https://repositorio.ufpb.br/jspui/handle/tede/7763 PPGER Thu, 03 Sep 2026 14:36:23 GMT 2026-09-03T14:36:23Z http://repositorio.ufpb.br:443/jspui/retrieve/37076/ https://repositorio.ufpb.br/jspui/handle/tede/7763 https://repositorio.ufpb.br/jspui/handle/123456789/38865 Título: Pirólise lenta do aguapé (Eichhornia crassipes) para obtenção de biocarvão visando ao sequestro de carbono Autor(es): Pimentel, Maxwell de Arandas Orientador: Andersen, Silvia Layara Floriani Abstract: Water hyacinth (Eichhornia crassipes), an invasive aquatic macrophyte characterized by rapid growth and commonly associated with eutrophication processes, represents an abundant and underexploited source of renewable carbon. This study aimed to evaluate the yield, physicochemical properties, and carbon sequestration potential of biochar produced via slow pyrolysis of water hyacinth biomass. In particular, the effects of final pyrolysis temperature (400, 500, and 600 °C) and residence time (30 and 60 min) on the specific greenhouse gas (GHG) emissions avoided per ton of dry biomass were investigated. Proximate analysis revealed moderate contents of fixed carbon (13.07%) and ash (27.41%), associated with significant concentrations of K (676.9 mgK/gash), Ca (65 mgCa/gash), and P (27.3 mgP/gash). These results highlight the suitability of water hyacinth as a feedstock for biochar production with potential agronomic applications and contributions to nutrient cycling. Elemental analysis indicated proportions of C (30.61%), O (35.53%), H (3.78%), N (2.35%), and S (0.32%), values consistent with those typically reported for biomass feedstocks used in slow pyrolysis processes. However, the low bulk density of the biomass (145.33 kg/m⁻³) imposes logistical constraints, requiring additional preprocessing steps in practical applications, such as briquetting or pelletization. Biochar yield decreased from 0.48 tbiochar/tbiomass (400 °C; 30 min) to 0.34 tbiochar/tbiomass (600 °C; 60 min), reflecting the increased intensity of devolatilization and thermal cracking reactions at higher temperatures and longer residence times. The elemental carbon fraction ranged from 0.36 to 0.18, while the molar H/C ratio decreased from 0.71 to 0.48, indicating increased aromaticity and recalcitrance of the carbon matrix. The stable carbon fraction (Fperm) ranged from 0.51 to 0.66, with higher values observed at elevated temperatures and longer residence times. Specific avoided GHG emissions ranged from 0.32 to 0.15 tCO₂eq/ t of dry biomass, suggesting that milder temperature conditions combined with longer residence times may enhance the overall carbon sequestration potential. From an economic– environmental feasibility perspective, water hyacinth-derived biochar shows the potential to generate carbon credits ranging from US$ 22.89 to US$ 50.37 per ton. Overall, the findings indicate that biochar produced from water hyacinth exhibits physicochemical characteristics compatible with applications in carbon sequestration and soil quality improvement. Moreover, its production represents a promising strategy for the sustainable management of invasive aquatic plants within the framework of a low-carbon bioeconomy. Editor: Universidade Federal da Paraíba Tipo: Dissertação Wed, 10 Dec 2025 00:00:00 GMT https://repositorio.ufpb.br/jspui/handle/123456789/38865 2025-12-10T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38862 Título: Avaliação do desempenho luminotécnico em ambientes educacionais com foco na eficiência energética: estudo de caso do auditório do Centro de Tecnologia da UFPB Autor(es): Diniz, Laura Rodolfo Orientador: Reis, Raphael Leite de Andrade Abstract: The distribution of light in an environment is essential for the comfort and productivity of its occupants, being crucial for the proper performance of activities. However, lighting design is still underexplored in indoor spaces, and the influence of natural aspects, such as lighting and ventilation, is often not considered, especially in facilities related to public educational institutions. As a result, there is excessive use of artificial lighting and air conditioning systems, often implemented without a rationale that promotes energy efficiency or environmental comfort. This study aims to characterize the analyzed building and evaluate its lighting performance, using both data collection and computer simulations. The results are correlated with energy efficiency criteria, and strategies are proposed to better harness available natural resources, aiming to reduce energy consumption and maximize lighting efficiency and visual comfort. To this end, the OriginPro software was used for plotting the collected data and generating lighting maps, which were validated in DIALux evo, in accordance with Brazilian lighting standards for indoor environments. The study was conducted in the auditorium of the Technology Center at the Federal University of Paraíba (UFPB), chosen for its representative conditions for research purposes. With the characterization of the site and the climatic and geographic evaluation, it was possible to understand the solar incidence on the building. Based on the analysis of natural lighting availability, specific solstice and equinox days were selected for on-site illuminance measurements. Lighting maps were plotted in the Origin software using the collected data and were subsequently validated through simulations in DIALux. Upon evaluating the scenarios, flaws were identified in the auditorium’s lighting design, with insufficient illuminance levels in certain areas. A comprehensive assessment of various scenarios revealed a significant reduction (70%) in energy consumption and, consequently, a decrease in environmental impact. This analysis supports the future implementation of lighting and energy efficiency strategies in educational environments, contributing to improved environmental performance and user comfort. Editor: Universidade Federal da Paraíba Tipo: Dissertação Thu, 31 Jul 2025 00:00:00 GMT https://repositorio.ufpb.br/jspui/handle/123456789/38862 2025-07-31T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38827 Título: Investigação das propriedades estruturais e eletroquímicas de óxidos tipo Perovskita aplicados em armazenamento de energia e eletrólise da água Autor(es): Andrade, Camila Rêgo de Orientador: Silva, Kelly Cristiane Gomes da Abstract: In the midst of growing energy demand and the search for sustainable solutions, the development of new materials for energy storage and conversion has become essential. In this context, supercapacitors and water electrolysis stand out, whose performances are directly related to the electrochemical properties of the materials employed. Knowing that, the objective of this work is to investigate the use of perovskites of PrMO3 and LaMO3 type (M = Co or Ni) as an active material applied as electrode in supercapacitor and as catalysts for the oxygen evolution reaction (OER, which is the anodic half-reaction of water electrolysis). For this purpose, these materials were obtained using the gelatine synthesis method, resulting in four samples (P1, P2, L1 and L2), which were, then, characterized, from a structural point of view, using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), UV–Vis spectrophotometry and Scanning Electron Microscopy (SEM), and, from a electrochemical point of view, using Cyclic Voltammetry (CV), Galvanostatic Charge–Discharge (GCD), Linear Sweep Voltammetry (LSV) and Electrochemical Impedance Spectroscopy (EIS), in order to evaluate the specific capacitance and catalytic activity of the materials. Based on the diffraction patterns, the formation of the perovskite phase was confirmed for all samples. FTIR spectra revealed the presence of bands associated with metal–oxygen bonds characteristic of the investigated perovskite families. From the UV–Vis spectra, the band gap energies of the materials were estimated as an indication of their electrical conductivity, which obtained values between 2,20 eV and 3,60 eV. SEM micrographs showed a good distribution of pores and submicrometric particles, forming some agglomerates. Regarding electrochemical performance, the samples exhibited pseudocapacitive behavior, with the highest specific capacitance values obtained for P1 (PrCoO₃ → 184.27 F g⁻¹ at 1 A g⁻¹) and L2 (LaNiO₃/NiO → 142.29 F g⁻¹ at 1 A g⁻¹). Concerning OER activity, the results suggest that the materials present excellent performance, with sample P2 (PrNiO₃/NiO/Pr₆O₁₁) obtaining the lowest overpotential (325 mV with a Tafel slope equal to 56.58 mV.dec⁻¹), the highest electrochemically active surface area (ECSA = 130 cm²), and the lowest charge-transfer resistance. Therefore, the investigated materials are promising candidates for applications as supercapacitor electrodes and OER catalysts. Editor: Universidade Federal da Paraíba Tipo: Dissertação Wed, 25 Feb 2026 00:00:00 GMT https://repositorio.ufpb.br/jspui/handle/123456789/38827 2026-02-25T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38563 Título: Filtro óptico de radiação para células solares utilizando filmes finos multicamadas de óxido de índio e estanho e prata Autor(es): França, Lucas Medeiros de Orientador: Gomes, Kelly Cristiane Abstract: The increase in global energy demand has led to massive consumption of fossil fuels, intensifying climate change. Electricity accounts for one-third of this demand – more than half concentrated in buildings, with 50% of this consumption for thermal comfort systems. To supply electricity generation in a clean and sustainable way, several alternative and renewable sources have emerged, with solar energy standing out as the most promising on a large scale. However, this technology still faces some challenges and is close to the point of maximum efficiency of the main material that makes up these photovoltaic conversion devices, silicon. However, other materials are emerging and new photovoltaic cells are being developed. Furthermore, current solar cell materials are not capable of absorbing the complete solar electromagnetic spectrum for energy generation, with a large portion of the energy being absorbed as heat – generating warming, loss of efficiency, and degradation. Therefore, this work proposes optical radiation filters with the aim of transmitting to photovoltaic cells only the radiation range suitable for the photoelectric effect and reflecting the undesirable radiation range. The optical filter is a thin multilayer film composed of alternating indium tin oxide (ITO) and silver (Ag), where the optical properties were simulated and optimized via software (OpenFilters) with respect to the number of layers (3 and 5) and thicknesses. The films with the best performance were manufactured by magnetron sputtering and annealed at 350 °C for 1 hour in a muffle furnace. Optical characterizations were performed by UV-Vis spectrophotometry and heat blocking tests with a thermographic camera in an outdoor environment after exposure to solar radiation for 1 hour. Simulations demonstrate that the film with the best results for the desired regions of the solar spectrum is ITO/Ag/ITO/Ag/ITO (IAIAI) with 35/5/80/5/35 nm (T = 83.65% in the visible spectrum and R = 87.29% from 1100 to 2500 nm). However, it was not possible to manufacture it satisfactorily, resulting in poor transmittance and thermal blocking results. The IAIAI10 film showed good simulation results (T = 66.41% in the visible spectrum and R = 93.50% from 1100 to 2500 nm) and spectrophotometry results (T = 66.17% in the visible spectrum and T = 5.65% from 1100 to 2500 nm), as well as satisfactory thermal blocking (an increase of 4 °C after 1 hour, versus increases of 8 to 22 °C in other samples). In both films, the heat treatment was not satisfactory. Thus, this work produced optical radiation filters that show potential for use in solar cells to reduce the operating temperature and, consequently, mitigate efficiency losses due to heating during the energy generation process. Editor: Universidade Federal da Paraíba Tipo: Dissertação Wed, 25 Feb 2026 00:00:00 GMT https://repositorio.ufpb.br/jspui/handle/123456789/38563 2026-02-25T00:00:00Z