Abstract
This paper will discuss about the utilization of supercritical fluid (SCF) process to produce fine particles. Supercritical fluids (SCFs) process can be considered as an emerging “clean” technology for the production of small-size or fine particles (e.g. micron-size). Microsphere is a material in micron scale which has been widely used as adsorbent, catalyst support, and drug delivery system. For advanced application, those materials are formulated in the form of porous microspheres. There are several methods that can be used using SCFs. Those method are, Rapid Expansion of Supercritical Solution (RESS), Gas Anti-Solvent/Supercritical Anti-Solvent (GAS/ SAS), Aerosol Solvent Extraction System (ASES), dan Solution Enhanced Dispersion by Supercritical Fluids (SEDS) and Particle from Gas-Saturated Solutions/Suspensions (PGSS). Considering the morphology of material which will be used to prepare microsphere, each of methods above has specific advantages and disadvantages toward the material. Based on the literatures, the ASES method is more likely to produce porous microparticles (microspheres). In the ASES method, porous microsphere formation is the result of interactions between: degrees of supersaturation, nucleation velocity and crystal growth.
Highlights
Microsphere is a micron-sized material that is widely used as an adsorbent, catalyst support, and drug delivery system
Detailed description of this technique is as follow: first, the solute is dispersed/dissolved in supercritical fluid (SCF), the high-pressure solution is sprayed/expanded adiabatically into low pressure vessel, which results in highly super-saturated solution, and leads to rapid nucleation and formation of fine/microsphere particles which collected in the precipitator [1, 13]
By using the Aerosol Solvent Extraction System (ASES) technique, they could produce microspheres measuring 0.1-1 μm. In this method the polymer solution was sprayed through a nozzle to form solution droplets into a compressed SCF fluid
Summary
Microsphere is a micron-sized material that is widely used as an adsorbent, catalyst support, and drug delivery system. The scCO2 is very widely used as SCF in polymer synthesis and processing due to several advantages, e.g. non-toxic (safe), non-flammable, non-corrosive, chemically inert, density regulation with pressure and the supercritical conditions achieved (Tc = 31.05 °C and Pc = 73.8 bar), relatively cheaper (low energy required). Because it is a non-polar compound, the solubility of carbon dioxide is enhanced by the addition of a polar compound called co-solvent [10]. 11.28 4.89 3.8 7.38 4.60 4.87 6.38 4.76 7.99 4.25 4.62 4.70 4.11 22.1 5.04 ρc (g/cm3)
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