http://repositorio.ufc.br/handle/riufc/429 2026-04-16T06:25:51Z 2026-04-16T06:25:51Z Alves, Alanderson Arthu Araújo http://repositorio.ufc.br/handle/riufc/85892 2026-04-16T01:38:07Z 2025-01-01T00:00:00Z

Título: Thermophysical properties of biofuel systems under high-pressure conditions Autor(es): Alves, Alanderson Arthu Araújo Abstract: The growing demand for sustainable alternatives to fossil fuels presents technical and scientific challenges related to the use of biofuels, particularly in understanding their thermophysical behavior under real operating conditions, such as high pressure. This thesis provides a comprehensive investigation of the thermophysical properties of biodiesel-based systems, encompassing both pure fuels and blends with 1-butanol and diesel. The objective is to address gaps in the literature, evaluate the feasibility of alternative formulations, and propose advances in predictive modeling. Properties such as density, speed of sound, isobaric heat capacity, and distillation profile were analyzed, along with derived properties such as compressibility, thermal expansivity, and excess properties. Experimental measurements were conducted over a wide pressure range, from atmospheric conditions to levels representative of the real operating environment of internal combustion engines, which can reach pressures up to 200 MPa. The addition of 1-butanol was explored as a strategy to mitigate the limitations of biodiesel, including its low volatility and poor performance at reduced temperatures, highlighting the potential of this alcohol as a promising renewable additive. In addition to generating novel experimental data, the study incorporates various modeling approaches, including the PC-SAFT equation of state, corresponding states models, and empirical correlations based on fatty ester composition, with the aim of improving the accuracy of property predictions. The results indicate that, although the evaluated models perform satisfactorily in specific contexts, targeted adaptations and parameterizations are essential for the accurate representation of multicomponent mixtures under high pressure. This work makes a significant contribution to the advanced characterization of biofuels, supporting the development of more efficient and sustainable fuels and enhancing modeling tools in process engineering. Tipo: Tese

2025-01-01T00:00:00Z Queiroz, Ana Beatriz Delfino de http://repositorio.ufc.br/handle/riufc/85725 2026-04-09T11:18:10Z 2026-01-01T00:00:00Z

Título: Eficiência de adsorção de microplásticos de poliestireno por carbono ativado modificado com óxido de ferro Autor(es): Queiroz, Ana Beatriz Delfino de Abstract: Microplastic pollution has emerged as a threat to aquatic ecosystems and human health due to its persistence against conventional treatment methods and its ability to adsorb and transport chemical pollutants. This study aimed to investigate the efficiency of granular activated carbon (GAC), both commercial and modified with iron oxide, in the removal of polystyrene microplastics (MPs) from aqueous solutions through adsorption processes. The modification of activated carbon by impregnation with iron oxide resulted in a significant increase in removal efficiency. The CBT-FeT6 showed better adsorption capacity compared to CBT-PD02, especially across a wider pH range, which is advantageous for real-world applications. At a concentration of 2.5 g/L, CBT-FeT6 exhibited equilibrium adsorption capacities (16 h) of 2.94 mg/g at pH 4 and 2.61 mg/g at pH 7, outperforming CBT-PD02, which showed equilibrium values (30 h) of 2.91 mg/g at pH 4 and only 0.63 mg/g at pH 7. Even at pH 10, where electrostatic repulsion predominated, CBT-FeT6 achieved an adsorption capacity of 1.07 mg/g using 2.5 g/L over 30 h. The adsorption isotherms followed the Langmuir model for CBT-FeT6 and the Freundlich model for CBT-PD02, suggesting that the adsorption process was favorably altered by the incorporation of iron oxide. Characterization tests revealed the chemical and morphological properties of both polystyrene and activated carbon, with SEM analyses confirming the experimental results. The study highlights the potential of iron oxide-modified activated carbon as an efficient and sustainable solution for the removal of polystyrene microplastics, emphasizing the need for additional treatment steps in Wastewater Treatment Plants (WWTPs) to combat the environmental threat posed by microplastics. Tipo: Dissertação

2026-01-01T00:00:00Z Bortoluzzi, Pamela Cunha http://repositorio.ufc.br/handle/riufc/85425 2026-03-31T19:34:46Z 2025-01-01T00:00:00Z

Título: Desenvolvimento e avaliação de hidrogéis bioativos para a cicatrização de feridas crônicas Autor(es): Bortoluzzi, Pamela Cunha Abstract: It is known that chronic wounds represent a clinical challenge that, despite the constant advancement of treatments, presents a gap to fill regarding products that are truly effective, making the development of new products with bioactivity attractive. Therefore, hydrogels of natural polymers become interesting considering their biocompatibility. Among their possible components, collagen offers benefits in wound healing, and its extraction from marine sources is currently being targeted, as well as its hydrolyzed byproduct called peptides, which often exhibit different bioactivities. Furthermore, the application of national natural products becomes interesting, considering the wide range of Brazilian flora; among these, buriti oil stands out due to its healing properties. Thus, the objective of this work is to develop and characterize different formulations of collagen-based hydrogels, incorporating collagen peptides and/or buriti oil as bioactives for chronic wounds. First, enzymatic hydrolysis of collagen with papain was performed, and the peptides obtained were characterized by Bradford and SDS-PAGE electrophoresis. Buriti oil was characterized by GC-MS. Subsequently, the bioactive components were characterized for cytotoxic, antimicrobial, and antioxidant activities. Variations of hydrogels were produced, two dry and two wet, combining collagen, alginate, buriti oil, polysorbate 80, and/or peptides. The success of collagen hydrolysis was verified by electrophoresis, showing a decrease in molecular weight in the sample. In addition, in silico modeling was performed, which indicated the possible resulting peptide composition in terms of frequency and bioactivities, verifying regulatory, inhibitory, antithrombotic, and antioxidant activities, among others. Cytotoxicity analyses were performed for HaCaT and L929 cell lines, demonstrating the best concentration for use of buriti oil (0.13% w/v) and peptides (0.8% w/v) for the hydrogel. Most hydrogels demonstrated good cell viability, especially in the first 24 hours of testing. However, for HaCaT, a decrease in viability was observed after 48 hours, with the best result for A2S at 60.43%, while sample A2U showed the lowest result at 55.58%. These factors may be caused by problems in sterilization or washing. For L929, this problem was only observed in hydrogel A1U (57.25%), while the others showed satisfactory results, with a maximum of 92.84% for A2S. In the cell migration test, the in vitro wound closed within 24 hours for all hydrogels, surpassing the control at some analyzed times. Antimicrobial activity analyses did not demonstrate significant activity for the oil and polysorbate 80 mixture, showing a maximum of 25.45% against S. aureus. This was also observed for the peptides, with a maximum inhibition of 56.47% against P. aeruginosa. Regarding the hydrogels, A2U showed the most significant inhibition with 83.82% against P. aeruginosa. The antioxidant activities of the peptides showed results superior to the positive controls for the FIC and BCB methods with 97.71% (81.7 µg/mL) and 84.15% (163.4 µg/mL), respectively. In conclusion, the results were satisfactory and demonstrated promising results for the application of hydrogels in wound healing, in addition to indicating the viability of using peptides as bioactive material for various applications. Tipo: Dissertação

2025-01-01T00:00:00Z Silva, Allison Ruan de Morais http://repositorio.ufc.br/handle/riufc/84619 2026-02-05T12:33:42Z 2026-01-01T00:00:00Z

Título: Immobilization of Eversa ® Transform 2.0 lipase on polymeric and biopolymeric matrices for packed-bed operation Autor(es): Silva, Allison Ruan de Morais Abstract: Immobilized lipases are key biocatalysts for advancing industrial biocatalysis. When integrated into packed-bed reactors (PBR), they combine low shear stress with catalyst retention and repeated reuse cycles under continuous operation. However, PBR performance is often constrained by mass-transfer phenomena and by how immobilization, support properties, and operating conditions interact along the bed. Building on a critical review of recent advances in PBR employing immobilized lipases (2019–2024), with emphasis on operational limitations and transport effects, this thesis develops a process-oriented basis for designing packed-bed biocatalysts containing the Eversa ® Transform 2.0 lipase (ETL) through (i) systematic characterization of ETL in its soluble form, (ii) development of a marine-derived biopolymeric support for ETL immobilization, and (iii) in situ immobilization under flow within the packed bed. The commercial ETL preparation exhibited a total protein concentration of 20.36 ± 1.09 mg mL -1 and an essentially single band by electrophoresis. Kinetic screening with p- nitrophenyl butyrate (pNPB) identified 50 mM as the best substrate concentration evaluated (103.36 ± 1.27 U) and 50 °C as the best reaction temperature evaluated, increasing activity by 85.62% relative to 25 °C (216.71 ± 7.87 U). Thermal stability between 60 and 80 °C was described using the Sadana–Henley model (1987), revealing exceptional resistance at 60 °C (no measurable half-life over 288 h) and accelerated deactivation at higher temperatures; nonlinear Arrhenius analysis yielded a low apparent deactivation energy (5.05 kJ mol -1 ). Circular dichroism measurements supported preservation of α-helical structure across the pH range and the absence of a cooperative denaturation transition up to 95 °C, consistent with deactivation governed by aggregation and local rearrangements. The isoelectric point was pH 4.56, and DLS at pH 7.0 indicated a tendency toward aggregate formation. Next, iota-carrageenan (i-CA) was extracted from Solieria filiformis and optimized using a face-centered experimental design, achieving a maximum yield of 33.31% (100 °C, 4 h). The extracted polysaccharide was incorporated into a chitosan/i-CA blend (1:3, w/w) chemically crosslinked with glutaraldehyde (0.61%, v/v) and evaluated as an immobilization support (1 mg protein g -1 support, 1 h, pH 7.0). The support retained 37.3 ± 2.7% of the offered enzyme and exhibited 35.1 ± 0.9 U g -1 , corresponding to 106.9 ± 10.4% of the ETL activity at an equivalent soluble-enzyme concentration. Thus, enzymatic activity was preserved. Subsequently, ETL was immobilized in situ by hydrophobic adsorption onto Amberlite ™ XAD 1180 in a packed-bed reactor. Breakthrough-curve analysis (C/C 0 vs. bed volumes) and derived characteristic metrics demonstrated the influence of external and internal mass-transfer effects on front dynamics and effective loading. Increasing the feed concentration intensified adsorption but produced non-monotonic loading at a fixed immobilization time (maximum q = 23.95 mg g resin -1 at C 0 = 1.0 mg mL -1 ; q = 18.92 mg g resin -1 at C 0 = 2.0 mg mL -1 ), indicating accessibility limitations at high C 0 . Expressed activity reached a maximum at Q = 0.75 mL min -1 (A bed = 198.50 U g -1 ; A eff = 66.27 U mg -1 ). The immobilized bed was reused (stable hydrolysis over eight cycles) and maintained conversion in esterification after reuse. Solvent compatibility was supported by unchanged FTIR spectra and preservation of overall textural properties (S BET = 616-640 m 2 g -1 ). Overall, the results establish an integrated framework linking enzyme properties, support synthesis, and immobilization processes for the operation of ETL biocatalysts in packed-bed reactors, explicitly accounting for transport constraints and operational stability. Tipo: Tese

2026-01-01T00:00:00Z