Kinetics of Simultaneous Dissolution of Zinc and Manganese from Electrolyte Paste of Spent Zinc-Carbon Dry Cell Battery in Sulfuric Acid Solution

摘要

Manganese and zinc contained in the electrolyte paste of spent zinc-carbon dry cell batteries were leached in sulfuric acid in presence of hydrogen peroxide as a reducing agent. Kinetic parameters were established from the time versus extent of dissolution curves using temperature as variable and keeping the other parameters fixed. Three reactions models (i) Liquid film diffusion controlled, (ii) Diffusion controlled through the product layer and (iii) Chemical reaction controlled were considered for the selection of the appropriate reaction model for the dissolution of manganese and zinc. The kinetic data of leaching for both manganese and zinc were found to follow the chemical reaction controlled process, i..e., where, τ = time for complete disappearance of particles and X = fraction of reacted particles. Activation energy of manganese and zinc were found to be 46.27 KJ/mol and 52.39 KJ/mol respectively; which again justified the appropriateness of the model. At a leaching temperature of 60°C, the extent of dissolution, under the conditions investigated, reached up to 81% for manganese within 21 minutes of leaching and 75% for zinc within 30 minutes of leaching.