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Oxidation catalysts prepared from biosorbents supported on zeolites

Figueiredo, Hugo; Neves, Isabel C.; Quintelas, C.; Tavares, M. T.; Taralunga, M.; Mijoin, J.; Magnoux, P.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /04/2006 ENG
Relevância na Pesquisa
37.32%
The catalytic oxidation of 1,2-dichlorobenzene was investigated over NaYand NaX zeolites, loaded with chromiumthrough the action of a robust biosorption system consisting of a bacterial biofilm supported on the zeolites. The results of biosorption showed that the maximum metal removal efficiencywas 20%, in both systems based on NaYorNaX, starting fromsolutions with chromium(VI) concentrations ranging from 50 to 250 mgCr/L. The bacterial biofilm, Arthrobacter viscosus, supported on the zeolite reduces Cr(VI) to Cr(III). The Cr(III) is retained in the zeolite by ion exchange. The new catalysts were characterized by spectroscopic methods (FTIR ), chemical analyses (ICP-AES), surface analysis (XRD) and thermal analysis (TGA). The various techniques of characterization show that this biosorption process does not modify the morphology and structure of the FAUzeolites. These catalysts,Cr/FAU, prepared through this newprocedure present good activity and selectivity for dichlorobenzene oxidation in wet air at 350 ºC. The Cr50-Y was selected as the most active, selective and stable catalyst for oxidation of 1,2-dichlorobenzene in wet air.; Departamento de Ciências da Terra of Universidade do Minho; Fundação para a Ciência e a Tecnologia (FCT) ; Agence de l’Environnement et de la Maîtrise de l’Energie (ADEME); Région Poitou-Charentes.

Encapsulated pyridazine Cr(III) complexes prepared from biosorbents supported in zeolites

Figueiredo, Hugo; Raposo, M. Manuela M.; Fonseca, A. Maurício C.; Neves, Isabel C.; Quintelas, C.; Tavares, M. T.
Fonte: Elsevier Publicador: Elsevier
Tipo: Parte de Livro
Publicado em //2005 ENG
Relevância na Pesquisa
37.32%
The encapsulation of a pyridazine Cr(III) complex was prepared from a robust biosorption system consisting of a bacterial biofilm supported on NaY or NaX zeolites. The maximum removal efficiency was 20% for Cr in both systems based in NaY or NaX. The bacterial biofilm, Arthrobacter viscosus, supported on the zeolite reduce Cr(VI) to Cr(III). The Cr(III) is retained in the zeolite by ion exchange. These occluded complexes were characterized by chemical analysis, spectroscopic methods (FTIR and UV/Vis) and surface analysis (DRX). The various techniques of characterization used show that the Cr(III) complex was effectively encapsulated in the zeolite and this process does not modified the morphology and structure of the NaY/NaX zeolites. These materials have potential applications in heterogeneous catalysis in mild conditions.; Departamento de Ciências da Terra of Universidade do Minho; Fundação para a Ciência e a Tecnologia (FCT)

Potentiation of 5-fluorouracil encapsulated in zeolites as drug delivery systems for in vitro models of colorectal carcinoma

Vilaça, Natália; Amorim, Ricardo; Machado, Ana F.; Parpot, Pier; Pereira, M. F. R.; Sardo, Mariana; Rocha, João; Fonseca, António Manuel; Neves, Isabel C.; Baltazar, Fátima
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2013 ENG
Relevância na Pesquisa
37.44%
The studies of potentiation of 5-fluorouracil (5-FU), a traditional drug used in the treatment of several cancers, including colorectal (CRC), were carried out with zeolites Faujasite in the sodium form, with different particle sizes (NaY, 700nm and nanoNaY, 150nm) and Linde type L in the potassium form (LTL) with a particle size of 80nm. 5-FU was loaded into zeolites by liquid-phase adsorption. Characterization by spectroscopic techniques (FTIR, 1H NMR and 13C and 27Al solid-state MAS NMR), chemical analysis, thermal analysis (TGA), nitrogen adsorption isotherms and scanning electron microscopy (SEM), demonstrated the successful loading of 5-FU into the zeolite hosts. In vitro drug release studies (PBS buffer pH 7.4, 37°C) revealed the release of 80-90% of 5-FU in the first 10min. To ascertain the drug release kinetics, the release profiles were fitted to zero-order, first-order, Higuchi, Hixson-Crowell, Korsmeyer-Peppas and Weibull kinetic models. The in vitro dissolution from the drug delivery systems (DDS) was explained by the Weibull model. The DDS efficacy was evaluated using two human colorectal carcinoma cell lines, HCT-15 and RKO. Unloaded zeolites presented no toxicity to both cancer cells, while all DDS allowed an important potentiation of the 5-FU effect on the cell viability. Immunofluorescence studies provided evidence for zeolite-cell internalization.