Kinetics of Thermal Degradation of VP-1AP Anion-Exchange Resin in the Nitrate Form

Abstract

Thermal degradation of VP-1AP anion-exchange resin in the nitrate form was studied by DSC–TG. The degradation occurs in steps and is accompanied by exothermic effects in the temperature ranges 170–190, 200–280, 280–390, and 400–550°С. The first two exothermic peaks are associated with thermal degradation of the sorbent, and all the other peaks, with oxidation of the matrix with atmospheric oxygen. The kinetic parameters of separate steps were determined. A mathematical model of degradation of VP-1AP anion-exchange resin in the nitrate form was developed. It can be applied to evaluation of the safety in handling this form of the sorbent. Principal possibility of constructing a kinetic model of degradation of ion-exchange materials on the basis of the results of DSC–TG experiments performed with milligram amounts of samples, applicable to simulation of enlarged installations, was demonstrated. An experimental cell suitable for ion-exchange materials was developed for validation of the degradation kinetic models constructed on the basis of the DSC data. The thermal explosion of VP-1AP in the nitrate form in the experimental cell is observed at a thermostat temperature of 245°С, but is not observed up to 230°С. The calculated critical temperature of thermal explosion of VP-1AP anion-exchange resin in the nitrate form under the experimental conditions is in the interval 237–242°С.