Química Nova

URI permanente para esta coleçãohttps://thoth.dti.ufv.br/handle/123456789/13323

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2008 - 200922010 - 20121

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Autor: search.filters.author.Guerreiro, Mário CésarTem arquivos: Sim

Resultados da Pesquisa

Agora exibindo 1 - 3 de 3
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    Espectroscopia no infravermelho médio e análise sensorial aplicada à detecção de adulteração de café torrado por adição de cascas de café
    (Sociedade Brasileira de Química, 2012) Tavares, Katiany Mansur; Pereira, Rosemary Gualberto Fonseca Alvarenga; Nunes, Cleiton Antônio; Pinheiro, Ana Carla Marques; Rodarte, Mírian Pereira; Guerreiro, Mário César
    Mid-infrared spectroscopy and chemometrics were used to identify adulteration in roasted and ground coffee by addition of coffee husks. Consumers’ sensory perception of the adulteration was evaluated by a triangular test of the coffee beverages. Samples containing above 0.5% of coffee husks from pure coffees were discriminated by principal component analysis of the infrared spectra. A partial least-squares regression estimated the husk content in samples and presented a root-mean-square error for prediction of 2.0%. The triangular test indicated that were than 10% of coffee husks are required to cause alterations in consumer perception about adulterated beverages.
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    Materiais à base de óxido de ferro para oxidação de compostos presentes no efluente da despolpa do café
    (Sociedade Brasileira de Química, 2008) Gonçalves, Maraísa; Guerreiro, Mário César; Oliveira, Luiz Carlos Alves; Rocha, Cristian Luciana da
    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.
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    Preparação e caracterização de carvão ativado produzido a partir de resíduos do beneficiamento do café
    (Sociedade Brasileira de Química, 2008) Brum, Sarah Silva; Bianchi, Maria Lucia; Silva, Vanésia Liane da; Gonçalves, Maraísa; Guerreiro, Mário César; Oliveira, Luiz Carlos Alves de
    Coffee fruit processing is one of the most polluting activities in agriculture due to the large amount of waste generated in the process. In this work, coffee parchment was employed as precursor for the production of carbons activated with ZnCl2 (CAP). The material was characterized using N2 adsorption/desorption at 77 K, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The material showed a surface area of 521.6 m²g-1 and microporous structure. CAP was applied as adsorbent for the removal of methylene blue dye in aqueous medium. The adsorption capacity was found to be about 188.7 mg g-1.