Detection of Mercury Ions Using PVP-Capped AgNPs for Wastewater Analysis

The present study reports comparative qualitative and quantitative detection of Hg2+ by using polyvinyl pyrrolidone-capped silver nanoparticle (PVP-AgNPs) from aqueous sample in a colorimetric detection system of PVP-AgNPs/aspartic acid/Hg2+ and PVP-AgNPs/L-arginine/Hg2+. PVP-AgNPs were synthesized using chemical reduction method. The prepared PVP-AgNPs were characterized by UV–visible spectrophotometer. On addition of electron-rich molecules like aspartic acid and L-arginine, the as-synthesized yellow colored PVP-AgNPs form conjugate with them. However, on addition of Hg2+, the solutions turn yellow to colorless. The variation in the intensity of yellow color which eventually turns colorless at higher concentration of Hg2+ can be utilized for the colorimetric sensing of Hg2+. This assay shows immediate color change with a naked-eye detection limit of 200 μM each for PVP-AgNPs/aspartic acid/Hg2+ and PVP-AgNPs/L-arginine/Hg2+ detection systems, respectively. Hg2+ is quantitatively determined using a UV–Vis spectrophotometer. PVP-AgNPs/L-Arginine/Hg2+ had better detection limit of 11.402 μM compared to 13.784 μM for PVP-AgNPs/aspartic acid/Hg2+ system.  This study concluded that PVP-AgNPs in the presence of a conjugating agents like L-arginine and aspartic acid can be helpful in development of colorimetric sensors for detection of Hg2+.