Green synthesis of carbon nanotubes impregnated with metallic nanoparticles: Characterization and application in glyphosate adsorption

In the present work, multi-walled carbon nanotubes (MWCNTs) were used as support material for the impregnation of metallic nanoparticles (MNPs) produced by green synthesis. The influences of the plant extracts (pomegranate (Punica Granatum), Eucalyptus, and pecan (Carya illinoinensis, leaves), metal species (copper and iron), metallic concentrations, and type of functionalization (OH and COOH) on the characteristics of the obtained materials were studied. The precursor and impregnated MWCNTs were characterized through X-ray diffraction, Fourier transformed infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, point of charge, N2 adsorption/desorption isotherms and, X-ray photoelectron spectroscopy. All the synthesized materials were tested as adsorbents to remove glyphosate (GLY) in an aqueous medium. The MWCNTs were resistant to withstand the synthesis process, preserving its structure and morphological characteristics. The copper and iron on the surface of MWCNTS confirm the successful synthesis and impregnation of the MNPs. The MWCNTs impregnated with high metallic concentrations showed favorable adsorption of GLY. The adsorption capacity and percentage of removal were 21.17 mg g−1 and 84.08%, respectively, for the MWCNTs impregnated with iron MNPs using the pecan leaves as a reducing agent. The results indicated that an advanced adsorbent for GLY could be obtained by green synthesis, using MWCNTs as precursors and pecan leaves as a reducing agent

Anais do V Encontro Brasileiro de Educomunicação: Educação midiática e políticas públicas

A presente coletânea, que chega ao público através de um suporte digital, tem como objetivo disponibilizar os papers, bem como os relatos de experiências educomunicativas apresentados durante o V ENCONTRO BRASILEIRO DE EDUCOMUNICAÇÃO, que teve como tema central: “Educação Midiática e Políticas Públicas”. O evento foi realizado em São Paulo, entre 19 e 21 de setembro de 2013, a partir de uma parceria entre o NCE/USP - Núcleo de Comunicação e Educação da USP, a Licenciatura em Educomunicação da ECA/USP, a ABPEducom – Associação Brasileira de Pesquisadores e Profissionais da Educomunicação e a FAPCOM – Faculdade Paulus de Tecnologia e Comunicação, que ofereceu seu campus, na Vila Mariana, para os atos do evento. Os presentes anais disponibilizam o texto de abertura, de autoria do coordenador geral do evento, denominado “Educação midiática e políticas públicas: vertentes históricas da emergência da Educomunicação na América Latina”. Na sequência, apresentam 61 papers sobre aspectos específicos da temática geral, resultantes de pesquisas na área, seguidos de 27 relatos de práticas educomunicativas, em nível nacional

Tratamiento eficaz de aguas residuales hospitalarias con diclofenaco e ibuprofeno en alta concentración utilizando una tecnología prometedora basada en una reacción de degradación catalizada por Fe0 bajo irradiación de microondas.

Real hospital wastewater was effectively treated by a promising technology based on degradation reaction catalyzed by Fe0 under microwave irradiation in this work. Fe0 powders were synthesized and characterized by different techniques, resulting in a single-phase sample with spherical particles. Optimum experimental conditions were determined by a central composite rotatable design combined with a response surface methodology, resulting in 96.8% of chemical oxygen demand reduction and 100% organic carbon removal, after applying MW power of 780 W and Fe0 dosage of 0.36 g L−1 for 60 min. Amongst the several organic compounds identified in the wastewater sample, diclofenac and ibuprofen were present in higher concentrations; therefore, they were set as target pollutants. Both compounds were completely degraded in 35 min of reaction time. Their plausible degradation pathways were investigated and proposed. Overall, the method developed in this work effectively removed high concentrations of pharmaceuticals in hospital wastewaterEn este trabajo, las aguas residuales hospitalarias reales fueron tratadas eficazmente mediante una tecnología prometedora basada en la reacción de degradación catalizada por Fe0 bajo irradiación de microondas. Los polvos de Fe0 se sintetizaron y caracterizaron mediante diferentes técnicas, dando como resultado una muestra monofásica con partículas esféricas. Las condiciones experimentales óptimas se determinaron mediante un diseño central compuesto giratorio combinado con una metodología de superficie de respuesta, lo que resultó en una reducción del 96,8% de la demanda química de oxígeno y una eliminación del 100% de carbono orgánico, después de aplicar una potencia de MW de 780 W y una dosis de Fe0 de 0,36 g L − 1. durante 60 min. Entre los varios compuestos orgánicos identificados en la muestra de aguas residuales, el diclofenaco y el ibuprofeno estaban presentes en concentraciones más altas; por lo tanto, se establecieron como contaminantes objetivo. Ambos compuestos se degradaron completamente en 35 min de tiempo de reacción. Se investigaron y propusieron sus posibles vías de degradación. En general, el método desarrollado en este trabajo eliminó de manera efectiva las altas concentraciones de productos farmacéuticos en las aguas residuales de los hospitales

New insights into glyphosate adsorption on modified carbon nanotubes via green synthesis: statistical physical modeling and steric and energetic interpretations

The present work used a statistical physics approach to present new insights into the adsorption of the pesticide glyphosate on modified carbon nanotubes via green synthesis (MWCNT/MPNs-Fe). The experimental equilibrium curves obtained for this system under pH 4 at temperatures 298, 308, 318, and 328 K were simulated from monolayer, double layer, and multilayer models, with 1 and 2 energies, considering real and ideal fluid approaches. Taking into account the statistical indicators and the physical meaning of the parameters, exploring simplifying hypotheses, the Hill model with 1 energy and ideal fluid approach (M1) presented the best prediction of the experimental data, indicating that glyphosate adsorption occurs by the formation of a monolayer and that pesticide interaction with MWCNT/MPNs-Fe are characterized by only one energy. Based on this approach, to assess the steric aspects of the system, the number of molecules adsorbed per site (n), the density of receptor sites (Nm), adsorption capacity at saturation (Qsat), and concentration at half-saturation (W) were interpreted. As for the energetic aspects, the adsorption energy (ΔE) was inferred. The combination of parameters to its evolution with temperature and the magnitude of ΔE indicated an exothermic process involving a physical interaction mechanism. Finally, the new insights showed that the MWCNT/MPNs-Fe adsorbent favored pesticide adsorption by interacting glyphosate molecules with the metallic iron nanoparticles present on the adsorbent surface. © 2021 Elsevier B.V