Equilibrium, thermodynamic and kinetic studies to study the sorption of rhodamine-b by moroccan clay

This study aimed to evaluate the sorption capability of an inexpensive and easily available Moroccan clay, called locally Ghassoul, to remove Rhodamine B (Rh-B) from aqueous solution. Experimental results showed that the equilibrium sorption data fitted well with the Langmuir isotherm and the monolayer sorption capacity was estimated as 448 mg g-1 at 298K. Kinetic analyses showed that the sorption rate was more accurately represented by a pseudo second-order model. The intra-particle diffusion was involved in the overall rate of the sorption process but it was not the only rate-controlling step. The calculated thermodynamics parameters showed the spontaneous and the endothermic nature of the sorption process. The activation energy found to be 5.36 kJ mol-1 could indicate a physical sorption process. The obtained results confirmed the applicability of this clay as an efficient and economical adsorbent for cationic dyes from contaminated water.