Estudos em compositos de celulose e acetato de celulose com oxido de zirconio (IV)

AUTOR(ES)
DATA DE PUBLICAÇÃO

1995

RESUMO

Composites of a-cellulose, Cel, or cellulose acetate, Ac, with ZrO2 were developed for ion adsorption. They were prepared by the reaction between the precursors, Zr(OPr)4 and ZrCI4, with Ac or Cel, respectively. The Cel was used as microfibers while Ac was used as sphere (Per) or membrane (Ac). The Ac and Per was prepared by the phase inversion method. The maximum quantities of oxide incorporated were 5.0, 0.51 and 1.3 % (weight of Zr /weight of polymer) for the composites of Cel, Cel/Zr, and composite membranes, Ac/Zr, and composite spheres, Per/Zr, respectively. On the Cel/Zr, oxide agglomerates are non-uniformly distributed and they have 2-8 mm of average diameter. While in the Ac/Zr and Per/Zr the oxide agglomerates are uniformly distributed and the average diameter is smaller than 100 Å. XPS studies shown a shift in the binding energies, BE O 1s, of oxygen polymers from (532.6 ± 0.3) eV, Cel and Ac, for (532.1 ± 0.3) eV, Cel/Zr, and (532 ± 0.3 eV), Ac/Zr. The Cel/Zr composite showed higher Cr(VI) adsorption at pH= 1.0, Per/Zr composite showed higher Cr(VI) adsorption at pH= 4.9 and higher P(V) adsorption at pH= 1.0. Therefore, the composite Cel/Zr was used as a Cr(VI) pre-concentration micro-column in a FIA experiment for Cr(VI) determination. The system showed a very satisfactory selectivity in presence of several ions, specially for Cr(lII) which interference factor ([Cr(III)]/[Cr(VI)] = 10) was 0.93. It also showed a high sensitivity in such small concentrations as 2 mg l (2 ppb) of Cr(VI) with a rsd of 6%. The Ac/Zr showed rejection rates for P(V) solutions, [P(V)]= 2-2.5 mg l, between (75 ± 10) % and (90 ± 10) %.

ASSUNTO(S)

materiais compostos oxido de zirconio celulose

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