Intensive Improvement of Reduction Rate of Hematite-Graphite Mixture by Mechanical Milling

The effect of ball milling of raw materials on the reaction behavior of composite mixture of hematite and graphite have been studied. Hematite was mixed with 19.84 wt% graphite (C/O ratio was 1.1 in composite mixture) and subjected to ball milling. The milling time was changed from 6 to 100 hr with the hematite–graphite mixture. On the other hand, graphite or hematite was milled alone and then mixed with non-milled hematite or graphite, respectively. The effect of milling time on reduction process in an Ar atmosphere was studied by TG-DTA. The samples were heated by a constant heating rate of 10°C/min from room temperature up to 1100°C and maintained for 30 min at this temperature. The rate of reaction (RTG) was obtained by the differentiation of weight loss curve. It was found that the RTG curve consisted of three reaction curves which were hematite–magnetite (HM), magnetite–wustite (MW) and wustite–metallic iron (WF) reductions. The curve corresponding to the HM reduction located in low temperature range and stood alone from other two reduction curves ( MW and WF reductions). The curves of MW and WF reductions were overlapped. The pulse-like reduction curve corresponding to WF reduction was observed in the longer milling time, which meant extremely high rate of reduction. The temperatures decreased and the reaction degrees at each peaks increased with increasing milling time. The kinetic analysis applying the single and consecutive reaction was carried out. The calculated reaction curves were in good agreement with the observations which showed that the reaction mainly occurred in this system was the solid oxide–solid carbon reaction. The variation of parameters of rate constant presented the different mechanism of reaction between shorter and longer milling time at the border of 24 hr

Facile synthesis of copper oxide nanoparticles using copper hydroxide by mechanochemical process

A facile mechanochemical-based method for synthesis of copper oxide (CuO) nanoparticles is here by introduced. For this purpose, copper hydroxide powder was synthesized through a facile solution method (CuSO4 + 2 Na(OH) → Cu(OH)2 + Na2SO4) after which milling of as-prepared Cu(OH)2 precursor and NaCl resulted in the mechanochemical dehydration of Cu(OH)2 and dispersion of CuO nanoparticles into the salt matrix (Cu(OH)2+2NaCl=CuCl2+2NaOH and then CuCl2+2NaOH=CuO+2NaCl+H2O). Subsequently, washing the milled powders led to the removal of salt matrix and separation of CuO particles. The main advantages of the introduced method are synthesis of CuO nanoparticles with narrow size distribution without subsequent annealing during the process. The results of X-ray diffraction (XRD) indicated that the dehydration of Cu(OH)2 into CuO was completed after three hours of milling. Structural analysis using scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and particle size analyzer (PSA) showed that CuO particles had moderately equiaxed shape with sizes ranging from 10-27 nm. Also, the results of UV–visible absorption spectroscopy indicated that CuO nanoparticles had a band gap of 2.5 eV

As, Sb, and Fe removal from industrial copper electrolyte by solvent displacement crystallization technique

The presence of impurities in the copper electrolyte increases the energy consumption of an electrorefining process and contaminates the deposited copper on cathode. The concentration of impurities increases over time making it necessary to remove them from the solution. This research introduces a fast, effective, and simple method to refine the industrial electrolyte from arsenic, iron and antimony by solvent displacement crystallisation technique. In this method, when alcohol is added to the electrolyte, the impurities precipitate from the solution as amorphous arsenato antimonite phase. Results show that Fe, Sb, and As are removed from the copper electrolyte by 75.2, 96.9 and 99.8%, respectively. Electro winning experiments show that the electric energy consumption for electrodeposition of copper is 15.5% lower when the electrolyte is free of impurities

Characterization of Rod-like High-purity Fluorapatite Nanopowders Obtained by Sol-gel Method

high purity fluorapatite (FA) with rod-like and spherical-like morphology was synthesized via sol-gel method. Chemical characterization of FA powders was done by XRD and FTIR analyses. Crystallite samples were calculated using Scherer method. Morphology of FA powders was investigated with TEM and SEM images. The results revealed that increasing the time of hydrolysis of phosphate sols significantly decreased the gelation time of FA sols. Also, mixing temperature of P and Ca sols affects the gelation time of samples and increasing pH decreases the gelation time of FA sols. Morphological and chemical characterization of samples showed that the FA powders have high purity and rod-like and spherical-like morphology

Electrosynthesis of Superhydrophilic Nickel Nanosheets on a Three-Dimensional Microporous Template: Applicability toward MOR

In this report, a nickel nanoscaled morphology was synthesized by two-step cathodic electrodeposition on a microporous copper template. The resulting morphology, nanosheets formed on 3D micropores, offers incredible cyclic stability of almost 100% and facilitates transport mechanisms while significantly preserving the active surface area. The origin of the nanosheets is assumed to be the presence of a small amount of iron cations in the electrolyte bath during the final deposition step. By altering the deposition current density of this step, three samples were prepared and compared in terms of the resulting morphology, chemical composition, surface area, wettability, and activation toward the methanol oxidation Reaction. Results show that an increase in the deposition current density in the range of this study produces finer and denser nanosheets, a higher content of reduced iron, a larger surface area, and greater activity toward MOR. The current density for methanol oxidation was exceptional among all other studies on nickel-containing electrocatalysts, yielding a steady-state current density of 135 mA cm–2 at 600 mV versus SCE. All samples offered superhydrophilicity