Resumo:
Oil spills in marine environments pose serious ecological risks, requiring sustainable and efficient response alternatives. This study investigated lignocellulosic fibers from coconut (Cocos nucifera L.) and açaí (Euterpe oleracea) as biosorbents for the removal of crude and weathered oils in saline waters, addressing several underexplored scientific gaps. The main gaps include the underutilization of açaí mesocarp fiber as a biosorbent, the scarcity of studies involving weathered oils with detailed geochemical characterization, the lack of meso-scale tests under hydrodynamic simulation, and the absence of sustainable pre-treatment approaches, such as the use of biosurfactants. The methodology involved a fractional factorial design (2⁵⁻¹), micro- and meso-scale tests, kinetic and equilibrium analyses, and physicochemical characterizations of the fibers (SEM, FTIR, XRD, and chemical composition). The fibers underwent various pre-treatments (acid, alkaline, thermal, mercerization/acetylation, sonication, and biosurfactant) and were tested with oils from the Campos, Sergipe, and Recôncavo basins, both before and after weathering. The main findings revealed that (i) pH and salinity did not significantly affect sorption, (ii) oil dose, concentration, and contact time were the most relevant factors, (iii) açaí fiber outperformed coconut fiber, especially after pre-treatment, (iv) the pseudo-second-order kinetic model and Langmuir isotherm best fit the sorption data for both fibers, (v) açaí fiber maintained more stable performance over three reuse cycles, with higher desorption efficiency than coconut fiber, (vi) sorption was lower at meso-scale due to wave-induced turbulence, which reduced the oil’s residence time at the fiber–water interface, (vii) weathering significantly influenced oil sorption, altering the fibers' response depending on the oil type. Crude oils were preferentially sorbed from the Sergipe Basin. After 30 days of weathering, the highest sorption occurred with oil from the Campos Basin, due to its higher residual fluidity and aromatic content, which favors π–π interactions with the fiber surface. Oil from the Recôncavo Basin showed low sorption under both conditions, and (viii) the biosurfactant pre-treatment, an innovative and unconventional approach, achieved the highest sorption capacity (8.71 g·g⁻¹) among all treatments. The findings highlight the potential of Brazilian plant fibers, especially biosurfactant-treated açaí fiber, as an efficient and sustainable solution for oil containment, in line with green chemistry, circular economy, and waste valorization principles. This research also aligns with Brazil’s commitments under the UN 2030 Agenda, contributing to SDG 14 (Life Below Water), with particular relevance to the Brazilian Equatorial Margin, an area of intense coconut and açaí production and significant agro-industrial waste generation with underexplored environmental reuse potential.
