Continuous synthesis of surface-modified zinc oxide nanoparticles in supercritical methanol

Veriansyah, Bambang; Kim, Jae Duck; Min, Byoung Koun; Shin, Young Ho; Lee, Youn Woo; Kim, Jae-Hoon

doi:10.1016/j.supflu.2009.11.010

Cited by 72 publications

(33 citation statements)

References 38 publications

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“…Particle size, morphology, and crystal structure can be controlled by varying synthesis conditions such as temperature, pressure, and time (Sue et al, 2004). Veriansyah et al (2010) examined the continuous hydrothermal synthesis of decanoic acid-modified and oleic acid-modified ZnO nanoparticles in scMeOH. The usage of scMeOH and the surface modifiers changed drastically the shape and size of the nanoparticles.…”

Section: Hydrothermal Methodsmentioning

confidence: 99%

Biodiesel production using solid metal oxide catalysts

Refaat

2010

Int. J. Environ. Sci. Technol.

258

158

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Biodiesel production is worthy of continued study and optimization of production procedures due to its environmentally beneficial attributes and its renewable nature. Heterogeneous transesterification is considered to be a green process. The process requires neither catalyst recovery nor aqueous treatment steps and very high yields of methyl esters can be obtained, close to the theoretical value. However, heterogeneously catalyzed transesterification generally requires more severe operating conditions, and the performance of heterogeneous catalysts is generally lower than that of the commonly used homogeneous catalysts. Heterogeneous catalysis for biodiesel production has been extensively investigated in the last few years. Many metal oxides have been studied for the transesterification process of oils; these include alkali earth metal oxides, transition metal oxides, mixed metal oxides and supported metal oxides. The use of solid metal oxides as catalysts in oil transesterification is well established, accordingly, researchers' attempts are now focused on how to attain the highest catalyst activity. Catalyst activity is a function of its specific surface area, base strength and base site concentration. High specific surface area, strong base strength and high concentration of base sites are characteristics of an active transesterification catalyst. This review provides a brief overview of the different metal oxides frequently used in the process of transesterification of oils for the production of biodiesel with special reference to the various methods of catalyst preparation and catalyst characterization. Reaction conditions and catalyst leaching analysis are also highlighted. Finally, concluding remarks regarding catalyst selection and catalyst preparation steps are provided.

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Section: Hydrothermal Methodsmentioning

confidence: 99%

Biodiesel production using solid metal oxide catalysts

Refaat

2010

Int. J. Environ. Sci. Technol.

258

158

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“…Recently, sizeand morphology-controlled inorganic-organic hybrid metal and metal oxide nanoparticles have been synthesized in supercritical fluids. Supercritical ethanol (scEtOH) yields monodisperse metal nanoparticles [29], supercritical methanol (scMeOH) [30,31] or supercritical water (SCW) [32] yields zinc oxide (ZnO) nanoparticles, while SCW alone yields CeO 2 [33], TiO 2 [34], and magnetite (Fe 3 O 4 ) [35] nanoparticles. All of these reactions proceed in a short reaction time (several seconds to several minutes) [36][37][38][39][40][41].…”

Section: Introductionmentioning

confidence: 99%

Versatility of one-pot, single-step synthetic approach for spherical porous (metal) oxide nanoparticles using supercritical alcohols

Wang

Ueno

Takigawa

et al. 2013

The Journal of Supercritical Fluids

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We developed a rapid, one-pot, single-step synthetic method for preparing spherical porous (metal) oxides, titanium dioxide, silica, zirconium dioxide, cerium dioxide, and zinc oxide with large surface areas in a supercritical alcohol containing formic acid or phthalic acid as organic additive in a very short reaction time (10 min). A new type of hollow TiO 2 nanoparticle was obtained by slowly heating the reaction mixtures. The shell thickness of hollow TiO 2 nanoparticles was controlled by adjusting the heating rate.The method proved highly versatile for synthesizing solid and hollow spherical meso/microporous nanoparticles. The spherical mesoporous TiO 2 nanoparticles photocatalytically degraded methylene blue in water under UV irradiation, and successfully transported DNA under biolistic bombardment.

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“…Among these processes, the sol-gel process synthesis in a supercritical fluid medium is the most advantageous. It is * E-mail: djameldjouadi@hotmail.fr simple, less expensive and allows the production of highly pure and ultrafine nanoparticles with a high degree of transparency [5][6][7]. Doping ZnO particles is generally carried out with transition metals or rare earths atoms to exalt the physical properties of the material.…”

Section: Introductionmentioning

confidence: 99%

Effect of cerium on structural and optical properties of ZnO aerogel synthesized in supercritical methanol

Meddouri

Hammiche

Slimi

et al. 2016

Materials Science-Poland

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Pure ZnO and Ce-doped (5 at.%) ZnO aerogels were prepared by dissociation of dihydrate zinc acetate and cerium nitrate in methanol, followed by drying in supercritical conditions of the solvent. The concentration of zinc acetate solution and the atomic ratio Ce/Zn were fixed at 0.2 mol/L and 0.05 mol/L, respectively. XRD results showed a hexagonal wurtzite structure of ZnO aerogel crystallites and a formation of a separate second phase of ceria cubic phase with fluorite structure and 7.4 nm in size. The introduction of cerium in the solution had a negative effect on the aerogel crystalline quality. The crystallites size was found to be 16 nm in pure ZnO and 27 nm in Ce-doped ZnO aerogels. The grains of Ce-doped ZnO aerogel had torus shaped morphology with hollow centers, but those of pure ZnO were flattened semispheres. The calculated values of different structural parameters showed that cerium ions introduced into the ZnO lattice occupied interstitial sites and Zn ions substituted Ce ones in ceria lattice during the formation process. FT-IR and UV-Vis absorption spectra have not revealed any particularities due to the presence of cerium atoms in ZnO, indicating that Ce (5 at.%) doping of ZnO crystallites synthesized in supercritical methanol did not strongly affect the optical gap of the semiconductor. Micro-Raman studies confirmed the formation of cubic fluorite structure ceria in ZnO aerogel and showed that Raman active modes of ZnO are amplified with the presence of ceria.

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Continuous synthesis of surface-modified zinc oxide nanoparticles in supercritical methanol

Cited by 72 publications

References 38 publications

Biodiesel production using solid metal oxide catalysts

Biodiesel production using solid metal oxide catalysts

Versatility of one-pot, single-step synthetic approach for spherical porous (metal) oxide nanoparticles using supercritical alcohols

Effect of cerium on structural and optical properties of ZnO aerogel synthesized in supercritical methanol

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