Regeneration of modified bentonite loaded with phenol using supercritical fluids

The desorption of phenol from organically modified bentonite (ODTMA-bentonite) using supercritical fluids was studied. Parameters such as pressure, temperature, supercritical fluid flow rate and co-solvent (entrainer) concentration were investigated. The maximum desorption of phenol (ca. 98 w/w%) using supercritical CO2 (SC CO,) was obtained by operating at 500 bar, 353 K and 3.33 x 10(-8) m(3) SC CO2/s. In the presence of ethanol as a co-solvent (10 v/v%), the maximum desorption of phenol attained a value of 97 w/w% using supercritical CO, at low temperature (313 K) and pressure (300 bar) and a high supercritical fluid flow rate (3.33 x 10(-8) m(3) SC CO2/s). In addition, the results showed that the regenerated ODTMA-bentonite retained its adsorption power towards phenol even after several regeneration cycles. It was therefore concluded that exhausted/used organobentonites might be regenerated via processes involving supercritical fluid extraction.