O Programa de Pós-Graduação em Ciência & Tecnologia Ambiental (PPGC&TAmb) da Universidade Federal do Maranhão (UFMA) tem como objetivo central fomentar a produção de conhecimento e formar recursos humanos para a pesquisa científica, tecnológica e de inovação, com ênfase nas Ciências e Tecnologias Ambientais. Sua criação representa um avanço significativo no ciclo de desenvolvimento do Centro de Ciências Exatas e Tecnologia (CCET) da UFMA, fortalecendo a pesquisa no contexto acadêmico da instituição. https://tedebc.ufma.br/jspui/handle/tede/5994 2026-06-25T11:29:14Z 2026-06-25T11:29:14Z COSTA, Bárbara Beatriz Caxilé https://tedebc.ufma.br/jspui/handle/tede/7058 2026-06-18T13:36:33Z 2026-02-27T00:00:00Z

Título: ESTUDO DO POTENCIAL ANTIOXIDANTE DO EXTRATO ETANÓLICO DA AMBURANA CEARENSIS COMO FATOR DETERMINANTE NA ESTABILIDADE OXIDATIVA DO BIODIESEL DE SOJA Autor: COSTA, Bárbara Beatriz Caxilé Primeiro orientador: PASSOS, Ionara Nayana Gomes Abstract: This master’s thesis aims to investigate the oxidative stability of biodiesel through the use of an ethanolic extract obtained from the exudate of Amburana cearensis as a natural antioxidant additive. The incorporation of antioxidants is a widely used strategy to mitigate the oxidative degradation of biodiesel; however, synthetic antioxidants are often associated with high cost, potential toxicity, and low biodegradability, making the discovery of new chemical substances an area of significant scientific advancement. Experimental results for the ethanol extract of Amburana cearensis demonstrated antioxidant efficacy as determined by the ABTS •⁺ radical scavenging assay, which showed high antioxidant activity even with mass loss over time. Thermogravimetric and differential thermal analysis (TG/DTA) revealed its thermal stability at high temperatures, with degradation beginning at 281°C. Chemical characterization by HPLC and DI-ESI-IT-MSn identified the compounds responsible for the antioxidant activity; the predominant metabolite was associated with coumarins, flavonoids, and phenolic acids. Fragments of five compounds were identified as butein, calicosin, cirsimaritin, 3,5,3-trihydroxy-7,4-dimethoxyflavone, and nevadensiv. The extract’s efficacy as an antioxidant in biodiesel was evaluated using the Rancimat method (EN 14112). The treated sample exhibited an induction time of 11.03 h with 3000 ppm of the ethanolic extract, coming very close to the limits established by the National Agency of Petroleum, Natural Gas, and Biofuels (ANP). Overall, the phytochemicals present in the exudate of Amburana cearensis demonstrate significant scientific, environmental, and socioeconomic potential, supporting its use as a green and regional alternative to synthetic antioxidants. Instituição: Universidade Federal do Maranhão Tipo do documento: Dissertação

2026-02-27T00:00:00Z MATA, Raylane Rocha da https://tedebc.ufma.br/jspui/handle/tede/7042 2026-06-11T14:36:46Z 2026-02-26T00:00:00Z

Título: Atividade inseticida, fagoinibidora e repelente de extratos e frações de Solanum paniculatum sobre Sitophilus zeamais (coleoptera: curculionidae) Autor: MATA, Raylane Rocha da Primeiro orientador: PASSOS, Ionara Nayana Gomes Abstract: Post-harvest losses caused by insect pests represent one of the main factors responsible for the reduction in the quality and quantity of stored grains, with the maize weevil, Sitophilus zeamais, standing out as one of the species of greatest economic importance. In this context, the present study aimed to evaluate the bioinsecticidal potential of extracts and fractions obtained from the leaves of Solanum paniculatum in the control of S. zeamais. The plant extracts were obtained through an extraction process and subsequently fractionated using solvents of different polarities, being evaluated through laboratory bioassays of mortality and insecticidal activity. Additionally, qualitative phytochemical and chromatographic analyses were performed to identify the main secondary metabolites present. The results demonstrated high bioinsecticidal activity of the tested extracts and fractions, with emphasis on the crude extract and the acetate organic fraction, which showed high insect mortality rates. Chemical analyses indicated the presence of phenolic compounds, flavonoids, and lipophilic substances, metabolites frequently associated with insecticidal activity. Therefore, it is concluded that Solanum paniculatum presents promising potential as a source of natural compounds for the development of bioinsecticides applicable to the sustainable management of stored-grain pests. Instituição: Universidade Federal do Maranhão Tipo do documento: Dissertação; Documento sob sigilo. Prazo provável para disponibilização total: 3 anos. Motivo do sigilo: publicação de artigo.

2026-02-26T00:00:00Z OLIVEIRA, Rainara Ribeiro https://tedebc.ufma.br/jspui/handle/tede/7038 2026-06-08T12:06:40Z 2026-02-26T00:00:00Z

Título: Efeito alelopático de Solanum paniculatum para o controle sustentável da planta daninha Leucaena leucocephala Autor: OLIVEIRA, Rainara Ribeiro Primeiro orientador: OLIVEIRA, Regina Maria Mendes Abstract: Despite advances in agriculture, productivity losses still occur due to the presence of invasive plants, which represent a major obstacle to agricultural production. Based on this assumption, the objective of this study was to evaluate the allelopathic potential of the crude extract and fractions of Solanum paniculatum, compared to glyphosate, on Leucaena leucocephala. The leaves of S. paniculatum were collected in the municipality of Anapurus-MA and identified in the CCAA/UFMA Herbarium under voucher no. 5399. The material was dried, crushed, and subjected to extraction. Two hundred grams of leaves were used in 99.5% ethanol and water, subjected to percolation for 30 days. The preparation of the crude extract and fractions was carried out at the Natural Products Chemistry Laboratory (LQPN/CAMQ/UFMA), followed by chemical characterization. L. leucocephala was used as the recipient plant, testing concentrations of 2% and 5%. Bioassays of bioherbicidal potential were conducted in a completely randomized design (CRD), with four treatments (including positive and negative controls) in four replicates. Statistical analysis was performed using ANOVA, followed by Tukey's test (5%), using InfoStat® (2010) and Excel® (2019) software for data tabulation and interpretation. The study evaluated the allelopathic potential of Solanum paniculatum on Leucaena leucocephala from the crude hydroalcoholic extract (EBH) and its fractions. The EBH was the most active, inhibiting 95% of germination at 5%, in addition to reducing radicle growth (76% at 5%) and hypocotyl growth (70% at 5%). Among the fractions, acetate performed best, with 65% inhibition of the radicle at 5% and 66% of the hypocotyl at 5%. The hexane phase stood out at 2%, with 72% inhibition of the radicle, while the aqueous phase was most effective at 1%, inhibiting 56% of the hypocotyl. Instituição: Universidade Federal do Maranhão Tipo do documento: Dissertação; Trabalho sob Sigilo.Motivo do sigilo: Publicação do Trabalho.Submetido, ainda não publicado. Mas no ato da submissão foi feita uma declaração de direito autoral à revista. Prazo previsto para disponibilização total: 3 anos.

2026-02-26T00:00:00Z RIBEIRO NETO, João Durval https://tedebc.ufma.br/jspui/handle/tede/7037 2026-06-03T19:02:53Z 2025-07-15T00:00:00Z

Título: Síntese e caracterização de um sensor a base de polianilina (PANI) fototermicamente estimulado para detecção de amônia Autor: RIBEIRO NETO, João Durval Primeiro orientador: MENDONÇA, Leonado Tadeu Boas Abstract: The field of gas and volatile compound sensing has gained prominence in the food, beverage, and fuel industries due to sensors' ability to detect and quantify substances imperceptible to humans. However, many sensors rely on metal oxides, which require high temperatures for analysis, making the search for new materials necessary. Among conductive materials, Polyaniline (PANI) stands out due to its electrical conductivity, optical properties, and broad applicability. This study proposes modifications to PANI using nanotechnology and photothermal effects to enhance its performance. The main objective was to obtain nanostructured conductive polymers and study their electrical behavior under photothermal stimulation in the presence of gases and volatile compounds. The PANI synthesis employed the surfactant Triton X-100. For photothermal characterization, a setup was assembled with an infrared LED (780 nm, 3W) to excite the samples dispersed in water, enabling the calculation of photothermal conversion efficiency. The synthesized samples were analyzed by X-ray diffraction (XRD) at UFMA’s central analytical facility. Particle morphology was examined using scanning electron microscopy (SEM), while FT-IR, UV-Vis, and XRD spectra were obtained to correlate structural and optical properties. Sensor fabrication employed spin-coating deposition onto a substrate, developed at the Colloids Laboratory (UFMA), to form thin films. Sensor tests were conducted using ammonium hydroxide (NH4OH), injected via microsyringe (0-100 µL) at varying concentrations, with injection cycles to estimate response times and signal recovery, using a vacuum system. Electrical resistance was monitored using a controlled voltage source and a 4 ½-digit multimeter. During testing, the sensor was stimulated by an infrared LED (3V) to evaluate its photothermal performance. The results demonstrated that photothermal conversion improved selectivity and response speed due to irradiation-induced heating. The study highlighted the potential of photothermally induced nanostructured polymers as sensors for volatile compounds and gases, establishing a new research direction. Instituição: Universidade Federal do Maranhão Tipo do documento: Dissertação

2025-07-15T00:00:00Z