Synthesis and Characterization of Functionalized Silver Nanoparticles for Selective Screening of Mercury (II) Ions

The current research work demonstrates a simple, fast, and sensitive colorimetric approach for visual and spectroscopic detection of mercury (Hg (II)) ions using silver nanoparticles. The compound, N-(3,5-bis(trifluoromethyl)phenyl)-2-(4-chlorophenyl) hydrazine carbothioamide (ThAm), is synthesized, characterized and reacted with AgNO3 in the presence of sodium borohydride (NaBH4) used as reducing agent to produce AgNPs having mean particle size of approximately 11 nm. The stability of nanoparticles (NPs) is studied at different conditions such temperature, time, pH and salt concentration. The NPs are characterized by commonly available techniques including UV–Visible spectroscopy, atomic force microscopy (AFM), Fourier transformed infrared spectroscopy (FTIR) and thermogravimetric/differential analyzer (TG/DTA). The AgNPs are selective to detect Hg (II) among the sixteen metal ions considered in this study. The yellow color of AgNPs solution disappears quickly by addition of Hg (II), along with a substantial variation in surface plasmon resonance band (SPRB). The limit of detection (LOD) is 2.2 µM and that of quantification (LOQ) 7.5 µM. The sensor also responded to the trace amount of Hg (II) ions in spiked water samples and in human blood plasma. Recoveries study of spiked real water samples was in range of 95–98%.