https://tede.unioeste.br/handle/tede/600 2026-09-29T02:49:24Z https://tede.unioeste.br/handle/tede/8655 Title: Filme polimérico fotocatalítico a base de polímero biodegradável com TiO2 para degradação do corante vermelho BF-4B Autor: Rosenberger, Andressa Giombelli Primeiro orientador: Modenes, Aparecido Nivaldo Abstract: Due to environmental pollution from textile industries, there has been interest in removing dyes from processes such as dyeing and washing. In this context, the application of polymeric fibers electrospun with TiO2 in the photodegradation of the dye Red BF-4B was studied. To produce the polymeric yarns, the polymer blend PBAT/PLA and TiO2 nanoparticles were used. The polymer solution was formed by dissolving the polymer (15% m/v) in a solvent mixture of chloroform and dimethylformamide (85:15% v/v) and finally adding the TiO2 nanoparticles (10% m/v) ). The fibers were electrospinned using the conditions of flow of 1.80 mL h-1, distance of 16 cm and voltage of 18 kV. The fibers obtained were characterized by morphological, structural and thermal techniques, then the photocatalytic tests were carried out and, finally, the viability of the polymeric film was evaluated after the photocatalytic process. PBAT/PLA/TiO2 fibers have cylindrical morphology with an average diameter of 1.12±0.26 μm, in addition they are rough and have small bumps along their lengths due to the presence of TiO2. By TEM analysis, it is possible to verify the dispersion of TiO2 nanoparticles along the fibers, and it is noted that the polymer surrounds them by a thin layer. Both fibers with and without TiO2 have a hydrophobic character at the beginning of the contact angle wettability analysis, but after 75 min the wettability increases due to physical mechanisms such as wetting and encrustation. The FTIR spectra show characteristic functional groups of PBAT and PLA polymers and in the fibers with TiO2 nanoparticles it is observed in the region between 1000 and 650 cm-1 Ti-O-Ti oscillations dominant over the characteristic bands of the polymer. In PBAT/PLA and PBAT/PLA/TiO2 fibers, the presence of an amorphous halo characteristic of PBAT/PLA polymer blends can be seen in X-ray diffractograms. Thermal analysis indicates a conformational change, so that the PLA polymer demonstrates greater stability, as opposed to the PBAT polymer, which became easier to be degraded. The pHpcz of the materials indicates that for anionic dyes such as BF-4B Red, a pH below 7.42 would facilitate the catalytic process. Furthermore, the mathematical adjustments indicate that at the beginning of the reaction, the kinetic model that best fits the experimental data is the zero-order model, then, at lower concentrations, the model becomes the pseudo-first-order model. The reuse of polymeric film showed good removals (86.60 to 93.07%) during six cycles of 600 min. After the photocatalytic process, in the first and sixth degradation cycle, the fibers remain cylindrical, with prominent protrusions, the presence of several fractured fibers and a reduction in their diameters, indicating degradation and wear of the polymer. Infrared vibrational spectra show that most of the functional groups did not change, except for the regions at 1755 (C=O) and 1714 cm-1 (C-O), showing a possible conformational alteration of the polymeric chains. The thermal degradation profiles also changed, but the maximum thermal decomposition temperatures showed few changes after the photocatalysis process and the thermal degradation began to increase slightly after the cycles. Furthermore, by X-ray diffractograms it is observed that TiO2 particles are more exposed after photocatalysis, demonstrating loss of polymeric material during this process. Thus, it is emphasized that PBAT/PLA fibers produced by the electrospinning technique are promising to be used as support material for the photocatalyst (TiO2) and application in the treatment of textile dye residues. Publisher: Universidade Estadual do Oeste do Paraná Tipo do documento: Tese 2021-12-20T00:00:00Z https://tede.unioeste.br/handle/tede/8647 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 2026-07-27T00:00:00Z https://tede.unioeste.br/handle/tede/8646 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 2026-07-03T00:00:00Z https://tede.unioeste.br/handle/tede/8496 Title: Predição do equilíbrio da adsorção multicomponente de gases utilizando o modelo aNRTL para cálculo dos coeficientes de atividade na fase adsorvida Autor: Reinehr, Thiago Olinek Primeiro orientador: Silva, Edson Antonio da Abstract: Three non-ideal models were developed to predict the adsorption behavior of binary mixtures based on the adjustment of parameters from single-component systems: the VSM-aNRTL and two Langmuir Thermodynamic Multi-Region Expanded models, one based on the maximum adsorption capacity (LTEMR) and another on the adsorbed molar area (LTEMR-area). All of them utilize the new Adsorption Non-Random Two-Liquid (aNRTL) model to calculate the activity coefficient in the adsorbed phase. Experimental single-component adsorption equilibrium data from the NIST/ARPA-E Database were adjusted to obtain the necessary parameters. These parameters were then used to predict equilibrium data for 12 binary systems at different temperatures, involving various gases. For comparison, the idealized model of the Ideal Adsorbed Solution Theory (IAST) and the traditional VSM, which employs Wilson's equations (VSM-Wilson) to calculate the activity coefficients in the adsorbed phase, were used. The proposed models proved effective in correlating the adsorption isotherms of pure components, with high correlation coefficients and a reduction in the number of adjustable parameters compared to VSM-Wilson. In predicting equilibrium data of binary mixtures, both VSM-aNRTL and LTEMR-area showed lower deviations compared to the IAST and VSM-Wilson models, notably the VSM-aNRTL, which significantly outperformed the comparison models. The superior performance of the proposed models was also confirmed by the Akaike Information Criterion (AIC). Notably, VSM-aNRTL and LTEMR-area achieved these results by incorporating only one additional parameter relative to IAST and with fewer parameters than VSM-Wilson, evidencing their efficiency and precision in predicting adsorption in binary systems. Publisher: Universidade Estadual do Oeste do Paraná Tipo do documento: Tese 2024-12-04T00:00:00Z