https://repositorio.ufu.br/handle/123456789/18929 2026-04-08T06:39:56Z https://repositorio.ufu.br/handle/123456789/47293 Title: Tratamento de fase glicerina resultante de processos produtivos de biodiesel por neutralização em diferentes ácidos e adsorção em carvão ativado: ensaios comparativos Abstract: Since 2004, Brazil has been adding biodiesel to fossil diesel, and by 2025 the mandatory content will be 15%. Legislation and technical tests have enabled the gradual increase of this blend. Biodiesel production generates the glycerin phase (a mixture rich in glycerol) as a byproduct, requiring commercial solutions for its utilization. Glycerol is a compound widely used in various production processes to obtain various derived products, with broad applications and uses throughout society. It can be used as a raw material in numerous industrial sectors, including the production of cosmetics, food, beverages, medicines, paper, and others. This paper presents the results of the treatment of the glycerin phase from production processes to obtain biodiesel and glycerol. Treatments were performed with silica, activated carbon (to remove moisture and adsorb impurities related to phase color), and reactions with HCl, H2SO4, C6H8O7 (citric acid), and C2H2O4 (acetic acid). The results were analyzed by oxidation/reduction volumetry (titration/back titration) with (i) potassium permanganate (KMnO4)/sodium oxalate (Na2C2O4) and (ii) potassium dichromate (K2Cr2O7)/ammoniacal iron (II) sulfate (Fe(NH4)2(SO4)2.6H2O); infrared absorption spectroscopy (FTIR) and thermogravimetric analysis (TGA). The data obtained were statistically treated by T-tests and F-tests. The treatment of the glycerin phase with acid resulted in spontaneous separation with formation of new phases with concentrated glycerol, being verified by (i) and (ii) in proportions, according to the use of acids (% phase with glycerol/acid used in the treatment): for (i) 52.27%/C6H8O7, 57.35%/C2H4O2, 67%/H2SO4 and 70.42%/HCl; and for (ii) 45.64%/C6H8O7, 52%/C2H4O2, 57.45%/H2SO4 and 65.16%/HCl. There was a better yield in the final glycerol content using the HCl treatment of 93.41%, according to data obtained in TGA. According to the results obtained by FTIR, the spectra revealed typical alcohol bands, such as O-H, C-H and C-O, confirming the presence of glycerol; primary and secondary group stretching bands (C-O) identified, characteristic of propane-1,2,3-triol. The results were considered satisfactory. 2025-09-01T00:00:00Z https://repositorio.ufu.br/handle/123456789/47014 Title: Análise bibliométrica e roadmap tecnológico para a produção de hidrogênio verde a partir de fontes renováveis: uma perspectiva da simbiose industrial Abstract: The growing dependence on fossil fuels has intensified greenhouse gas (GHG) emissions, exacerbating environmental impacts and driving the search for sustainable energy solutions. In this context, green hydrogen (GH), produced from renewable sources, has emerged as a promising alternative for the decarbonization of industrial and transportation sectors. However, its large-scale implementation still faces technical, economic, and structural barriers. Industrial symbiosis (IS) has emerged as a strategic approach to address some of these challenges by enabling waste utilization, integration between production processes, and optimization of energy resources. This study aimed to conduct a bibliometric analysis of the convergence between IS and GH production, complemented by the development of a technological roadmap indicating strategic directions for the development of this production chain based on sustainable sources. The methodology involved a review of scientific publications indexed in the Scopus database, applying selection criteria to ensure the relevance and timeliness of the analyzed documents. Indicators such as the number of publications over time, co-authorship networks, geographical distribution of authors, and frequency of keywords were examined. The results revealed a steady growth in academic interest in the subject, although direct interactions between GH and IS remain in their early stages. China led scientific production during the analyzed period, followed by European countries and India, reflecting global engagement in the pursuit of clean and innovative energy solutions. The second stage of the study involved the construction of a technological roadmap focused on GH production with an emphasis on IS applications. This tool made it possible to map technological challenges, identify innovation opportunities, and outline potential synergies among industrial sectors, considering different time horizons: short, medium, and long term.This approach contributed to the definition of strategic pathways aimed at the efficient and environmentally responsible industrial implementation of GH. The integration of bibliometric findings with the technological roadmap reinforced the importance of structured public policies, targeted investments, and cross-sector partnerships to accelerate the consolidation of GH as an energy vector. The results also highlighted the need to foster collaborative research networks and interdisciplinary approaches capable of enhancing the technological and operational maturity of the field. 2025-07-04T00:00:00Z https://repositorio.ufu.br/handle/123456789/46454 Title: Caracterização e avaliação do potencial de uso dos resíduos da cafeicultura na produção de biocombustíveis sólidos Abstract: Coffee is a highly prominent crop in Brazilian agribusiness, with Brazil being the world’s largest producer since the 19th century and the state of Minas Gerais accounting for about one-third of the country’s coffee production. This large-scale coffee production, which is expected to continue growing to meet market demands, results in significant waste generation. Considering that for every 1 kilogram of processed coffee, 1 kilogram of coffee husks and 0.3 kilograms of parchment are produced, it is clear how improper disposal of these byproducts could harm the environment. Aligning with concerns about waste management, there is a growing need to expand energy production methods, particularly those that generate renewable and clean energy, to meet energy market demands while reducing greenhouse gas emissions and dependence on fossil fuels. Combining these two perspectives, the abundance of coffee farming residues and the demand for sustainable energy, this study focuses on transforming coffee husks and parchment into pellets through compaction. Pellets are a solid biofuel option with versatile applications. To ensure quality, the biomass was analyzed for elemental and structural composition, calorific value, and thermogravimetric properties, while the pellets underwent tests for moisture, density, and durability, complying with current standards. The results demonstrate that coffee husks and parchment have significant potential as raw materials for pellet production. Parchment pellets exhibited superior qualities and required no additional processing to meet regulatory standards, whereas coffee husk pellets needed extended post-production drying. Thus, both types of pellets can be considered viable renewable energy sources and a sustainable solution for coffee farming waste disposal. 2025-07-18T00:00:00Z https://repositorio.ufu.br/handle/123456789/46443 Title: Efeito do pré-tratamento com hidróxido de amônio na sacarificação de bagaço de cana-de-açúcar e sabugo de milho e produção de etanol 2G Abstract: The pretreatment of lignocellulosic biomass is a fundamental step in the production of second- generation (2G) ethanol. In this study, sugarcane bagasse (SBC) and corn cobs (CC) were pretreated with 28–30% ammonium hydroxide (NH₄OH) to break down the biomass for subsequent saccharification and alcoholic fermentation. The pretreatment promoted high delignification, reaching 65.50% for SBC and 73.50% for CC, with preservation of the polysaccharide fraction. The pretreated solid fractions were subjected to enzymatic hydrolysis with different substrate loads (10 to 30%), using 12.5 FPU/g of cellulose from the commercial Cellic CTec3 cocktail. Batch hydrolysis fed with 30% biomass resulted in higher concentrations of total reducing sugars (TRS) compared to the conventional batch process (10%), reaching 65.15 g/L in pretreated bagasse (SBCT) and 70.18 g/L in pretreated cob (CCT). In addition, low concentrations of acids and inhibitors were detected in the hydrolysates, demonstrating the effectiveness of this pretreatment. The hydrolysates obtained in the fed-batch process had high levels of fermentable sugars, containing 43.75 g/L of glucose and 18.12 g/L of xylose in SBCT, and 41.63 g/L of glucose and 18.75 g/L of xylose in CCT, respectively. After fermentation, the highest ethanol yields were obtained with the ST hydrolysate, with 19.20 g/L (Yp/s of 0.49 and Qp of 0.87), using Saccharomyces cerevisiae Y904, and 26.34 g/L with the pentose-fermenting yeast. Spathaspora passalidarum Y7204 (Yp/s of 0.44 and Qp of 0.73). Although the co- cultures showed promising results, aspects such as metabolic synergism, competition for substrates, and catabolic repression by glucose still require investigation. These results demonstrate the efficiency of pretreatment with NH₄OH as a low-cost method with low inhibitor formation, highlighting the potential of pretreated hydrolysates for 2G ethanol production. 2025-07-16T00:00:00Z