Synthesis of MgO powder from magnesium nitrate using spray pyrolysis T. Pradita, S. J. Shih, B. B. Aji, and Sudibyo
Citation: AIP Conference Proceedings 1823, 020016 (2017); doi: 10.1063/1.4978089 View online: http://dx.doi.org/10.1063/1.4978089 View Table of Contents: http://aip.scitation.org/toc/apc/1823/1 Published by the American Institute of Physics
Synthesis of MgO Powder From Magnesium Nitrate Using Spray Pyrolysis T. Pradita1,a, S.J. Shih2,b, B.B. Aji3,c, Sudibyo3,d 1
Department of Chemical Engineering, Serang Raya University, Jalan Raya Serang-Cilegon, KM.5, Taman Drangong, Serang, Banten, Indonesia. 2 Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, keelung road, Sec. 4, taipei, 10607, taiwan, ROC. 3 Research Unit for Minerals Technology, Indonesian Institute of Sciences, Jalan Ir. Sutami KM.15, South Lampung 35361, Indonesia Corresponding author: a
[email protected] b
[email protected] c
[email protected] d
[email protected] Abstract. A variety of advantages such as catalyst, paints, flame retardants, semiconductors, additives in refractory and solid adsorbent can be obtained from Magnesium Oxide (MgO) based material. Ultrasonic spray pyrolysis (SP) process was conducted to synthesize MgO from Mg(NO3)2.6H2O (MgN) precursor. The MgO particles were characterized using Thermogravimetric Analysis (TGA), X-Ray Diffraction analysis (XRD) and Field Emission-Secondary Electron Microscopy (FE-SEM). In this study, Hollow spherical and irregular MgO particles were successfully obtained. It suggests that the particle size will decrease along with the increasing of the SP temperature, the smallest particle size obtained is in the range of 354±104 nm at 900oC SP temperature.
INTRODUCTION Various alkaline earth metal oxides have been known to be a promising metal based material which possessed many advantages. Magnesium Oxide (MgO) is one of the alkaline earth metal oxide which has been studied for the past decades. MgO powders has been utilized as catalyst [1–5], refractory materials [6], reflecting and anti-reflecting coating [7], additive to heavy fuel oil [8], toxic waste remediation [9], carbon dioxide chemisorbents [10]. With such many and diverse advantages, synthesizing MgO powder using the most effective and efficient method are the aim of this research. Commonly, MgO powders can be successfully synthesize from the decomposition of magnesium salts such as magnesium nitrate and magnesium carbonate [1]. Other method such as precipitation method [11–13], sol-gel method [14] and hydrothermal method [15]. Precipitation and sol-gel method exhibit relatively large and varied grain size due to the agglomeration of MgO particles. As for hydrothermal method, controlling the particle shape, nanostructure particle and crystallite size are well facilitated with this method [15]. However, specific condition, requirement such as high pressure atmospheric, and complexity control process such stirring control, gas flow control and temperature make this method is relative high cost and need special design equipment. Various solution techniques have been developed to synthesize ceramic powders with improved physical and chemical characteristic. Most solution-precipitated powder must undergo subsequent calcination and milling steps, processes that can negate some of the advantage of the solution process. Therefore, there has been significant effort to produce high-quality powders using spray pyrolysis method. Spray pyrolysis offers simplicity and high
International Conference on Chemistry, Chemical Process and Engineering (IC3PE) 2017 AIP Conf. Proc. 1823, 020016-1–020016-5; doi: 10.1063/1.4978089 Published by AIP Publishing. 978-0-7354-1491-4/$30.00
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productivity on a large scale process. In addition to its simplicity, SP has other advantages; continuous process, high purity product, easy to control the chemical compositions of particles and surface modification abilities [16].
EXPERIMENTAL PROCEDURE Material Synthesis MgO powders were synthesized using SP process. The MgO solutions were prepared from 0.05 M Mg(NO3)2.6H2O. The precursor was dissolved in 1 lt of deionized water (DI Water) to form Mg(OH) 2 solutions. Then the solution dispersed into fine droplets using ultrasonic nebulizer (King Ultrasonics CO., Taiwan). Afterwards, these droplets were heated in the tube furnace with the calcination temperature of 700, 800 and 900 oC. These droplets will undergo three SP stages of thermal treatment; pre-heating stage, calcination stage and cooling stage. In the pre-heating stage, the solvent of the droplets will be evaporated and the remaining solute will be precipitate in the calcination stage. In this stage, the decomposition of MgN to form MgO particles was also occurred. Lastly, the cooling stage will decrease the particles temperature for easier powder collection from the stainless steel collector tube.
Characterization MgO powders were characterized using X-ray diffraction analysis (XRD) to investigate the crystal phase of the particle, thermogravimetric analysis (TGA) to determine the decomposition temperature and field emission scanning electron microscopy (FE-SEM) to observe the surface morphology.
RESULT AND DISCUSSION Thermogravimetric Analysis (TGA) The decomposition temperature of the MgN was investigated using thermogravimetric analysis (TGA). Figure 1. shows the decomposition curve of MgN precursor under air and atmosphere condition with the heating rates of 10 °C/min. The weight loss at temperature 0-150oC indicates the loss of water molecules. The MgN precursor is starting to decompose at 350oC and after 600oC the TGA curve shows just a small amount of weight loss which indicates that the MgN precursor has mostly decomposed into MgO. Thus, the SP variation temperatures in this research were 700, 800 and 900oC. Mg(NO3)2.6H2O
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FIGURE 1. Thermogravimetric Analysis of MgN
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X-Ray Diffraction Analysis (XRD) The X-Ray Diffraction analysis was conducted to investigate the phase and crystallographic structure of the powders. Figure 2. shows all the major peaks appear in 2ȧ: 36.94o, 42.92o, 62.30o, 74.69o, 78.63o are corresponding with the MgO plane of (111), (200), (220), (311) and (222) respectively (JCPDF 450964). Although from this XRD pattern it also shown some Mg(OH)2 peaks, this result prove that SP process was successfully synthesize MgO powders from MgN precursor.
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o MgO JCPDF No. 450946)
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FIGURE 2. X-Ray Diffraction patterns of MgO from MgN at 700, 800 and 900oC
Morphological Analysis (FE-SEM) The FE-SEM was used to investigate the surface morphology analysis. From Fig. 3, it was shown that for all SP variation temperatures most of the MgO particles were in the spherical shape. However, it also can be seen some of the particles were in the irregular shape. These occurrences were greatly influenced by the increasing of the SP temperature and the size of the particles. The particle size distributions that are measured from FE-SEM images are shown in (Fig.4).The average particle size of MgO at SP temperature of 700 oC, 800oC and 900oC are 548 ± 306 nm, 487 ± 331 nm and 354 ± 104 nm respectively. The size of the MgO particles were decreasing as the increasing of the SP temperatures (Fig.4), this phenomenon occurs due to most of the bigger particles explodes and creating smaller particles. These particles explosion was caused by the increasing of the particle internal pressure along with the increasing of SP temperature. As seen in Fig.3 (c), the existence of exploded particle also suggests a hollow structure form.
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(a)
(b)
(c) FIGURE 3. SEM images of MgO from MgN at (a) 700, (b) 800 and (c) 900oC 50
PSD : 548
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(c) FIGURE 4. Particle size distribution histogram of MgO from MgN at (a) 700, (b) 800 and (c) 900 oC
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CONCLUSIONS The formation of MgO particles has been characterized using Thermogravimetric Analysis (TGA), X-Ray Diffraction (XRD) and Field Emission-Scanning Electron Microscopy (FE-SEM). The MgO powders were successfully obtained from MgN precursor at SP temperature of 700, 800 and 900oC. These SP temperature variations have a significant effect on the particle size distribution of MgO particles. Based on the result, increased SP temperature will decrease the particle size distribution of MgO particles. At SP temperature of 900oC the MgO particles has the smallest particle size among the other SP variation temperatures. Another significant result was also shown from the shape of the particle. The formation of hollow spherical and irregular particle shape was also influenced by the variation of SP temperatures. Thus, the particle formation mechanism of MgO using SP process needs further investigation.
ACKNOWLEDGEMENT Author would like to thank you the financial support by National Taiwan University of Science and Technology under grant. No. MOST 104-222-E-011-017 and financial support from Indonesian institute of sciences and Ministry of Research, Technology and Higher Education -Republic of Indonesia through INSINAS research grant no. RT-2016-0227.
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