Colorimetric detection of Hg(II) ions present in industrial wastewater using zinc nanoparticle synthesized biologically with Rauwolfia vomitoria leaf extract

Abstract

This study highlights the synthesis of zinc nanoparticle using Rauwolfia vomitoria leaf extract for the colorimetric detection of Hg (II) ions in industrial wastewater. Characterization of zinc nanoparticlcles using UV-vis spectroscopy, revealed that maximum absorption was obtained at 219nm which indicated surface plasmon absorption of zinc nanoparticle. The XRD analysis of the zinc nanoparticle indicated that the zinc nanoparticles formed are crystalline in nature with a mixed irregular phase structure (polygonal and spherical) in shape. The average crystallite size of the zinc nanoparticle was found to be 57nm. FTIR analysis was carried out to ascertain the possible functional groups responsible for the reduction of zinc ion to zinc nanoparticle. The reduction was observed by the disappearance of C-O (due to ether) in the FTIR spectrum of the reduce compound, which that this functional group was involved in the reduction of zinc ions to zinc nanoparticle. Scanning electron microscopy (SEM) revealed that the morphology of the zinc nanoparticle possessed polygonal, spherical or faceted shape of various sizes that are agglomerated. Further magnifications revealed that these images possessed rough surfaces. Detection of Hg(II) ions in industrial wastewater using the colloidal zinc nanoparticle was feasible  even at very low concentration. However, absorption peak became more intense with increasing concentration. The results and findings of our study provide commendation for the use of economic synthesis of zinc nanoparticle in the detection of Hg (II) ions present in industrial wastewater.