Coupling of Solvent Extraction and Ultrasonic Waves for Regeneration of Spent Activated Carbon after Treatment of Polluted Air with Toluene Vapor

A batch process was used to evaluate the potential of regeneration of spent activated carbon (AC) by solvent extraction technique with synergetic to ultra-sonication. Experiments were undertaken as a function of the initial concentration of toluene. Freundlich and Langmuir models were used to study the adsorption isotherms and the data well fitted the Langmuir expression. The maximum adsorption capacities of toluene were found to be 0.108 µg/g activated carbon for Type-I Langmuir. Extraction of the used AC by both methanol solvent and ultrasonic radiation yielded up to 95% reactivation of the spent AC in the first run. Nearly up to 88 % recovery of activity could be achieved after further regeneration and reusing of the spent AC. The results indicate that the coupling of solvent extraction with ultrasonic waves in the AC treatment is comparable and perhaps superior to the conventional regeneration techniques in many cases. This is mainly due to the single step process applied which is less energy consuming; in addition to the nearly comprehensive recovery of the adsorptive capacity of spent AC.