Phytofabrication of iron nanoparticles and their catalytic activity

Abstract

Metallic nanoparticles that have photocatalytic activity can be synthesized using aqueous plant extracts. The aim of this study was to synthesize iron nanoparticles using Lantana trifolia extracts and to evaluate their ability to degrade Congo red dye. The nanoparticles were characterized using UV–Vis spectrophotometer (UV–Vis), Fourier transform infra-red spectrophotometer, wide angle X-ray diffractometer, dynamic light scattering, transmission electron microscopy (TEM), and thermal gravimetric analyzer to determine the functional groups, thermal properties, crystalline phases and diameter distribution of the particles. Cyclic voltammetry was used to evaluate the redox potential of the extracts while photocatalytic activity of the nanoparticles was evaluated using a UV–Vis spectrophotometer. Functional groups analysis revealed presence of secondary metabolites having OH and C=C groups while a redox potential of + 0.3 V was an indication that the extracts can reduce iron. The presence of sharp peaks at 2θ values of 19.87°, 20.22°, 22.88°, 28.81°, 32.73°, 35.32°, 38.45°, 40.23° and 41.08° correspond to cubic crystal system of iron nanoparticles while particle aggregation was observed on TEM micrographs which also indicated that they were less than 200 nm. In the presence of H2O2, the nanoparticles catalyzed degradation of Congo red dye in a first order reaction that was temperature dependent. In conclusion, secondary metabolites in L. trifolia can reduce metallic ion to iron nanoparticles which can degrade Congo red dye.