超临界流体沉淀技术制备超细粒子研究

超临界流体沉淀(简称SFP)技术以其特有的优点成为引人注目的在无机化学、有机化学、医药等领域具有广阔应用前景的超细微粒制备方法.为充分发挥SFP技术的优势,科研工作者以RESS与SAS为基础提出了ASES、SEDS、SAS-EM等各种新技术.本文着重综述了以RESS及SAS为基础发展起来的SFP新技术的原理、特点及相关的应用,指出了目前SFP技术存在的问题及今后的研究方向.

Progress in Generation of Fine Particles Using Supercriticai Fluid Precipitation

Supercritical fluid precipitation (SFP) technologies, such as RESS and SAS, are novel micronization processes having promising applications in various fields such as inorganic chemistry, organic chemistry and Pharmaceuticals. RESS consists of saturating a supercritical fluid (SF) with the substrate (s), then depressurizing the solution through a nozzle into a low-pressure chamber to cause an extremely rapid nucleation of the substrate (s) in the form of very small particles. SAS consists of decreasing the solvent powder of a liquid solvent in which the substrate is dissolved by saturating it with a SF, resulting in the substrate precipitation or recrystallization. Based on RESS and SAS, some improved SFP technologies, such as AESE, SEDS and SAS-EM have been developed to obtain smaller particles. AESE process involves spraying the solution through a nozzle as fine droplets into SF anti-solvent. SEDS, an improvement of ASES, consists of using a nozzle with two coaxial passages to achieve smaller droplets and intense mixing of SF and solution for increased transfer rates. SAS-EM, a modification of SAS, depends on deflecting the solution jet by a surface vibrating at an ultrasonic frequency that atomizes the jet into small micro droplets. A sintered porous plate or 'frit' nozzle, which could be manufactured more easily and was unlikely to be plugged due to blockage by the presence of a single particle in comparison with capillary nozzles, was used in RESS process. Specialized nozzles are used in AESE to generate and focus the preferred high frequency sonic waves that have been shown to maximize the production of extremely small droplets in the precipitation zone, leading to the precipitation of the very small particles. In this review, the concepts, characteristics and the related application of the SFP processes are introduced, and current issues relating to the SFP processes are addressed.