TY - JOUR
T1 - A new method of particle powder formation from aqueous solutions using the joule-thomson effect of high-density carbon dioxide
AU - Akimoto, Keita
AU - Ota, Masaki
AU - Sato, Yoshiyuki
AU - Inomata, Hiroshi
PY - 2014/1/1
Y1 - 2014/1/1
N2 - A new spray-drying process of nanoparticle-dispersed aqueous solutions was proposed to produce metal/metal oxide fine-particle powder with controlled particle aggregation, in which high-density carbon dioxide is used as both an aqueous colloid dispersing solvent and a compressible fluid for spraying. An experimental setup was built based on the proposed idea and verified with aqueous solutions of 8-nm zirconia particles. The aqueous colloidal content was set to be more than 10 wt% from the viewpoint of practical production. This is an extremely high content in the high-density CO2 phase from the viewpoint of thermodynamic stability and leads to colloid aggregation within a short time, followed by phase separation. The proposed idea focuses on the time scale of such unstable colloids and requires the colloids in CO2 media to be sprayed via a nozzle within the short time before colloid aggregation begins. In addition, the sprayed colloids could be broken down into small droplets and frozen due to Joule-Thomson expansion of high-density CO2. The results showed that powders made of nanoparticles contained in frozen droplets could be generated with controlled particle aggregation.
AB - A new spray-drying process of nanoparticle-dispersed aqueous solutions was proposed to produce metal/metal oxide fine-particle powder with controlled particle aggregation, in which high-density carbon dioxide is used as both an aqueous colloid dispersing solvent and a compressible fluid for spraying. An experimental setup was built based on the proposed idea and verified with aqueous solutions of 8-nm zirconia particles. The aqueous colloidal content was set to be more than 10 wt% from the viewpoint of practical production. This is an extremely high content in the high-density CO2 phase from the viewpoint of thermodynamic stability and leads to colloid aggregation within a short time, followed by phase separation. The proposed idea focuses on the time scale of such unstable colloids and requires the colloids in CO2 media to be sprayed via a nozzle within the short time before colloid aggregation begins. In addition, the sprayed colloids could be broken down into small droplets and frozen due to Joule-Thomson expansion of high-density CO2. The results showed that powders made of nanoparticles contained in frozen droplets could be generated with controlled particle aggregation.
KW - Colloid
KW - Particle drying process
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U2 - 10.1252/kakoronbunshu.40.79
DO - 10.1252/kakoronbunshu.40.79
M3 - Article
AN - SCOPUS:84896462671
VL - 40
SP - 79
EP - 83
JO - Kagaku Kogaku Ronbunshu
JF - Kagaku Kogaku Ronbunshu
SN - 0386-216X
IS - 2
ER -