Sharif Digital Repository

In this study, chalcopyrite concentrate produced in Sarcheshmeh copper plant was subjected to oxidative leaching investigation by cupric ion to determine the effect of several parameters on the copper and iron dissolution, including temperature of leaching, time of holding and cupric concentration as oxidant agent in a range of 38–97 °C, 1.5–8.5 h and 0.2–0.8 M, respectively. The leaching media was chloride providing with 3 M HCl 37% and CuCl2. The experiments were designed by central composite design method. The dissolution of copper and iron was examined. The maximum dissolution of copper 62.64%, was obtained at 85 °C, 7 h and oxidant concentration of 0.7 M. The kinetics model of... 

A red pigment has been prepared by substituting chromium ions in aluminum ion sites in YAlO3 perovskite structure. In a first step, effect of various mineralizers on YAlO3 formation has been investigated, which resulted in decrease of formation temperature down to 1400 °C. In the next step, a red pigment corresponding to YAl1-yCryO3 (y = 0.05), has been prepared by heating a mixture containing Y2O3, Al2O3 and Cr2O3 at 1500 °C for 6 h. Later, effect of the doped chromium amount on the pigment redness (a*) has been studied. The highest redness has been obtained when y was 0.04(YAl1-yCryO3). Application of the prepared red pigment in low and high temperature glazes, demonstrated its high... 

L-Ascorbate anion electro-oxidation on a silver electrode in hydroxide solution in the absence and presence of sodium polysulfide of concentrations from 1 × 10 -5 to 4.5 × 10 -4 mol/L was studied using cyclic voltammetry and electrochemical impedance spectroscopy. Both hydroxide and polysulfide ions inhibited L-ascorbate ion oxidation, with the poisoning effect of polysulfide ion being more pronounced in the potential range of -0.3 to -0.2 V/SCE. The time constants for L-ascorbate ion oxidation in the absence and presence of polysulfide were, 10 -3 to 1 × 10 -2 s and 1 × 10 -4 to 1 × 10 -2 s, respectively depending on the potential used for the impedance analysis. Based on the cyclic... 

By a single-step supercritical hydrothermal synthesis method, yttrium oxide nanoparticles were successfully prepared without additional treatment. Yttrium oxide nanoparticles were employed as an adsorbent to study the adsorption of some heavy metal ions. This study revealed that nano structure yttrium oxide was an effective adsorbent for removal of lead ions from aqueous solutions  

Electro-oxidation of methanol on Ni in NaOH solutions with the alkali concentration in the range of 0.05-0.5 M and in the presence of 0.5 M Na 2SO4 supporting electrolyte is studied. All the mentioned species compete for adsorption on Ni and OH- is essential for the electro-oxidation process. The electro-oxidation seems to proceed through the electro-chemical reactions of adsorbed methanol and hydroxide species and the removal of the resulting intermediate by adsorbed hydroxyl groups. The mechanism is consistent with the cyclic voltammetry and impedance spectroscopy results and can semi-quantitatively account for the appearance of capacitive, inductive and negative resistance loops as well... 

TiO2 and transition metal (Cr, Mn, Fe, Co, Ni, Cu, and Zn) doped TiO2 nanoparticles were synthesized by the sol-gel method using 2-hydroxylethylammonium formate as an ionic liquid. All the prepared samples were calcined at 500 °C and characterized by X-ray diffraction (XRD), BET surface area determination, energy dispersive X-ray (EDX) analysis, diffuse reflectance spectroscopy (DRS), and Fourier transformed infrared (FT-IR) techniques. The studies revealed that transition metal (TM) doped nanoparticles have smaller crystalline size and higher surface area than pure TiO2. Dopant ions in the TiO2 structure caused significant absorption shift into the visible region. The results of...