Relative Supersaturation Ratio and Separation Factor in Crystallization with High Pressure C02

Crystallization in the presence of high pressure gas as antisolvent could be applied for the recovery of valuable compounds from liquid solution. A study of separation behavior is presented here for a mixture of anthracene (AN) and anthraquinone (AQ) in cyclohexanone (CX) expanded with a gaseous antisolvent, CO₂. The pressure range was 0.1 to 12 MPa; the temperature was either 292 or 313K. Separation factors were obtained from the measured salted-out yields and the supersaturation of each solute could be also obtained for this pressure-tuning crystallization. The separation factor varies almost linearly with relative supersaturation ratio in the crystallization of anthracene-anthraquinone from cyclohexanone and CO₂.