Advancements in water purification: green synthesis of pineapple peel-derived iron manganese binary oxide magnetic nanocomposites for efficient methylene blue adsorption

The present study explored the green synthesis of a pineapple peel-iron manganese binary oxide magnetic nanocomposite (PP-IMBMN) and its effectiveness in adsorbing cationic methylene blue dye (MBD) from synthetically contaminated water. The PP-IMBMN adsorbent was characterized using SEM/EDAX, TEM, XRD, FTIR, VSM, and point of zero charge analyses. Batch experiments used varying operational parameters, including pH, initial dye concentration, adsorbent dosage, and temperature. Under optimum adsorption conditions, a removal efficiency of 92.68% was achieved. The Langmuir and Freundlich adsorption isotherm models provided good fits to the equilibrium data, albeit with a slightly superior correlation observed for the Langmuir model compared to the Freundlich model. Pseudo-second-order kinetics provides the best explanation for the adsorption data. The thermodynamic study suggested that the adsorption was feasible, endothermic, and accompanied by increased entropy. HCl was observed as the most effective desorbing agent, allowing the PP-IMBMN to be regenerated up to five times in the regeneration trials. Therefore, the PP-IMBMN) stands out as a compelling solution for removing MBD from industrial effluents, showcasing its novelty through remarkable adsorption affinity for dyes, ease of separation, affordability, and reusability.