Desorption of salicylic acid from modified bentonite by using supercritical fluids in packed bed column

Desorption of salicylic acid from organically modified bentonite by using supercritical fluids (SCFs) was studied. The parameters, such as pressure, temperature, SCF flow rate, and cosolvent (entrainer) concentration, were investigated. A desorption yield of 40 wt% salicylic acid was obtained by using supercritical CO2 by operating at low pressure (300 bar), low temperature (40degreesC), and 2 mL CO2/min, it reached up to 77 wt% in the presence of ethanol as cosolvent 10 vol%. Similarly, a maximum desorption yield of 76 wt% salicylic acid was obtained by using supercritical CO2 by operating at high pressure (500 bar), high temperature (80degreesC), 2 mL SC CO2/min, it reached up to 98 wt% in the presence of ethanol as cosolvent 10 vol%. Hence, it was concluded that the mean contents in the desorbed solute are approximately 1.5-2-fold higher by addition of 10 vol% ethanol than only supercritical CO2 desorption process.