https://repositorio.ufu.br/handle/123456789/5468 2026-07-28T06:09:12Z 2026-07-28T06:09:12Z https://repositorio.ufu.br/handle/123456789/48957 2026-07-22T06:28:29Z 2026-05-29T00:00:00Z

Title: Lixiviação dos metais lítio e manganês presentes em baterias do tipo botão (LiMn2O4) Abstract: The increasing consumption of electronic devices has intensified the generation of waste from lithium-ion batteries (LIBs), which contain potentially toxic metals such as Li, Co, Ni, and Mn, posing risks to the environment and human health. In this context, the development of more sustainable recycling routes have become essential. Among commercial systems, the spinel LiMn₂O₄ (LMO) has been widely applied due to its low cost and good stability, with manganese being a key component in these batteries. Hydrometallurgy has emerged as a promising alternative for LIB recycling, particularly through the use of organic acids such as malic acid and ascorbic acid, which present a lower environmental impact. However, leaching kinetics may be limited, and the use of reducing agents, such as hydrogen peroxide, is commonly employed to enhance the process. This study aimed to recover lithium and manganese from button-type batteries (CR2032) using leaching with DL-malic acid combined with reducing agents. Preliminary tests with inorganic and organic acids indicated that malic acid achieved lithium extraction efficiencies close to 100%, while manganese showed good extraction efficiency, although still higher than those obtained with sulfiric acid, hydrochloric acid, propionic acid, and acetic acid. Following the preliminary tests, a central composite design was applied to evaluate the influence of malic acid concentration and the solid-to-liquid ratio. The highest efficiencies were obtained at lower solid-to-liquid ratios and intermediate acid concentrations. Subsequently, experiments were conducted using malic acid in combination with ascorbic acid and hydrogen peroxide as reducing agents. These experiments were carried out over 10 minutes at temperatures of 28, 40, 50, and 60 °C. The results demonstrated that malic acid alone showed low efficiency for manganese and high efficiency for lithium. The addition of ascorbic acid promoted moderate improvements, whereas the use of hydrogen peroxide resulted in a expressive synergistic effect, achieving extraction efficiencies of approximately 95% for Mn and 96% for Li in only 10 minutes, even at low temperatures (28 °C). Kinetic analysis revealed that, in the absence of hydrogen peroxide, manganese leaching is predominantly controlled by chemical reaction, with an activation energy of 62.7 kJ•mol⁻¹, while lithium exhibits a lower energy barrier (10.55 kJ•mol⁻¹). The addition of ascorbic acid reduces the activation energy of Mn, indicating a mixed control regime. In systems containing H₂O₂, low activation energy values were observed, characteristic of diffusion-controlled processes, highlighting a shift in the rate-limiting mechanism and enhanced manganese dissolution associated with the reduction of Mn(IV) to Mn(II). Therefore, the results demonstrate that the malic acid–H₂O₂ system presents high potential as an efficient and sustainable alternative for lithium-ion battery recycling, enabling high extraction efficiencies under mild operating conditions.

2026-05-29T00:00:00Z https://repositorio.ufu.br/handle/123456789/48774 2026-06-24T06:19:05Z 2026-02-13T00:00:00Z

Title: Explorando a produção de hidrogênio a partir da co-gaseificação de biomassa–plástico: um estudo integrado de simulação e aprendizado de máquina Abstract: Biomass–plastic co-gasification is a promising route for producing low-carbon syngas and hydrogen; however, its optimization is challenged by nonlinear interactions among temperature, equivalence ratio, and feed composition. In this work, an integrated approach combining steady-state thermochemical process modelling and machine learning was developed to predict and optimize the performance of biomass–plastic systems. A phenomenological model was implemented in the AVEVA PRO/II simulator, structured into drying, pyrolysis, gasification, and restricted chemical-equilibrium stages, using air as the gasifying agent. The model was validated against experimental literature data, reproducing the order of magnitude of the molar fractions of H₂, CO, CO₂, and CH₄ under different operating conditions. Based on this validated platform, a synthetic dataset of 3,000 simulations was generated via Latin Hypercube Sampling, covering five plastics (HDPE, PE, PP, PS, and PET), 35 lignocellulosic biomasses, and representative ranges of temperature and equivalence ratio. Extreme Gradient Boosting (XGBoost) models were then trained to predict syngas composition (H₂, CO, and CO₂), total gas yield, lower heating value, and the H₂/CO ratio. The split into training, validation, and test sets was assessed using distance-based metrics (1-NN, MMD, and Energy Distance), ensuring representativeness and generalization. The models achieved high performance, with out-of-sample coefficients of determination above 0.98. Interpretability was examined using explainable AI techniques based on SHAP values, indicating that temperature and equivalence ratio are key drivers of H₂ formation, whereas carbon and fixed carbon contents govern CO generation. The applicability domain was verified using Mahalanobis distance, ensuring prediction reliability. Finally, Differential Evolution optimization identified synergistic biomass–plastic pairs and operating conditions that maximize hydrogen production and syngas quality. The optimal solutions favored polypropylene-rich blends with lignocellulosic biomasses, yielding H₂ fractions of approximately 28%, H₂/CO ratios close to 1.1, and lower heating values around 6.5 MJ·Nm⁻³. The proposed approach integrates mechanistic modelling, explainable machine learning, and optimization, supporting the rational design of hydrogen-oriented co-gasification systems.

2026-02-13T00:00:00Z https://repositorio.ufu.br/handle/123456789/48325 2026-02-20T06:25:55Z 2026-02-13T00:00:00Z

Title: Formulação de fluidos de perfuração sintético leves empregando esferas ocas de vidro Abstract: Brazil is a leading oil and gas producer in Latin America, with vast reserves and a welldeveloped infrastructure. The advancement of offshore exploration in increasingly deep waters necessitates the development of drilling fluids with enhanced properties. These fluids must be capable of balancing the pressure differential between the hydrostatic column of seawater and the geological formation while minimizing environmental impact. With the gradual depletion of reservoirs at shallow and medium depths, drilling in ultradeep water has become crucial for continued production. However, these operations demand high-performance fluids that can withstand high pressures and temperatures, in addition to complex geological formations. In this context, hollow glass microspheres (HGMs) are being studied as promising additives for drilling fluids, enabling the viability of wells with narrow pressure windows. Due to their incompressibility, these microspheres allow for a reduction in fluid density without compromising their essential rheological properties. In this study, a Central Composite Design (CCD) was conducted to evaluate the influence of key variables—such as HGM concentration, viscosifier concentration, and oil-to-water ratio (%O/W)—on the properties of synthetic drilling fluid. The properties studied included L600, L300, L200, L100, L6, L3, fluid loss, and density. The filtration mechanism of an ultra lightweight, 6.2 ppg, 100% olefinic fluid containing HGMs was also investigated. The results demonstrated the viability of applying HGMs, highlighting their potential for formulating drilling fluids in geologically complex environments.

2026-02-13T00:00:00Z https://repositorio.ufu.br/handle/123456789/46103 2025-06-12T06:18:15Z 2025-02-27T00:00:00Z

Title: Produção de carbonato de cálcio provenientes de rejeitos de minério de Irecê: estudo experimental Abstract: The concern for sustainability and industrial waste management, combined with the environmental, social, and economic demands of the sector, motivated this study on the production of CaCO₃ from fertilizer industry waste. The main objective is to reutilize lime sludge, a waste generated during the phosphate ore concentration process, and carbon dioxide (CO₂), a byproduct of ore calcination, to produce calcium carbonate. The study was conducted through a series of carbonation experiments, investigating the influence of operational variables such as solid content, CO₂ concentration, and mixing speed on reaction time and carbonate mass formation. A central composite design (CCD) was employed to optimize process conditions. The results demonstrated that increasing the CO₂ concentration from 12.5% to 30% and the solid content from 1.0% to 1.8% enhanced reaction efficiency. The optimized conditions for maximizing product yield and minimizing reaction time were a solid content of 1.75%, a mixing speed of 390 rpm, and a CO₂ concentration of 28.5%, achieving a process time of 28 minutes and a CaCO₃ mass of 13.52 g. The study confirms the technical feasibility of reusing waste materials such as lime sludge and CO₂, contributing to the development of sustainable processes aligned with circular economy principles and providing an alternative for the fertilizer industry and related sectors. This work reinforces the potential of sustainable practices in the fertilizer industry, offering an efficient solution for waste management and environmental liability reduction.

2025-02-27T00:00:00Z