KINETICS OF STRONTIUM SULFATE PRECIPITATION FROM AQUEOUS-ELECTROLYTE SOLUTIONS

The kinetics of spontaneous precipitation of strontium sulfate in a batch reactor was investigated at various temperatures, pressures, and ionic strengths. Precipitation rate constants were determined at temperatures of 303 to 398 K, pressures from saturation to 13.8 MPa, and initial ionic strengths of 0.02 to 4.5 molal. The precipitation obeyed a second-order rate equation at moderate and small supersaturations and appeared to obey a first-order rate equation when the supersaturation was very low. The rate constant was found to be nearly independent of pressure and a strong function of temperature with an apparent activation energy of 59 kJ/mol. The rate constant decreased rapidly with an increase in ionic strength in the range of low ionic strengths, and decreased very slowly at ionic strengths greater than 2 molal.