Papers by Keyword: Reducing Agent

Abstract: Electrochemical research is devoted to the development of a method of processing secondary raw materials containing tungsten in the form of a pseudoalloy of the carbide type WC–Co in sulfate solutions. The target processing products are: powders of tungsten oxides of lower oxidation states, which can be reduced to metallic tungsten with lower costs. Using the methods of linear and cyclic voltammetry, it was established that the selective dissolution of the cobalt component of the pseudoalloy in the studied solutions occurs at potentials more positive than 0.2 V, carbon is removed from the working electrode at a potential > 0.8 V. At the same time, tungsten is oxidized to the higher oxide WO₃. It was determined that in sulfuric acid, with an increase in its concentration from 1 to 5 mol∙dm-3, the current density decreases, which is associated with the formation of a solid surface layer of tungsten oxide on the surface of the anode, which passivates the surface. It was established experimentally that when adding 1 mol∙dm^-3 of H₂SO₄ hexamine (C₆H₁₂N₄) with a concentration of 0.9 mol∙dm^-3 to a solution, it is possible to block the process of formation of a passivating film and obtain powders of tungsten oxides of lower oxidation states.

Abstract: Bamboo saw dust (BSD) as reducing agent in low-grade manganese ore leaching is used, and therefore the performance of cellulose hydrolysis will affect the percent recovery of Mn ore. This work is studies the effect of sulphuric acid and speed rotation on hydrolysis of BSD. The crytallinity of BSD were investigated. The parameters considered in this work are sulphuric acid concentration and the speed rotation by using 2³ +3 factorial design. The significant factor, main and interaction effect were investigated based on Analysis of Variance obtained from statistical software. It shows that the sulphuric acid concentration is the main factors that affects the percentercent crystallinity compared to rotation speed. It is proved by the DOE analysis and supported by the crystallinity analysis of BSD before and after hydrolysis process. The optimum condition that can be suggested to obtain low percent crystallinity are when the sulphuric acid concentration and speed rotation at 4M and 400 rpm respectively. This indicates that reducing agent can be obtained from BSD in mild condition of hydrolysis due to decrement of cellulose crystallinity

Abstract: This article presents the results of research on the development of an effective technology for the production of non-fired pellets using a binder additive and a reducing agent. The proposed method will make it possible to obtain pellets using material of class 0-5 mm, i.e. eliminates the costliest part of the pellet production technology - regrinding. It is also important that the non-fired agglomeration of the material almost unchanged the composition and properties of the feedstock, as a result of which the reduction processes in them begin earlier and proceed more intensively. Using the results of physical and chemical studies, a technology has been developed for pelletizing fines of manganese ore from the Western Kamys deposit using clay from the Sazdinsky deposit as a binder and smelting ferrosilicon manganese using manganese pellets.

Abstract: The aim of this work is to investigate the synthesis of reduced graphene oxide (rGO) aqueous suspension by a conventional heating method using vitamin C as a reducing agent. The influences of reaction temperatures (70, 90 and 100 °C) and heating times (30, 45 and 60 min) on the chemical reduction of graphene oxide (GO) were studied. Then, the obtained rGO samples were characterized by FT-IR, Raman and UV-Vis spectroscopy. The FT-IR and Raman results showed that the reduction degree of GO to rGO was increased with the rising of the reaction temperature and time. Moreover, the UV-Vis spectra demonstrated that the absorption band at around 230 nm (π-π*) of pristine GO had shift to the longer wavelength upon the chemical reduction, indicating that GO is reduced to rGO. The optimal condition of the chemical reduction of GO to achievable rGO was the temperature of 90 °C with the 45 min of heating time. This condition yielded the rGO black aqueous suspension with the high quality and stability. Thus, this method of synthesis has an advantage of the rGO dispersion which led to many potential applications.

Abstract: Synthesis of silver nanoparticles (AgNPs) by reduction of AgNO₃ with o-hydroxybenzoic, p-hydroxybenzoic and o,p-dihydroxybenzoic acids as reducing agents was investigated. This research was conducted to determine the effect of the position and number of hydroxyl groups towards the size, shape and stability of the resulted AgNPs. Surface Plasmon Resonance (SPR) of AgNPs was characterized by UV/Vis spectrophotometer, the shape and size of AgNPs was determined by Transmission Electron Microscope (TEM). The results showed that the reducing agent that has substituents in the para position (p-hydroxybenzoic acid) has the higher reduction ability than the others. AgNPs were yielded by all types of reducing agents in alkaline system. Reducing agents which have greater number of substituents (o,p-dihydroxybenzoic acid) could produce AgNPs with smaller concentration of AgNO₃ than the others. AgNPs that was produced by reducing agent having substituents on the para position (p-hydroxybenzoic acid) was more stable and smaller particle size, i.e. 34 ± 1.78 nm than reducing agent that has substituent on the ortho para positions (with particle size 45 + 3.67 nm) and ortho positions (with particle size 70 ± 4.96 nm).

Abstract: This research deals with the interest in production of Cu-Sn-Zn ternary alloy coating via electroplating on carbon substrate by using less hazardous electrolyte. A detailed study was made on the effect of different concentration of reducing and complexing agents. The surface morphology and phase structure of the deposited layers were examined by scanning electron microscope (SEM) equipped with energy dispersive x-ray spectroscopy (EDS), respectively. The results confirmed that the layers of Cu-Sn-Zn was obtained with this less hazardous electrolyte.

Abstract: High surface area Ag/ZnO with an average diameter of 13.95 nm was successfully synthesized through a facile route, using ascorbic acid and silica rice husk as reducing agent and amorphous support respectively. This nanomaterial was characterized by transmission electron microscopy, N₂ adsorption-desorption, atomic absorption spectrometry and particle size analyzer. This simple method resulted in the production of almost spherical Ag/ZnO nanoparticles with high BET surface area and large pore volume of 341.46 m²g^-1 and 0.59 cm³g^-1 respectively. This preliminary study revealed the successful inclusion of metal cations into the silica framework without damaging the mesoporosity nature of silica.

Abstract: Highly stable silver nanoparticles synthesized in single-step green method by mixing silver nitrate and aqueous extract of Almond (Prunus amygdalus). Experiments were conducted to influence the change in the silver nitrate concentration and time on the synthesis of silver nanoparticles at room temperature under dispersed sun light. The almond extract acted both as the reducing and stabilizing agent for the synthesis of silver nanoparticles. The change in the color of the reaction mixture was monitored using UV-Visible spectrometry whereas particles synthesized were characterized using Scanning Electron Microscopy, Dynamic Light Scattering and Fourier Transform Infrared Spectroscopy. The synthesized nanoparticles were almost spherical in shape with an average size about 20 nm and they exhibited bacteriostatic property against E. coli.

Abstract: In this work, highly mesoporous Ag/ZnO was rapidly developed from rice husk, a cheap agricultural biomass with urea as the reducing agent at acidic medium. A facile and cheap sol-gel method combined with calcination was employed to produce Ag/ZnO 0-D nanoparticles. TEM investigation revealed the formation of spherical and discreet nanoparticles with an average particle size of 13.55 nm. Ag/ZnO with semi-crystalline nature was confirmed from the high-angle XRD study. A type IV isotherm with high Brunauer–Emmett–Teller surface area of 416.78 m²g^-1 was exhibited by Ag/ZnO nanoparticles.

Abstract: Selected reducing agents were applied to cotton knitting dyeing with C.I. sulfur black 1, and followed by acid cellulase treatment. The K/S value, fuzz removal rate, sulphurs content of fabric and COD value of the residues was measured to evaluate the cellulase performance. The results show that minimum sulphur content detected when glucose was used as reducing agent, which exhibited maximum fuzz removal, whereas maximum sulphur content detected when sodium sulfide was used as reducing agent, which gave minimum fuzz removal. It is concludes that ecological sulfur black dyeing with sulphur-free reducing agent could decline the suphur content in the fabric and promote cellulase performance.