Navegando por Palavras-chave "Vermiculite"

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    Obtenção de leito filtrante à base de zeólita e vermiculita com propriedade bactericida
    (Universidade Federal de São Paulo, 2017-08-25) Calabria, Giovanna Dias [UNIFESP]; Martins, Tereza da Silva [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The bad conditions of the treated water distribution pipes can compromise the quality of this well until it arrives at the residences. In view of this problem, the objective of this study was to incorporate zinc and silver ions into minerals with high cation exchange capacity, such as zeolites and vermiculites, and to evaluate their efficacy as a filter medium with bactericidal action in water purifiers. The incorporation of the Zn2+ and Ag+ ions on the study minerals was tested by three methods: batch, hydrothermal and heating at 380°C. In the batch test it was verified that the vermiculite has a greater capacity to retain zinc (9.5 mg g-1) than zeolite (4.9 mg g-1). While in the case of the silver, zeolite was the most efficient (18.14 mg g-1) in relation to vermiculite (8.69 mg g-1). The hydrothermal system wasn't efficient in the retention of zinc by zeolite, however, the zinc content incorporated by the zeolite by the heating method at 380 ° C was very high (11.42% of ZnO). It was verified, therefore, that the vermiculite easily incorporates Zn2+ by the batch method and the zeolite by the heating method. In the case of Ag+, the zeolite was the one that obtained better results by means of batch. Therefore, these samples were selected for the desorption test carried out on columns of percolation of water under constant flow, whose results indicated that the Zn2+ ions of the vermiculite and the Ag+ of the zeolite are constantly released always below the established maximum concentration limit By the World Health Organization (WHO) for drinking water. On the other hand, the bactericidal action tests of zeolite incorporated with zinc by the heating method found that the desorbed content of Zn2+ wasn't able to remove E.coli bacteria in the start of life of the filter bed (50 L). However, the test carried out with a bed prepared with a mixture of zeolite-Ag+ and vermiculite-Zn2+ was more successful, being able to reduce bacteriological contamination completely in the first 50 liters. On the other hand, at 950 L the same efficiency wasn't observed, since the bacteria were only partially removed. It is believed that changing some experimental parameters, such as lower water flow rate, may in turn improve those results.