An electrochemical sensor based on polyvinyl alcohol/chitosan-thermally reduced graphene composite modified glassy carbon electrode for sensitive voltammetric detection of lead

摘要

A novel polyviny] alcohol/chitosan-thermally reduced graphene modified glassy carbon electrode (PVA/chito-san-TRG/GCE) has been studied for determination of lead (Pb) in aqueous samples by square wave anodic stripping voltammetry (SWASV). The graphene was obtained from thermal exfoliation-reduction of graphite oxide in the nitrogen atmosphere with an eco-friendly procedure. Chitosan was blended with polyvinyl alcohol to obtain advances in electrochemical and mechanical properties. The surface of the PVA/chitosan-TRG composite exhibited a homogeneous and well-dispersed status, as observed from FESEM images. The electrochemical characteristics of the electrode before and after the modification were characterized via electrochemical impedance spectroscopy (EIS) and SWASV. The effects of experimental conditions such as buffer pH, pre-concentration time, pre-concentration potential, ratio of graphene to PVA/chitosan were systematically investigated. The modified electrode displayed a significant enhancement in sensitivity and selectivity for the detection of Pb. Under optimized conditions, the modified electrode revealed a detection range from 1 ppb to 50 ppb for Pb with a correlation coefficient of 0.996. The limit of detection (LOD) at the modified electrode, based on the signal-to-noise ratio (S/N = 3), gave a value of 0.05 ppb with a preconcentration time of 5 min. The selectivity study revealed that most common foreign ions did not bring significant interference for Pb detection. Besides, the electrode has been successfully applied for Pb detection in real water samples. The proposed method offers scope for on-site detection of Pb at trace level in aqueous samples with a cost-effective, easy-to-use, and environmentally friendly procedure without using complicated apparatus.