Study of Kinetics of Interaction Between Ammonium Bisulfate and Potassium Chloride for Fertilizers
Abstract
This study aims to scientifically substantiate the reaction between potassium chloride and ammonium bisulfate based on thermodynamic and kinetic studies, as well as thermal analysis. The experimental work was conducted in a laboratory shaft electric furnace with observations of changes in the reaction mass and determination of the pH of the gas phase. The produced products, physicochemical changes of reaction mixtures, and synthesized salts were studied together with the thermodynamic evaluation of the reactions. For the incubation period in the range of 187-260 °C, the apparent activation energy (Ea) was 4385 Cal/mol. For the most linear section of the main period, the Eа was calculated to be 21848 Cal/mol. A negative Ea indicates heat dissipation (cooling) rather than heat input. This may be associated with the presence of an exothermic exchange reaction, which initiates at a lower temperature. Such interaction is more likely because potassium cations, with more pronounced basic properties, tend to form compounds with anions of stronger acids. Hydrosulfates, having more acidic properties, are capable of earlier interactions. Considering the Ea of the ammonium bisulfate and potassium chloride reaction, the limiting factor is kinetic. The incubation period involves the components of the reaction mixture entering an exchange reaction without gas release. The main interaction period begins with the evolution of gaseous products and the formation of a double salt, which decomposes into potassium and ammonium sulfates. The third stage is the pyrolysis of ammonium sulfate, which is a source of ammonia and liquid ammonium bisulfate.