(97b) Supercritical Fluid Aided Microencapsulation of Calcium Oxide

Microencapsulation of Calcium Oxide

Raquel Carvallo, Aydin Sunol

Chemical Engineering Department

University of South Florida

ABSTRACT

Coating of fine particles to produce tailored surface properties is currently a key development of supercritical fluids applications, in different areas like: pharmaceutical, nutraceutical, cosmetic, agrochemical, electronic and specialty chemistry industries. During the encapsulation process the particle surface can be engineered with specific properties by spreading a thin film of material on the surface of the particles.

On this work Chitosan, a natural biodegradable polymer was used. Chitosan has some properties that make it very attractive for pharmaceutical applications like: biocompatible, biodegrade to normal body constituents, safe and non toxic, bacteriostatic, anticancerogen, and versatile.

The objective of this research had been to encapsulate solid particles under 5?Ým with a biopolymer, Chitosan, using supercritical CO2 as one of the solvents. Using the operation conditions determined from cloud point and solubility experiments, this supercritical mixture Chitosan-DMSO-CO2 was then introduced into a fluidized bed with nonporous CaO particles as a one phase system, then the Chitosan was precipitated as a consequence of a temperature change and the free solvent (DMSO) was extracted with supercritical CO2.

TEM, SEM and AFM confirm particles of one micron or less have been encapsulated with a thickness of less than 5 nm. AFM shows particle roughness on the nanometer range, 46 nm or more for uncoated particles and 2-4 nm for the encapsulated ones.

FTIR, NMR and DSC-TGA analysis indicates that the chemical structure of the Chitosan remains constant before and after processing, and the changes observed were attributed to some DMSO and moisture adsorbed during the encapsulation process.