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Item type: Item , Simulation and thermodynamic evaluation of woody biomass waste torrefaction(2025) Gonzales, Thiago da Silva; Silva, Simone Monteiro e; Lamas, Giulia Cruz; Rodrigues, Pedro Paulo de Oliveira; Siqueira, Mario Benjamim Baptista de; Follegatti Romero, Luis Alberto; Silveira, Edgar AmaralTorrefaction is a thermochemical pretreatment that enhances biomass properties, improving energy density, decomposition resistance, and hydrophobicity, making it a viable alternative as biofuel. This study performed a thermodynamic assessment of the torrefaction process for urban forest waste, integrating experimental data with two-step reaction kinetic modeling to evaluate the torrefaction product yields and properties using Aspen Plus software. The process was modeled with a yield reactor, employing the Peng−Robinson equation to describe vapor-phase behavior and empirical correlations to predict solid-phase properties. Simulations were validated against experimental data for temperatures between 225 and 275 °C, achieving an absolute deviation of less than 5%. Energy consumption ranged from 368 kJ·h−1 for light torrefaction to 1853 kJ·h−1 for severe torrefaction. Process irreversibility varied from 326 kJ·h−1 (3% exergy destruction) in light torrefaction to 3993 kJ·h−1 (16% exergy destruction) in severe torrefaction. The research provides a robust model for torrefaction scale-up that is adaptable to diverse biomass feedstocks and process conditions, highlighting its potential for optimizing energy use and improving sustainability in biomass utilization.Item type: Item , Statistical and multivariate evaluation of olive oil degradation during long-term storage(2025) Almeida, Erislene Silva de; Silva, Danyel Ferreira da; Oliveira, Natália Soares de; Fernandes, Juliana S.; Oliveira, Bruna Cecília de Sousa; Silva, Simone Monteiro e; Almeida, Fernanda Vasconcelos de; Braga, Jez Willian Batista; Dias, Ana Cristi BasileExtra virgin olive oil (EVOO) is valued for its flavor and health benefits. However, its quality can decline during storage, reducing food quality and the effectiveness of therapeutic compounds when used as a pharmaceutical excipient. While the oxidative stability of extra virgin olive oil has been widely studied for food quality and shelf life, its crucial role as a pharmaceutical excipient and the impact of long-term degradation on the effectiveness and stability of active compounds remain largely unexplored. This study examined 14 commercial EVOO samples immediately after opening and after three years of storage. Standard methods were used to measure the peroxide value, p-anisidine value, acidity, antioxidant activity, and extinction coefficients. The data were analyzed with statistical and chemometric tools. Initially, all oils met international quality standards. After three years, most samples showed significant deterioration, especially a decline in antioxidant activity and an increase in K232 values. Statistical tests confirmed differences among samples, and pairwise comparisons indicated significant differences consistent with degradation between T0 and T1. Principal component analysis (PCA) identified three main patterns related to oxidation and antioxidant capacity, and clustering distinguished between stable and unstable samples. Overall, the stability of the studied EVOOs varied by brand, influenced by their natural composition and storage conditions. Multivariate analysis confirmed that antioxidant activity and extinction coefficients are key indicators of oxidative degradation. This finding highlights multivariate analysis as a valuable approach for monitoring the oxidative stability of oils and ensuring EVOO quality for both food and pharmaceutical application.Item type: Item , Multiparameter optimization of torrefaction for achieving carbon-negative biocoal: integrating quality parameters, thermodynamics, and environmental performance(2025) Lamas, Giulia Cruz; Gonzales, Thiago da Silva; Rodrigues, Pedro Paulo de Oliveira; Macedo, Lucélia Alves de; Rodrigues, Thiago Oliveira; Rousset, Patrick Louis Albert; Protásio, Thiago de Paula; Pires, Armando de Azevedo Caldeira; Silveira, Edgar AmaralThis study advances the torrefaction field by proposing a framework that integrates energy, exergy, and environmental analyses with the quality assessment of torrefaction products, while evaluating process carbon neutrality and carbon-negative outcomes. While biocoal properties are often emphasized, multi-objective analyses addressing critical aspects such as exergy efficiency and life cycle assessment are frequently overlooked. This research critically addresses inconsistencies in life cycle assessment related to functional units, system boundaries, and impact allocation of products, fostering a consistent and robust environmental diagnostic. Experimental data from urban forest waste torrefaction, combined with a two-step kinetic modeling, enabled the simulation of a scaled-up system using Aspen Plus. This integrative approach assessed the properties of biocoal, bio-oil, and torgas, as well as mass and energy flows, irreversibilities, and process emissions. Life cycle assessment quantified and allocated environmental impacts. The framework accounted for CO2 uptake by biomass, revealing trade-offs arising from the severity of torrefaction and the definition of the functional unit. Response surface methodology served as a unifying optimization tool, allowing the simultaneous integration and evaluation of all indicators. Results identified bottlenecks, formulated an equation to evaluate carbon neutrality and determined optimal conditions, offering a scalable and replicable pathway for sustainable torrefaction. Optimal conditions at 256 °C for 41 min yielded biocoal with 87.82 % mass retention, a heating value of 20.98 MJ kg−1, a fuel ratio of 0.34, and an ash content of 4.98 %. The system required 20.99 kWh for drying and 4.04 kWh for torrefaction, with the irreversibility of 81.5 MJ h−1 and a global warming potential of –0.504 kg CO2 eq. per GJ of biocoal.Item type: Item , Kinetic parameter sensitivity in microbial electrolysis cell performance modeling(2026) Demarqui, Gabriela Simonete; Felizardo, Marcos Paulo; Tussolini, Loyse; Andrade, Laiane Alves de; Miranda, Júlio César de CarvalhoMicrobial Electrolysis Cells (MEC) represent a promising technology for hydrogen production from wastewater, requiring low applied voltages compared to conventional water electrolysis. However, system performance remains limited due to complex microbial interactions, making mathematical modeling essential for process optimization. This work replicates and analyzes the multi-population dynamic model proposed by Pinto et al. (2011), focusing on sensitivity analysis of maximum substrate consumption rates (qmax) for electrogenic, fermentative, and acetoclastic methanogenic microorganisms. Fifteen simulations were conducted, varying each parameter within its respective uncertainty intervals, and sensitivity was quantified using normalized indices. Results revealed a clear hierarchical importance: qmax,e (electrogenic) showed the highest impact with sensitivity indices (Smean) ranging from 3.8 to 6.2 for competitive microbial populations; qmax,f (fermentative) demonstrated transient influence primarily during reactor startup (Smean ranging from 0.65 to 0.78); while qmax,m (methanogenic) affected only anodic methane production (Smean of approximately 0.96). Notably, electrochemical performance variables (current, H2 production) proved robust to all three parameters at steady state, indicating that once the electrogenic biofilm is established, the system exhibits significant operational stability. These findings provide practical guidance for MEC design and operation, identifying qmax,e as the critical parameter requiring precise estimation for accurate prediction of microbial competition dynamics.Item type: Item , Activated carbon-supported Pt catalysts intended for the hydroprocessing of lipid feedstocks: effects of support surface composition and impregnation protocol(2025) Brandão, Ruana Domingos; Freitas Júnior, Antônio Martins de; Linares León, José Joaquín; Suarez, Paulo Anselmo Ziani; Dutra, Romulo Coriolano; Garnier, Jeremie; Tonhá, Myller de Sousa; Ballesteros Plata, Daniel; Rodríguez Castellón, Enrique; Prauchner, Marcos JulianoThis work concerns the preparation of Pt/AC catalysts (Pt supported on activated carbon) and their application to the synthesis of hydrocarbon biofuels through the HEFA (hydroprocessing of esters and fatty acids) route. The key motivation for the work was that catalysts based on sulfided Mo supported on γ-Al2O3, traditionally employed in the hydroprocessing of petroleum derivatives, (i) are unstable in the HDO (hydrodeoxygenation) of biomass-derived feedstocks and (ii) can contaminate the resulting biofuels with sulfur. In this context, a systematic study on the effects of preparation conditions on the properties of the resulting Pt/AC catalysts and their performance in HEFA was carried out for the first time. Efficient catalysts were obtained, which led to the complete deoxygenation of lauric acid and coconut oil, yielding products composed primarily of n-alkanes. The highest HDO activity was verified for the catalyst prepared using as a support an AC previously subjected to thermal treatment up to 800 ◦C in a H2 atmosphere (which removed most of the surface acidic oxygenated groups), depositing Pt over the surface of this support via wet impregnation using a H2PtCl6 solution acidified with HCl. The obtained results showed the great potential of the Pt/AC catalysts for the production of hydrocarbon biofuels through the HEFA route.