Kinetics of cyanate decomposition in alkaline solutions of high ionic strength: the catalytic effect of bicarbonate

This paper clarifies the catalytic effect of bicarbonate on the decomposition of cyanate in highly alkaline solutions of high ionic strength at 94 degreesC containing sodium cyanate (0.019 M), sodium hydroxide (0.1-0.9 M), and sodium carbonate (0-1.1 M). Activity coefficients were calculated to account for nonideality in determining the concentration of bicarbonate in solutions with a pH above pK(a,HCO3)-. A rate equation is presented, and parameter estimation was used to obtain values for the rate constants based on the experimental data. Finally our data and literature data was used to derive the temperature dependence of the relevant rate constants and compare the predictions of the kinetic model against the experimental results with three kraft pulp mill green liquors.