Extraction and precipitation particle coating using supercritical CO2

Abstract

A modified RESS process for particle coating with a solution of polymer in supercritical CO 2 was studied in this research. This technique involves extracting the polymer with supercritical CO 2 , with or without a cosolvent in an extraction vessel, and then precipitating the polymer onto the surface of host particles in a second precipitation vessel by adjusting the pressure and temperature inside the precipitator to lower its solubility. The research was performed using a pilot-scale supercritical apparatus, glass beads as host particles and two different polymers as coating materials. Experiments showed that the coating of glass beads with polyvinyl chloride-co-vinyl acetate (PVCVA) and hydroxypropyl cellulose (HPC) was successfully achieved. Scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), energy dispersive X-ray mapping and thermogravimetric analysis (TGA) were used to characterize the coatings obtained. The results indicate that the process of particle coating with supercritical solution is a promising environmentally friendly, alternative coating method with little or no organic solvents required.

Comparative Physicochemical Characterization of Phospholipids Complex of Puerarin Formulated by Conventional and Supercritical Methods

“…It has now been clearly established that supercritical fluids especially supercritical carbon dioxide are particle or pharmaceutical formulations formation media of great interest because they offer the possibility of processing materials as diverse as polymers, proteins, and inorganics, with minimized quantity of solvent or even in solvent-free conditions (28). Several research groups have presented their techniques or methods for using supercritical fluids in particle preparation, microencapsulation, surface coating of an active substance particle with a polymer or co-crystallization, co-precipitation with excipients such as polyvinyl pyrrolidone (PVP), poly ethylene glycol (PEG), ethyl cellulose (EC), poly lactic acid (PLA), Gelucire and other polymers, or host molecules like cyclodextrins (29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40). In addition to micronization, the pharmaceutical application of the SCF process enables to modify the solid-state properties of drug particles.…”

Formation of organic coating on ultrafine silver particles using a gas-phase process

“…Dry particle coating technology (Pfe er, Dave, Wei, & Ramlakhan, 2001) directly attaches submicron-sized guest particles onto relatively larger, micron-sized host particles through the application of mechanical forces. However, it is not applicable to bioactive materials due to the high shear force and local temperature increase produced in the process and is only limited to host particles above 1 m. Recently, formation of composite and polymer encapsulated particles using supercritical uids (SCFs) has become of great interest for several industrial applications such as controlled drug release, food and agriculture (Wang et al, 2002). Kim, Paxton, and Tomasko (1996) reported the microencapsulation of naproxen with poly-L-lactic acid (PLA) polymer using a supercritical CO 2 process.…”

Supercritical Fluid Processes for Polymer Particle Engineering

“…The polymer was dissolved in CO 2 /CHClF 2 in a first extraction column, and pyrene was dissolved in pure CO 2 in a second vessel. In addition, the coating of spherical glass beads (315 and 500 µm) with poly(vinyl chloride-co-vinyl acetate) (PVCVA) or hydroxypropylcellulose (HPC) was also recently reported with this modified RESS process [49]. The most recent example [44] of RESS coprecipitation using SC CO 2 is the formation of 10-to 90-µm particles of L-PLA (M w = 2000 g/mol) loaded with naproxen, a nonsteroidal anti-inflammatory drug.…”