Spectroscopic measurement of solid solubility in supercritical fluids

Different in situ spectroscopic techniques, including infrared, ultraviolet , and fluorescence, were developed to measure the solubility of organic sol ids in supercritical carbon dioxide (scCO(2)). These techniques are applica ble over a wide range of concentrations, as low as 10 (-6) or 10 (-7) mol f raction, where the conventional flow method is ineffective and less accurat e. No separate calibration is required; in fact, the molar absorptivity is determined at the saturation point as an additional benefit. While this tec hnique requires more time per data point, it is more accurate and unbiased than traditional methods at lower concentrations. The Patel-Teja equation o f state was used to correlate the data and expand the data for the ternary system. Data are reported for anthracene, 1,4-naphthoquinone, and 2-naphtho l in scCO(2) and CO2 with methanol cosolvent at 313 K and a pressure range from 7 to 21 MPa.