Thermodynamics and kinetics to develop an analytical method for sensing of aqueous Hg(II) using caffeic acid decorated AgNPs

Mercury (Hg) and its compounds are exceptionally noxious and extensively distributed in the atmosphere. We have used caffeic acid decorated silver nanoparticles (CA-AgNPs) for the colorimetric detection of the Hg(II) ions in the aqueous systems. In this method, a paper strip was simply used as a dipstick type device for the fast and selective detection of the aqueous Hg(II) ions. The paper strip displays a color change within 50 seconds with superior selectivity after being dipped into the solution containing a concentration of Hg(II) ions in the range of 20-0.0001 ppm. The developed method allows us to detect Hg(II) through naked eyes with a LOD of 0.0001 ppm. The interaction between prepared CA-AgNPs and Hg(II) was also studied using reactive kinetics, thermodynamic parameters and density functional theory (DFT). The proposed method can be a cost-effective tool for field-level applications for on-site real-time detection of mercury.