Biochar supported metal oxide nanocomposites for electrochemical estimation of simazine in water samples

Abstract

Simazine (SZ), a hazardous herbicide from the chloro-triazine family, poses serious risks to human health and the environment. To mitigate these concerns, an ultrasensitive electrochemical (EC) sensor was developed for SZ detection using biochar (BC) derived nanocomposites (NCs). This study focuses on the synthesis and characterization of biochar ferrite (BCF) and biochar ferrite niobium (BFN) NCs by incorporating ferrite and niobium pentoxide nanoparticles (NPs) into the BC matrix. The NCs were characterized using Fourier transform infrared spectroscopy, ultraviolet diffuse reflectance, scanning electron microscopy (SEM) and X-ray diffraction. SEM analysis revealed a uniform distribution of granular metal NPs within the flaky BC matrix, with crystallite size (nm) of BCF and BFN as 21.12 and 21.72, respectively. Working electrodes (WEs) were fabricated by coating a slurry of the NCs and polyvinyl butyral in N-Methyl-2-pyrrolidone onto a stainless steel plate. Their EC performance was evaluated using cyclic voltammetry (CV) and square wave voltammetry. Current–voltage measurements confirmed Ohmic behavior of the WEs at room temperature. The BFN derived WEs demonstrated enhanced DC conductivity compared to the BCF derived WEs. CV analysis revealed characteristic semi-redox peaks of SZ in 0.1 M KCl at pH 2.75, under a current of 1 mA and a potential range of -0.2 to 0.8 V. The limit of detection (LOD) and limit of quantification (LOQ) for BCF derived WE was estimated to be 8.12 μM and 24.59 μM, respectively. In comparison, BFN derived WE exhibited enhanced sensitivity with LOD and LOQ as 5.39 μM and 6.33 μM. Furthermore, SZ detection was successfully validated in spiked real water samples, confirming the high sensitivity and reliability of the sensor platform. These findings emphasize the potential of BFN-based NCs as promising materials for ultrasensitive SZ detection, offering significant prospects for environmental monitoring.

Graphical abstract