Antonio Alves de Melo Filho

This study describes the synthesis and application of Alg@hydrochar hydrobeads, derived from Amazonian tucumã residues, for the efficient removal of Pb2+ and Hg2+ from aqueous effluents. The hydrochar was produced via hydrothermal carbonization and encapsulated in a calcium alginate matrix. Physicochemical characterization revealed that the incorporation of hydrochar increased the surface area (21.73 m2 g-1), effective network density (1.1 × 103 mol cm-3), and thermal stability compared to pure alginate spheres. Fixed-bed column experiments demonstrated that the Alg@hydrochar composite achieves removal efficiencies between 98 and 100% for both metals under optimized conditions (25 mg of adsorbent, 5.0 mL min-1 flow rate). Kinetic studies showed that the process follows the pseudo-first-order model, reaching equilibrium within 60 min, with intraparticle diffusion identified as the primary transport mechanism. Equilibrium data were best described by the Freundlich isotherm (coefficient of determination (R2) > 0.97), indicating adsorption on a heterogeneous surface with maximum theoretical capacities of 16.96 mg g-1 for Pb2+ and 17.21 mg g-1 for Hg2+. Furthermore, the hydrobeads exhibited high selectivity for heavy metals in a complex tap water matrix and maintained performance over 20 adsorption-desorption cycles. These results consolidate Alg@hydrochar as a low-cost, eco-friendly, and high-performance technology for water remediation.

Astrocaryum vulgare Mart. es una palmera perteneciente a la familia Arecaceae, conocida popularmente como Tucumã do Pará. Esta especie produce frutos con mesocarpio de color anaranjado y endocarpio blanco. El aceite extraído de la pulpa es rico en ácidos grasos insaturados, los cuales aportan beneficios a la salud. El objetivo de esta investigación fue realizar análisis fisicoquímicos y biológicos en los aceites extraídos de la pulpa y de la almendra del tucumã. Los frutos fueron recolectados en el municipio de Cantá/RR. El estudio se desarrolló en el Laboratorio de Química Ambiental de la Universidad Federal de Roraima. Se evaluó la toxicidad de los aceites frente al micro crustáceo Artemia salina. Los resultados mostraron rendimientos de 37,58% y 32,62%, respectivamente, para la pulpa y la almendra. Los principales constituyentes químicos del aceite de la pulpa fueron el ácido oleico, ácido esteárico y ácido palmítico, mientras que en el aceite de la almendra predominan los ácidos grasos saturados. El aceite de la pulpa presentó un menor índice de saponificación (210,36 ± 2,64 mg KOH g-1) y un mayor índice de peróxido (3,40 ± 0,12 meq 100 g-1) en comparación con el aceite de la almendra, que registró 245,24 ± 6,03 mg KOH g-1 de saponificación y 3,08 ± 0,51 meq 100 g-1 de peróxido. Respecto a la densidad, el aceite de la pulpa presentó 0,92 g mL-1, considerado viscoso, mientras que el aceite de la almendra registró 0,91 g mL-1. En la prueba de toxicidad frente a A. salina, se aplicó un análisis de regresión polinómica y se obtuvo un valor de CL₅₀ = 1946,53 mg L-1 para ambos aceites, lo que indica baja toxicidad. Se concluye que ambos aceites son opciones prometedoras para su inclusión en la alimentación humana y en la formulación de bioproductos (cosméticos), ya que presentan excelentes características fisicoquímicas y biológicas.

La Cúrcuma longa es una planta herbácea perenne, conocida popularmente como azafrán. Pertenece a la familia Zingiberaceae y es originaria de Asia. La parte más utilizada de la planta es el rizoma, que se vende como condimento, y las hojas son un subproducto de este proceso. El objetivo de esta investigación fue determinar los componentes químicos y las propiedades fisicoquímicas del aceite esencial de las hojas de C. longa y su actividad biológica contra el microcrustáceo vivo Artemia salina. El material botánico se recolectó en el municipio de Caroebe/RR, y la parte experimental se desarrolló en el Laboratorio de Química Ambiental de la Universidad Federal de Roraima. El aceite esencial se sometió a análisis fisicoquímicos, cromatografía de gases/espectrometría de masas (GC/MS) y pruebas de toxicidad contra A. salina. Resultados: El aceite esencial presentó una coloración amarilla translúcida y un olor característico de los aceites esenciales, con un rendimiento del 0,36%, una densidad de 0,920 g.mL-1, un índice de refracción de 1,475 y una viscosidad cinemática de 1,504 mm2.s-1. La identificación química determinó que el α-felandreno era el componente mayoritario (35,13%). La toxicidad contra A. salina resultó en una CL50 de 309,16 mg.L-1, considerada de toxicidad moderada. Por lo tanto, se encontró que el aceite esencial de hojas de C. longa contiene compuestos bioactivos que refuerzan las características presentadas y justifican la continuación y profundización de la investigación relacionada con el aceite, convirtiéndose en una opción prometedora para su aplicación en biotecnología.

A espécie Mauritia flexuosa L. f., popularmente conhecida como buriti, é uma palmeira pertencente à família Arecaceae, amplamente encontrada nas regiões Norte e Nordeste do Brasil. Seu fruto possui reconhecido valor nutricional, terapêutico e industrial. O óleo extraído da polpa é rico em ácidos graxos insaturados, relacionados a efeitos benéficos para a saúde, como a diminuição dos níveis de colesterol e triglicerídeos. O objetivo deste trabalho foi realizar a caracterização físico-química e a análise da toxicidade do óleo fixo obtido da polpa do buriti. Os frutos foram colhidos no município de Cantá, em Roraima, submetidos à secagem e os óleos extraídos a quente utilizando o método de Soxhlet com hexano como solvente. Os óleos foram filtrados, purificados e avaliados quanto ao índice de peróxido, índice de saponificação, viscosidade e densidade, além de teste de toxicidade utilizando Artemia salina como organismo-alvo. Os rendimentos obtidos foram de 34,37% para a liofilização e 34,38% para a secagem em estufa. O óleo apresentou índice de saponificação de 207,18 ± 1,46 mg KOH g⁻¹, índice de peróxido de 8,02 ± 0,23 meq kg⁻¹ e densidade de 0,91 g mL⁻¹, sendo classificado como viscoso. O teste de toxicidade revelou um valor de CL50 de 7154,85 mg L⁻¹, indicando baixa toxicidade. Os dados obtidos comprovam que o óleo fixo extraído da polpa do buriti possui excelentes características físico-químicas e potencial de uso nas áreas alimentícia e cosmética, evidenciando a relevância dessa palmeira como um recurso valioso da biodiversidade da região amazônica.

Background: Among major public health problems, malaria stands out as a tropical disease caused by the Plasmodium protozoan, with mosquitoes of the Anopheles genus serving as its vectors. This disease affects a significant portion of the population, with the highest incidence in the Legal Amazon, a region responsible for 99% of cases. Although vector control strategies, such as the use of chemical insecticides, are commonly employed, mosquito resistance, environmental impacts, and risks to human health are driving the search for natural alternatives, including the application of essential oils. Objectives: This study investigates the larvicidal activity of Trattinnickia burserifolia Mart. essential oil against Anopheles darlingi. Methods: The essential oil was obtained through hydrodistillation, and its chemical composition was identified using gas chromatography–mass spectrometry. The larvicidal assay followed WHO protocols, testing oil concentrations ranging from 20 to 100 µg mL⁻¹. Results: Efficacy was evaluated after 24, 48, and 72 h to determine LC₅₀, LC₉₀, and other parameters. Chemical composition analysis revealed the presence of 40 compounds, primarily terpenes such as tricyclene, β-pinene, limonene, and α-pinene, which possess bioactive properties that contribute to vector control. The larvicidal activity test showed that LC₅₀ decreased with longer exposure times, indica ting increased efficacy over time. After 72 h, the LC₅₀ was 14.51 µg mL⁻¹, classifying the essential oil as highly effective. Conclusions: Therefore, T. burserifolia Mart. essential oil represents a promising natural alternative for malaria vector control.

A disciplina de química, no ensino médio, visa que o aluno compreenda conceitos abstratos, a exemplo as equações, as fórmulas e os modelos matemáticos, que, por muitos anos, devido ao método de ensino tradicional, fez com que alunos definissem os conteúdos programáticos como tedioso e cansativo. Ocorre que, a partir de uma metodologia de pesquisa bibliográfica em Periódicos da Capes, Google Acadêmico, Scielo, Química Nova e Química Nova na Escola, publicados de 2010 a 2024, verificou-se que o cenário de ensino-aprendizagem da disciplina de química passou por transformação, sobretudo com o avanço das tecnologias. Desse modo, a partir desse cenário, percebe-se a ascensão do uso das metodologias ativas e a utilização dos TICs no ensino de química a partir do uso de jogos e laboratórios virtuais, resultando num ensino mais dinâmico responsável por promover a melhora na motivação e interesse do aluno pelo aprendizado da disciplina de química.

The use of synthetic insecticides to control pests in agriculture may negatively affect the environment, human health, and contribute to the emergence of resistant pest populations. This study aimed to investigate the chemical composition and evaluate the bioactivity of ethanolic leaf extracts and hexanic seed extracts of Annona montana Macfad. against Aphis craccivora Koch. Bioassays were conducted to assess toxicity, feeding repellency and translaminar activity. For the chemical characterization of the hexanic seed extract, 97.2 % of the constituents were identified, with the linoleic (37 %), oleic (36.7 %), palmitic (16.9 %) and stearic (5.2 %) acids as the major compounds. For the ethanolic leaf extract, 83.31 % of the constituents were identified, mainly α-tocopherol (19.97 %), β-sitosterol (10.16 %), cyclohexanecarboxylic acid, heptadecyl ester (6.26 %), methyl linolenate (5.35 %) and phytol (4.43 %). Both extracts showed toxic effects on A. craccivora, with the ethanolic extract exhibiting a higher toxicity against nymphs and adults of the cowpea aphid. Repellent and translaminar effects were also observed, with the hexanic seed extract showing a more pronounced activity in both cases.

Extracts and essential oils (EOs) from the leaves and flowers of Hyptis dilatata were studied on the larvae control of Anopheles spp, Anopheles darlingi and on larvicide and adulticide activity for Aedes aegypti. Hexanic and ethanolic extracts were obtained from leaves and flowers (dry and rainy periods), totaling 4 samples, the oils from the leaves of the dry and rainy periods – morning, afternoon and night – with 6 samples and 02 oils from the flower, one for each climatic period. Bioassays with larvae of Anopheles spp., Ae. aegypti and Rockefeller strain were performed, adulticide and efficacy test of the product prototype with leaf’s EO (rainy period/night) for Ae. Aegypti. The hexanic extracts of the flower from both climatic periods were toxic, with 83.3% and 76.7% of mortality rates for Ae. aegypti, and for Rockefeller the mortality rate was 90% and 80%, both in the dry and rainy periods, respectively. For the EOs of leaves and flowers, 100% of mortality was obtained for Ae. aegypti and for Rockefeller, however, for Anopheles spp., it was around 50%. The EOs from the leaves of the night time (dry and rainy) were the most toxic to the Ae. aegypti larvae, CL50 of 47.02 e 55.69 µg/mL after 24 hours. For An. darlingi the oil from the dry period flower was the most toxic one, with CL50 169.68 µg/mL. For Ae. aegypti adult forms, the EO from the rainy/night period leaf was active after 15 minutes of exposure, with 50% mortality. The product prototype was effective within 10 minutes, with 68.3% of knockdown effect. The results indicate that H. dilatata essential oils are effective agents against larval and adult forms of Ae. aegypti and An. darlingi.

The seeds of bacupari, tucumã, and peach palm fruits have distinct characteristics that significantly influence their industrial applications and nutritional value. These seeds have slightly acidic pH levels (5.88 − 6.79), indicating the presence of organic acids. The tucumã seed, for instance, stands out with a high lipid content of 19.35 g 100 g−1, contributing to a high energy value, while the bacupari seed has low lipid levels (0.73 g 100 g−1). Bacupari seeds exhibit high antioxidant potential using the β-carotene/linoleic acid method (244% inhibition) and vitamin C (91.17 mg AA 100 g−1). There were significant variations in phenolic compounds and antioxidant capacity among the seeds analyzed. The fatty acid profile, with a predominance of saturated acids, 90.42 and 88.66%, for tucumã and peach palm oil, respectively. However, the high atherogenicity and thrombogenicity rates suggest caution in consumption. The analysis of triacylglycerol molecules in pupunha and tucumã seeds demonstrated the predominance of mono-, di- and triacylglycerols. When analyzing the acidity index throughout the storage period, a clear trend towards an increase in its results is observed. Therefore, proposing control measures is essential for its correct use.

Bauhinia ungulata is an antioxidant medicinal plant that has been manipuled in Brazil to lower glycemic index as well is for alternative treatment for diabetes. Therefore, the present hearch has aimed to investigates the antioxidant effects of the essential oil of Bauhinia ungulata L. (EOBU) collected in Amazon region better specified in Boa Vista, Roraima, Brazil, located in the Amazon region. Gas chromatography had been used to characterize the components, and antioxidant assays such as DPPH, TAC, reducing power, Fe²⁺ chelation, and total phenols had also been performed. The major constituents had molecularly anchored with the human catalase (CAT) enzyme, and maltol has showed as a positive control. Among the 25 revealed components, the main ones have been α‐bisabolol (27.2 %), β‐Caryophyllene (12.5 %) and Epi‐γ‐eudesmol (13.6 %). The EOBU has comproved a TAC value of 618.79 mg of ascorbic acid equivalent, free radical scavenging capacity (DPPH) around 53.7 % and 65.27 %, Fe²⁺ chelation capacity of 161±6 and 126.7±39.6, for 0.1 mg.mL⁻¹ and 0.5 mg.mL⁻¹, respectively. The power around the EOBU has appeared percentages equals to 28.66 %, 44.6 %, and 77.03 % in the concentrations tested. As well as, 96.5 % of total phenols. The compounds α‐bisabolol (−5.7±0.4 Kcal.mol⁻¹) and β‐caryophyllene (−6.1±0.5 Kcal.mol⁻¹) have showed good interaction with CAT compared to Maltol (−4.4±0.4 Kcal.mol⁻¹). The present work has demonstrated that EOBU functions as a potent antioxidant, capable of scavenging free radicals and reducing oxidative stress damage.