching and in the presence of chlorine gas it gets dissolved. Then copper, iron, zinc and cobalt are removed from the resultant liquor and the purified sulphate-chloride solution goes in the electrolysis cells where high-purity nickel cathodes are produced. The authors analyzed the compositions of the key components in the studied materials of the nickel processing line. Special attention is given to the behaviour of silicon dioxide as one of the impurities causing most problems in the new process.

Non-isothermal decomposition of lead oxalate-iron (II) oxalate mixture. DTA-TG, XRD, FT-IR and Mössbauer studies

The thermal decomposition of PbC2O4–FeC2O4.2H2O mixture (1:2 mol ratio) in air, prepared using impregnation method, aiming at the production of mixed oxides; PbO–Fe2O3 (1:1 mol ratio) system have been followed using differential thermal analysis-thermogravimetry (DTA-TG). The decomposition products as well as the phases’ transformations up to the ferrites production were characterized using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and Mössbauer spectroscopic techniques. DTA-TG showed the formation of mixed oxides at 400 °C through three well-defined steps due to dehydration and oxalates’ decomposition step. XRD, FT-IR and Mössbauer measurements at different calcination temperatures indicated the formation of paramagnetic fine grained Fe2O3 particles at early decomposition stages up to 250 °C followed by their transformation into magnetically ordered one by increasing calcination to 400 °C. The precursor calcined at 650 °C showed the initiation of PbFe4O7 ferrite formation besides the presence of unreacted PbO and Fe2O3 oxides. At 750 °C, only PbFe4O7 and PbFe2O5 ferrites can be detected. Kinetic analysis of TG steps using different computational methods, in the view of different solid–state reaction kinetic models, revealed the occurrence of the decomposition up to PbO–Fe2O3 through the random nucleation growth mechanism (A2). The activation parameters calculation indicated that the fine grained Fe2O3 particles formed at early stages increasing the interfaces between lead oxalate grains and thus facilitating the decomposition.

Synthesis of limonene β-amino alcohol from (R)-(+)-α-methylbenzylamine and (+)-limonene 1,2-epoxide

Two new compounds of β-amino alcohol are obtained using (R) - (+) - α-methylbenzylamine as starting material which is converted into two amines. Each of these compounds reacted in excess with a 1: 1 mixture of cis and trans-limonene oxide in the presence of water as a catalyst. The products obtained show that β-amino alcohol derived from trans-limonene oxide is obtained and unreacted cis-limonene oxide from the reaction mixture as well as the amine is attained. Whereas the addition of the synthesized carbamate of the same primary amine over the 1: 1 mixture of cis and trans -limonene oxide in the presence of water results in the hydrolysis product and the recovery of unreacted trans-limonene oxide.

Compressive strength development and microstructure of magnesium phosphate cement concrete

In order to verify the feasibility of preparing structural concrete with magnesium phosphate cement (MPC), the workability, temperature rise and compressive strength of MPC concrete were studied. The hydration products, pore structure and fractural morphology of MPC concrete were also investigated. The results show that the hardened MPC stone is a ceramic-like structure by cementation of unreacted magnesium oxide and fly ash with the solid solution of the hydration products of fly ash and struvite. The continuity of this kind of ceramic-like structure will be broken when the aggregate is added to prepare concrete, and a weak interface transition zone will be formed between the ceramic-like structure and aggregate due to the “wall” effect, but the 2-hour compressive strength can still reach more than 40 MPa. The heterogeneous structure of MPC concrete results in a power function decreasing of concrete compressive strength in later stage with the increase of specimen sizes.

Kinetic Separation of cis-and trans-Limonene Epoxide: Reaction of Diastereomeric Mixture of Limonene Oxides with Secondary Amine and Carbamate

A simple kinetic separation of (1:1) diastereomeric mixture of limonene oxides was used to purify cis-and trans-diastereomers of (R)-(+)-limonene oxide. The epoxide ring of trans-isomer was selectively opened by (R)-N-methyl-(α-methyl-benzyl)amine. This secondary nucleophilic amine left cis-limonene oxide largely unreacted and was obtained up to 90% yield. In a diverse way, (R)-N-(α-methylbenzyl) ethyl carbamate, selectively catalyze hydrolysis of cis-limonene oxide to 1,2-limonene diol leaving trans-limonene oxide largely unreacted. The unreacted trans-limonene oxide was recovered in up to 75% yield. HPLC and NMR analyses were used to demonstrate that the isolation of cis-and trans-diastereomers of (R)-(+)-limonene oxide has shown that > 98% were pure. As a result, depending on the realization of the secondary amine or carbamate in the presence of water, either cis-or trans-limonene oxide may be obtained in high diastereomeric purity.

Mineralogical and Leaching Characteristics of Altered Ilmenite Beach Placer Sands

In order to have a good understanding of the treatment process and improvement on the market value of ilmenite beach placer sands, knowledge of its mineral composition and phase distribution is fundamental. In this study, a combination of characterization techniques including high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron (HR-TEM) microscope, and X-ray diffraction (XRD) techniques was used to understand the mineralogical characteristics of ilmenite beach placer sands obtained from Richards Bay, South Africa. The mineral phase constituents of the ilmenite beach placer sands were studied before pre-oxidation and additive leaching in a chloride environment. During observations using XRD and HR-SEM, the ilmenite beach placer sands exhibited signature rhombohedral crystal form and crescentic pits with evidence of alteration phases. The characterized pre-oxidized ilmenite showed the presence of a ferric oxide film deposit of the particles. The leaching characteristics of both raw and pre-oxidized ilmenite was studied in the presence of additives. The leaching efficiency of the pre-oxidized ilmenite in the presence of additives increased by 20% at atmospheric conditions. The characterized residues show the improved amenability of pre-oxidized leach in chloride media. The formation of new phases containing pseudo-rutile indicated crystallographic disintegration by the movement of atoms during dissolution. Some particles retained the crescentic pit and the subangular grain structure; however, the phase changes were observed at the grain boundaries and grain edges. The leached residue’s EDS results still indicated the presence of pseudo-rutile and some minor unreacted oxides such as SiO2, Al2O3, and other trace metals. The trace metals impurities present in the as-received ilmenite were reduced by 80% in the final residue after the leaching.

Indirect Spectrophotometric Determination of Cefalexin monohydrate, Ceftriaxone Sodium and Cefotaxim Sodium in Pharmaceuticals Using N-Bromosuccinimde and Evans Blue Dye

An indirect sensitive and selective spectrophotometric method has been developed for the determination of cephalexin monohydrate (CEM) ceftriaxone sodium (CFX) and cefotaxim sodium (CEF) in bulk and pharmaceutical formulation. The method is based on the oxidation of (CEM), (CFX) and (CEF) in hydrochloric acid medium with known excess on N-Bromosuccinimde and subsequent determination of unreacted oxidant by decolorization of Evans blue dye (EB) and measure the absorbance of residual dye at 608 nm. Calibration curves of evans blue dye in the presence of drugs were rectilinear over the ranges 1.0-9.0 , 1.0-8.0 and 1.0-9.0 µg/ml with molar absorptivity 2.75×104 , 9.28×104 and 7.81×104 l.mol-1.cm-1 and average recoveries 98.97, 102.08 and 100.08% for CEM, CFX and CEF respectively with RSD of less than 3.29%. The method was free from interference of many excipients and additives commonly found in pharmaceutical formulations. The developed method was successfully applied for determination of the studied drugs in their pharmaceutical formulation resulted in a good agreement with certified value and standard addition procedure.

Indirect Spectrofluorometric Method for the Determination of Cefotaxime Sodium, Ciprofloxacin Hydrochloride and Famotidine in Pharmaceuticals Using Bromate-Bromide and Acriflavine Dye

An Indirect simple sensitive and applicable spectrofluorometric method has been developed for the determination of Cefotaxime Sodium (CEF), ciprofloxacin Hydrochloride (CIP) and Famotidine (FAM) using reaction system bromate-bromide and acriflavine (AF) as fluorescent dye. The method is based on the oxidation of drugs with known excess bromate-bromide mixture in acidic medium and subsequent determination of unreacted oxidant by quenching fluorescence of AF. Fluorescence intensity of residual AF was measured at 528 nm after excitation at 402 nm. The fluorescence-concentration plots were rectilinear over the ranges 0.1-3.0, 0.05-2.6 and 0.1-3.8 µg ml-1 with lower detection limits of 0.013, 0.018 and 0.021 µg ml-1 and quantitation limits of 0.044, 0.060 and 0.069 µg ml-1 for CEF, CIP and FAM respectively. The common excipients and additives didn’t interfere in their determination. The developed method was successfully applied for determination of the studied drugs in their dosage forms resulted in a good agreement with standard British pharmacopeia method and standard addition procedure.

The impact of the curing process on the efflorescence and mechanical properties of basalt fibre reinforced fly ash-based geopolymer composites

Efflorescence is one of the limitations of the widespread use of geopolymers. This problem is caused by excess unreacted sodium oxide remaining inside materials. Unreacted sodium oxide creates white efflorescence on the surface of the produced material in the form of sodium carbonate heptahydrate Na2CO3∙ 7H2O. It decreases not only the aesthetic value of the final products, but also the mechanical properties of the material. The aim of this article is to analyse the influence of the curing method on the appearance of efflorescence on geopolymer composites reinforced by short basalt, especially on mechanical properties. Class F fly ash from the ‘Skawina’ coal-fired power plant (located in Skawina, Lesser Poland, Poland) was used as raw material for the geopolymerization process. The article compares two methods of curing: typical laboratory conditions (in the air) and samples submerged in water. Three series of fly ash-based geopolymer were cast: basalt fibres were added as 1% and 2% by weight of fly ash and one control series without any fibres. The investigation was performed using visual analysis, including microstructure investigation, and the testing of mechanical properties (compressive strength at ambient temperature) after 28 days.

Research of the combustion of gas-generating compositions with additives of carbon powders

Carbon materials obtained from secondary plant raw materials are widely used in various industries, where they are applied as catalysts, adsorbents and in pyrotechnics for creating gas-forming systems. In this work, activated carbon of two types– obtained from the walnut shell and as a product of utilization of gas adsorbents was used. The combustion of a three-component mixture of sodium nitrate, magnesium, and carbon obtained by carbonization of a walnut shell or by grinding gas mask elements was studied. It was found that at a low carbon content, the combustion of the mixture occurs at a high rate in a convective mode. As the working composition, a mixture with a component ratio of 60% – NaNO3, 20% – Mg, 20% – C was chosen, which is characterized by rather high values of gas productivity. The burning rate of a composition based on carbon from walnut is about two times higher than in the case of carbon from a gas mask, and the flame temperature is higher by about 500 K. X-ray phase analysis of solid combustion products showed that the main products are magnesium oxide and sodium carbonate. The presence of a partially unreacted initial oxidant of sodium nitrate has also been found, and its content in combustion products of a carbon-based incendiary composition from a gas mask is higher than in the case of combustion of a mixture based on carbon obtained from a walnut shell. This can probably be explained by the fact that gaseous products are released during combustion, and this leads to partial dispersion of the initial components in the combustion wave, which is more pronounced when using carbon obtained from a gas mask. As a result of the research the prospect of using such a mixture in gas generator cartridges is shown.