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 L1 and an adsorbent dosage of 1 g L1, but increasing the contact time and adsorbent dosage improved the removal efficiency. For instance, at an initial MB concentration of 50 mg L1, the removal percentage increased from 76 to 99.9%, with increasing adsorbent dosage from 0.5 to 3 g L1. 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%.