در محلول اسيد سولفوريك PB-52N- O.O8CA ارزيابي خواص الكتوركاتاليتيكي آلياژ

An Assessment of Electro-Catalytic Properties of Pb-2Sn-0.08Ca Alloy in Sulphuric Acid

During previous research studies, Pb-2Sn-0.08Ca alloy was found to be the most suitable composition among Lead-Tin-Calcium compositions for fabricating anode electrodes for use in copper electro winning cells from the viewpoints of mechanical properties and corrosion resistance. In this paper the electro-catalytical behavior of the selected lead alloy is studied within a set range of applied current densities together with kinetics and reversibility capabilities of oxidation-reduction processes and the effect of Co^3+ ions on reduction of over voltage of H2O anodic reaction during copper electro winning process using cyclic voltametry technique (1 to 7 cycles), in applied potential range of -1300 to 2600 mV (vs. SCE) and at various scan rates. Then, the chemical phases of oxide layers formed over the Lead Anode surface within the applied potential range when inside 180 g/l H2SO4 solution, was determined via XRD analysis. The obtained results indicate that the electrolyte resistively increases simultaneously, as the porous complex of Oxy-SuIphate Lead film is formed. Also at potentials more than 1.4V (vs. SCE), PbO2 film forms which has a good electro-catalytic property and high electrical conductivity. It is also true to say that this film (PbO2) is responsible for protecting the base metal from corrosion during copper electro winning process. In addition it has been shown that the kinetic of oxidation process, which yields to the formation of protective oxide layer is faster than the reduction process responsible for degradation of the protective film. Also the presence of Co^3+ ions at 100ppm concentration can reduce the over voltage of H2O anodic reaction to as much as 200 mV.