Valorization of sugar palm agro-waste into cellulose biosorbents for highly effective methylene blue remediation

Water pollution from cationic dyes in industrial and municipal wastewater remains a pressing environmental concern, with conventional adsorbents such as activated carbon often limited by high cost and disposal issues. This study valorizes sugar palm fiber (SPF), an abundant agro-waste, into sugar palm cellulose (SPC) through sequential delignification and mercerization, producing sustainable bio-sorbents with enhanced adsorption performance. The objectives were to characterize the structural, chemical, morphological, and thermal changes induced by the treatments and evaluate the adsorption capacity of SPF and SPC for methylene blue (MB) removal under optimized batch conditions. Physicochemical analyses (FTIR, XRD, SEM, BET) confirmed lignin removal, increased crystallinity, and improved surface accessibility, with BET surface areas of 3.9607 m²/g (SPF) and 5.0101 m²/g (SPC). At optimum pH, contact time, and dosage, removal efficiencies reached 98.70 % (SPF) and 98.44 % (SPC), following pseudo-second-order kinetics and Langmuir isotherms, indicating chemisorption and monolayer adsorption. Thermodynamic studies revealed spontaneity (ΔG < 0), endothermicity (ΔH > 0), and increased interfacial randomness (ΔS > 0). The novelty of this work lies in the first-time dual-chemical treatment of SPF for dye removal applications, demonstrating that high removal can be achieved despite low surface area due to strong chemical interactions. These findings bridge a gap in the literature by introducing an underutilized biomass-based adsorbent with competitive performance, cost advantages, and potential scalability for industrial wastewater treatment.