Rapid colorimetric and spectroscopy based sensing of mercury by surface functionalized silver nanoparticles in the presence of tyrosine

Abstract

Heavy metals are considered as the major environmental pollutant and it reached through mining and industrial waste water, among which mercury is the most toxic heavy metal. The current study reports on Hg2+ detection by using 3-(Trimethoxysilyl) propyl methacrylate (TMPM) functionalized silver nanoparticles (Ag NPs). The prepared Ag NPs was characterized by UV–visible spectrophotometer, particle size analyser, emission-dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), and zeta sizer. UV–visible spectrophotometer study of Ag NPs showed λmax at 404 nm. The average diameter of the particles was found to be 10 ± 1.4 nm and it possessed a zeta potential of −34.32 ± 3 mV. The Hg2+ detection by Ag NPs was observed in the variation in colour from pale yellow to colourless. The peak disappearance was observed in UV–visible spectrophotometer absorption spectra after addition of Hg2+ and measurements of particle size and surface charge of Ag NPs confirmed the aggregation. The detection of Hg2+ by the probe was not interfered by other metal ions in the test solution. The paper and gel-based methods were also developed to detect the Hg2+ from aqueous sample. A linear relationship of y = 0.0007x − 0.0081, R2=0.9816 was obtained between the plot of concentration of Hg2+ ion and the absorbance of Ag NPs on quantification of mercury. The amount of mercury present in the aqueous sample collected from Bhavani River was estimated to be 62.3 ± 1.9 nM which was further confirmed with atomic absorption spectrophotometric analysis. The study found that the prepared probe is highly responsive and specific towards the Hg2+ detection at nano molar level. Hence, the probe is a great tool for effective detection and estimation of Hg2+ from various environmental samples.