Supercritical CO2-assisted impregnation of cellulose microparticles with R-carvone: Effect of process variables on impregnation yield

Abstract

In this work, the supercritical CO2-assisted impregnation of microcrystalline cellulose (MCC) particles with R-(−)-carvone, an antimicrobial monoterpene, was investigated. The effect of CO2 density (278–600 kg m−3), temperature (40–60 °C), carvone:MCC mass ratio (0.5–1.0), and depressurization mode (cold–hot), on the impregnation yield was studied. Carvone loadings were obtained in the range of 0.6–3.6 wt%, and the addition of ethanol (2 wt%) as cosolvent enhanced the impregnation yield up to 10 wt%. The high crystallinity of cellulose (81–84%) remained unchanged after the supercritical process, although SEM analysis showed a partial separation of fiber agglomerates. Carvone release in simulated saliva solution from particles impregnated using cosolvent was slightly slower than from the pure CO2-impregnated particles. The observed release profile could be useful for pharmaceutical and biomedical applications, such as the prevention of oral cavity infections or their treatment at early stages.