Galena Non-oxidative Dissolution Kinetics in Seawater

The rate of non-oxidative galena dissolution in seawater compositions over the pH range of 2-4.5 was determined from batch reactor experiments. The derivative at zero time of a polynomial fit of the Pb concentration versus time data for the first 30 min was used to determine the rate. A plot of R-Gn (rate of galena dissolution) versus pH for data from six experiments is linear (R-2 = 0.96), with a slope of 0.5. The rate equation describing the rate of galena dissolution as a function of hydrogen ion activity is R-Gn = 10(-10.72)(a(H+))(0.50) Varying the concentration of dissolved oxygen produced no significant effect on the measured rates. The activation energy, based on four experiments carried out over the temperature range of 7-30 degrees C, is 61.1 kJ/mol.