HIGH-PRESSURE FLOW GRAVIMETRIC APPARATUS FOR SUPERCRITICAL-FLUID EXTRACTION STUDIES

An experimental apparatus has been developed for real time measurement s of fluid-solid adsorption (or desorption) rates and equilibria at el evated pressures. In addition to controlling pressure and flow rates s imultaneously, this setup is able to operate at higher flow rates than previously possible in supercritical fluid experiments. The system co nsists of a high pressure microbalance, two high pressure syringe pump s, and an absorbance detector. The microbalance enables the collection of data at a greater time resolution, resulting in a more accurate me asurement of rate data. Because of the dual syringe pump design, there is no pressure drop in the system, making it possible to operate at a wide range of flow rates (at experimental conditions). The buoyancy f orce was measured with helium experiments, while the hydrodynamic forc es were measured using a clean solid sample and supercritical carbon d ioxide at different flow rates. It was found that the hydrodynamic for ce increased with flow rate as expected. The apparatus was tested by c onducting two desorption experiments of phenol from activated carbon a t 141+/-0.07 bar, 36.0+/-0.02 degrees C, and 0.47 ml/min (at experimen tal conditions). The amount of phenol removed was 16.4% and 18%, respe ctively! in the two runs which is consistent with previously published results and indicates the difficulty of regenerating activated carbon loaded with phenol. (C) 1997 American Institute of Physics.