Equilibrium, thermodynamic and kinetic studies on adsorption of commercial dye by activated carbon derived from olive-waste cakes

Adsorption of Lanaset Grey G, an industrial metal complex dye, on activated carbon derived from Tunisian olive-waste cakes was explored. The equilibrium adsorption data, obtained at 25 °C, were analyzed by Langmuir Freundlich and Temkin models. The results indicate that the Langmuir model provides the best correlation of the experimental data. The adsorption capacity of the sorbent for Lanaset Grey G was found to be 108.7 mg g−1 which is better than the capacity of a commercial activated carbon. The kinetic studies, conducted at three temperatures (10, 25 and 37 °C), indicated that the adsorption process followed the pseudo-first-order kinetic model and increase of temperature enhanced both rate and efficiency of the dye uptake. The application of the intra-particle diffusion model revealed that the adsorption mechanism of this dye is rather a complex process and the intra-particle diffusion is involved in the overall rate of the adsorption process but it is not the only rate-controlling step. The calculated thermodynamics parameters showed the spontaneous and the endothermic nature of the adsorption process. The activation energy found to be 32.1 kJ mol−1, could indicate a physical adsorption process. The presence of other components, commonly used in the textile industrial bath, did not affect the uptake extent of the target dye by the activated carbon. Olive-waste cakes activated carbon was shown to be a promising adsorbent for the efficient removal of metal complex dyes.