Enhanced Removal of Pb from Electrolytic Manganese Anode Slime by Vacuum Carbothermal Reduction

Electrolytic manganese anode slime (EMAS) is produced during the production of electrolytic manganese metal. In this study, a method based on vacuum carbothermal reduction was used for Pb removal in EMAS. A Pb-removal efficiency of 99.85% and MnO purity in EMAS of 97.34 wt.% was obtained for a reduction temperature of 950°C and a carbon mass ratio of 10% for a holding time of 100 min. The dense structure of the EMAS was destroyed, a large number of multidimensional pores and cracks were formed, and the Pd-containing compound was reduced to elemental Pb by the vacuum carbothermal reduction. A recovery efficiency for chemical MnO2 of 36.6% was obtained via preparation from Pd-removed EMAS through the “roasting-pickling disproportionation” process, with an acid washing time of 100 min, acid washing temperature of 70°C, H2SO4 concentration of 0.8 mol/L, liquid-solid mass ratio of 7 mL/g, calcination temperature of 60°C and calcination time of 2.5 h. Moreover, the crystal form of the prepared chemical MnO2 was found to be basically the same as that of electrolytic MnO2, and its specific surface area, micropore volume and discharge capacity were all higher than that of electrolytic MnO2. This study provides a new method for Pd removal and recycling for EMAS.

Synthesis of Al(OH)3 nanoparticles from Indonesian bauxite and tomato waste extract as chelating agent for nanofluids applications

This study aimed to determine the effect of calcination time on the properties of Al(OH)3 or gibbsite nanoparticles in the sol-gel process, which was then used as the basic material in the manufacturing of water-Al(OH)3 based nanofluids. Nanofluid is a mixture of basic fluids such as water with solid nanoparticles. Al(OH)3 nanoparticles have been successfully synthesized from Indonesia local mineral bauxite using the sol-gel method by utilizing tomato waste extract as a chelating agent at a calcination temperature of 700ºC for 1 hour, 3 hours, and 5 hours. The obtained calcined powders were characterized using X-ray diffractometer (XRD). The evaluation toward nanofluids application based on theirs stability based on visual observation and zeta potential. Based on XRD analysis, all calcined powders has single Al(OH)3 or gibbsite phase. Increasing the calcined temperature gave impact on crystallinity, crystallite size, and reorientation of crystal. The water-Al(OH)3 nanofluid was relatively less stable with a zeta potential value of -25.2 mV; -26.4 mV; and -17.4 mV for calcination time 1 h, 3 h, and 5 h, respectively.

PREPARATION OF ATO NANOPOWDERS WITH Co-PRECIPITATION AND THEIR LASER-REFLECTION PROPERTIES

Antimony tin oxide (ATO) nanoparticles were prepared using co-precipitation with tin chloride and antimony chloride as the main raw materials. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and ultraviolet-visible spectrophotometry were used to characterize the crystal structure, morphology and laser reflectivity. The effects of the pH value, co-precipitation reaction temperature, calcination temperature and calcination time on the laser reflectivity of ATO nanoparticles were studied. The results show that, compared with the undoped SnO2 powder, the reflectivity of a Sb-doped ATO powder at a laser wavelength of 1.06 µm is significantly reduced, and with an increase in the Sb doping, the reflectivity of the ATO powder at 1.06 µm first decreases and then increases. When the Sb/Sn molar ratio is 2/10, the reflectivity decreases to the lowest point, which is caused by the high concentration of Sb5+. ATO powders (Sb/Sn = 2/10) prepared at a titration-end-point pH of 2, co-precipitation temperature of 70 °C, calcination temperature of 800 °C and calcination time of 6 h have the lowest laser reflectivity at the laser wavelength of 1.06 µm, which is less than 0.02 %.

Synthesis of Belite-Ye’elimite-Ternesite Cement Clinker

Belite - ye’elimite - ternesite (BYT) cement clinker has attracted much attention due to its advantages of wide range of raw materials, low energy consumption and low carbon emission compared with ordinary portland cement (OPC). In this experiment, chemical reagents were used as raw materials. The effects of calcination temperature and calcination time on clinker synthesis were studied. The best sintering temperature was determined by sintering in rang of 1150-1300°C (setting a temperature point every 30 °C), and then the samples were sintering for 1-6 hours (setting every hour) to determine the best sintering time. The stable condition of the BYT clinker was determined. The phase composition and microstructure of cement clinker were analyzed by X-ray powder diffraction (XRD) Rietveld refinement and Scanning Electronic Microscopy (SEM). The results showed that the desired clinker could be obtained by sintering at 1210°C for 2 hours. In the presence of C4A3$, the hydration of C5S2$ was accompanied by the formation of gypsum and the precipitation of ettringite.

Influence of Calcination conditions on the Adsorption Properties of the Wasted Sea Shell to the Dibutyl phthalate

<p>The calcined clam seashell powders were applied as adsorbent to adsorb Dibutyl phthalate (DBP), from an aqueous solution. The influence of calcination conditions including temperature and time on its adsorption capability to DBP was investigated. The shell powders calcined at 500 oC had the best adsorption capability. As the calcination time extending under different temperatures, the adsorption capabilities showed the same tendency and reached peak values at the calcination time of 10mins. Calcination time extension also led to the increase of crystal unit cell Sizes of CaCO3 inside the clam seashells at the first 10mins and then decreased to the stable value, Correspondingly, the calcined shell specific surface areas decreased firstly to the minimum at 10mins and then gradually increased, as the calcination process lasting at 500oC. The maximum adsorption capability as 1.237mg/g, the lowest specific surface area as 14.2m2/g, and the largest unit cell size as 60.7nm of CaCO3 simultaneously exhibited at the calcination time of 10mins. The Freundlich isotherm model and the pseudo-second-order-kinetics model were appropriate for describing the adsorption isotherm and kinetics of DBP at 30oC, respectively. It is inferred that the interaction between calcined shell and DBP is chemical adsorption.</p>

Enhanced C2 and C3 Product Selectivity in Electrochemical CO2 Reduction on Carbon-Doped Copper Oxide Catalysts Prepared by Deep Eutectic Solvent Calcination

Copper and its oxides are the main catalyst materials able to promote the formation of hydrocarbons from the electrocatalytic CO2 conversion. Herein, we describe a novel preparation method for carbon-doped copper oxide catalysts based on an oxidative thermal treatment of copper-containing deep eutectic solvents (DES). XRD and EDX analysis of the samples show that thermal treatment at 500 °C in air for a prolonged time (60 min) provides exclusively carbon-doped copper(II) oxide catalysts, whereas shorter calcination time leads to a mixture of less oxidized forms of copper (Cu2O and Cu0), CuO, and a higher carbon content from the DES. Chronoamperometry of the electrode containing the prepared materials in 0.5 M KHCO3 electrolyte show the reduction of CuO to less oxidized copper species. The materials prepared by the use of different DES, copper precursors and calcination times were used as electrocatalysts for the electrochemical CO2 reduction. Chemical analysis of the products reveals an enhanced selectivity toward C2 and C3 products for the catalyst prepared from the DES galactose-urea with copper nanoparticles and calcination for 60 min in air. The electrocatalytic activity of the prepared materials were compared to commercial CuO and showed a higher product concentration at −1.7 V vs. Ag/AgCl, with formation rates of 7.4, 6.0, and 10.4 µmol h−1 cm−2 for ethanol, n-propanol, and ethylene, respectively.

Superparamagnetic α-Fe2O3/Fe3O4 Heterogeneous Nanoparticles with Enhanced Biocompatibility

A novel type of magnetic α-Fe2O3/Fe3O4 heterogeneous nanoparticles was prepared via a facile solution combustion process with ferric nitrate and urea as raw materials, and they were characterized by XRD, SEM, TEM, and VSM techniques. The effects of the calcination temperature, the calcination time, the ratio of ferric nitrate and urea, and the heating rate on the relative content of Fe3O4 in the heterogeneous nanoparticles were investigated. The toxicity of α-Fe2O3/Fe3O4 heterogeneous nanoparticles to human hepatocytes L-02, the blood routine, and the histopathological section observation of mice were explored. The results showed that the ratio of ferric nitrate and urea was a key factor to affect the relative content of Fe3O4 in the heterogeneous nanoparticles. The calcination temperature and the calcination time had similar influences, and the corresponding calcination temperature and the calcination time were selected according to their own needs. The CCK8 results initially revealed that α-Fe2O3/Fe3O4 heterogeneous nanoparticles had no effect on cell viability when the concentration of the heterogeneous nanoparticles was less than 100 ng/mL, which suggested their excellent biocompatibility. At the same time, the tail vein administration concentration of 0.9 mg/kg had good biological safety.

Hierarchical Nanocauliflower Chemical Assembly Composed of Copper Oxide and Single-Walled Carbon Nanotubes for Enhanced Photocatalytic Dye Degradation

We present the fabrication and proficient photocatalytic performance of a series of heterojunction nanocomposites with cauliflower-like architecture synthesized from copper(II) oxide (CuO) nanocrystals and carbon nanotubes with single walls (SWCNTs). These unique photocatalysts were constructed via simplistic recrystallization succeeded by calcination and were labeled as CuOSC-1, CuOSC-2, and CuOSC-3 (representing the components; CuO and SC for SWCNTs, and the calcination time in hours). The photocatalytic potency of the fabricated nanocomposites was investigated on the basis of their capability to decompose methylene blue (MB) dye under visible-light irradiation. Every as-synthesized nanocomposite was effective photocatalyst for the photodecomposition of an MB solution. Moreover, CuOSC-3 exhibited the best photocatalytic activity, with 96% degradation of the visible-light irradiated MB solution in 2 h. Pure CuO nanocrystals generated through the same route and pure SWCNTs were used as controls, where the photocatalytic actions of the nanocomposite samples were found to be remarkably better than that of either the pure CuO or the pure SWCNTs. The recycling proficiency of the photocatalysts was also explored; the results disclosed that the samples could be applied for five cycles without exhibiting a notable change in photocatalytic performance or morphology.

Synthesis and Transformation of Hollow Rutile Titania Wires by Single Spinneret Electrospinning with Sol-Gel Chemistry

The work described below was carried out to understand how to control the morphology of nanostructured titania calcined from electrospun nanofibers. This is the first report of hollow rutile nanofibers synthesized from electrospun nanofibers with short calcination time. Titanium isopropoxide was incorporated into the nanofibers as the titania precursor. The electrospinning technique was used to fabricate ceramic/polymer hybrid nanofibers. The electrospun nanofibers were then calcined to produce rutile titania nanofibers with different morphologies (hollow or solid nanofibers), which were characterized by SEM and TEM. The initial concentration of ceramic precursor and the calcination time were shown to control the morphology of the nanofiber. The hollow morphology was only obtained with a concentration of the precursor within a certain level and with short calcination times. The heat treatment profile contributed to particle growth. At longer times, the particle growth led to the closure of the hollow core and all the nanofibers resembled strings of solid particles. A formation mechanism for the hollow nanofibers is also proposed.