https://repositorio.ufpb.br/jspui/handle/tede/7029 PPGQ 2026-09-19T16:16:59Z https://repositorio.ufpb.br/jspui/handle/123456789/38902 Título: Uso de solventes eutéticos profundos ternários na extração de cafeína a partir da borra do café Autor(es): Santos, Aline Mendes Gomes dos Orientador: Pontes, Liliana de Fátima Bezerra Lira de Abstract: The growing global demand for coffee results in massive production of coffee waste, primarily in the form of used coffee grounds. This residue, despite being a potentially rich source of bioactive compounds, is often discarded without efficient utilization. Among the bioactive compounds present in used coffee grounds, caffeine stands out due to its stimulating properties and its various applications in the food, pharmaceutical, and cosmetic industries. This study aimed to investigate the use of ternary deep eutectic solvents in the extraction of caffeine from coffee grounds. For this purpose, two eutectic solvents were synthesized using choline chloride as a hydrogen bond acceptor and citric acid, lactic acid, and glucose as hydrogen bond donors. A 22 experimental design was applied to evaluate the influence of temperature and time variables on the caffeine extraction process. Caffeine extraction from used coffee grounds (Coffea arabica) was performed using 0,1 g of grounds and 3 mL of solvent with 10% water addition. All extractions were conducted in a heated bath with vortex assistance. The experimental design showed that temperature had the greatest influence on caffeine extraction, resulting in higher caffeine concentrations (42,90 mg g⁻¹) in the experiment conducted at 85°C for 45 minutes. Overall, caffeine extraction with ternary Deep Eutectic Solvents proved to be an efficient alternative with good recovery rates. The deep eutectic solvent composed of choline chloride, citric acid, and lactic acid demonstrated the highest extraction capacity due to the larger number of hydroxyl sites in its chemical structure, making it an excellent caffeine extraction solvent. However, further research is needed to investigate caffeine degradation processes at higher temperatures. Editor: Universidade Federal da Paraíba Tipo: Dissertação 2025-05-13T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38861 Título: Determinação de HPAS em cachaça e açúcar utilizando membranas de náilon, espectroscopia de fluorescência e PARAFAC Autor(es): Sousa, Larissa Ferreira de Orientador: Fragoso, Wallace Duarte Abstract: Polycyclic aromatic hydrocarbons (PAHs) are formed from the incomplete combustion of organic matter, being classified as persistent organic pollutants, with some recognized as carcinogenic. In the context of sugarcane, the practice of burning for agricultural management or energy production can generate PAHs, which contaminate derived products such as cachaça and sugar. These products are widely consumed in Brazil, highlighting the importance of monitoring PAHs in these matrices. Chromatography is the reference technique for determining these contaminants; however, it is costly and requires a significant amount of analysis time. In this study, alternative approaches based on fluorescence spectroscopy using nylon membranes combined with second-order calibration (PARAFAC) were evaluated for the determination of PAHs. Two preconcentration systems were employed: (i) positive-pressure filtration using a filter holder, applied to cachaça samples, and (ii) rotating-disk sorptive extraction (RDSE), applied to sugar samples. The PAHs studied were benzo[a]pyrene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[g,h,i]perylene, and dibenzo[a,h]anthracene. For sugar samples, the RDSE system exhibited problems caused by the presence of sucrose, which hindered the achievement of satisfactory results. In addition to the high viscosity of sugar solutions, sucrose impregnated the membrane, leading to fluorescence suppression, thereby evidencing a strong matrix effect. Reflectance and fluorescence spectra of sugar samples were presented in this study to demonstrate this effect. The filtration system for cachaça proved quantitative and effective for detecting PAHs in the range of 24 to 225 ng L⁻¹. The method yielded apparent recoveries between 91% and 105%. RMSEP values ranged from 11 to 17 ng L⁻¹, while limits of detection were between 16 and 27 ng L⁻¹, demonstrating good sensitivity associated with low method errors. Editor: Universidade Federal da Paraíba Tipo: Dissertação 2025-10-24T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38815 Título: Produção de biocarvão a partir de ligninas residuais de biomassas pelo processo de pirólise Autor(es): Almeida, Thiago Claudino Mendes de Orientador: Santos, Nataly Albuquerque dos Abstract: Lignin is the most structurally complex component present in lignocellulosic biomass. Each year, thousands of tons of lignin-rich residues from enzymatic hydrolysis may be generated in a sugarcane cellulosic ethanol bioreûnery. The present study uses lignin extracted from sugarcane bagasse as a feedstock for biochar production, as an alternative to the direct use of raw bagasse. In addition, lignin is also present in the mesocarp of coconut, a residue that is often improperly disposed of. Therefore, the production of biochar from this lignin via pyrolysis, as well as the potential applications of the resulting material, were investigated. The lignin samples derived from sugarcane bagasse and coconut ûbers, as well as their corresponding biochars, were characterized and systematically compared with commercial kraft lignin and its biochar through elemental analysis, higher heating value determination, spectroscopic techniques, thermal analyses, X-ray diûraction, and scanning electron microscopy coupled with energy-dispersive spectroscopy. The results indicated higher efficiency in the lignin extraction process from sugarcane bagasse and further confirmed the amorphous nature of both the extracted lignin and the derived biochar. An O/C ratio of approximately 0,3 was obtained for the sugarcane bagasse lignin biochar based on both elemental and Raman spectroscopy analyses. Both elemental composition assessment and Raman spectroscopic analysis indicated that all biochar specimens exhibited hydrogen-to-carbon (H/C) ratios exceeding 0,5, however, the O/C and H/C ratios in the sugarcane bagasse lignin biochar indicated the occurrence of partially oxidized carbon, with a significant portion of fixed carbon, in a biochar with moderate stability and low levels of contamination. Analyses of the effect of an intermediate pyrolysis temperature on a recalcitrant material such as lignin indicated that the biochar derived from sugarcane lignin exhibited higher energy density, in the value of 25,95 MJ/kg, and a high carbon content, in the value of 61,64%. The proposed approach, therefore, provides promising alternatives for the valorization of lignin waste and the generation of biochar for both energy applications and as a multifunctional material, combining high energy density with structural stability, which significantly expands its industrial application potential. Editor: Universidade Federal da Paraíba Tipo: Tese 2025-12-11T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38765 Título: Síntese de mono e diésteres, cetoésteres e 2-selenoacetanilidas derivados de ftalimida: atividade antimicrobiana, sinergismo, mecanismo de ação e ecotoxicidade Autor(es): Alves, Francinara da Silva Orientador: Athayde Filho, Petrônio Filgueiras de Abstract: Phthalimide stands out as a promising block in the synthesis of new drug candidates. Its results show several pharmacological activities, including antimicrobial, antitumor, antiinflammatory, among others. Thus, this study describes the description of four families of compounds, including potassium phthalimide (3a-e) and potassium phthaloylglycinate (4a-e), which were produced from 4-chlorobutyl benzoate precursors. Potassium phthaloylglycinate derivatives with 4-substituted 2-bromoacetophenones (6f-j) and phthaloylglycine derivatives with 2-selenoacetanilide (9k-n), in addition to phthaloylglycine monoesters (11o-u) and tetrachlorophthaloylglycine (12o-u) were also used to evaluate the impact of electrode and electrowithdrawing groups, as well as hydrocarbon spacers, on the antimicrobial properties. In total, thirty-three final compounds were synthesized, eighteen of which were new, using simplified synthetic routes and a reduced number of steps. The compounds were subjected to in vitro antimicrobial evaluation, where compounds 3a-c and 4a-d showed activity against the three bacterial strains and the four yeast strains with values ranging from 128 to 1024 μg mL-1. Compound 3b (monoester with 4-methyl substitute) derived from potassium phthalimide, showed protection against all strains of bacteria and yeasts tested, with MIC = 128 μg mL-1, lower than the standard drug for fungi (fluconazole). Thus, compound 3b was investigated in order to know its mechanism of action, where it associated with ergosterol led to an increase in MIC from 128 to 1024 μg mL-1. Compound 3b was also tested in association with chloramphenicol for the strain of Peseudomonas aeruginosa with the ICIF value = 0.5 μg mL-1 decreasing the synergism. Compound 9k (2-selenoacetanilide with phthaloylglycine) showed very significant activity against strains of Candida gattii and Aspergillus niger with MIC = 2.5 and 10 μg mL-1, respectively, and MIC of 80 and 40 μg mL-1 for Klebsiella pneumoniae and Salmonella typhimurium, respectively. Compounds 11r, 12p, 12s and 12t showed activity against strains of bacteria and fungi with MIC value = 512 and 1024 μg mL-1, where, with the increase of the carbonic extension, the impact increased. The selenide compound was obtained with sufficient crystallization quality to be diffracted and a crystallographic study was carried out, where it presented a monoclinic system. An in silico study was conducted with the most promising compounds, all of which met the Lipinski criteria, indicating good oral bioavailability in a possible application, in addition to showing low toxicity. Thus, the most promising compounds (3b, 3c, 4a and 4c) were evaluated for toxicity on Artemia salina, being classified as moderately toxic and non-toxic. Editor: Universidade Federal da Paraíba Tipo: Tese 2025-02-06T00:00:00Z