Modeling of hydrazodicarbonamide oxidation by chlorine in a gas–liquid–solid system

Abstract

The oxidation reaction of solid hydrazodicarbonamide with chlorine in aqueous solution is experimentally studied in a 1 l agitated glass vessel reactor with a four-blade paddle stirrer. Based on the film theory, a model is first developed for this complicated system by taking account of the gas–liquid and solid–liquid mass transfer, solid dissolution, and instantaneous reaction, especially the reduction of solid–liquid mass transfer interfacial area arising from the solid reactant dissolution. The model can reasonably and well describe the experimental data. According to the values of gas–liquid and solid–liquid mass transfer coefficients estimated with the proposed model, it is found that the gas–liquid mass transfer is a rate-controlling step in the majority of the reaction course, but the solid–liquid mass transfer becomes a rate-controlling step when the reaction is close to the final stage of the process.