Study of Ultrasonic Regeneration and Adsorption of Humic Acid on Activated Carbon

Background: Humic acid is a trihalomethane component in water supplies, causing various health disorders in humans. Objectives: This study was performed to examine humic acid adsorption on saturated activated carbon and to evaluate adsorbent regeneration through ultrasonic processes. Methods: In the present study, effects of various parameters, including initial concentration of humic acid, pH, contact time, adsorbent dose, and temperature, on the adsorption stage were investigated. Also, effects of different parameters, such as regeneration time, pH, and number of saturation-regeneration cycles, were studied in the regeneration stage. Results: The highest percentage of humic acid removal was reported at pH of three and initial humic acid concentration of 10 mg/L. The highest adsorption capacity of activated carbon was 29.7 mg/g at adsorbent dosage of 0.1 g/L and contact time of 10 minutes. The results of thermodynamic experiments showed that removal of humic acid by saturated activated carbon was endothermic. Also, maximum regeneration occurred at pH of 11 and contact time of 60 minutes. Finally, the adsorption capacity of saturated activated carbon changed from 42.94 to 42.14 mg/g after five cycles of saturation and regeneration. Conclusions: The results of this study showed that activated carbon is an effective adsorbent in the removal of humic acid from water. Also, the ultrasonic process is effective in regeneration of activated carbon, saturated with humic acid.