A comparative study on the adsorption of methylene blue in aqueous media by activated carbon and carbon nanosheets derived from olive stones

Background: Olive stones, a byproduct of agricultural processes, hold significant potential for sustainable applications. In this study, activated carbon and carbon nanosheets derived from olive stones were utilized as adsorbents for removing methylene blue (MB) dye from aqueous solutions. Methods: The preparation of activated carbon and carbon nanosheets involved grinding olive stones, followed by pyrolysis and ultrasonic treatment. The structural and morphological properties of the adsorbents were characterized using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analyses. Batch adsorption experiments were conducted to evaluate the influence of adsorbent dose, pH, initial dye concentration, and temperature on the adsorption process. Results: Under optimized conditions, the removal efficiencies of activated carbon and carbon nanosheets were 63% and 76%, respectively, with corresponding adsorption capacities of 50.6 and 60.9 mg/g. Adsorption isotherms were well described by the Langmuir model for both adsorbents, while kinetic studies revealed conformity to the pseudo-second-order model. Conclusion: The findings confirm that activated carbon and carbon nanosheets derived from olive stones are efficient and cost-effective adsorbents, exhibiting high adsorption capacities for MB and rapid equilibrium times in aqueous solutions.