Thermokinetic study of magnesium hydroxide obtained from seawater
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Thermokinetic study of magnesium hydroxide obtained from seawater Jelena Jakić1 · Miće Jakić1 · Miroslav Labor1 Received: 26 November 2019 / Accepted: 14 September 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract In this paper, magnesium hydroxide has been obtained from seawater by a well-known industrial process which involves the chemical reaction between magnesium ions of seawater with dolomite lime to produce the magnesium hydroxide precipitate. Furthermore, the precipitate was modified by ultrasound of high intensity. The purpose was to obtain magnesium hydroxide with high purity and reduced particle size without agglomeration. The precipitated magnesium hydroxide is characterized by the particle size distribution determined by the laser scattering method in the range of 20 nm–2 mm, and by the SEM analysis. Likewise, in order to investigate the effect of particle size on the thermal stability, thermokinetic study of magnesium hydroxide samples was performed by non-isothermal thermogravimetry in an inert atmosphere at different heating rates. The gained thermogravimetric data were utilized for the kinetic analysis, which was performed by using the isoconversional Friedman method in combination with the multivariate nonlinear regression method. For each degradation stage of investigated samples, kinetic parameters (activation energy, pre-exponential factor and kinetic model) were calculated and compared. Keywords Kinetic analysis · Magnesium hydroxide · SEM/EDS analysis · Thermal degradation · Ultrasound
Introduction Magnesium hydroxide (Mg(OH) 2) is a very important inorganic compound with good physical and chemical properties. The physicochemical properties of magnesium hydroxide are defined with shape, size and degree of diversity of the particles. The exceptionally diverse morphology of Mg(OH)2 particles: from needles, platelets, rods, and spheres to “flowers” and “stars”, make them suited for use in the production of modern and advanced materials [1, 2]. It has wide application in many fields, such as flame retardant in polymers, wastewater treatment, in the paper industry, as a catalyst, additive. The unique properties of synthetic magnesium hydroxide with a specific morphology and structure of particles also create possible applications in such fields as electronics, optics, special ceramics and nanocomposites. Magnesium hydroxide can be produced by different methods such as precipitation, solvothermal and hydrothermal methods, microwave methods, electrochemical methods, the sol–gel method, dehydratation and hydration * Miće Jakić mjakic@ktf‑split.hr 1
Faculty of Chemistry and Technology, University of Split, Ruđera Boškovića 35, 21000 Split, Croatia
of commercial forms of Mg(OH)2 and MgO, and the use of dolomite or seawater [3–5]. The precipitation crystallization method is the most economic one for industrial continuous production, having a simple process and low energy consumption [5]. In this paper, magnesium hydroxide has been obtained from seawater by a well-known industrial process
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