Green route of silver nanoparticles synthesis using watermelon (Citrullus lanatus) fruit extract for mercury ions detection

In this paper, we report the green synthesis of silver nanoparticles using a reductant of fruit extract of watermelon (Citrullus lanatus), and its application for mercury ions detection. Silver nanoparticles were made from small amount of silver nitrate, assisted with sunlight irradiation. After 30 minutes of irradiation, the yellowish-brown silver nanoparticles were formed with peak absorbance at 420 nm wavelength. The formed silver nanoparticles were then tested to various alkaline, alkaline earth and transition metals. Most of the metals has no effect to the silver nanoparticles except for mercury ions that change the color of silver nanoparticles to colorless. Therefore, silver nanoparticles are selective to detect mercury ions in aqueous solution. Compared to the reference method, the developed colorimetry method for mercury ions detection was accurate up to 99.38%.