Application of oak charcoal-based activated carbon for the removal of methylene blue dye from aqueous solutions: kinetics, equilibrium, and reusability studies

Abstract

The present study investigated the use of oak charcoal-based activated carbon (OC-AC) as an adsorbent for the removal of methylene blue (MB) dye from aqueous solutions. The study examined the effects of key operational variables, including pH, equilibrium time, adsorbent dosage, and initial dye concentration. The results showed that pH had no significant effect on MB adsorption for the initial MB concentration below 50 mg L−1 and an adsorbent dosage of 1 g L−1, but increasing the contact time and adsorbent dosage improved the removal efficiency. For instance, at an initial MB concentration of 50 mg L−1, the removal percentage increased from 76 to 99.9%, with increasing adsorbent dosage from 0.5 to 3 g L−1. In addition, with increasing contact time from 5 to 300 min, the removal percentage increased from 45.43 to 87.42%. The study also analyzed the kinetics and isotherm behavior of MB adsorption and found that the Avrami fractional order kinetic model and the Freundlich isotherm model provided the best fit for the experimental data. MB removal from real water samples showed that OC-AC could be used as an efficient and environmentally friendly adsorbent for removing MB dye from contaminated effluents with the removal percentage ranging from 83 to 97%. HIGHLIGHTS Activated carbon was prepared from oak charcoal as low-cost precursors.; The effects of operational variables on the adsorption of methylene blue dye were investigated.; The experimental data were fitted to nonlinear kinetic and isotherm models.; The Avrami fractional order kinetic model and the Freundlich isotherm model well described the adsorption process.;

Keywords

• activated carbon
• adsorption
• aqueous solutions
• methylene blue