Célia Karina Maia Cardoso

This study provides the first comprehensive multiscale evaluation of raw coconut fibers as biosorbents for crude oil removal, encompassing laboratory adsorption tests, mesoscale hydrodynamic simulations, and field trials in marine environments. Fibers were characterized by SEM, FTIR, XRD, XPS, and chemical composition analysis (NREL method), confirming their lignocellulosic nature, high lignin content, and functional groups favorable for hydrocarbon adsorption. At the microscale, a 2⁵⁻¹ fractional factorial design evaluated the influence of dosage, concentration, contact time, temperature, and pH, followed by kinetic and equilibrium model fitting and regeneration tests. Dosage, concentration, and contact time were the most significant factors, while low sensitivity to salinity highlighted the material’s robustness under marine conditions. Adsorption followed pseudo-second-order kinetics, with an equilibrium adsorption capacity of 4.18 ± 0.19 g/g, and it was best described by the Langmuir isotherm, indicating chemisorption and monolayer formation. Mechanical regeneration by centrifugation allowed for reuse for up to five cycles without chemical reagents, aligning with circular economy principles. In mesoscale and field applications, fibers maintained structural integrity, buoyancy, and adsorption efficiency. These results provide strong technical support for the practical use of raw coconut fibers in oil spill response, offering a renewable, accessible, and cost-effective solution for scalable applications in coastal and marine environments.

Marine oil spills remain a recurring environmental concern, particularly in coastal and estuarine areas. Among the available strategies for managing spilled oil, sorbents derived from natural fibers have attracted considerable interest as viable alternatives to synthetic materials due to their biodegradability, low cost, and alignment with circular economy principles. This review synthesizes recent advances by connecting technical and environmental aspects with operational applications. It emphasizes structural and surface modifications of lignocellulosic fibers to enhance petroleum sorption capacity, selectivity, buoyancy, and reusability. Physical, chemical, and biological approaches are discussed, focusing on how these modifications influence sorption dynamics under realistic conditions. The review also highlights the incorporation of agricultural and industrial residues as raw materials, along with regeneration and reuse strategies that support waste valorization. However, significant gaps remain, such as the lack of studies with weathered crude oils, the limitation of larger-scale testing, and the need for standardized methods and evaluation of the final fate of exhausted biosorbents. Through the integration of technical, environmental, and operational criteria, this review provides a critical foundation for developing more efficient and circular marine oil spill response technologies.