Activated carbon derived from waste orange and lemon peels for the adsorption of methyl orange and methylene blue dyes from wastewater

The study of adsorbent behaviour in laboratory conditions helps to predict the adsorption process in a large industrial scale. In this study, orange and lemon peels-derived activated carbon (OLPAC) was successfully synthesized and activated using phosphoric acid. Characterization was performed on the OLPAC and the material was used for the removal of methyl orange (MO) and methylene (MB) dyes from wastewater. The results of the scanning electron microscope and N₂ adsorption/desorption examination affirmed that the prepared nanocomposite is permeable, which is an advantage for the efficient removal of contaminants. Optimal conditions for the batch removal process were investigated using a one-factor time approach in different conditions of adsorption (Dye concentration 50-200 mg L^-1, pH 2-10, adsorbent mass 0.010-0.8, and contact time 5-180 min. The adsorption isotherm equilibrium data were examined by Langmuir, Freundlich, and Temkin, isotherm model. As shown by the correlation coefficient (R²), the data were best described by Langmuir isotherms with maximum adsorption capacities of 33 and 38 mg g^─1 for methyl orange and methylene blue, respectively. Adsorption kinetic data were described using the pseudo-second-order model which suggests that adsorption of MO and MB was by chemisorption mechanism. The method was applicable to real wastewater samples, with satisfactory removal percentages of OM and MB (96 and 98 %). The results of this study show that OLPAC is an inexpensive biosorbent that is successfully utilized in removing methyl orange and methylene blue dyes from wastewater.