Photocatalytic degradation of synthetic dyes using iron (III) oxide nanoparticles (Fe 2 O 3 -Nps) synthesised using Rhizophora mucronata Lam.

Biosynthesis of nanoparticles through plant extracts is gaining attention due to the toxic free synthesis process. The environmental engineering applications of many metal oxide nanoparticles have been reported. In this study, iron oxide nanoparticles (Fe ₂ O ₃ -Nps) were synthesised using a simple biosynthetic method using a leaf extract of a mangrove plant Rhizophora mucronata through reduction of 0.01 M ferric chloride. Fe ₂ O ₃ -Np synthesis was revealed by a greenish colour formation with a surface plasmon band observed close to 368 nm. The stable Fe ₂ O ₃ -Np possessed excitation and emission wavelength of 368.0 and 370.5 nm, respectively. The Fourier-transform infrared spectral analysis revealed the changes in functional groups during formation of Fe ₂ O ₃ -Np. Agglomerations of nanoparticles were observed during scanning electron microscopic analysis and energy-dispersive X-ray spectroscopic analysis confirmed the ferric oxide nature. The average particle size of Fe ₂ O ₃ -Np based on dynamic light scattering was 65 nm. Based on transmission electron microscopic analysis, particles were spherical in shape and the crystalline size was confirmed by selected area electron diffraction pattern analysis. The synthesised Fe ₂ O ₃ -Np exhibited a good photodegradation efficiency with a reduction of 83 and 95% of phenol red and crystal violet under irradiation of sunlight and florescent light, respectively. This report is a facile synthesis method for Fe ₂ O ₃ -Np with high photodegradation efficiency.