VOLTAMMETRIC BEHAVIOR OF MERCURY(I,II) IONS AT AN AMIDE-FUNCTIONALIZED HUMIC ACIDS MODIFIED CARBON-PASTE ELECTRODE

Amide-functionalized humic acids (AHA) was synthetized by two step rea ctions, in which humic acids first reacted with thionyl chloride(SOCl2 ) and then reacted with ammonia liquor. The AHA was characterized by F ourier transform infrared (FTIR) spectra and elemental analysis method . The reaction properties between AHA and mercury ions(I,II) were inve stigated at an AI-IA chemically modified carbon paste electrode (AHA-C MCPE) using cyclic voltammetry (CV) and linear sweep stripping voltamm etry (LSSV). Moreover, the binding behavior of numerous other ions at the AHA-CMCPE was also tested. In an open circuit, Both Hg-I and Hg-II were accumulated from a stirred 0.1M H2SO4 solution onto the AHA-CMCP E. The subsequent electrochemical measurement was performed in another clean supporting electrolyte of 0.5M H2SO4 Factors affecting the accu mulation and electrode reaction steps were investigated and an optimiz ed procedure for quantifying mercury was developed. Under optimized co nditions, a calibration plot for mercury concentration in the range 4. 98 x 10(6)-4.98 x 10(8) was obtained. The new electrode can be used to determine mercury whether in the Hg-I or Hg-II forms.