A rapid colorimetric sensor for the detection of mercury in environmental samples employing 2 aminobenzohydrazide schiff base functionalized silver nanoparticles

Abstract

Mercury (Hg²⁺) is an extremely toxic and dangerous element for living organisms. Herein, a simple and selective sensor based on the Schiff base of 2-aminobenzohydrazide with triazole thiazole substituted vanillin (EAHT) functionalized silver nanoparticles (EAHT-AgNPs) is proposed for the detection of Hg²⁺ in environmental water samples. The chemical reduction method was employed to synthesize EAHT-AgNPs using sodium borohydride as the reducing agent. The synthesized nanoparticles were initially confirmed by UV-visible and FTIR spectroscopy, followed by analysis with a zeta sizer to determine their average size, surface charge and polydispersity index. The atomic force microscopy (AFM) and scanning electron microscopy (SEM) were employed to determine the size and morphology of EAHT-AgNPs. Additionally, the functionalized particles exhibited stability at varying pH values, salinity concentrations and elevated temperature. The addition of Hg²⁺ altered the yellow color of EAHT-AgNPs to colorless, confirming the complex formation. The analytical response constructed as a decrease in absorbance versus concentration showed linearity (R² = 0. 991) from 0.1 to 100 µM with a limit of detection of 0.04 µM (40 nM) and limit of quantification of 0.085 µM (85 nM). The sensor was successfully applied for the detection of Hg²⁺ ions in tap water. In conclusion, Schiff base of 2-aminobenzohydrozide with triazole thiazole substituted vanillin silver nanoparticle-based chemosensor is highly sensitive and selective for the detection of Hg²⁺ in water samples. The proposed sensor has been applied for mercury detection tap water, future research should explore its applications in more complex samples like industrial wastewater and marine environments. Further, studies may focus on the integrating of the approach into the portable devices such as smartphone for on-site detection of mercury.