Batch and continuous column adsorption of indigo carmine onto activated carbon derived from date palm petiole

In this work, the date palm petiole was transformed into activated carbon implying sodium hydroxide as the activating agent. The carbon obtained was exerted for the adsorption of indigo carmine in batch and continuous mode. The properties of activated carbon were established. The effects of pH, adsorbent mass, contact time, initial concentration and temperature on the adsorption of indigo carmine were examined in batch mode. The models of Langmuir, Freundlich, Temkin and Dubinin-Radushkevich were used for modeling adsorption isotherms. The Langmuir model appears to be the most appropriate for describing the adsorption of indigo carmine. The adsorption mechanism was governed by the pseudo-second order model and can be explained by physisorption accompanied by chemisorption. From the thermodynamic point of view, the adsorption was spontaneous and exothermic. In continuous adsorption, The Bohart-Adams model fit perfectly to the initial part of the breakthrough curve ((C-t/C-o) < 0.5), and the hole curve was well fit by the Yoon-Nelson and Thomas models.