Eco friendly synthesis of gold and silver nanoparticles for selective and ultrasensitive spectroscopic detection of mercuric ion in aqueous systems

Abstract

Metal poisoning in humans can cause health hazards such as insomnia, mental retardation, nervous disorders and blindness. Most of the commonly used toxic metals are mercury, arsenic, lead and cadmium. Among these toxic metals, mercury (Hg) has been declared to be highly toxic by the World Health Organization (WHO) and Environmental Protection Agency (EPA). Mercury can exist in three oxidation states, namely Hg0, Hg1+ and Hg2+, newlineamong which the mercurous ion possesses the lowest reactivity and hence is less toxic than the other forms. The metallic mercury and mercuric ion are amenable for facile oxidation / reduction in aqueous environments to produce the highly toxic methyl mercury. Mercury poisoning is known to cause severe impairment of the cardiovascular system, central nervous system and kidney leading to severe health damage, or even death. Thus, it is of high significance to improve the efficiency of mercury detection in potable water. Several analytical methods have been developed to meet these demands and some of these techniques have found application for routine analysis. Among the various methods, UV/Visible spectrophotometry and fluorescence spectroscopy have received great attention in the determination of mercuric ions in very low concentration, due to their high selectivity and sensitivity towards the metal ions. Sensors that can detect Hg and Hg2+ in aqueous newlinesolutions can be based on metals, metal oxides, metal alloys and carbon-based materials. The concentrations of the targets are estimated through the analytical estimation of the sensor-target systems. Metals in nano size have exhibited unique optical properties that have been beneficially used for the detection of organic moieties and metals in aqueous and non-aqueous environments newline newline