Rungrattanachai C.Amornsakchai T.Amornsakchai P.Mahidol University2025-10-262025-10-262025-10-21ACS Omega Vol.10 No.41 (2025) , 48711-48722https://repository.li.mahidol.ac.th/handle/123456789/112755Synthetic dyes like methylene blue (MB) are widely used in textiles and pharmaceuticals but pose environmental risks when discharged into wastewater. This study evaluates pineapple leaf biomass as a low-cost, biodegradable adsorbent for MB removal. Four materials─raw fiber (PALF), nonfibrous material (NFM), alkali-treated microfibers (PALMF), and ultrasonically treated PALMF (Ultra_PALMF)─were prepared and characterized. PALF achieved the highest adsorption capacity (53.93 mg g^–1), while NFM showed excellent reusability, retaining >96% efficiency after three cycles. Nonlinear kinetic analysis indicated that adsorption generally followed the pseudo-second-order model, though PALF was better described by the pseudo-first-order model. Equilibrium data were best represented by the Sips model, confirming the heterogeneous nature of the adsorption sites. Thermodynamic analysis confirmed a spontaneous, exothermic process. These findings highlight pineapple leaf waste as a sustainable alternative for dye removal, with NFM offering strong potential for practical reuse.Chemical EngineeringChemistryArticleSCOPUS10.1021/acsomega.5c067232-s2.0-10501909006224701343