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Desenvolvimento de método para determinação de glicerol livre em biodiesel a partir da extração em barra de agitação revestida com celulose e quantificação por HPLC-DAD

Wed, 27 May 2026 00:00:00 GMT

Title: Desenvolvimento de método para determinação de glicerol livre em biodiesel a partir da extração em barra de agitação revestida com celulose e quantificação por HPLC-DAD Abstract: An analytical method based on stir-bar sorptive extraction (SBSE), using monolithic cellulose coated rods, coupled with high-performance liquid chromatography (HPLC), was developed for the determination of free glycerol in biodiesel. The sorbent phases were obtained by reprecipitation of cellulose acetate, followed by in situ deacetylation, resulting in a hierarchically porous structure with high surface area and high affinity for glycerol, mainly attributed to hydrogen bonding interactions between the hydroxyl groups of cellulose and the analyte. Structural characterization by FTIR, N2 adsorption/desorption isotherms, and BET/BJH analyses confirmed the efficient conversion of the precursor and the formation of a mesoporous structure suitable for adsorption and mass transfer processes. The extraction and desorption conditions in the SBSE technique were optimized using a multivariate design via the Doehlert Matrix. The extracts obtained were derivatized with benzoyl chloride, producing glyceryl tribenzoate, a species highly absorbent of UV radiation at 239 nm. Monolithic cellulose rods, 10 mm long, showed better analytical performance, with recoveries close to 100% and low variability in response during glycerol extraction. The maximum adsorption capacity was estimated at 63.0 μg g-1, consistent with the Langmuir model. The method was validated according to document SANTE 11312/2021.v2026, showing linearity between 0.00002 and 0.02000 % (w/w) (r = 0.9991), limits of detection and quantification of 7.8 × 10-6 and 2.4 × 10-5 % (w/w), respectively, as well as satisfactory precision (RSD < 7.5 %) and recovery rates between 94.7 and 113.9 %. The proposed method was successfully applied to the determination of free glycerol in biodiesels obtained from different raw material sources, with results in accordance with ASTM D6751 and EN 14214 standards. Compared to the official AOCS Ca 14 56 method, the proposed method showed greater analytical sensitivity and lower limits of detection. The sorbent bars demonstrated good stability after multiple reuse cycles, while the AGREEprep (0.77) and BAGI (75) metrics evidenced the reduced environmental impact of the methodology. Thus, the developed SBSE-HPLC method constitutes a simple, sensitive, selective, and environmentally sustainable alternative for the determination of free glycerol in biodiesel.

Tratamento de fase glicerina resultante de processos produtivos de biodiesel por neutralização em diferentes ácidos e adsorção em carvão ativado: ensaios comparativos

Mon, 01 Sep 2025 00:00:00 GMT

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.

Análise bibliométrica e roadmap tecnológico para a produção de hidrogênio verde a partir de fontes renováveis: uma perspectiva da simbiose industrial

Fri, 04 Jul 2025 00:00:00 GMT

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.

Caracterização e avaliação do potencial de uso dos resíduos da cafeicultura na produção de biocombustíveis sólidos

Fri, 18 Jul 2025 00:00:00 GMT

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.