Investigating Thermodynamics and Kinetics of Methylene Blue and Eriochrome Black-T Adsorption on Activated Carbon Prepared from Coconut Husk

In this research, the adsorption process was studied for methylene blue eriochrome black-T from aqueous solutions on the surface of activated carbon prepared from coconut husk by chemical activation with potassium hydroxide. The results show that the adsorption isotherm for methylene blue follows the Langmuir model while it follows the Freundlich model and the maximum adsorption capacity was 909 mg/g for methylene blue and 262 mg/g for eriochrome black-T. The equilibrium contact time reached in about 90 minutes at lower concentrations and 120 minutes at higher concentrations. Two simplified kinetic models including pseudo-first-order and pseudo-second-order equations were selected to follow the adsorption processes. Kinetic studies showed that the adsorption followed pseudo-second order model for both methylene blue and eriochrome black-T dyes. Various thermodynamic parameters such as Δ , Δ and Δ were evaluated. The results in this study indicated that the coconut husk could be employed as a promising substance to produce activated carbons with high adsorption capacities