Gold dissolves electrochemically in alkaline solutions containing ligands to form complex ions with gold ion. Therefore, selective leaching of noble metals is expected without dissolution of base metals such as steels...Gold dissolves electrochemically in alkaline solutions containing ligands to form complex ions with gold ion. Therefore, selective leaching of noble metals is expected without dissolution of base metals such as steels, aluminum alloys in scrap treatment. Gold electrodes were investigated using linear sweep voltammetry, EQCM method and potentiostatic electrolysis in alkaline solutions containing thiourea, Na 2SO 3 and Na 2S 2O 3. The solution composition, electrode potential affect gold dissolution rate and current efficiency. The gold dissolved from anode electrode forms complex ions, suspension particles as compound precipitates and deposits on cathode electrode as a metal. Anodic efficiency for gold dissolution is between 10% and 22%. This is caused by the oxidation decomposition of sulfite ions and thiourea. The stability of the alkaline solution containing these elements was also estimated by capillary electrophoresis technique.展开更多
The fibrous nickel oxide particles were prepared by chemical precipitation and pyrolysis method. The NiO precursors were firstly precipitated from nickel ions solution with addition of oxalate salt, and then the final...The fibrous nickel oxide particles were prepared by chemical precipitation and pyrolysis method. The NiO precursors were firstly precipitated from nickel ions solution with addition of oxalate salt, and then the final NiO particles were obtained by pyrolysis of the precursor. The effects of the pH value, precipitation temperature, reactant concentration, addition of surfactant on the morphology of the precursor particles were investigated. The crystallinity, purity, morphology of the fibrous NiO were analyzed by XRD and SEM. The fibrous NiO particles with 100120 in axis/diameter ratio may be produced under the optimal process conditions that are proposed: the Ni2+ concentration is （0.5）0.8 mol/L, pH value is 8.38.9, precipitation temperature is 6075 ℃, pyrolysis temperature is 500600 ℃.展开更多
文摘Gold dissolves electrochemically in alkaline solutions containing ligands to form complex ions with gold ion. Therefore, selective leaching of noble metals is expected without dissolution of base metals such as steels, aluminum alloys in scrap treatment. Gold electrodes were investigated using linear sweep voltammetry, EQCM method and potentiostatic electrolysis in alkaline solutions containing thiourea, Na 2SO 3 and Na 2S 2O 3. The solution composition, electrode potential affect gold dissolution rate and current efficiency. The gold dissolved from anode electrode forms complex ions, suspension particles as compound precipitates and deposits on cathode electrode as a metal. Anodic efficiency for gold dissolution is between 10% and 22%. This is caused by the oxidation decomposition of sulfite ions and thiourea. The stability of the alkaline solution containing these elements was also estimated by capillary electrophoresis technique.
文摘The fibrous nickel oxide particles were prepared by chemical precipitation and pyrolysis method. The NiO precursors were firstly precipitated from nickel ions solution with addition of oxalate salt, and then the final NiO particles were obtained by pyrolysis of the precursor. The effects of the pH value, precipitation temperature, reactant concentration, addition of surfactant on the morphology of the precursor particles were investigated. The crystallinity, purity, morphology of the fibrous NiO were analyzed by XRD and SEM. The fibrous NiO particles with 100120 in axis/diameter ratio may be produced under the optimal process conditions that are proposed: the Ni2+ concentration is （0.5）0.8 mol/L, pH value is 8.38.9, precipitation temperature is 6075 ℃, pyrolysis temperature is 500600 ℃.
