Biogenic synthesis of maghemite nanoparticles (γ-Fe2O3) using Tridax leaf extract and its application for removal of fly ash heavy metals (Pb, Cd)

Abstract

This study investigated the applicability of maghemite (γ-Fe2O3) nanoparticles for the selective removal of toxic heavy metals from the 20% aqueous solution of fly ash. Maghemite nanoparticles of size 20-40 nm was synthesized by using leaf extract of Tridax plant by sonochemical process as confirmed by HRTEM. The spherical shape and aggregation of the particles revealed by SEM and EDS spectra showed the peak for Fe and O along with Carbon and Na. Na is present as an impurity, due to improper washing and C from the plant extract. XRD, FTIR and Raman confirmed the micro-structure of the maghemite nanoparticle and its crystalline nature. The magnetization was 1.258 emu analysed by VSM. A 20% fly ash solution used as source heavy metal and after every regular time interval an aliquot of sample was collected and analysed by ICP-OES. Pb was removed up to 85% within two hours only and at 24 hours it was removed up to 96%. While Cd concentration reached below the ND value i.e. 0.01 ppm after two hours.