In the present study, an analytical method was developed by using graphene oxide (GO) stabilized silver nanoparticles (AgNPs) for colorimetric and naked eye detection of trace Hg2+ in the environmental water samples. In this regard, a stable aqueous dispersion of GO has been synthesized by employing sugar beet bagasse as carbon source. Subsequently, AgNPs were decorated on the surface of as-synthesized GO by in-situ reduction of Ag+. Follow by, Hg2+ detection process was performed by consideration of the influence of several key factors including sensor stability over time, sample pH, response time, selectivity and sensitivity of the sensor. The obtained results revealed that the produced nanosensor has a good sensitivity and selectivity to Hg2+ detection with response time of 2 min with linear range of 10 to 100 μM. The sensing mechanism of analyte was based on the selective amalgam reaction between AgNPs and Hg2+. Moreover, the naked eye detection was investigated by the sensor's color changed from yellow to colorless. The detection limit of the produced sensor was 0.64 nM. This sensor was also applied to detect Hg2+ in the environmental water samples with recoveries in the range of 92.17% to 105.57%. The produced nanosensor exhibited good selectivity of Hg2+ in the presence of high concentration of other ions.
