Functionalized silver nanoparticles as chemosensor for pH, Hg2+ and Fe3+ in aqueous medium

A novel p-phenylenediamine (p-PDA) functionalized silver nanoparticles (AgNPs) was applied for the detection of metal ions in aqueous medium. This system showed a visually detectable color change from brownish-yellow to colorless for the selective detection of highly toxic Hg2+. However, the surface plasmon resonance (SPR) absorption band of AgNPs at 411 nm was disappeared with the addition of both Hg2+ and Fe3+ ions due to the aggregation of nanoparticles. Also, this system showed excellent selectivity for Hg2+ and Fe3+ ions over other interfering metal ions including Cu2+, Ni2+, Co2+, Pb2+, Cd2+, Ba2+, Mn2+, Mg2+, Fe2+, Al3+ and Zn2+. The developed system is simple and sensitive to detect Hg2+ and Fe3+ ions with a detection limit down to 0.80 μM and 1.29 μM, respectively. Furthermore, this system can also be used as a colorimetric sensor for the detection of low pH.