Adsorption of reactive blue 2 dye from aqueous solution by cocoa (Theobroma) cacao shell: An agro solid waste

Activated carbon prepared from agro waste cocoa (Theobroma cacao) shell has been utilized as the adsorbent for the removal of Reactive blue 2 dye from aqueous solution. Adsorption studies were carried out at different initial concentration and contact time, pH of solution and temperature. Adsorption data were modeled using Langmuir, Freundlich, Tempkin and Dubinin-Raduskevich isotherms. Based on correlation coefficient (r²) values, equilibrium data found fitted well to the Langmuir isotherm. Adsorption kinetics was verified by pseudo-first order, pseudo-second order and Intraparticle diffusion models. The kinetic adsorption data fitted the pseudo-second order kinetic model well and also followed the intra-particle diffusion model. Thermodynamic parameters such as ΔH°, ΔS°, and ΔG° were evaluated. The positive enthalpy shows that the adsorption process was endothermic in nature.