https://repositorio.ufba.br/handle/ri/4912 Mon, 04 May 2026 11:03:37 GMT 2026-05-04T11:03:37Z 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 Thu, 27 Mar 2025 00:00:00 GMT https://repositorio.ufba.br/handle/ri/44348 2025-03-27T00:00:00Z https://repositorio.ufba.br/handle/ri/44266 Título: Desenvolvimento de nanocompósitos de quitosana e nanocelulose obtida por liquídos iônicos para mimetização óssea Autor(es): Vieira, Suellen Rocha Primeiro Orientador: Assis, Denilson de Jesus Abstract: The use of chitosan (CS) in the production of scaffolds, three-dimensional (3D), porous structures that play an important role as support for the growth of new tissues, has emerged as a promising alternative for biomedical applications, particularly in bone tissue regeneration. However, the low mechanical strength of these materials suggests the incorporation of nanomaterials, such as nanocellulose (NC), to provide structural reinforcement and broaden their application potential. NC is biodegradable, biocompatible, renewable, and exhibits a high surface area and mechanical strength, but its traditional production by acid hydrolysis (H₂SO₄ and HCl) leads to environmental impacts. In this context, ionic liquids (ILs) can be employed as a sustainable alternative for producing these nanoparticles. This study aimed to map technologies involving cellulose dissolution methods in ILs, identify major technological gaps, and develop CS-based scaffolds reinforced with NC obtained from ILs to support bone tissue regeneration. NC was produced from eucalyptus pulp using the ionic liquid 3-dimethylamino1-propylammonium hexanoate (DMAPA[Hex]) and characterized in terms of yield, zeta potential, Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). A central composite design (CCD) was used to optimize reaction time and temperature. Patent analysis indicated that the technology is in an early stage of maturity, with a predominance of applications in polymer chemistry and machinery, while uses in medical, pharmaceutical, and micro/nanotechnology fields remain incipient, representing opportunities for innovation. The optimal condition identified was 75 °C for 14.5 h, resulting in stable cellulose nanofibrils (CNF) with well-defined morphology and a zeta potential of approximately 7.0 mV, favorable for colloidal stability. The nanostructured scaffolds composed of purified chitosan (CS-P) and CNF were produced in 3D format and characterized by XRD, scanning electron microscopy (SEM), FTIR, and in vitro cell viability assays. The structures exhibited interconnected porous networks with pores larger than 100 µm, providing a voluminous matrix suitable for cell growth. CS-P improved the structural integrity of the biomaterial, and cell viability tests demonstrated high biocompatibility. The integration of technical performance, biocompatibility, and environmental responsibility positions the CNF/CS-P scaffolds as promising candidates for regenerative medicine and advanced biomaterials research. Editora / Evento / Instituição: Universidade Federal da Bahia Tipo: Tese Sat, 19 Dec 2026 00:00:00 GMT https://repositorio.ufba.br/handle/ri/44266 2026-12-19T00:00:00Z https://repositorio.ufba.br/handle/ri/43634 Título: Síntese de compósitos baseados em óxido de ferro, dióxido de titânio e material carbonáceo pelo método da combustão para aplicação em fotocatálise heterogênea Autor(es): Castro, Lucas Malone Ferreira de Primeiro Orientador: Brandão, Soraia Teixeira Abstract: Environmental contamination is a growing global concern, driving the development of alternative mitigation strategies. Heterogeneous photocatalysis is a promising approach, yet conventional semiconductors such as titanium dioxide and iron oxide face limitations, including the need for artificial UV radiation and rapid electron-hole recombination. This work explores the synthesis and application of novel composites based on titanium dioxide, iron oxide, and carbonaceous material derived from mango residue, using solution combustion synthesis with urea as fuel. Seven samples were produced with varying reagent ratios, resulting in distinct thermal profiles (TG/DTG/DTA), crystalline phases (hematite, maghemite, magnetite; XRD, FTIR), increased specific surface area in carbon-containing samples, diverse morphologies (SEM/EDS), and altered optical properties (UV–Vis spectroscopy, band gap), confirming the formation of new compounds with unique characteristics. Photocatalytic tests under UV irradiation (125 W) demonstrated that the FeTi-1-1 sample achieved the highest degradation efficiency for both pharmaceuticals and dyes. However, when dyes were mixed or solar illumination was applied, FeTi-1-2 and FeTiC-2-1-1 samples performed better. Exposure to natural light for 30 minutes led to selective inhibition of E. coli (Gram-negative) bacteria. The addition of mango residue enhanced the magnetic response, facilitating separation and reuse of the catalysts. Overall, incorporating the residue improved solar light absorption and photocatalytic efficiency under solar irradiation. Editora / Evento / Instituição: UNIVERSIDADE FEDERAL DA BAHIA Tipo: Tese Fri, 01 Sep 0002 00:00:00 GMT https://repositorio.ufba.br/handle/ri/43634 0002-09-01T00:00:00Z https://repositorio.ufba.br/handle/ri/43583 Título: Valorização da ananas comosus na produção de insumos industriais via pirólise catalítica sobre a zeólita MCM-22 Autor(es): Carvalho, Mateus da Silva Primeiro Orientador: Rangel, Maria do Carmo Abstract: The search for sustainable alternatives to fossil fuels has stimulated the valorization of agro-industrial waste through conversion into higher-value chemical products. The abundant and inexpensive peel of Ananas comosus (pineapple) is a promising raw material, but its thermal pyrolysis produces bio-oil rich in oxygenated compounds, giving it undesirable properties. This problem can be overcome by using catalytic pyrolysis, which promotes deoxygenation, cracking, and aromatization, increasing selectivity to target compounds and reducing refining steps. In this context, zeolites stand out as promising catalysts due to their acidity, microporosity, and stability, especially zeolite MCM-22, due to its independent pore system. This study investigated the valorization of pineapple peel and its fractions (cellulose, hemicellulose, and lignin), as well as the extractive-free fraction. Catalytic pyrolysis was performed on desilicated and/or nickel-containing MCM-22 zeolites (3% w/w) to evaluate the influence of these modifications on catalytic activity and selectivity. Nickel reduced the Brønsted to Lewis acid ratio, while desilication produced species more resistant to reduction. Catalytic pyrolysis modifies the product profile compared to thermal pyrolysis, mainly increasing the production of aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylenes (BTEX), followed by a decrease in oxygenated compounds. The use of different biomasses also alters the product distribution profile. Extractive removal increases phenol production, decreases oxygenated compound formation, and virtually eliminates polyaromatic compounds, to a catalyst-dependent extent. The cellulose- and hemicellulose-rich fractions formed mainly oxygenated compounds, BTEX, and phenols, while the lignin-rich fraction predominantly formed BTEX and phenols. The highest BTEX production was observed over the acidic form of the MCM-22-based catalyst during pineapple peel pyrolysis. Modifying the catalysts with nickel or desilication altered the product distribution but did not favor BTEX production. Among these compounds, toluene was the predominant product across all catalysts and biomasses. Editora / Evento / Instituição: Universidade Federal da Bahia Tipo: Tese Fri, 03 Oct 2025 00:00:00 GMT https://repositorio.ufba.br/handle/ri/43583 2025-10-03T00:00:00Z