HIGH TEMPERATURE KINETICS OF PRECIPITATION AND DISSOLUTION OF FERROUS-CARBONATE

Ferrous carbonate has been studied in batch reactions under rigorously anoxic conditions to determine thermodynamic and kinetic information about the compound. This information is particularly of interest in corrosion control and in the comparison of FeCO{dollar}sb3{dollar} to CaCO{dollar}sb3{dollar}, a compound which has been studied extensively. The enthalpy of the dissolution reaction has been calculated to be {dollar}-22.8{dollar} {dollar}pm{dollar} 0.6 kJ/mole, which is close to the NBS (1) reported value. The precipitation kinetics fit an empirical second order rate law with an activation energy of (9.31 {dollar}pm{dollar} 1.47) {dollar}times{dollar} {dollar}10sp4{dollar} J/mole, indicating surface reaction control. The dissolution kinetics fit an empirical second order rate law more closely than a first order rate law; however, more research is needed to decisively determine the reaction order. With either rate law, the activation energy for dissolution is large enough to suggest surface reaction control.