Abstract
The performance of a ZnO nanoparticle-based electrochemical sensor, fabricated by different treatments of ZnO on glassy carbon electrode, was evaluated for the determination of 4-nitrophenol (4-NP) in aqueous medium. The sensing performance of ZnO film-coated GCE (ZnO/F/GCE) was compared with a variety of electrodes, which included GCEs modified with ZnO powder, RGO (reduced graphene oxide), and RGO-Nafion (R) composite. Among the fabricated electrodes, the ZnO film-coated electrode, prepared by dispersing the well-sonicated chloroform suspension of ZnO on the GCE, showed excellent response toward the sensitive detection of 4-NP in aqueous medium, and a significant enhancement in the reduction peak current predicted the suitability of the developed sensor. Square wave voltammetry (SWV) detection mode was applied for the determination of 4-NP. The reproducibility and accuracy of ZnO/F/GCE were evaluated in the linear concentration ranges of 0.035 mu M to 1.4 mu M and 2.1 mu M to 6.3 mu M. Appreciably low SWV detection limits of 0.008 mu M and 0.02 mu M were estimated. Minimal influence was observed from the interfering species, added into the sample solution, on the determination of 4-NP. The performance of the developed electrode was initially optimized for 4-NP samples prepared in-house and finally tested against two real samples collected from municipality wastewater. The recovery of the ZnO/F/GCE varied from 96.8% to 105.7%.