Assessing the potential of palm oil processing wastes to produce cellulose and activated carbon for water treatment

In this study, six types of palm oil processing wastes (fiber, leaves, stems, sludge, rachis, and seeds) were characterized and transformed into high-value materials. The lignocellulosic content ranged from cellulose (15.8–39.8%), hemicellulose (12.2–25.2%), and lignin (13.7–47.0%), variations that influenced the yield (23–43%) and textural properties of the synthesized activated carbon (AC). Based on complexity stages and energy demand associated with biomass treatment before and after AC synthesis, MF was selected for detailed adsorption tests and cellulose extraction. AC obtained from fiber (AC-MF) had the largest surface area (310.5 m 2 /g) and pore volume (0.123 cm 3 /g). Characterization of AC-MF by XRD revealed the presence of K 2 CO 3 , graphitic domains and turbostratic carbon; in addition, basic functional groups, such as pyrone, phenolic and carboxylic, were identified, with a zero charge point of 7.62. Methylene blue (MB) removal was evaluated using response surface methodology, particularly a 3 3 full-factorial design varying the dye concentration (10–30 mg/L), AC-MF dose (0.3–1 g/L), and pH (3−10). Statistical results showed that pH had no significant effect and that the optimum operating point (20 mg/L MB, 1 g/L AC, pH 6.5) achieved a MB removal of 98.6%. The reusability tests evidenced that the AC-MF preserved its adsorption capacity after five consecutive cycles, with a performance comparable to a commercial AC. The extracted cellulose showed 95% purity, type I structure, and a crystallinity index of 60%. After acid hydrolysis, the zeta potential (-20.4 mV) and particle size (40.72 μm) indicated the production of microcellulose. These results demonstrate the industrial potential of this waste to generate efficient adsorbents for water remediation and high-purity biopolymers.