Application of supercritical fluid technology has been gradually extraction, chemical reaction extended to the more traditional areas of fine particles prepared by the new area. Supercritical fluid method of preparation of fine particles divided into two: one for the RESS [1-3] method (Rapid Expansion of Supercritical Solution); two methods for the GAS (Gas Anti-Solvent).They are developed over a decade of supercritical fluid (SCF) of new applications, the purification, separation of material has the advantages of conventional methods can not match. Rapid expansion of supercritical solution (RESS) combined with liquid - liquid extraction (based on differences in physical solubility) and distillation (based on material differences between volatility) features, by adjusting the temperature and pressure to change the material's solubility in SCF.RESS process is characterized by: fast delivery disturbance, high solute supersaturation, the former lead to uniform medium solute components, forming a narrow particle size distribution, which lead to fine particles of [4-6] . This article focuses on the rapid expansion of supercritical solution (RESS) fine particles prepared by the application.
Rapid expansion of supercritical solution Research Status
The chemical sensitizers - Poly - dimethylsiloxane fine particles prepared were studied. Now growing field of portable chemical sensor high demand, these additional sensors can be used for chemical gas agents, industrial pollutants and hazardous waste identification. Tepper of the Poly with the RESS technique - fine particles coated with dimethylsiloxane increase in chemical sensor devices. The rapid expansion of supercritical solution (RESS) obtained the α-asarone of fine particles. Investigated the expansion pressure, pre-expansion temperature, sedimentation chamber temperature, nozzle diameter and processing conditions on the impact of fine particle size. The results show that higher inflation pressure, the lower pre-expansion temperature and room temperature deposition, the smaller the nozzle diameter, facilitates access to the smaller average particle size of fine particles.Yan Chen et alstudied by the rapid expansion of supercritical fluid solution (RESS) fine particles fabricated by the process of griseofulvin. In the experimental device designed study the RESS process of the operating variables on the prepared particle size of griseofulvin. The results show that the RESS method can meet the size requirements of the system was fine products griseofulvin.
5 Conclusions
Fine particles in the current high-tech has become a hot area, the materials, chemicals, light industry, metallurgy, electronics, bio-medicine is widely used. Rapid Expansion of Supercritical Solution Preparation of fine particles as a new technology has obvious advantages.First, low temperature (room temperature or slightly higher), especially for heat-sensitive biological materials, or drug preparation materials, ultrafine; Second, both the dual characteristics of liquids and gases, diffusion coefficient, viscosity, permeability to obtain high purity products, small and uniform particle size. Because of its simple, short procedure, no follow-up pollution, can control the size distribution of particle size and many other advantages, is becoming increasingly widespread attention and application. Carried out abroad in the application of a more extensive study, particularly as drug sustained release. Determine the breadth of its application prospects of this technology is the micro-studies on the preparation of particles.
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