Amine extraction from hexagonal mesoporous silica materials by means of methanol-enhanced supercritical CO2: Experimental and modeling

In this work, dodecylamine was extracted from freshly synthesized hexagonal mesoporous silica materials under pressure of 15.0-25.0 MPa and temperature of 50-105 degrees C with methanol-enhanced supercritical carbon dioxide. The effects of pressure, temperature, and solvent flow rate on the amine extraction recovery were studied. The experimental results show over 95% of the total amine used was extracted within 1 h at 25.0 MPa and 85 degrees C, and that the extraction recovery increased with pressure. supercritical solvent flow rate or methanol flow rate. The extraction data were described by an empirical model, a hot ball Crank model and a diffusion-layer theory model and the relative merits of the models were demonstrated. The calculations were compared with those experimentally obtained. Very nice agreement between the diffusion-layer theory model and our experimental measurements was achieved as reflected by the average absolute relative deviation being less than 6.0%. The empirical and hot ball Crank models both gave relatively poorer fit than the diffusion-layer theory model. (C) 2010 Elsevier B.V. All rights reserved.