Precipitation with a compressed

D. J. Dixon, "Formation of Polymeric Materials by Precipitation with a Compressed Fluid Antisolvent," Ph.D. Dissertation, University of Texas at Austin, Austin, Tex., 1992. 

PCA [Precipitation with a compressed anti-solvent] A process for making a solid with unusual morphology by spraying a solution of it into a supercritical fluid. The process resembles spray drying into a supercritical fluid. Used for making microspheres, microporous fibers, and hollow microporous fibers. 

Dixon, D. J., Johnston, K. P. and Bodmeier, R. A. AIChE Jl. 39 (1993) 127. Polymeric materials formed by precipitation with a compressed fluid antisolvent. 

Gas anti-solvent processes (GASR, gas anti-solvent recrystallization GASP, gas antisolvent precipitation SAS, supercritical anti-solvent fractionation PCA, precipitation with a compressed fluid anti-solvent SEDS, solution-enhanced dispersion of solids) differ in the way the contact between solution and anti-solvent is achieved. This may be by spraying the solution in a supercritical gas, spraying the gas into the liquid solution. 

Jarmer DJ, Lengsfeld CS, Randolph TW. 2006. Scale-up criteria for an injector with a confined mixing chamber during precipitation with a compressed fluid antisolvent. J. Supercritical Fluids 37 242-253. 

In the last ten years new, innovative processes utilizing supercritical fluids have received increasing attention. Here, we focus on two examples the Gas /IntLSolvent process (GAS) [1], also known as PC A (Precipitation with a Compressed fluid /Intisolvent) [2], and Supercritical /Intisolvent induced phase Separation (SAS)[3, 4],... 

Jarmer, D.J. Lengsfeld, C.S. Randolph, T.W. Manipulation of particle size distribution of poly(-lactic acid) nanoparticles with a jet-swirl nozzle during precipitation with a compressed antisolvent. J. Supercrit. Fluids 2003, 27 (3), 317-336. 

Gas antisolvent processes can be performed in a semicontinuous mode. In this case the solution and the antisolvent are continuously introduced in the system until the desired amount of the product is formed. The introduction of the solution is then stopped and the DG flux extracts the residual solvent from the system. The system is then depressurized to enable collection of the product. The solution is generally introduced through an atomization nozzle that favors the prompt expansion of the solution and the formation of small particles. Different process configurations have been utilized, i.e., co- and countercurrent introduction of the solution and antisolvent fluxes and various nozzles have been designed. The process is referred to by different acronyms such as ASES (aerosol solvent extraction system), SAS (supercritical antisolvent), SEDS (solution enhanced dispersion by supercritical fluids), PCA (precipitation with a compressed fluid antisolvent), GASR (gas antisolvent recrystallization), GASP (gas antisolvent precipitation). 

PRECIPITATION WITH A COMPRESSED FLUID ANTISOLVENT (PCA), A SUPERCRITICAL ANTISOLVENT (SAS), AND THE AEROSOL SOLVENT EXTRACTION SYSTEM (ASES) PROCESSES... 

Dozens of drugs have been recrystallized by means of the precipitation with a compressed fluid antisolvent (PCA) and the supercritical antisolvent (SAS) and aerosol solvent extraction system (ASES) processes. 

Mawson S, Kanakia S, Johnston KP. Coaxial nozzle for control of particle morphology in precipitation with a compressed fluid antisolvent. J Appl Poly Sci 1997 64 2105-2118. 

Magnan C, Badens E, Commenges N, Charbit G. Soy lecithin micronization by precipitation with a compressed fluid antisolvent—influence of process parameters. J Supercrit Fluids 2000 19 69-77. 

Falk R, Randolph TW, Meyer JD, Kelly RM, Manning MC. Controlled release of ionic compounds from poly(L-lactide) microspheres produced by precipitation with a compressed antisolvent. J Controlled Release 1997 44 77-85. 

The organic-C02 interface plays a central role in physical particle formation processes including rapid expansion from supercritical solution (RESS), precipitation with a compressed antisolvent (PCA, also called SAS... 

Mawson S, Johnston KP, Betts DE, McClain JB, DeSimone JM. Stabilized polymer microparticles by precipitation with a compressed fluid antisolvent. I. Poly(fluoro acrylates). Macromolecules 1997 30, 71-77. 

Mawson S, Yates MZ, O Neill ML, Johnston KP. Stabilized pol5mer microparticles by precipitation with a compressed fluid antisolvent. 2. Poly(propylene oxide) and poly(butylene oxide)-based copolymers. Langmuir 1997 13 1519-1528. 

Gallagher PM, Coffey MP, Krukonis VJ, Klasutis N. Gas anti-solvent recrystallization new process to recrystallize compounds insoluble in supercritical fluids. In Johnston KP, Penniger JML, eds. Supercritical Fluid Science and Technology. Washington, DC American Chemical Society, 1989 334-354. Dixon D, Johnston KP, Bodmeier R. Polymeric materials formed by precipitation with a compressed fluid antisolvent. AIChE J 1993 39 127-136. Chattopadhyay P, Gupta RB. Production of griseofulvin nanoparticles using supercritical CO2 antisolvent with enhanced mass transfer. Int J Pharm 2001 228 19-31. 

Magnan C, Commenges H, Badens E, Charbit G. Fine phospholipid particles formed by precipitation with a compressed fluid anti-solvent. Proceedings of the GVC-Fachaussschuss Hochdruckverfahrenstechnik, 1999 223. 

Many volatile low-molecular-weight organics are completely miscible with carbon dioxide at relatively modest temperatures and pressures. However, nonvolatile compounds or those with higher molecular weights, especially polymers, are often insoluble. Insoluble liquid compounds may be dispersed into CO2 with the aid of appropriate surfactants to form a kinetically stable o/c emulsion [10,11]. Stable emulsions are important in separation processes, heterogeneous reactions and materials formation processes, such as precipitation with a compressed fluid antisolvent [40]. These emulsions are the precursors to solid latex particles in dispersion polymerization. Stabilization of o/c emulsions has been studied in-situ to understand surfactant design for polymerization [10,11]. 

At high pressures a considerable amount of a gas can be dissolved in a liquid solution. Once dissolved in the liquid phase it may act as an anti solvent. In literature this type of drowning out is often referred to as the Gas Anti-Solvent (GAS) process, it is also known as the Supercritical Anti-Solvent (SAS) process or as Precipitation with a Compressed fluid Anti solvent (PCA). 

Luna-Bdrcenas G., Kanakia S.K., Sanchez I.C., Johnston K.P., Semicrystalline microribrils and hollow fibres by precipitation with a compressed-fluid antisolvent, POLYMER, 1995, (36-16), 3173-3182... 

DIX Dixon, D.J. and Johnston, K.P., Formation of microporous polymer fibers and fibrils by precipitation with a compressed fluid antisolvent, J. Appl. Polym. Sci., 50, 1929, 1993. 

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