Abstract
The hydration of different active MgO under an unforced and ultrasonic condition was conducted in this paper to investigate the chemical kinetics model of the apparent reaction and discuss the mechanism combined with the product morphology. The dynamics fitting result shows that both the first-order and multi-rate model describe the hydration process under ultrasound well, while only the multi-rate model was right for the hydration process under an unforced condition. It indicated that the rate order of hydration was different in the hydration process under an unforced condition. The XRD and SEM show that the MgO hydration was a process of dissolution and crystallization. Part of the magnesium ions produced by dissolution of MgO did not diffuse into the solution in time, and adhered to the magnesium oxide surface and grew in situ instead. As a result, the difference in the hydration rate of the remaining MgO particles becomes wider and not in the same order (order of magnitude). The ultrasonic cavitation could prevent the in-situ growth of Mg(OH)2 crystal nuclei on the surface of MgO. It not only greatly improved the hydration rate of MgO and produced monodisperse Mg(OH)2 particles, but also made the first-order kinetics model fit the hydration process of MgO well.
Highlights
Magnesium hydroxide (Mg(OH)2 ) is a nontoxic, efficient, thermally stable, smoke suppression, and environment-friendly flame retardant [1,2,3,4,5]
The process of magnesium oxide hydration seems a simple precipitation reaction, some factors need to be carefully controlled during the reaction so as to obtain magnesium hydroxide with the desired properties [14]
The hydration of magnesium oxide has been studied since the 1960s [17,18,19,20], and it has been found that the reaction step of the magnesium oxide hydration is not a simple two-step boundary expansion growth process, but a complex multi-step reaction including dissolution, diffusion, precipitation, and more
Summary
Magnesium hydroxide (Mg(OH)2 ) is a nontoxic, efficient, thermally stable, smoke suppression, and environment-friendly flame retardant [1,2,3,4,5]. It is used to neutralize acid waste water and gases rich in sulfuric oxides, applied in the biomedical field [6,7,8,9]. The process of magnesium oxide hydration seems a simple precipitation reaction, some factors need to be carefully controlled during the reaction so as to obtain magnesium hydroxide with the desired properties [14]. Otherwise, problems such as a low rate of hydration, agglomeration, and bad morphology occur, limiting the application prospect of magnesium hydroxide on the material properties [15,16]. The hydration process is affected by many factors, such as the magnesium oxide properties, external force environment, hydration
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
