Influence of phase structure of MnO2 for enhancing the electrochemical sensitivity of environmental pollutant chlortetracycline

Abstract

Electrochemical sensing of chlortetracycline (CTC) using α and β- MnO2 nanowires has been studied. The influence of different phase structures (α and β) of MnO2 nanowires on the determination of chlortetracycline (CTC) was studied systematically. To enhance the sensitivity of MnO2, a high conductivity microporous carbon (MC) was employed as a support matrix for MnO2. The electrochemical sensing results illustrate that the α-MnO2 exhibited better electrochemical performance than β-MnO2. This better activity was correlated with its excellent properties like more exposed MnO6 edges, higher conductivity, and lowest average oxidation state . The kinetics study illustrated that the MnO2 modified electrodes perform much better than the bare electrodes. The number of electron transfer, electron transfer coefficient, and diffusion coefficient of CTC were calculated from the scan rate effect; the values are 1, 0.50, and 1.581 × 10−6 cm2 s−1 respectively. Amperometry was used to calculate the lowest detection limit (LOD) at a potential of 0.82 V. The α-MnO2/MC electrode exhibits a better linear range (1–55 µM) with a LOD value of 103 nM towards CTC. Furthermore, the proposed sensor exhibited better anti-interference ability towards KCl, kanamycin sulfate, zinc acetate, magnesium chloride, tetracycline, streptomycin sulfate, and oxytetracycline. The sensor's ability to accurately determine the level of CTC in samples of drinking water, tap water, poultry farm soil, and milk highlights its suitability for industrial applications. The developed sensor showed better reproducibility (RSD=0.45%) and repeatability (RSD=2.06%) towards CTC. Therefore, the proposed sensor can be used as a more practical platform for monitoring environmental contaminants.