Materiais à base de óxido de ferro para oxidação de compostos presentes no efluente da despolpa do café

Materials based on pure iron oxide and impregnated with niobia (Nb2O5) were prepared. Their catalytic activities were tested on the oxidation of compounds present in the wastewater from the processing of coffee berries. Particularly caffeine and catechol were tested. The oxidation reactions were carried out with the following systems (i) UV/H2O2, (ii) photo-Fenton and (iii) heterogeneous Fenton. All materials were characterized with X-ray diffraction, Mössbauer and infrared spectroscopy. Iron was mainly in the forms of goethite and maghemite. The oxidation kinetics were monitored by UV-vis and the oxidation products were monitored by mass spectrometry. The photo-Fenton reaction presented highest oxidation efficiency, removing 98% of all caffeine and catechol contents

Pure niobia as catalyst for the oxidation of organic contaminants: Mechanism study via ESI-MS and theoretical calculations

In this work, synthetic and natural niobium oxide (niobia), were used to promote the oxidation of methylene blue dye. The samples were characterized by XRD, XPS and FTIR measurements. The presence of reactive species on the surface of the samples strongly increases the oxidation rate of the methylene blue dye. The reaction mechanism was studied by ESI-MS analyses. Moreover, kinetic data and XPS spectroscopy suggest that the oxidation of the organic dye involves oxidizing species mainly generated after previous treatment with H2O2. The results also showed that the oxidation takes place by a homolytic mechanism via radical intermediates.Fil: Oliveira, Luiz C. A.. Universidad Federal de Lavras; BrasilFil: Ramalho, Teodorico C.. Universidad Federal de Lavras; BrasilFil: Gonçalves, Maraísa. Universidad Federal de Lavras; BrasilFil: Cereda, Flávia. Universidad Federal de Lavras; BrasilFil: Carvalho, Kele T.. Universidad Federal de Lavras; BrasilFil: Nazzarro, Marcelo Sandro. Universidad Nacional de San Luis. Facultad de Ciencias Fisico Matematicas y Naturales. Departamento de Fisica. Laboratorio de Ciencias de Superficies y Medios Porosos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; ArgentinaFil: Sapag, Manuel Karim. Universidad Nacional de San Luis. Facultad de Ciencias Fisico Matematicas y Naturales. Departamento de Fisica. Laboratorio de Ciencias de Superficies y Medios Porosos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; Argentin

Produção e caracterização de carvão ativado produzido a partir do defeito preto, verde, ardido (PVA) do café

The black, green and sour coffee defect (PVA) contributes with 20% of the total coffee production. It should be separate from the normal coffee grains in order to improve the final quality of the beverage. In this way, the present work has the objective to use the PVA reject for the production of activated carbon. The activated carbon (CA) was prepared from PVA defect using zinc chloride as activating agent. The prepared material (CA PVA) was characterized and the adsorption tests were carried out using as organic models methylene blue (AM) and reactive red (VR). The CA PVA revealed to be more efficient in the removal of the organic contaminants compared to a commercial activated carbon

Intoxicação natural por Leucaena spp em equinos no Município de Volta Redonda / Natural intoxication by Leucaena spp in horses in the Municipality of Volta Redonda

Leucena [Leucaena leucocephala (Lam.) R. de Wit] é uma leguminosa originária da América Central, amplamente utilizada na alimentação animal, por seu alto valor nutritivo e boa palatabilidade, porém, a presença do princípio tóxico, a mimosina, um aminoácido capaz de promover efeitos inibitórios e antagonistas de várias funções fisiológicas, restringe sua utilização. A intoxicação por leucena foi relatada em bovinos, equinos, caprinos, ovinos e coelhos; o principal sinal clínico é a perda de pelos em consequência a um quadro de hipotireoidismo. No Brasil foram descritos 4 relatos de intoxicação natural por essa planta em equinos, estudos que carecem de informações quanto às avaliações hematológicas. Este trabalho objetiva descrever a intoxicação por leucena em dois equinos fêmeas e avaliar os níveis séricos dos hormônios tireoidianos. Os resultados mostraram que a leucena foi capaz de alterar o hematócrito e promover anisocitose com predominância de hemácias microcíticas, bem como promoveu diminuição dos níveis de T4 livre e T4 total

Nióbia magnética como adsorvente de contaminantes orgânicos em meio aquoso: efeito da temperatura e do pH Magnetic niobia as adsorbent of organic contaminants in aqueous medium: effect of temperature and pH

<abstract language="eng">This work describes novel materials based on pure iron oxide and iron oxide/niobia composite to produce a magnetic adsorbent. These materials were prepared with synthetic iron oxide and characterized by powder XRD, SEM, FTIR, TPR and Mössbauer spectroscopy. Results showed that the main iron oxides formed were goethite (aFeOOH) and maghemite (gFe2O3) with small particle size. The iron oxide and iron oxide/niobia composite showed high adsorption ability for organic compounds. The positive enthalpy indicated an endothermic adsorption process suggesting physical adsorption

Remoção de compostos orgânicos em água empregando carvão ativado impregnado com óxido de ferro: ação combinada de adsorção e oxidação em presença de H2O2 Removal of organic compounds from water by activated carbon impregnated with iron oxide: combined action of adsorption and oxidation in the presence of H2O2

<abstract language="eng">In this work, composites based on activated carbon/iron oxide (AC/Fe) were prepared in two different proportions (AC/Fe 5/1 and 1/1) and evaluated in the removal of the organic dye methylene blue (MB). Physical-chemical properties of the composites were determined by X-ray diffraction (XRD), adsorption/dessorption of N2 isotherm, temperature programmed reduction (TPR) and scanning electron microscopy (SEM). Results showed that goethite (&#945;- FeOOH), with nanometer particle size, was formed over carbon surface for both composites. These materials showed high efficiency to remove MB from solution by combined adsorption and oxidation process. The AC/Fe 1/1 showed to be more active in (MB) oxidation then AC/Fe 5/1

Modified Zeolite with Transition Metals Cu and Fe for Removal of Methylene Blue from Aqueous Medium: Mass Spectrometry Study

Textile industries are one of the main sources of water pollution. Wastewater containing dyes present a serious environmental problem because of its high toxicity and possible accumulation in the environ- ment. In this work were explored the characteristics of removal of methylene blue dye employing zeo- lites modified with transition metals (Cu, Fe). The zeolites with iron or copper were prepared by using NaY and Naβ zeolites as precursors, replacing part of ion sodium for copper or iron ions through the ion exchange method. All materials were characterized by several analytical techniques, in order to gain information about the structure and catalytic activity. Modified zeolites showed a remarkable ac- tivity in H2O2 decomposition and in the discoloration an organic dye in aqueous medium. ESI-MS stud- ies of the methylene blue oxidation showed that the oxidation of the dye occurs via a Fenton type sys- tem in which *OH radicals are formed in situ and added to the ring structure of the organic substrate. In addition, modification of the zeolite with transition metal proved to be an interesting pathway to produce efficient catalysts for the oxidation of organic molecules, i.e. dyes in aqueous media. Copyright © 2015 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)

Síntese e caracterização de nanopartículas de óxido de ferro suportadas em matriz carbonácea: remoção do corante orgânico azul de metileno em água

In this work were prepared composites of iron oxide and carbonaceous materials in two different weight proportions (Carbon/Fe 1/1 and 1/2). The physico-chemical properties of the composites were determined by temperature programmed reduction (TPR), adsorption/dessorption of N2, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and pulse titration H2. The XRD and XPS analysis showed a cubic iron oxide phase, identified as maghemite, formed over the carbon surface. The particle size of maghemite showed to be within 10-30 nm. Carbon/Fe 1/2 was the most active in MB removal kinetics and ESI-MS studies showed that MB removal by both composites leads to oxidized intermediates

Micro Mesoporous Activated Carbon from Coffee Husk as Biomass Waste for Environmental Applications

Activated carbons (ACs) with a highly developed porosity have been prepared from a lignocellulosic precursor (coffee husk) for environmental pollutant adsorption. Characterization results show that these materials exhibit a high amount oxygen groups and high specific surface area with micro mesopores. From SEM results we can see the collapse of large pores at longer activation times. The ACs obtained from coffee husk waste is a promising adsorbent material, with high adsorption capacity for the methylene blue dye (MB). Thus, the use of the coffee husk for AC preparation, with porosity development, showed as a good alternative for the waste transformation. Results also showed that the adsorption of MB by the AC-1/1 was much better than commercial AC from Merck.Fil: Gonçalves, Maraísa. Universidade Federal de Lavras. Department of Chemistry; BrasilFil: Guerreiro, Mário C.. Universidade Federal de Lavras. Department of Chemistry; BrasilFil: Oliveira, Luiz C. A.. Universidade Federal do Minas Gerais; BrasilFil: Solar, Cecilia Ines. Universidad Nacional de San Luis. Laboratorio de Ciencias de Superficies y Medios Porosos; ArgentinaFil: Nazzarro, Marcelo Sandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; Argentina. Universidad Nacional de San Luis. Laboratorio de Ciencias de Superficies y Medios Porosos; ArgentinaFil: Sapag, Manuel Karim. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; Argentina. Universidad Nacional de San Luis. Laboratorio de Ciencias de Superficies y Medios Porosos; Argentin