Adsorption of cationic dye from aqueous solution onto activated carbon prepared from olive stones

• Thermal carbonization is carried out at 800 °C and 60 min.
• The maximum adsorption of MB dye by OSAC occurred at a pH 5.
• Equilibrium data were best fitted to Temkin isotherm.
• Adsorption kinetics follows the pseudo-second-order kinetic model.

The use of agriculture solid waste as low-cost adsorbents is considered as an ecofriendly adsorbent due to their contribution in the reduction of costs for waste disposal. The present study investigates the adsorption efficiency of raw olive stone (OS) and activated carbon prepared from Egyptian olive stones (OSAC). Batch adsorption experiments were conducted under varying conditions of contact time, initial concentration of methylene blue dye (MB), adsorbent dosage, pH and temperature. The experimental equilibrium data were examined using Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, and Harkins–Jura isotherms. The adsorption kinetic dye was analyzed using pseudo-first order, pseudo-second order and the intraparticle diffusion model. The results showed that the percentage of dye removal increased as the temperature increased but it decreased with the increase in initial dye concentration. The optimum pH required for maximum adsorption was found to be 5. Kinetic studies showed that the adsorption MB onto OS and OSAC followed pseudo-second order kinetic model. The results indicated that olive stone activated carbon could be used as a low-cost adsorbent for the removal of methylene blue from aqueous solution.