Adsorption of methylene blue by activated carbon derived from various fruit peels

In this study, activated carbon (AC) derived from orange, mandarin, and banana peels has been utilized as an adsorbent for the removal of a cationic dye, methylene blue, from aqueous solutions. The batch adsorption technique was used with these materials under different conditions of contact time, initial dye concentration (10–100 mg/L), solution pH (4–12), and AC dosage (0.05–0.5 g). The characteristics of the prepared ACs were studied via FTIR, mercury porosimetry, and iodine number determination. Banana peels showed the highest removal efficiency compared with the other fruit peels. Adsorption isotherms were modeled with the Langmuir and Freundlich isotherms, and good fitting to the Freundlich isotherm was obtained. The kinetic data were analyzed using pseudo-first-order, second-order, and intraparticles diffusion models, with good fitting to the pseudo-second-order model. The obtained results indicate that AC represents an efficient low-cost adsorbent for the removal of MB from aqueous solutions.