Regeneration of Modified Bentonite Loaded with Phenol Using Supercritical Fluids

Abstract

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 CO 2 (SC CO 2 ) was obtained by operating at 500 bar, 353 K and 3.33 × 10 −8 m 3 SC CO 2 /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 2 at low temperature (313 K) and pressure (300 bar) and a high supercritical fluid flow rate (3.33 × 10 −8 m 3 SC CO 2 /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.