Naphthalene-based silica nanoparticles as a highly sensitive fluorescent chemosensor for mercury detection in real seawater

Mercury is considered one of the most harmful contaminants threatening human lives and the aquatic environment. Naphthalene and its derivatives have excellent fluorescence properties that can be exploited for mercury (Hg2+) sensing applications. Herein, we covalently attached naphthalene with silica nanoparticles (NSPs) using one-pot multiple steps synthesis approach. The NSPs were characterized by 1H NMR, FTIR, TGA, FESEM, and UV–vis spectroscopy. The fluorescent properties were analyzed in deionized water under normal and UV-light illumination. Finally, the synthesized NSPs were investigated as a chemosensor for Hg2+ ions detection in real seawater samples via photoluminescence (PL) spectroscopy. The results indicate that the fluorescence properties of NSPs (20 ppm) were quenched upon Hg2+ addition in the range from 0 to 50 ppm. The studies demonstrated that NSPs acted as a potential host for Hg2+ ions compared to other interfering ions present in the seawater sample. The NSPs chemosensor provides a linearity range (5 – 1000 ppb) and limit of detection LOD (1 ppb; 5 nM), even below the values suggested by US EPA drinking water safety regulations, which indicates its potential utilization for mercury sensing in seawater environments.