Facile and On-line Colorimetric Detection of Hgbased on Localized Surface Plasmon Resonance (LSPR) of Ag Nanotriangles

A rapid and sensitive colorimetric detection method for the determination of Hg has been successfully developed in this research. Citrate-functionalized silver nanotriangles (AgTrngs) were synthesized via one-pot sodium borohydride method with the edge-length range of 30 - 40 nm. The obtained AgTrngs were fully characterized using UV-Vis spectrophotometry, transmission electron microscopy (TEM), energy dispersed spectroscopy (EDS) and X-ray diffractometer. The efficiency of the developed sensor was optimum at pH= 8 due to interfering effect of H ions for Hg under acidic conditions. The successful detection of mercury in aqueous solutions in the concentration range of 10 nmol L-50 μmol L indicated the applicability of the developed sensor for effective monitoring and controlling the level of Hg in industrial effluents. The ability of Hg ion to interact with Ag and form the Hg-Ag alloy (amalgam) over the surface of AgTrngs resulted in an obvious color change from blue to violet. UV-Vis spectrophotometry showed that the sensor has the limit of detection (LOD) value of as low as 4 nmol L which was below the safety level of Hgions (10 nmol L) in drinking water. The proposed method can be used for on-line determination of Hg in the complex aqueous solutions.