https://repositorio.ufba.br/handle/ri/2612 2026-05-06T23:22:46Z https://repositorio.ufba.br/handle/ri/44432 Título: Modificação da fibra da luffa cylindrica (l. aegyptiacal) com ácidos graxos para aplicação como biossorvente de óleo diesel Autor(es): Melo, Luciana Lima Primeiro Orientador: Vidal, Rosangela Regia Lima Abstract: 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. Editora / Evento / Instituição: Universidade Federal da Bahia Tipo: Dissertação 0002-02-27T00:00:00Z https://repositorio.ufba.br/handle/ri/44348 Título: Aplicação de técnicas não convencionais de extração para obtenção de bioativos em torta prensada de sementes de pracaxi [(Pentaclethra macroloba (Willd.) Kuntze)] Autor(es): Rodrigues, Willias da Luz Primeiro Orientador: Silva, Silvana Mattedi e Abstract: This doctoral research aimed to enhance the value of pracaxi press cake, a byproduct of oil extraction, by applying innovative and sustainable techniques aligned with the principles of green chemistry. The study focused on extracting bioactive compounds with antioxidant activity to enrich this industrial residue and strengthen the pracaxi production chain in the Amazon, thereby benefiting local communities. The methodology involved comprehensively characterizing the press cake and residual oil, including compositional, elemental, and mineral analyses. The microscopic structure of the press cake was examined using scanning electron microscopy (SEM), while Fourier-transform infrared spectroscopy (FTIR) was employed to identify functional groups. The physicochemical properties of pracaxi oil, such as density, viscosity, refractive index, and fatty acid composition, were investigated. Pressurized liquid extraction (PLE) techniques were applied using five solvents of different polarities (propane, ethyl acetate, ethanol, 75% aqueous ethanol solution, and water) with two distinct procedures: single-solvent extraction (SSE) and sequential two-solvent extraction (STSE). Mathematical modeling of pressurized liquid extraction kinetics was performed using models such as the two-line spline and the two-site desorption model. Additionally, enzyme-assisted extraction (EAE) was conducted using three commercial enzymatic complexes (Celluclast® 1.5L, Pectinex® Ultra SP-L, and Viscozyme® L), with water as the solvent. The obtained extracts were evaluated for their total phenolic and flavonoid content as well as their antioxidant activity (DPPH and FRAP assays). Furthermore, their antimicrobial activity against Staphylococcus aureus and Escherichia coli was investigated. The results demonstrated that pracaxi press cake is a rich source of bioactive compounds, with high crude protein (28.66%) and crude fiber (16.79%), while exhibiting low levels of potentially toxic elements. Elemental analysis indicated a predominance of carbon (50.50%) and nitrogen (4.18%), with molar ratios typical of lignocellulosic biomass. PLE proved to be effective in extracting phenolic compounds and flavonoids, with polar solvents such as ethanol-water (EtOH75) yielding the best results. The sequential two-solvent extraction (STSE) procedure, which used propane as a pretreatment, enhanced the efficiency of phenolic compound extraction. EAE, employing enzymes such as Pectinex® Ultra SP-L and Celluclast® 1.5L, improved the recovery of bioactive compounds, achieving high antioxidant activity—in some cases surpassing the results obtained with PLE. Mathematical modeling of extraction kinetics provided valuable insights for process optimization, enabling the identification of mass transfer mechanisms and optimal extraction times. The obtained extracts exhibited significant antioxidant activity, correlating with their total phenolic and flavonoid content, although no antimicrobial activity was observed under the tested conditions. This research highlights the potential of pracaxi press cake as a sustainable source of bioactive compounds, emphasizing the effectiveness of PLE and EAE techniques in their recovery. PLE offers flexibility in solvent and procedure selection, whereas EAE stands out for its use of an environmentally friendly solvent, water. These findings contribute to the full valorization of this agro-industrial residue, aligning with circular economy principles and promoting the sustainable development of the Amazon region Editora / Evento / Instituição: Universidade Federal da Bahia Tipo: Tese 2025-03-27T00:00:00Z https://repositorio.ufba.br/handle/ri/44297 Título: Determinação do coeficiente de transferência de massa na remoção de propanona por absorção Autor(es): Barbosa, Isabel Barbosa e Primeiro Orientador: Góis, Luiz Mário Nelson de Abstract: Air pollution from industries has been a frequently discussed topic today, generating the need to carry out studies on ways to reduce these impacts. Propanone is classified as a VOC (volatile organic compound) because it is a substance that in high concentrations generates risks to human health; and as it is present in industrial gas effluents, it is necessary to search for appropriate means to purify these gases. To carry out this type of treatment, studies focused on mass transfer through absorption were developed. The present work aims to determine the volumetric mass transfer coefficient of the liquid phase, KLa, in the removal of propanone present in the air by water using a stuffed absorption tower. The equipment used is 1,00 m high, 0,07 m in diameter and 0,79 m high filling glass rings. 33 experiments were carried out, at room temperature, at flow rates varying between 0,86 and 1,04 L min-1 of water and 0,4 to 1,2 L min-1 of air, in which, after contact between the liquid and gaseous streams, the Water samples are taken at an interval of 0 to 3,5 min to quantify the transferred propanone. The volumetric mass transfer coefficients on the liquid side obtained belonged to a range of 0,0044 to 0,0277 s-1, with a greater influence of the air flow on the KLa values in relation to the influence of the liquid flow. The equation developed in the dimensional analysis proved to be coherent, presenting an average error of 24%, and, when compared with some methods available in the literature, a better performance was observed, evidenced by the average error difference equivalent to more than 9%. Therefore, this study proved to be effective in the propanone transfer process, adding new data and empirical equations for the study of KLa. Editora / Evento / Instituição: Universidade Federal da Bahia Tipo: Dissertação 2024-07-12T00:00:00Z https://repositorio.ufba.br/handle/ri/44288 Título: Otimização do cultivo de chlorolobion braunii em associação de concentrado salino e água salobra: um bioprocesso para obtenção de biomassa e produção de biodiesel Autor(es): Medeiros, Ravena Maria de Almeida Primeiro Orientador: Cardoso, Lucas Guimarães Abstract: Effluents used as a culture medium for microalgae represent a strategy that combines wastewater treatment—promoting nutrient removal—with the generation of high value-added biomass. The ability of microalgae to accumulate lipids and carbohydrates in their biomass makes them a promising source for biofuel production. The aim of this study was to optimize the production and characterize the biomass of the microalga Chlorolobion braunii using a combination of brackish water and saline concentrate, a condition not previously explored. In addition, the potential of this biomass for biodiesel production was evaluated. The experiments were carried out in Erlenmeyer-type bioreactors (1 L), and the best biomass production condition was determined using a central composite rotational design with the following factors: volume of saline concentrate in brackish water (0–100%) and urea concentration (0.00– 0.08 g/L). The optimized condition was defined as 36.6% saline concentrate, 63.4% brackish water, and 0.02 g/L urea. The best treatment was the experiment with 50% brackish water and 50% saline concentrate, which produced 0.556 g/L of biomass with an average productivity of 0.014 g/L/day, and high levels of biomolecules such as 21.14% carbohydrates and 29.40% lipids. It also achieved bioremediation of 86.25% of nitrates (NO₃⁻), 79.17% of phosphates (PO₄³⁻), and a 23.18% reduction in salinity. The biomass showed high fatty acid content, with 24.94% C16:0 (palmitic acid) and 38.44% C18:1n9c (oleic acid), producing biodiesel that meets the quality standards of the American Society for Testing and Materials (ASTM D6751) and the Brazilian National Agency of Petroleum, Natural Gas and Biofuels (ANP). This study optimized the biomass production of Chlorolobion braunii and demonstrated the feasibility of using only a combination of brackish water and saline concentrate—without prior treatment and without the addition of synthetic medium—resulting in high levels of biomolecules that can serve as feedstock for the generation of high value-added bioproducts. Editora / Evento / Instituição: Universidade Federal da Bahia Tipo: Dissertação 2025-03-14T00:00:00Z