Abstract
Synthetic 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 materialsraw 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.