Abstract:Abstract. Natural zeolite is abundantly available in Indonesia and well distributed especially in the volcano area like Java, Sumatera, and Sulawesi. So far, natural zeolite from Klaten, Central Java is one of the most interesting zeolites has been widely studied. This research aims to know the effect of seed-assisted synthesis under a hydrothermal condition at 120 °C for 24 hours of Klaten's zeolite toward the structural change and phase transformation of the original structure. According to XRD and XRF analy… Show more
“…In addition, the type of mineralization agent also has a great influence on the quality and growth rate of the crystal. Studies have shown that the use of acids, such as HCl, H 2 SO 4 , H 3 PO 4 , HNO 3 , and HCOOH, as mineralizers can reduce the crystal growth temperature to below 300 °C, thus allowing the use of relatively simpler autoclaves [51,52]. Tani et al [53] summarized the effect of mineralizers on ZrO 2 crystallization using the hydrothermal method as shown in Table 1.…”
With the continuous development and progress of materials science, increasingly more attention has been paid to the new technology of powder synthesis and material preparation. The hydrothermal method is a promising liquid phase preparation technology that has developed rapidly during recent years. It is widely used in many fields, such as the piezoelectric, ferroelectric, ceramic powder, and oxide film fields. The hydrothermal method has resulted in many new methods during the long-term research process, such as adding other force fields to the hydrothermal condition reaction system. These force fields mainly include direct current, electric, magnetic (autoclaves composed of non-ferroelectric materials), and microwave fields. Among them, the microwave hydrothermal method, as an extension of the hydrothermal reaction, cleverly uses the microwave temperature to compensate for the lack of temperature in the hydrothermal method, allowing better practical application. This paper reviews the development of the hydrothermal and microwave hydrothermal methods, introduces their reaction mechanisms, and focuses on the practical application of the two methods.
“…In addition, the type of mineralization agent also has a great influence on the quality and growth rate of the crystal. Studies have shown that the use of acids, such as HCl, H 2 SO 4 , H 3 PO 4 , HNO 3 , and HCOOH, as mineralizers can reduce the crystal growth temperature to below 300 °C, thus allowing the use of relatively simpler autoclaves [51,52]. Tani et al [53] summarized the effect of mineralizers on ZrO 2 crystallization using the hydrothermal method as shown in Table 1.…”
With the continuous development and progress of materials science, increasingly more attention has been paid to the new technology of powder synthesis and material preparation. The hydrothermal method is a promising liquid phase preparation technology that has developed rapidly during recent years. It is widely used in many fields, such as the piezoelectric, ferroelectric, ceramic powder, and oxide film fields. The hydrothermal method has resulted in many new methods during the long-term research process, such as adding other force fields to the hydrothermal condition reaction system. These force fields mainly include direct current, electric, magnetic (autoclaves composed of non-ferroelectric materials), and microwave fields. Among them, the microwave hydrothermal method, as an extension of the hydrothermal reaction, cleverly uses the microwave temperature to compensate for the lack of temperature in the hydrothermal method, allowing better practical application. This paper reviews the development of the hydrothermal and microwave hydrothermal methods, introduces their reaction mechanisms, and focuses on the practical application of the two methods.
“…The well-established procedure involves alkali fusion from CFA followed by hydrothermal treatment to achieve a desired X-type zeolite structure [2]. For instance, the conversion of Indonesian zeolite into analcime (ANA) form was conducted under hot-water conditions [3] leading to zeolites with high crystallinity. Sandoval et al suggest that ANA can be manufactured from natural clinker [4].…”
Fly ashes as a residue from combustion processes of coal in coal-fired power stations can be applied for zeolite formation. The zeolite synthesis has considerable effect on their structure following further catalytic use. The formation of analcime is guided by the operation of the silicate framework in the company of Na+, [Al(OH)4]−, [H2SiO4]2− species, coming from fly ash processing. Here, we have highlighted the importance of conducting the coal fly ash waste management towards monomineralic zeolite synthesis, in the form of powder analcime. It is the first report on powder analcime production without fly ash residues, confirmed by SEM and XRD analysis. The obtained analcime-zeolite was further explored as biodiesel catalyst based on base-catalyzed transesterification process. The effect of analcime catalyst usage on the biodiesel yield was determined with observed 97.2 % conversion efficiency under the concentration of 4%wt at 230 °C, with three times reusable analcime catalysts. Coal fly ash-derived monominerals on a large scale can significantly contribute to the sustainability goals and efficient waste management.
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