Electrochemical study of chemically modified and screen-printed graphite electrodes with

Abstract

The preparation and electrochemical characterization of graphite electrodes modified with hexadecylpyridinium-bis(chlorilato)-antimonyl(V), [SbVO(CHL)2]Hex, (CMEs) as well as their behavior as electrocatalysts toward the oxidation of sulfide are described. The self-exchange rate constant ko of immobilized [SbVO(CHL)2]Hex and the effect of the surface coverage were evaluated. [SbVO(CHL)2]Hex is a new compound. Synthesis protocol and some identification studies are given. The fabrication of screen-printed electrodes (SPEs) with a mixture of 5% (w/ w) [SbVO(CHL)2]Hex/graphite powder in 1.5% (w/v) ethyl cellulose in 2-butoxyethyl acetate is also described. SPEs, poised at +0.08 mV versus Ag/AgCl, at pH 6.5 were utilized for the determination of sulfide in simulated wastewater samples. Interference of various compounds was also tested. The proposed method correlates well with a colorimetric method. Calibration graphs were linear over the range 0.01-0.7 mM sodium sulfide and the CV was 2.8% (n = 8) for 0.1 mM sodium sulfide. Recovery ranged from 94 to 102%. Both [SbVO(CHL)2]Hex CMEs and SPE showed very good storage stability. [SbVO(CHL)2]Hex CMEs showed poor working stability in contrast to printed electrodes, which operated with no remarkable loss of their initial activity for more than 100 runs.