Thermal dehydration of calcium sulfate dihydrate: physico-geometrical kinetic modeling and the influence of self-generated water vapor

Abstract

Complex kinetic behaviors in the thermal dehydration of CaSO4∙2H2O under varying water vapor pressure (p(H2O)) conditions impel researchers in the field of solid-state kinetics to gain a more comprehensive understanding....

Kinetics and Mechanism of the Dehydration of Calcium Sulfate Dihydrate: A Comprehensive Approach for Studying the Dehydration of Ionic Hydrates under Controlled Temperature and Water Vapor Pressure

“…A recent work reveals the variations in the reaction pathways and kinetics behaviors with the selfgenerated water vapor pressure conditions in the case of the thermal dehydration of calcium sulfate dehydrate. 22 Another possible reason for this gap in the literature is likely to be related to the fact that most of the current literature in heterogeneous reaction kinetics uses the following expression to express reaction rate dα dt = A exp − E RT f α…”

“…Indeed, in the case of thermal decomposition of solids, both the self-generated and the atmospheric gas partial pressure are responsible for determining the overall kinetic behaviors, and experimental control of the self-generated pressure is a great challenge. A recent work reveals the variations in the reaction pathways and kinetics behaviors with the self-generated water vapor pressure conditions in the case of the thermal dehydration of calcium sulfate dehydrate …”

An advanced kinetic approach to the multistep thermal dehydration of calcium sulfate dihydrate under different heating and water vapor conditions: kinetic deconvolution and universal isoconversional analyses

“…On heating CS-DH at a lower temperature in an inert gas atmosphere to realize thermal dehydration proceeding at a moderate reaction rate under a low water vapor pressure (p(H 2 O)) condition, thermal dehydration of CS-DH occurs to directly form anhydride. 2,3 CaSO 4 Á 2H 2 OðsÞ ! CaSO 4 ðsÞ þ 2H 2 OðgÞ…”

“…The same is observed due to self-generated water vapor, when CS-DH is heated at a higher temperature in a semi-closed system. 2,[11][12][13][14] On further heating the solid product (CS-HH) at a higher temperature, the thermal dehydration of CS-HH When CS-DH is heated under linear nonisothermal conditions at a fixed heating rate (b) under atmospheric conditions at different p(H 2 O) values, the mass-loss curves change from the single-step mass-loss of CS-DH to anhydride at a lower p(H 2 O) value to the two-step mass loss of CS-DH to anhydride via the CS-HH intermediate with an increase in the p(H 2 O) value. 2 The two-step mass-loss process initially appears as a partially overlapping process and completely separates at a higher p(H 2 O).…”

Effects of Particle Size on the Kinetics of Physico-geometrical Consecutive Reactions in Solid–Gas Systems: Thermal Decomposition of Potassium Hydrogen Carbonate

“…The kinetic data for the physico-geometrical consecutive process are recorded as macroscopically averaged data using thermoanalytical (TA) techniques. Elucidating the kinetic behavior of each physico-geometrical reaction step through kinetic analysis of the TA data of the overall process is currently a challenge. − It would enable the further detailed interpretations of the mutual relationship between the component reaction steps and the changes in the overall kinetic behavior of the thermal decomposition of solids with sample and reaction conditions. − Notably, the challenge is a necessary step to reveal the kinetics of the linear advancement of the reaction interface and the physico-chemical events occurring at the reaction interface.…”