Color precipitate sensor by nano zerovalent iron for naked eye selective detection of Pb+2

Heavy metal pollution in water is a worldwide and serious environmental issue due to their toxicity and carcinogenicity [1]. Rapid and high precision detection of toxic metal ions is one of the chief requirements today to combat environment pollution [2]. Pb+2 poisoning, is great attention due to its serious ill effects. It causes many diseases like skin lesions, cancer, heart and lung related problems etc, in human beings [1].In this work we synthesized a simple, inexpensive and clean nano zerovalent iron wich was used as a colorimetric precipitate naked eye sensor for detection of pb2+ in aqueous solution. NZVI was synthesized by reduction of ferric ion (Fe+3) in ethanol medium with starch in the presence of Ascorbic acid. The formation of nanoparticles was confirmed by ultra violet spectroscopy (UV-vis) and characterized by particle size analyzer (DLS), FESEM, energy dispersive spectroscopy (EDX). The fresh synthesized nanoparticles are black in color. In the presence of pb2+ the NZVI solution was turned to colloidal immediately and brown precipitate was observed. The supernatant was colorless. The NZVI aggregate in presence of pb+2 .While other alkali metal (Na+, K+), alkali earth metal (Mg2+,Ba2+,Sr2+) and Transition –metal ( Co2+, Zn2+, Na2+, Cd2+,V3+) and Al3+ ions did not show any change. The lowest Pb2+ concentration by naked eye was 7.5 × 10-1 mmol L-1. These results indicate that the synthesized NZVI can be used for selective and sensitive colorimetric detection of Pb2+ .