http://repositorio.ufc.br/handle/riufc/457 2026-05-20T08:07:22Z http://repositorio.ufc.br/handle/riufc/85892 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 http://repositorio.ufc.br/handle/riufc/84619 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 http://repositorio.ufc.br/handle/riufc/84210 Título: Tecnologias não térmicas para valorização de resíduos agroindustriais: influência das condições de processamento no perfil de compostos bioativos Autor(es): Decker, Betina Louise Angioletti Abstract: Agroindustrial wastes are rich sources of bioactive compounds, such as phenolic compounds, and have a high potential for reuse. In this perspective, this work aimed to study the influence of processing parameters of ultrasound and pulsed electric field (PEF), non-thermal technologies, on the extraction of bioactive compounds from grape pomace and orange peel, two important agroindustrial wastes, using green solvents and thus promoting their valorization. Initially (chapter 3), the extraction of anthocyanins from grape pomace (oven-dried and freeze-dried) was studied using ultrasound-assisted extraction (UAE) with acidified water as a solvent. Extraction conditions, power density (8.3 - 16.7 W/mL), pulse interval (0 - 2 s), and extraction time (1 - 5 min), were optimized for total anthocyanins. Based on the results for total anthocyanins, oven-dried pomace was selected for further studies. Specific anthocyanins were also quantified and optimized by nuclear magnetic resonance (NMR) spectroscopy and identified by liquid chromatography-mass spectrometry (LC-MS). Results showed that different processing conditions favored the extraction of different anthocyanins. Total anthocyanins and malvidin monoglucoside had maximum contents when power density = 16,7 W/mL, pulse = 2 s, and extraction time = 5 min. In comparison, the optimal condition for the extraction of malvidin diglucoside was at power density = 11.7 W/mL, pulse = 0.9 s, and extraction time = 4 min. The condition with the highest total anthocyanin content was chosen for spray drying of the extract (chapter 4). The influence of the inlet air temperature (120, 130, 140, 150, 160, and 170 °C) on anthocyanin extract drying was then studied. Spray drying at 140 °C resulted in the highest anthocyanin recovery, as well as adequate moisture content and water activity, promoting product stability and safety. For all the temperatures tested, the powder showed poor flowability. Finally, in chapter 5, extraction studies were extended to another food matrix and new non-thermal technologies. The combination of PEF and UAE for extracting bioactive compounds from orange peel using water as a solvent was evaluated. The process variables studied were electric field strength (0.6 - 1.2 kW/cm2) and number of pulses (200 - 400) for PEF; and amplitude (40 - 80%) and pulse duration (0.4 - 0.8 s) for UAE. The results demonstrate that the application of CEP, especially with higher electric field intensity and 400 pulses, promoted cell disintegration and increased the content of phenolic compounds in the extract obtained. In addition, 15 compounds were identified by LC- MS, divided into 5 classes, which were optimized. Different processing conditions favored different classes. In general, the results of this work demonstrate that UAE, as well as the combination of PEF and UAE, are promising non-thermal technologies for the extraction of bioactive compounds using green solvents. Optimization of extraction, as well as the study of the changes on compound profiles, increases the knowledge of the process and the products, thus ensuring the obtaining of the product according to each industrial need, promoting the valorization of agroindustrial residues. Tipo: Tese 2025-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/84044 Título: Estabilidade de adsorventes de secagem de gás natural: combinando protocolo de envelhecimento com a dinâmica de adsorção em leito fixo. Autor(es): Nascimento, Beatriz Oliveira Abstract: Natural gas is the second most used fuel in Brazil. It is composed mainly of methane and other hydrocarbons; however, it could present some contaminants. Among them, water may cause several problems like heat capacity reduction, transport impairments and corrosion in pipelines and equipment. Water removal may be performed by the TSA (Temperature Swing Adsorption) process, in which case separation takes place by adsorption at low temperatures and bed regeneration occurs at high temperatures upon water desorption. In this work, two kinds of adsorbents typically employed in natural gas dehydration were assessed: LTA zeolite and activated alumina, which were subject to an accelerated aging protocol that emulated a TSA process. The samples were placed in a Parr reactor, where they were humidified, mixed with n-heptane (0.6 mL g -1 ), and pressurized by CO 2 and methane to mimic the natural gas composition. Then, the samples were heated at 250°C and cooled down to room temperature cyclically, samples being withdrawn in the 14 th , 24 th , and 35 th cycles. The Ray-X Diffraction pattern of the alumina sample shows that it underwent a phase transition process after 35 cycles. In the FTIR analysis, both samples present bands around 1560 and 1380 cm -1 after 35 aging cycles, which were associated with PAHs (polyaromatic hydrocarbons), suggesting that organic species were formed inside the samples. Water adsorption isotherms present the characteristic type II, which is due to the characteristic of macroporous binder material, with LTA zeolite showing the highest CO 2 and methane adsorption capacity, which could be associated with the higher micropore volume in this sample. Breakthrough experiments of CO 2 and H 2 O as single and binary compound were carried out. In CO 2 /H 2 O mixtures, CO 2 adsorption capacity was strongly affected by the vapor water presence, resulting in a reduction in its adsorption capacity of up to 90 %. The column adsorption model, after being validated by the breakthrough experiments, was run using the equilibrium and kinetic data of the LTA and alumina aged samples. In both cases, the dynamic adsorption capacity was consistent with the isotherm outputs. In the LTA, the adsorption amount decreases progressively for increasing aging cycles. On the other hand, the alumina sample showed a significant dynamic and equilibrium capacity reduction in the first 14 cycles, stabilizing at that level of degradation. Furthermore, the aging process also affects the adsorption kinetic due to pore blockage. In such cases, changes in the breakthrough shape may occur, leading to an earlier breakpoint. Tipo: Tese 2025-01-01T00:00:00Z