Electrochemical evaluation of catalytic effect of silver in reducing 4-nitroaniline: Analytical application

Abstract

The present work reports on electrocatalytic activity of silver electrode for 4-nitroaniline (4-NA) reduction, where its performance is compared with conventionally used electrodes (gold, graphite and glassy carbon). The voltammetric behavior of 4-nitroaniline (4-NA) is explored where a sensitive cathodic peak has appeared at about −0.26V (vs. Ag/AgCl/3M KCl) in Britton Robinson buffer solution (pH2.0). This peak results from the irreversible reduction of 4-NA at metallic silver electrode. The catalytic effect was evaluated using cyclic voltammetry and chronoamperometry. Indeed, the cathodic transfer coefficient was 0.57 and electron transfer rate constant was evaluated to be 7.38×10−5cm2s−1. Electrochemical impedance spectroscopy also confirms our experimental results as the silver electrode shows least charge transfer resistance. In order to provide electrochemical detection to reducing the nitro groups of 4-NA on the silver electrode surface, the differential pulse voltammograms were used in the potential range between 0.2V and −1V vs. Ag/AgCl/(sat. KCl).Furthermore, silver electrode can be used successfully to improve the detection of 4-NA at very low concentration levels with high sensitivity. The linear calibration range was from 8.0×10−9 to 1.0×10−3molL−1. The limit of detection (LOD) was found to be 4.74×10−9molL−1, while relative standard deviation (RSD) at 1.0×10−4molL−1 4-NA concentration was 1.94% for eight repetitions. Then, the proposed method was applied to detect 4-NA in wastewater and drinking water with satisfactory results.