Search for: nitric-acid-concentration
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    Kinetics of silver dissolution in nitric acid from Ag-Au0.04-Cu0.10 and Ag-Cu0.23 scraps

    , Article Journal of Materials Science and Technology ; Volume 22, Issue 5 , 2006 , Pages 696-700 ; 10050302 (ISSN) Sadrnezhaad, S. K ; Ahmadi, E ; Mozammel, M ; Sharif University of Technology
    Kinetics of dissolution of silver present in precious metal scraps in HNO3 was studied in temperature range of 26-85°C. Dissolution rate of silver was much faster than that of copper at all temperatures. Effects of particle size, stirring speed, acid concentration and temperature on the rate of dissolving of silver were evaluated. Dissolution rate decreases with particle size and increases with temperature. Dissolving was accelerated with acid concentrations less than 10 mol/L, Concentrations greater than 10 mol/L resulted in slowing down of the dissolution rate. Shrinking core model with internal diffusion equation t/τ = 1 - 3 (1-x)2/3 + 2 (1-x) could be used to explain the mechanism of the... 

    Biodiesel production using CaO/γ-Al2O3 catalyst synthesized by sol-gel method

    , Article Canadian Journal of Chemical Engineering ; Volume 93, Issue 9 , July , 2015 , Pages 1531-1538 ; 00084034 (ISSN) Moradi, G ; Mohadesi, M ; Rezaei, R ; Moradi, R ; Sharif University of Technology
    Wiley-Liss Inc  2015
    In this study, 40% CaO/γ-Al2O3 catalyst was used for biodiesel production from corn oil. A transesterification reaction was done for 5h at a temperature of 65°C in the presence of corn oil, methanol (methanol to oil molar ratio of 12:1), and CaO/γ-Al2O3 catalyst (0.06g/g (6wt%)). Catalyst used in this study was synthesized using the sol-gel method. In this method, two parameters of gelation temperature and nitric acid concentration were used as variables in the catalyst synthesis step, and experiments were designed using central composite design (CCD). The results indicate that the optimal point is achieved at a gelation temperature of 70°C and... 

    Process optimization and kinetics for leaching of cerium, lanthanum and neodymium elements from iron ore waste's apatite by nitric acid

    , Article Transactions of Nonferrous Metals Society of China (English Edition) ; Volume 27, Issue 2 , 2017 , Pages 420-428 ; 10036326 (ISSN) Ferdowsi, A ; Yoozbashizadeh, H ; Sharif University of Technology
    Nonferrous Metals Society of China  2017
    The leaching of rare earth elements (REEs) including cerium, lanthanum and neodymium from apatite concentrate obtained from iron ore wastes by nitric acid was studied. The effects of nitric acid concentration, solid to liquid ratio and leaching time on the recoveries of Ce, La and Nd were investigated using response surface methodology. The results showed that the acid concentration and solid to liquid ratio have significant effect on the leaching recoveries while the time has a little effect. The maximum REE leaching recoveries of 66.1%, 56.8% and 51.7% for Ce, La and Nd, respectively were achieved at the optimum leaching condition with 18% nitric acid concentration, 0.06 solid to liquid...