Supercritical CO₂ Spray Drying of Ethyl Cellulose (EC) for Preparing Microparticles

Abstract

Even though common spray drying has been widely used for drying food and related products, the effect of drying conditions of supercritical CO₂ spray drying on the particle sizes of dried products has not been well studied. The objective of this study was to study the effect of drying conditions and design parameters on the particle sizes of biomaterials dried with supercritical CO₂ spray drying. The ethyl cellulose (EC) microparticles were prepared with supercritical CO₂ as the dry medium using an experimental spray-drying apparatus. This research studied the influences of spray nozzle diameter, mass ratio of gas to liquid, solution concentration, temperature, and pressure on the physical characteristics of ethyl cellulose microparticles. The results indicated that the average size of the dried particles ranged from 1.07 to 9.84 µm. The spray nozzle with 8-mm diameter produced smaller microparticles with narrower distribution than the 4-mm spray nozzle. The average particle size increased with the increase of the ratio of gas to liquid. Also, the average size and distribution of the microparticles increased with the rise of temperature and solution concentration but decreased with the increase of pressure.

Keywords:

• Ethyl cellulose
• Microparticle
• Spray drying
• Supercritical CO₂

ACKNOWLEDGMENTS

This research was supported by Shanghai Leading Academic Discipline Project (No. T0503), and the National Natural Science Foundation of China (No. 30772183).