Estudos voltametricos de eletrodos quimicamente modificados a base de pasta de carbono e silica gel funicionalizada para determinação de cobre e prata

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

A chemically modified electrode based on carbon paste and functionalized sílica gel-containing 3(2- thiobenzimidazoly)propyl (EPCQM) who used for Cu and Ag preconcentration and determination by differential-pulse voltametry with a scan rate of 5 mV s and a pulse amplitude of 50 mV for Cu and 100 mV for Ag. The research was carried out in aqueous solution with KSCN, KCl and KNO3 0,01 mol L, where the Cu and Ag are preconcentraded at the electrode surface without applied potencial. It was found that the adsorption on the electrode surface depends on the solution s pH, time, solution used for pre-concentration, sample composition and some other factors. This pre-concentration was made in solution of 20,00 mL HNO3 1,00x10 mo1 L (pH=5,0) with the scan potencial from -0,4 V a +0,6 V of Cu and -0,2 V a 0,3 V Ag (anodic scan). The irreversibility of the electrode process was noted by the absence of the cathodic wave when cyclic voltametry was used. The results obtained showed the process to be applicable in the range of 2,74x10 mol L to 1,89x10 mol L for copper and 2,74x10 mol L a 1,09x10 mol L for silver, where a linearity, with 5 minutes of pre-concentration with a minimum detected limit of 1,10x10 mol L for both Cu and Agwas obtained. This electrode was considered to be used for determinations in sugar cane distillates ( cachaças ). Determinations were realized by means of the standard addition method. The developed procedure gave good results.

ASSUNTO(S)

eletrodos determinação mineralogica silica gel

ACESSO AO ARTIGO

Documentos Relacionados