Circular adsorbent composites reinforced with agroforestry residue from eucalyptus for petroleum remediation

This study proposes developing sustainable polymer composites by incorporating micro- and nanofibrillated cellulose (CMNFs) derived from eucalyptus bark and wood chips into an upcycled polymer matrix derived from post-consumer coffee capsules. This approach represents a low-impact strategy to reduce waste while valorizing agro-industrial and urban residues. Applying these composites as crude oil adsorbents offers a promising strategy to advance the circular economy and address environmental challenges related to plastic pollution, forest residues, and oil spill remediation. To produce CMNFs, fibers from both samples underwent alkaline pretreatment to remove amorphous components such as lignin and hemicellulose, followed by steam explosion for defibrillation. The resulting fibers were incorporated into a recycled coffee capsule polymer matrix at concentrations of 5, 10, and 20% w/w. The composites were then evaluated for their oil adsorption performance. Thermal analysis (TG/DTG) revealed that the combined alkaline and steam explosion treatment improved the thermal stability of eucalyptus bark fibers, while decreasing the thermal stability of the wood chip fibers, likely due to structural differences in their lignocellulosic composition. Microscopy images showed improved adhesion between the polymer matrix and nanofibers derived from both bark and wood chips, compared with microfibers. BET analysis indicated that bark-derived nanofibers exhibited higher specific surface area and pore volume but smaller pore sizes, potentially contributing to their oil adsorption performance. Additionally, the treatments increased the crystallinity of all cellulose samples. Among the tested composites, those reinforced with 20% w/w micro- and nanofiber cellulose from bark achieved the highest oil adsorption efficiency, highlighting their potential as a novel, effective material for environmental remediation.