Preparação, caracterização e aplicações do material celulose-oxido de zirconio

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

This work describes the preparation and characterization of the cellulose (Cel) and cellulose acetate (Acel) fibers and cellulose acetate film (Macel) coated with ZrO2. Furthermore, they were modified by reacting phosphoric acid, resulting in the modified materials: Cel/ZrO2/Phosphate and Acel/ZrO2/Phosphate fibers and Macel/ZrO2/Phosphate films. The zirconium and phosphorus chemical analyses for Cel/ZrO2/Phosphate, Acel/ZrO2/Phosphate and Macel/ZrO2/Phosphate indicated a reasonable amount of adsorption. The P CPMAS NMR spectra for Cel/ZrO2/Phosphate e ..Acel/ZrO2/Phosphate .materials indicated that HPO4 is the species present on the fiber surface. The X-ray energy dispersive spectrometry indicated that zirconium and phosphorous atoms are highly dispersed on the fiber surface and in the film. The ion exchange reaction isotherms of Cel/ZrO2/Phosphate and Acel/ZrO2/Phosphate .with Li, Na and K were obtained. The ion exchange capacities for Li, Na and K ions were determined from ion exchange isotherms and an efficient separation capacity for K and Na ions was observed when compared with Li ion. The results obtained in flow experiments observed when compared with Li+ ion. The results obtained in flow experiments showed a retention and recovery of 97% of the K and 93% o the Na ions by Acel/ZrO2/Phosphate, Li was not retained. Electrochemical studies were carried out on a thin membrane of the Macel/ZrO2/Phosphate/methylene blue material by testing as an electrochemical sensor for NADH (Nicotinamide Adenine Dinucleotide Reduced Form) coenzyme. Cyclic voltammetric experiments, carried out on a thin membrane of the material adhered on a platinum disk, showed a redox process whose midpoint potential was Em= -0.15 V. The enhancement of the anodic current peak intensities, observed when a NADH solution was successively added, is as an indication of a catalytic oxidation of NADH. From NADH electrocatalysis information from the modified electrode, chronoamperometry experiments were undertaken. The observed response time (current vs. time) was 6 s. A linear correlation of 0.999, for a NADH concentration range from 0 to 250, mmol was obtained, indicating the potential use of the material to make a NADH sensor.

ASSUNTO(S)

acido fosforico celulose oxido de zirconio

ACESSO AO ARTIGO

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