https://repositorio.ufpb.br/jspui/handle/123456789/11874 PPGEQ 2026-07-15T05:38:27Z https://repositorio.ufpb.br/jspui/handle/123456789/38277 Título: Estudo cinético da pirólise do caroço de açaí (Euterpe Oleracea Mart.) uma primeira fase para obtenção de bio-óleo Autor(es): Silva, Daniel Arnóbio Dantas da Orientador: Silva, Giovanilton Ferreira da Abstract: The kinetic study of the pyrolysis reaction is characterized as a primordial step, since the knowledge of parameters such as activation energy (Eaα), pre-exponential factor (Aα) and reaction model (f(α)), allow us to glimpse the feasibility of the process, as well as the energy demand, and its dimensioning on an industrial scale. Therefore, the objective was to evaluate the potential of the process of fast pyrolysis of the açaí seed, the main residue of the açaí industry, for the production of bio-oil, through a kinetic study, and physical-chemical characterization by immediate analysis, thermogravimetry (TG ) and Fourier transform infrared spectroscopy (FTIR).The determination of the kinetic parameters of the reaction was carried out by applying the isoconversional methods of Friedman (FR), Ozawa-Flynn-Wall (OFW), and Kissinger-Akahira-Sunose (KAS) to thermogravimetric data obtained in five different heating ratios (2, 5, 20, 50, 75 and 100 oC.min-1 ) and N2 fluxes varying in 25, 50 and 75 mL.min- 1. It was possible to verify that, in relation to the chemical composition of the studied biomass, it can be said that it has promising characteristics if it is directed to the production of bio-oil, such as low moisture content (9.30%), high content of volatile material (83.5%) and low amount of ash (1.75%). The study of the thermal decomposition of the açaí seed in an inert atmosphere showed three characteristic regions of mass loss defined as drying, fast pyrolysis and slow pyrolysis, where it was possible to observe, respectively, mass losses for such regions of 11.91 ± 0.2 %, 77.71 ± 1.97 % and 9.01 ± 1.40%. The analysis of the variation of activation energy as a function of the conversion in N2 flux of 50 mL.min-1 , allowed to distinguish Eaα results for hemicellulose and cellulose in agreement with results reported in the literature. For the region of variation attributed to hemicellulose, the Eaα values were 177.00 ± 14.09 kJ.mol-1 , 167.32 ± 14.02 kJ.mol-1 and 166.30 ± 14.60 kJ.mol-1 , using the FR, FWO and KAS methods, respectively. For the variation zone attributed to the thermal decomposition of cellulose, the values obtained were 189.83 ± 6.67 kJ.mol-1 , 184.79 ± 10,12 kJ.mol-1 , and 184.29 ± 10.46 kJ.mol-1 , using the FR, FWO and KAS methods, respectively. In addition, the study of the influence of the flow of N2 submitted to the sample indicated that the reactivity of the constituents is modified, being observed the reduction of the value of the apparent activation energy with the increase of the flow of N2 25 mL.min-1 to 75 mL.min-1 , for all isoconversional methods applied. The results obtained showed that the açaí seed stands out as a promising biomass, where the kinetic parameters obtained are evidenced as important information for the advancement in the evaluation of the viability of the fast pyrolysis route to produce aviation biokerosene. Editor: Universidade Federal da Paraíba Tipo: Dissertação 2022-02-23T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38273 Título: Potencialidades biotecnológicas de consórcio de microalgas cultivadas em efluente de biodigestor Autor(es): Costa, Maria Helena Juvito da Orientador: Santos, Sharline Florentino de Melo Abstract: Microalgae are photosynthetic microorganisms found in aquatic (fresh and marine) and terrestrial environments, known for their ability to synthesize a variety of bioactives that arouse interest in their exploitation. The residues generated in agro-industrial processes have high levels of C, N, P and some toxic components that require a treatment step before their disposal in order to avoid compromising ecosystems. Microalgae have the ability to act as bioremediation agents of these residues, in addition, the biomass generated at the end of the process can be destined for some biotechnological application. The present study aimed to carry out a systematic review of the literature on the main occurrences and applications of microalgae consortia; as well as to investigate the potential of the intercropped biomass of microalgae cultivated in different alternative media, the remediation potential of the consortium in the alternative medium and the biochemical composition of the biomass produced, for this we sought to carry out the cultivation of two types of consortium (C5 and C10): five (Monoraphidium litorale, Ankistrodesmus densus, Scenedesmus quadricauda, Pediastrum tetras e Scenedesmus quadricauda) and ten strains of microalgae (Monoraphidium littorale, Chlamydomonas sp., Ankistrodesmus densus, Scenedesmus quadricauda, Pediastrum tetras, Neochloris pseudoestigmata, Scenedesmus communis, Coelastrum microporum, Scenedesmus quadricauda e Pandorina cf morum) all from the microalgae culture bank of LARBIM/UFPB. The cultures were developed in synthetic (WC) and alternative media: poultry biofertilizer (BA), swine biofertilizer (BS) and poultry+swine biofertilizer (BSA) in three different dilutions (1%, 2% and 4%). all in triplicate under controlled conditions of light and temperature, with a photoperiod of 12 hours. Culture development was monitored by in vivo fluorescence within 48 hours for a period of 15 days. The results of the systematic review reveal that studies on microalgae consortium have gained prominence in recent years. The role of consortia in the treatment of effluents and the improvement of microalgal biomass in the quantification of bioactives of interest was highlighted as a recurring theme in the literature. The CBA 4% medium was considered the best medium for the development of the 713.3 mg/L (Consortium of 10 strains - CE10) and 666.7 g/mL (Consortium of 5 strains - CE5) consortia. Removal rates were determined for the selected medium, the biochemical compositions and the profile of fatty acid methyl esters. CE5 was more efficient in removing ammonia (91.6%) and phosphorus (39.45%). The consortia in alternative medium showed high levels of protein (41.08 – 58.23 g/100g). For carbohydrates, the maximum values obtained were for CE5 (16.35 ± 1.57 g/100g) and CS5 (12.73 ± 0.86 g/100g). The fatty acid profiles showed high levels of α-linolenic acid in the alternative media while for oleic acid the predominance was for the consortia in synthetic media. Thermal stability was evaluated for the consortium of five strains (C5) in relation to strains grown in monocultures. The thermal curves showed three events showing that the bioactive compounds start the degradation process at a temperature higher than 185 °C. The results demonstrated the viability of the consortium being cultivated in an alternative medium associated with the production of compounds in the obtained biomass. Editor: Universidade Federal da Paraíba Tipo: Dissertação 2021-12-13T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/37361 Título: Obtenção da levedura Saccharomyces cerevisiae em pó pelo método da secagem em camada de espuma Autor(es): Melo, Geniellen Maria Paiva Costa de Orientador: Cavalcante, Josilene de Assis Abstract: The yeast Saccharomyces cerevisiae is an importantraw material in the food and beverageindustry, generating large amounts of residual biomass. In order to add value to this residue, this study proposes the use of the foam layer drying technique to produce yeast powder from biomass discarded from the fermentation of cachaça. This technique employs thickening and stabilizing agents to form a stable foam that resists dehydration under increasing temperature. The study also aims to evaluate the physicochemical characteristics of the yeast powder obtained by this technique. The foam production followed a 2³ +3 centrais points factorial experimental design that evaluated the influence of biomass dilution, foaming agent concentration (Porto gel) and agitation time on the physical characterization of the foam. The results indicated that the optimal combination to obtain a stable and high-quality foam is: ½ dilution, 20% foaming agent concentration and agitation time of 16 minutes. Under these conditions, the foam showed excellent properties, including air entrainment of 283%, density of 0.232 g/cm³ and excellent stability, with no collapse after 2 hours. Furthermore, an inverse relationship was observed between foam density and air entrainment, suggesting that lighter and more porous foams tend to be more stable. For powder production, since dilution is a crucial factor in foam production, a new 22 + 2 centrais points factorial experimental design was designed, setting the maximum dilution at 1:2 and the agitation time at 16 minutes, with the foaming agent concentration and drying temperature as inputs variables and the drying time and final moisture content as response variables. The experiments performed showed that temperature is the main factor influencing the drying kinetics of Saccharomyces cerevisiae yeast powder. Comprehensive physical-chemical tests were performed to characterize the powder obtained after drying, including analyses of moisture, soluble solids, water activity, pH, ash content, lipids, proteins, carbohydrates, granulometry and process yield. The results showed that the material presented low moisture content of 7.06% and water activity of 0.195 at a temperature of 45ºC, indicating stability for prolonged storage, average content of 13% proteins, 12% lipids and 38% carbohydrates suggesting potential as a nutritional supplement for animals and high ash content (20%), indicating the presence of mineral salts and vitamins essential for animal diet. The granulometric analysis classified the yeast powder as ultrafine. The results achieved define a new paradigm for the use of yeast biomass in drying processes and create promising perspectives for applications such as animals nutritional supplementation. Editor: Universidade Federal da Paraíba Tipo: Dissertação 2025-02-26T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/37161 Título: Avaliação da formação de etringita por modelagem termodinâmica do sistema CAO–Al₂O₃–CaSO₄–NaCl em ambiente com CO₂ Autor(es): Texeira, Alan Henrique Orientador: Rojas, Leopoldo Oswaldo Alcázar Abstract: Portland cement is the primary material used in civil construction, accounting for approximately 90% of buildings worldwide. During hydration, clinquer forms phases such as C-S-H, portlandite, and ettringite, which are essential for the mechanical development of concrete. Ettringite plays a dual role: when formed in a controlled manner at early ages, it enhances initial strength and microstructural densification; however, its delayed or excessive formation—especially in environments with high humidity, extreme temperatures, or the presence of ions such as carbonate and chloride—can lead to expansion, cracking, and premature deterioration. This study investigates, through thermodynamic modeling using the GEMS software, the factors that govern the formation and stability of ettringite, with emphasis on the effects of minor compounds such as carbonates and chlorides. The simulations are based on Gibbs free energy minimization, enabling the prediction of stable solid phases and dissolved species. Results indicated that the highest ettringite formation (~41 g) occurs at the 2:5:4 mass ratio of the CaO–Al₂O₃–CaSO₄ system. The addition of CO₂ promotes the dissolution of carbonate species and shifts the pH toward favorable conditions for ettringite formation, although with no significant increase in its quantity. The approach based on Taylor’s (1997) stability criteria demonstrated the robustness of the model, revealing the influence of salts on the formation of new phases and on the reduction of ettringite. These findings reinforce the potential of thermodynamic modeling as a predictive and strategic tool for optimizing performance and durability in cementitious systems. Editor: Universidade Federal da Paraíba Tipo: Dissertação 2025-07-30T00:00:00Z