Chitosan-stabilized Silver Nanoparticles for Colorimetric Assay of Mercury (II) Ions in aqueous system

Mercury is considered as dangerous pollutant. Among the many form of mercury, the most stable and soluble in water is mercury (II) ions which it cause threat to human health and surroundings. Silver nanoparticles (AgNPs) used in this method were prepared by chitosan (chi) which act as stabilizing agent. The Chi-AgNPs has good dispersity with size ranging from 2.50 to 6.00 nm as shown by transmission electron microscopy (TEM) analysis and it is stable for 3 months. Color of Chi-AgNPs fades from brownish-yellow to colorless only with Hg2+ ions, but it shows no significant changes upon addition of other metal ions such as Al3+, Ba2+, Ca2+, Cd2+, Cr3+, Co2+, Cu2+, Fe2+, K+, Mg2+, Mn2+, Na+, Ni2+, Pb2+, and Zn2+. The detection limit for Hg2+ ions by bare-eye is estimated to be similar to 1 mu M. This method can be used for sensing mercury(II) ions in numerous water samples.