Desenvolvimento de metodos voltametricos para a determinação de zinco, cobre, chumbo, niquel, estanho e cromo em aguas de efluentes de industrias de galvanoplastias

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

This thesis describes the application of stripping voltammetric methods for the simultaneous determination of Zn, Pb, Cu, Ni, Cr, and Sn in treated wastewater of galvanic processes. Parameters such as supporting electrolyte composition, concentration, pH, deposition time and deposition potential were optimized, employing the hanging mercury drop electrode and Ag/AgCl, KClsat., as working and reference electrode, respectively. The optimization of the experimental conditions was performed using a factorial design. Cu, Pb, Zn and Sn were determined by anodic stripping voltammetry, while Ni and Cr after reaction with dimethylglioxime and diethyltriaminopentacetic acid were determined by adsorptive stripping voltammetry. Excepting Sn, all metals were determined in aqueous supporting electrolytes. The separation of Sn and Pb was only possible in a 1.80 mol L HCl + ethanol + i-propanol (20 + 60 + 20 v/v/v) supporting electrolyte. The method was validated through evaluation of the following parameters: linear range, linearity, limit of detection and determination, sensitivity, selectivity, precision and accuracy. The accuracy of the method was evaluated by comparison of the results obtained by the analyses of the metals in wastewater by stripping voltammetry through the standard addition method and the official method recommended by CETESB (atomic absorption spectrometry). The quantification limit was 0.640 mg mL for Zn, 0.130 mg mL for Pb, 0.575 mg mL for Cu, 0.049 mg mL for Ni, 0.045 mg mL for Cr and 1.50 mg mL for Sn. The method was employed for the analyses of galvanic industry wastewaters, presenting adequate selectivity and sensitivity for the monitoring of Cu, Pb, Zn, Ni, Cr and Sn after treatment of the wastewater by precipitation or ionic change.

ASSUNTO(S)

galvanoplastia metais pesados

ACESSO AO ARTIGO

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