https://ri.ufs.br/jspui/handle/riufs/8143 2026-09-14T06:33:14Z https://ri.ufs.br/jspui/handle/riufs/26085 Título: Investigação teórica de complexos luminescentes de eu3+: elucidação dos mecanismos de transferência de energia e desenvolvimento de um protocolo computacional para predição do rendimento quântico Autor(es): Rodrigues, Jocelia Silva Machado Abstract: This work aimed to theoretically investigate the luminescent propertiesof Eu3+complexes containing β-diketonate ligands, focusing on understandingtheenergytransfer and backtransfer mechanisms responsible for the luminescent efficiencyofthese systems. Using semi-empirical methodologies, four complexes withpotential technological applications were studied: [Eu(tta)3(5,5’-dmbpy)] and [Eu(btfa)3(5,5’-dmbpy)], applied in the construction of OLED devices, and [Eu(tta)3(δ-val)(H2O)] and[Eu(btfa)3(δ-val)(H2O)], investigated as luminescent markers for gunshot residue.The theoretical investigation of these systems was necessary to understand, at themicroscopic scale, the photophysical processes that govern the luminescentperformance of the complexes, allowing them to be correlated withtheoptical properties observed experimentally. The theoretical results obtained agreedwell withthe experimental data provided by collaborators, demonstrating that thecalculatedproperties consistently describe the luminescent behavior of the studiedcompoundsand explain their efficiency in different technological applications. Inadditiontophotophysical studies, this thesis also involved the development of anewcomputational protocol for predicting the quantum yield in Eu 3+ complexes. Themodel was parameterized and validated using experimental quantumyield dataavailableinthe literature for a library composed of 17 Eu 3+ complexes. The results demonstratedhigh accuracy in reproducing the experimental quantum yields, presentingameanabsolute error of around 10%, a value significantly lower than those observedfortheanalytical models traditionally employed in the literature, whose mean errorsrangedbetween approximately 20% and 55%. Thus, this work contributes to theelucidationof the photophysical mechanisms of Eu 3+ complexes and presentsanewcomputational methodology for the precise prediction of quantumyield. 2026-07-27T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/25394 Título: Remoção de poluentes emergentes por adsorventes desenvolvidos a partir de resíduo sólido de estação de tratamento de água Autor(es): Fernandes, Erica Porto Abstract: The increasing presence of pharmaceutical compounds in aquatic environments has caused significant environmental impacts. Conventional treatment methods face challenges at the industrial scale, while abundant and low-cost adsorbents, such as industrial process residues, offer a sustainable alternative for the removal of pharmaceuticals. In this study, adsorbent materials were developed from sludge generated by the water treatment system of a thermoelectric power plant. Adsorption studies were carried out using unmodified sludge (RPL), chemically modified sludge with dodecyl trimethylammonium chloride (RMQ), and thermally modified sludge (RMT). The materials were applied for the removal of ibuprofen, diclofenac, hydroxychloroquine, and losartan in aqueous medium. Different characterization techniques were performed for the adsorbents. X-ray fluorescence (XRF) revealed the presence of Si, Al, and Fe as the predominant elements. Fourier transform infrared spectroscopy (FTIR) showed vibrational bands associated with Si-O-Si, Si-O-Al, Si-O, Si-OH, and CH₂ groups, while X-ray diffraction (XRD) indicated similar patterns among the materials, with crystalline phases such as SiO₂ and NaAlSi₃O₈. The chemical modification of the residue promoted a moderate increase in surface area and led to an improvement in the removal efficiency of the pharmaceuticals, with values higher than 70.00%.The adsorption capacities obtained in batch adsorption studies were 101.43 mg g-1 for losartan, 73.77 mg g-1 for diclofenac, 24.81 mg g-1 for ibuprofen, and 39.25 mg g-1 for hydroxychloroquine. In fixedbed column adsorption studies, the adsorption capacities were 46.71, 51.70, 44.86, and 20.43 mg g-1 for hydroxychloroquine, losartan, diclofenac, and ibuprofen, respectively. Chemical regeneration of the adsorbents allowed their reuse for most pharmaceuticals, although a reduction in adsorption capacity was observed after successive cycles. The electrochemical degradation of the pharmaceuticals was evidenced by the reduction of the characteristic anodic peaks in the voltammograms, indicating a decrease in the concentration of electroactive species in solution. Ecotoxicity tests using pharmaceutical solutions resulted in EC50,48 h values of 3.81, 24.11, 175.50, and 53.92 mg L-1 for hydroxychloroquine, diclofenac, losartan, and ibuprofen, respectively. The results obtained in this study demonstrated the feasibility of using this residue due to its efficiency in removing pharmaceuticals and its potential applicability at an industrial scale. Furthermore, the reuse of this residue may contribute to reducing its environmental impacts. 2026-03-27T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/24753 Título: Materiais adsorventes obtidos da biomassa de Ingá-cipó (Inga edulis): remoção de metais pesados e avaliação ecotoxicológica Autor(es): Lima, Lucas dos Santos Abstract: Water contamination by toxic metals, especially hexavalent chromium Cr(VI) and divalent lead Pb(II), represents a significant environmental challenge due to their persistence and harmful effects on aquatic organisms. In this study, two adsorbent materials derived from the biomass of Inga edulis bark were developed and evaluated: raw biomass (BMIG) and sulfuric acid–activated biomass (BMIGA). The materials were characterized using physicochemical techniques, which confirmed structural modifications and the presence of functional groups capable of interacting with the studied metals. Batch adsorption experiments enabled the identification of favorable operational conditions and showed that BMIGA exhibited maximum adsorption capacities of 356.6 and 222.1 mg g-1 for Cr(VI) and Pb(II) ions, respectively, compared to BMIG, which presented an adsorption capacity of 46.0 mg g-1 for Cr(VI) and showed no removal of Pb(II) ions. Chemical activation resulted in an increase in surface area and the introduction of oxygenated functional groups, which enhanced the adsorption of both metal ions. Kinetic models indicated that Cr(VI) adsorption by BMIG and BMIGA followed the Elovich model, characterizing a chemisorption process on a heterogeneous surface. For BMIGA and Pb(II), the best fit was obtained with the pseudo-second-order model, suggesting interaction with oxygenated functional groups. In isotherm studies, Cr(VI) adsorption fitted both the Langmuir and Freundlich models, whereas Pb(II) showed a better fit to the Freundlich model. Thermodynamic analyses demonstrated that Cr(VI) adsorption by BMIG was non-spontaneous, while BMIGA promoted spontaneous adsorption for both metals. Under continuous-flow conditions, fixed-bed columns exhibited stable performance, with breakthrough times of 200.0 min and 281.7 min for Cr(VI) adsorption and 554.8 min for Pb(II) adsorption at low concentrations, which were compatible with practical applications and showed good agreement with the Thomas, Yoon–Nelson, and Clark models. The ecotoxicological assessment performed with Daphnia similis confirmed the high toxicity of solutions containing Cr(VI) and Pb(II) ions prior to treatment. After adsorption, no acute effects were observed on the organisms, demonstrating that the materials were able to significantly reduce toxicity. Finally, the saturated adsorbents were applied in electrochemical tests for green hydrogen and oxygen production, revealing potential for reuse and value addition after environmental application. Overall, the results demonstrate that Inga edulis bark is a promising biomass for the production of sustainable and efficient adsorbents with multifunctional potential, contributing to pollution mitigation strategies and technologies associated with the circular economy. 2026-01-27T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/24203 Título: Síntese e caracterização de biocarvões a partir do coco verde (Cocos nucifera L.) para potencialidade eletroanalítica Autor(es): Almeida, Yslaine Andrade de Abstract: The growth of the agro-industry has intensified the generation of lignocellulosic waste, whose improper disposal represents an environmental and economic challenge, while also highlighting the need for sustainable strategies for its valorization. In this context, the conversion of this waste into functional materials emerges as a promising alternative. Given this problem, this research proposed the sustainable use of agro-industrial waste using green coconut mesocarp to produce cbiochars via pyrolysis and chemical activation, with the aim of developing carbonaceous materials with high porosity and electrical conductivity applicable in electrochemical sensors. Different activation methods (pre- and post-pyrolysis) using phosphoric acid and potassium hydroxide were evaluated, resulting in porous and thermally stable structures. Morphological and structural characterizations were performed using elemental analysis, FT-IR, TG, EDX, XPS, SEM/EDS, TEM/EDS, and N2 adsorption, with statistical processing through Principal Component Analysis. The synthesized biochars exhibited high thermal stability, significant modifications in lignocellulosic structure, and adsorption properties directly related to surface area and pore distribution, highlighting their potential as functional platforms. The produced biochars were applied to modify electrodes for the detection of heavy metals and emerging contaminants. In the first application, the electrode modified with activated biochar with orthophosphoric acid showed excellent performance in the simultaneous detection of Cd2+, Pb2+, and Hg2+ by differential pulse voltammetry, with sensitivities of 42.75 µA L µmol-1 (Cd2+), 38.96 µA L µmol-1 (Pb2+), and 8.07 µA L µmol-1 (Hg2+), as well as very low detection limits, particularly for Cd2+ (1,4 nmol L-1 ). The sensor showed satisfactory selectivity and reproducibility, with recovery values between 89% and 106% in real samples (sewage, tap water, and cosmetics), confirming its practical feasibility, low cost, and sustainable nature. In a second application, the activated biochar with potassium hydroxide was functionalized with bimetallic Au@Pd nanoparticles, yielding the CMB500-Au@Pd electrode, which was used for the determination of the synthetic hormone 17α-ethinylestradiol (EE2). The sensor displayed a linear response in the range of 0.05-5.0 µM (R2= 0.9993), a detection limit of 2.53 nmol L -1 , and a quantification limit of 8.43 nmol L-1 , approximately 2,000 times lower than those obtained by HPLC. Reproducibility tests showed intra-day and inter-day RSDs of 5.77% and 8.14%, respectively. Selectivity studies indicated significant interference only for structurally related compounds (17β-estradiol and ascorbic acid), while urea, NaCl, and caffeine produced negligible effects. The method was successfully validated in real and simulated samples (groundwater, artificial breast milk, synthetic urine, saline solution, and contraceptive tablets), with recoveries ranging from 58.20% to 133.65%. Overall, the results prove the high potential of biochars derived from green coconut mesocarp as functional materials for sustainable electrochemical sensors. The developed electrodes combine high sensitivity, selectivity, and stability, representing cost-effective and environmentally responsible alternatives for monitoring toxic metals and hormonal contaminants in diverse matrices. 2025-12-16T00:00:00Z