Electrochemical and spectroscopic insights of interactions between alizarin red S and arsenite ions

Abstract

Interferences of arsenite ions on electrocatalytic oxidation of alizarin red S (ARS) was studied using Pt and ITO electrodes. A Pt electrode can oxidize both arsenite ions and ARS molecules simultaneously. The oxidation wave of ARS exceeds that of arsenite until the [AsO₂⁻]/[ARS] ratio surpasses 0.07. Meanwhile, an ITO electrode can oxidize only ARS molecules. It was seen that the diffusion coefficient of ARS molecules decreased from 4.3 × 10⁻⁶ cm² s⁻¹ to 1.68 × 10⁻⁷ cm² s⁻¹ in the presence of arsenite ions. The electrokinetic investigation shows that ARS oxidation was a two-electron transfer consecutive process. The EIS studies showed that charge transfer resistance was increased in the presence of arsenite ions during ARS oxidation.