Continuous Synthesis of Surface-modified Ceria Oxide Nanoparticles using Supercritical Methanol for Highly Stabilized Nanofluids

Title
Continuous Synthesis of Surface-modified Ceria Oxide Nanoparticles using Supercritical Methanol for Highly Stabilized Nanofluids
Authors
Bambang Veriansyah김재훈김재덕이윤우
Issue Date
2009-05
Publisher
9th International Symposium on Supercritical Fluids
Abstract
Continuous synthesis of surface-modified ceria oxide (CeO2) nanoparticles was carried out using supercritical methanol to prepare highly dispersable nanofluids. The surfacemodified ceria oxide nanoparticles were prepared by introducing a solution of ceria (III) nitrate (Ce(NO3)3) and decanoic acid (as a surface modifier) in methanol to a continuous flow reactor system at 400 oC, 300 bar and a residence time of ~ 40 s. Transmission electron microscopy (TEM) showed that the addition of decanoic acid changed drastically the shape and size of the nanoparticles. When 0.3 M of decanoic acid was used, primary particles with 2-3 nm in diameter were loosely aggregated and formed secondary particles with size of 30- 40 nm. Wide angle X-ray diffraction (WAXD) pattern revealed that the surface-modified nanoparticles had CeO2 crystalline structure. Fourier transform infrared (FT-IR) analysis showed that the surface of the nanoparticles comprised of aliphatic groups associated with decanoic acid and hydroxyl group. The particles were dispersed in heat transfer fluids including water, ethylene glycol and transformer oil. Aggregation and precipitation were observed when the surface-modified nanoparticles were dispersed in water or transformer oil while good dispersion stability was observed when the surface-modified particles were dispersed in ethylene glycol. This unique dispersion behavior was attributed to a balance between the hydrophobic group (aliphatic group) and hydrophilic group (hydroxyl group) on the surface of the nanoparticles.
URI
http://pubs.kist.re.kr/handle/201004/35275
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KIST Publication > Conference Paper
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