Control of particle size, at micrometric and nanometric range, using supercritical antisolvent precipitation from solvent mixtures: Application to PVP

The control of particle size at micrometric and nanometric range is of relevant interest in many industrial applications. In this work, Supercritical AntiSolvent (SAS) precipitation, using solvent mixtures has been used to increase process flexibility in particle size control. The biopolymer polyvinylpyrrolidone (PVP) has been used as a model solute. PVP is slightly soluble in acetone (AC) and largely soluble in dimethylsulfoxide (DMSO), ethyl alcohol (EtOH) and N-methylpyrrolidone (NMP); therefore, solvent mixtures of AC and these other solvents have been used. The experiments using EtOH/AC solvent mixture were performed to study the effect of the solvation power alone, considering that both pure solvents show similar mixing behaviors with scCO(2). Experiments using the solvent mixtures NMP/AC and DMSO/AC were performed to study both the influence of the solvation power and the influence of the jet/spray mixing behavior with supercritical carbon dioxide (scCO(2)) on the characteristics of the PVP precipitates. Using pure DMSO, NMP or EtOH, it is possible to produce spherical PVP microparticles (with a mean diameter lower than 3.8 mu m); whereas, using mixtures of these solvents with acetone, PVP nanoparticles (with a mean diameter down to 0.11 mu m) were precipitated. (C) 2015 Elsevier B.V. All rights reserved.