Measuring and modeling adsorption equilibria of non-volatile compounds dissolved in supercritical carbon dioxide on nanoparticles using dynamic methods

• Nanoparticles can be used for dynamic adsorption measurement methods when the appropriate packing method is used.
• AlO(OH) hollow spheres show increased adsorption compared to solid spheres.
• R/S-Ibuprofen adsorption on AlO(OH) hollow spheres is of BET-type and increases with decreasing pressure.
• A thermodynamic PR-EoS/RAST/BET model agrees excellently with the experimental data.

Adsorption equilibria of benzoic acid and ibuprofen on AlO(OH) nanoparticles were measured for the first time using a dynamic method, frontal analysis. Possible techniques for creating packed beds of nanoparticles are presented and their suitability for different chromatographic adsorption measurement methods is discussed. Benzoic acid adsorption was measured at 40 °C and 16 MPa on AlO(OH) solid and hollow spheres, ibuprofen adsorption was measured at 40 °C and varying pressures of 10, 15 and 20 MPa on AlO(OH) hollow spheres. A dry packing method was used to create packed beds for the adsorption experiments. The experimental data was modeled with a Peng-Robinson EoS/RAST/BET approach, which shows excellent agreement with the data. The model is discussed as a way to model adsorption in high pressure drop packed beds.

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