Resumo:
The high demand for and widespread use of petroleum and its derivatives, such as diesel oil, across various economic sectors have caused significant impacts on the environment and human health. In the environment, these compounds have become major pollutants, primarily due to spills. In this context, sorption processes emerge as a promising alternative for removing oily pollutants from water, underscoring the need for biodegradable, low-cost, and highly efficient materials. Luffa cylindrica fiber (vegetable sponge) shows potential as a biosorbent due to its porous structure and mechanical stability. However, its sorptive capacity still requires improvement. Thus, this work proposes the surface modification of Luffa cylindrica fiber with fatty acids (lauric, palmitic, stearic, oleic, and linoleic acids) to increase its affinity for oily compounds. The main objective was to evaluate the effect of these modifications on the sorption capacity of diesel oil. Sample characterization was performed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Sorption studies were conducted by varying sorbent mass, process time, agitation speed, and temperature. Batch experiments were carried out using reference systems (diesel oil, distilled water, or saline water) and systems containing diesel oil spilled into distilled or saline water. The results indicated that oleic acid modification provided the most significant increase in diesel oil sorption capacity among the evaluated systems. The pseudo-second-order model showed the best fit to the kinetic data, indicating that the process is controlled by surface interactions. The predominant mechanism is driven primarily by hydrophobic interactions and van der Waals forces, reflecting the nonpolar affinity between diesel oil and the modified fiber surface. It is concluded that modifying Luffa cylindrica fiber with oleic acid increases its hydrophobicity and sorption efficiency, highlighting the material's potential for oil spill remediation.
