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 materials.
RESS fine particles prepared mainly by using the solubility of the solute and supercritical fluid density relationship, as from the rapid expansion of supercritical fluid state to a low pressure, low temperature gas state, a sharp decline in the solubility of the solute, the change to the rapid nucleation and Solute grow into particles and deposition .
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 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 fine particles fabricated by the process of griseofulvin. In the experimental device designed study the repid expansion of supercritical fluid solution 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.
Preparation of Fine Particles RESS device consists of four modules: freezing unit, pump unit, dissolve unit and collection unit. Supercritical fluid extraction device is composed by the four units, two of the same first three modules can be generic, are from the air tank, refrigerator, pressure pump and extractor component. But the fourth unit, collection unit is completely different. Extraction device from the separation tank, buffer tank and the rot meter composition of fine particles prepared by the collecting chamber devices, nozzles, flow meters and other components. Nozzle is to collect a key component of the cell.
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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