Oxido de titanio (IV) hidratado disperso na superficie da x-celulose : preparação, caracterização e aplicações

AUTOR(ES)
DATA DE PUBLICAÇÃO

1996

RESUMO

The interation of titanium chloride with a-cellulose surface and the modifications introduced on the morphology were studied by means of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The chemical analysis of the surface was carried out by X-ray photoelectron spectroscopy (XPS) and changes in the crystallinity upon chemical treatment was studied by X-ray diffraction (XRD) technique. Interaction of titanium with cellulose occurs only at the surface. The decrease of crystallinity was observed and was correlated with the amount of metal oxide incorporated into the solid matrix. Aqueous Cr(VI) solution in a concentration range between 10 and 50 ppb was analised using a column packed with the composite material in line with a flow injection analysis (FIA). The presence of other ions such as Cu(II), Mn(II), Hg(II) and Fe(III), and the anions VO3, MoO4, PO4 and SO4 did not interfere significantly in the separation process. Horseradish peroxidase (HRP) immobilized on the matrix surface was used to study a flow injection system the oxidation of pyrogallol to purpurogalline. The Michaelis-Menten constants for the enzymatic oxidation were determined: Km=47 mM and Vmáx=22 mmol.min. For free enzyme, Km=11 mM and Vmáx= 53 mmol.min were obtained. The activity of the immobilized enzyme is reduced presumably due to its interaction with the oxide surface. However, the level of activity of the immobilized phase did not decrease with time.

ASSUNTO(S)

dioxido de titanio enzimas imobilizadas celulose

ACESSO AO ARTIGO

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