Transcript elkim_03
15/16 Semester genap Teknik Elektrokimia Instructor: Rama Oktavian Email: [email protected] Office Hr.: T. 11-12, Th. 08-10; 13-15, F. 08-10; 13-15 Teknik elektrokimia Electrorefining An electrochemical technique suitable for refining metals produced by electrowinning or smelter. The anode is the impure metal Teknik elektrokimia Electrorefining a piece of impure metal is made the anode of the cell. It is oxidized to the cation and then reduced to the pure metal at the cathode. Electrorefining technique is used to obtain ultrapure silver, lead and copper. Teknik elektrokimia Electrorefining Impure metal is oxidized at the anode and pure metal is reduced at the cathode. Teknik elektrokimia Electrorefining Teknik elektrokimia Aqueous Electrorefining aqueous processes presently predominate due to their ease of handling, more developed chemistry and familiarity with aqueous process liquors and electrolytes Teknik elektrokimia Aqueous Electrorefining Teknik elektrokimia Electrorefining of copper Teknik elektrokimia Electrorefining of copper Main reaction Teknik elektrokimia Electrorefining of copper Metal distribution during electrorefining Teknik elektrokimia Electrorefining of copper Metal distribution during electrorefining Teknik elektrokimia Electrorefining of copper Teknik elektrokimia Electrorefining of copper Electrolyte composition Teknik elektrokimia Electrorefining of copper Operating condition Teknik elektrokimia Electrorefining of copper Refining of electrolyte - removing copper, As and Sb by cathodic deposition in separate electrochemical cells with insoluble anodes - the neutralization of the free sulfuric acid by dissolving copper - the electrolyte is freed from Cu, As and Sb by electrolysis in a separate cell and from Ni, Zn and Fe by evaporation Teknik elektrokimia Electrorefining of copper Processing of anodic slime - Copper is removed from the anodic slime by dissolution in hot dilute sulfuric acid with air circulation - Silver of 99.99 % purity is extracted from the alloy by the process of anodic dissolution in a solution of silver nitrate Teknik elektrokimia Electrolytic preparation of inorganic compound Fluorine (F) - Halogen family that has atomic number 9 - an extremely reactive element and reacts with itself to form Fluorine Gas - the 13th most abundant element by weight Teknik elektrokimia Electrolytic preparation of inorganic compound Fluorine (F) Fluorine is found in earth’s crust in different forms: - Fluorspar or Fluorite (CaF2) - Fluoroapatite [3(Ca3 (PO4)2.CaF2)] - Cryolite (Na3AlF6) Teknik elektrokimia Electrolytic preparation of inorganic compound Uses of Fluorine (F) - required for the preparation of uranium(VI) fluoride - used for manufacture of chlorofluorocarbons (CFCs) which are used as refrigerant, aerosol propellants and foaming agent in polymers - Fluoroalkene an important compound of Fluorine on polymerization gives Teflon Teknik elektrokimia Electrolytic preparation of inorganic compound Production of Fluorine (F) - Electrolysis is the only method for the isolation of the element fluorine Overall reaction: Teknik elektrokimia Electrolytic preparation of inorganic compound Production of Fluorine (F) - Electrolysis is the only method for the isolation of the element fluorine Teknik elektrokimia Electrolytic preparation of inorganic compound Production of Fluorine (F) Teknik elektrokimia Electrolytic preparation of inorganic compound Production of Fluorine (F) Teknik elektrokimia Electrolytic preparation of inorganic compound Production of Fluorine (F)