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Análise de operabilidade da produção de gás de síntese a partir do processo sequencial de reforma a seco e reforma a vapor do biogás

Thu, 17 Jul 2025 00:00:00 GMT

Title: Análise de operabilidade da produção de gás de síntese a partir do processo sequencial de reforma a seco e reforma a vapor do biogás Autor: Costa Sobrinho, Thales Uchoa da Primeiro orientador: Borba, Carlos Eduardo Abstract: This dissertation presents a mathematical modeling-based integrated analysis of synthesis gas (syngas) production from biogas through the sequential combination of dry reforming of methane (DRM) and steam reforming of methane (SRM) processes. The adopted methodology involved the development of a thermodynamic model based on the minimization of Gibbs free energy, accounting for non-idealities via the fugacity coefficient of each species in the mixture, capable of predicting the equilibrium composition of the involved species, and its validation using experimental data from the literature. The study assessed the impact of operational variables such as temperature (in the range of 600–1500 K), CH4/CO2 feed molar ratio (1.5 to 4), and water vapor molar flow rate (4 to 16 kmol·h−1) on process outputs such as syngas composition, H2/CO molar ratio, and carbon formation. The best results were obtained at temperatures of 1000 K and 1150 K in the DRM (R1) and SRM (R2) reactors, respectively, CH4/CO2 feed ratio ≥ 1.5, and a steam flow rate of 8 kmol·h−1, corresponding to a steam-to-carbon ratio (S/C) of 1.33. These conditions enabled the achievement of an H2/CO ratio ≥ 2.0, high reactant conversion, and low carbon formation, under operating conditions comparable to those used in industrial reformers. Furthermore, the operability index (OI) was determined as an optimization tool, identifying safe and efficient operational regions of the process. The OI reached a value of 81.64%, indicating a good overlap between achievable and desirable output sets. The results demonstrate that the reforming process employing sequential reactors is a viable and promising alternative for the conversion of the main components of biogas into synthesis gas, offering high flexibility and selectivity - especially when combined with operability analysis methods - thus contributing to the development of sustainable syngas production technologies from renewable waste sources. Publisher: Universidade Estadual do Oeste do Paraná Tipo do documento: Dissertação

Fotossensibilizadores naturais e sintéticos aplicados à inativação fotodinâmica antimicrobiana: caracterização fotoquímica, espectroscópica e avaliação biológica

Mon, 27 Jul 2026 00:00:00 GMT

Title: Fotossensibilizadores naturais e sintéticos aplicados à inativação fotodinâmica antimicrobiana: caracterização fotoquímica, espectroscópica e avaliação biológica Autor: Marcon, Caroline Toigo Primeiro orientador: Fiorese, Monica Lady Abstract: Antimicrobial resistance and foodborne and cutaneous infections have intensified the search for alternative antimicrobial strategies. Antimicrobial photodynamic inactivation (aPDI) has emerged as a promising approach based on the generation of reactive oxygen species through the interaction of a photosensitizer, light, and molecular oxygen, exerting multifactorial effects on microbial cellular structures. This study investigated the potential of natural and synthetic photosensitizers for antimicrobial aPDI through phytochemical, spectroscopic, and photochemical characterization, assessment of antioxidant activity, and determination of antimicrobial efficacy against microorganisms of clinical and food-related relevance. In addition, a standardized aPDI protocol was developed and integrated into a custom-built LED illumination system designed for 96-well microplates. The system enabled irradiance control, wavelength selection, and homogeneous light distribution, allowing the simultaneous assessment of photosensitizer concentration and optical fluence with improved reproducibility and experimental throughput. The phenothiazinium dyes Azure A (AZA) and Toluidine Blue O (TBO) were evaluated as synthetic photosensitizers, whereas a hydroethanolic extract obtained from the flowers of Plumeria rubra L. (Apocynaceae) by ultrasound-assisted extraction was investigated as a natural photosensitizer. AZA and TBO exhibited absorption profiles in the visible region that were compatible with the red LED source used at 630 nm. Both dyes showed similar singlet oxygen generation rates and photodynamic saturation at concentrations above 34 µM. In the aPDI assays, both photosensitizers achieved complete inactivation of Cutibacterium acnes at the same concentrations, with minimum bactericidal concentrations (MBCs) ranging from 6.25 µM at 12 J/cm² to 0.78 µM at 50 J/cm². Against Staphylococcus epidermidis, AZA exhibited greater efficacy than TBO, with MBC values twofold lower at all evaluated fluences. Phytochemical analysis of the Plumeria rubra extract by UHPLC–MS/MS identified 21 compounds, with rutin (83.96 mg/g) and chlorogenic acid (13.38 mg/g) as the predominant constituents. The extract exhibited high antioxidant activity in the TBARS assay (EC₅₀ = 0.145 mg/mL) and broad spectral absorption between 400 and 630 nm, which was compatible with the white-light source used. In the absence of light, the extract showed no antibacterial activity under the tested conditions. Upon irradiation, however, it induced fluence-dependent photodynamic inactivation of all six Gram-positive strains evaluated, including methicillin-resistant Staphylococcus aureus (MRSA), with an MBC of 0.78 mg/mL at 18 J/cm². Lower efficacy was observed against Gram-negative bacteria.These findings demonstrate that AZA is an effective synthetic photosensitizer for antimicrobial photodynamic inactivation, with potential applications in the treatment of acne vulgaris. Furthermore, the Plumeria rubra extract represents a promising natural photosensitizer, combining a relevant phytochemical profile, photodynamic selectivity, and bactericidal activity against pathogens of clinical and food-related importance, including multidrug-resistant strains. Publisher: Universidade Estadual do Oeste do Paraná Tipo do documento: Tese

Produção de biochar a partir de sabugo de milho: caracterização, adsorção de nitrogênio amoniacal e Scale-up da pirólise em reator de tambor rotativo

Fri, 03 Jul 2026 00:00:00 GMT

Title: Produção de biochar a partir de sabugo de milho: caracterização, adsorção de nitrogênio amoniacal e Scale-up da pirólise em reator de tambor rotativo Autor: Alberti, Schaline Winck Primeiro orientador: Silva, Edson Antonio da Abstract: Biochar has been extensively investigated as an adsorbent material for environmental applications. Although its use in agriculture has traditionally been associated with soil conditioning and carbon sequestration, biochar also exhibits high potential for wastewater treatment. In this context, the production of biochar from agricultural residues stands out as a sustainable alternative, enabling the valorization of these materials and the development of low-cost adsorbents, while providing additional environmental benefits such as CO₂ emission reduction and promotion of the circular economy. In this research project, biochar was produced by pyrolysis of corn cob, an abundant agricultural residue. Initially, the raw material was conditioned and characterized through thermogravimetric analysis (TGA), moisture and ash content determination, elemental composition, extractives content, lignin, and holocellulose analyses. Biochar production was conducted using a mixed 2 × 3 factorial experimental design, varying the carrier gas (N2 and autopyrolysis), particle size, and temperature, aiming to obtain a biochar with high cation exchange capacity and suitable properties for ionic adsorption. After the experimental design, segregation of corn cob composition during particle size separation was observed, as well as differences in adsorption capacities. This behavior motivated the production of powdered biochar under the best-defined atmospheric and temperature conditions, followed by post-pyrolysis acid treatment with phosphoric acid (H3PO4), resulting in the biochars denoted as Bp and BpH. Subsequently, physicochemical and functional characterizations were performed, including pH, point of zero charge (pHpzc), water retention capacity (WRC), electrical conductivity, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and total reflection X-ray fluorescence (TXRF), in addition to planned complementary analyses such as N2 physisorption, toxicity, and leaching tests. Characterization results indicated that acid treatment significantly altered the biochar surface, leading to reductions in pH, ash content, and conductivity, as well as modifications in surface functional groups. The pHpzc obtained for BpH was close to 3, providing a favorable condition for ammonium nitrogen (NH4+ < pKa = 8.8 < NH₃) adsorption. Considering the application in ammonium nitrogen removal, the BpH biochar (acid-treated) showed favorable kinetics, with the pseudo-first-order (PFO) model fitting the data, suggesting an overall kinetic controlled by external mass transfer and progressive site occupation, and an experimental ammonium nitrogen adsorption capacity (q) of ~53 mg g-1 in just 180 min. Equilibrium data showed sigmoidal behavior, and the Sips model provided the best fit, with an estimated maximum capacity of 64.07 mg g-1. In water from a fish farming depuration tank, an ammonium nitrogen adsorption capacity of 1.07 mg g-1 was obtained, similar to that obtained with a synthetic solution of similar concentration, in addition to reductions in concentrations of elements such as Na, P, K, and Ca, and inorganic carbon q = 3.90 mg g-1 and total carbon q = 2.73 mg g-1. In scale-up, corn cob pyrolysis in a rotary drum reactor resulted in a biochar yield of 24.86% and a pyrolytic liquid yield of 20.54% with acidic characteristics. The results demonstrated the viability of integrating corn cob valorization, biochar production, and its application in ammonium nitrogen removal, although operational adjustments and complementary evaluations are necessary for its continuous application. Publisher: Universidade Estadual do Oeste do Paraná Tipo do documento: Tese

Pirólise lenta da cama de aviário: modelagem, simulação e análise de um reator de forno rotativo em escala piloto

Tue, 09 Dec 2025 00:00:00 GMT

Title: Pirólise lenta da cama de aviário: modelagem, simulação e análise de um reator de forno rotativo em escala piloto Autor: Silva, Marlon Henrique da Primeiro orientador: Silva, Edson Antonio da Abstract: The valorization of agro-industrial waste, such as poultry litter, through thermochemical processes is a sustainable alternative for generating value-added products, such as biochar. However, the phenomenological modeling of slow pyrolysis in pilot-scale rotary kiln reactors is still a poorly explored area. In this context, this study aimed to model, simulate, and analyze the slow pyrolysis of poultry litter, using operational data from a pilot-scale reactor operated by the startup Terraxy, incubated by King Abdullah University of Science and Technology (KAUST). Two steady-state models were developed and evaluated: one with constant heating throughout the reactor (MAS) and another with a central heating zone (MAC), more faithfully representing the experimental configuration. Batch simulations aided in the selection of the first-order kinetic model with three parallel reactions, formulated by THURNER e MANN (1981), to represent the biomass decomposition. The results indicated a biochar yield of approximately 30% for both models, below the experimental value of 39,4%. However, the MAC exhibited more realistic thermal behavior, with temperature profiles that captured the heat regeneration phenomenon and showed a difference of only 20 K (less than 1 standard deviation) compared to the temperature measured on the drum wall. Through a parametric sensitivity analysis, it was possible to correlate the influence of operational parameters, such as the heat supplied and the solids feed flow rate, with the process stability, identifying conditions that can lead to the extinction of pyrolysis. This work demonstrates the applicability of phenomenological models for the analysis and optimization of pilot-scale pyrolysis reactors, providing valuable support for process control and scalability. Publisher: Universidade Estadual do Oeste do Paraná Tipo do documento: Dissertação