Dye adsorption onto iron oxide prepared by green method mediated by leaf extract of Falcaria vulgaris

Abstract

ABSTRACT Iron oxide nanoparticles were green synthesised by Falcaria vulgaris extract. Characterisation of samples was carried out by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). Investigating factors, such as pH, adsorbent dosage, temperature, contact time and the dose effect of the initial concentration of methylene blue dye, was done on adsorption of methylene blue. The synthesised nanoparticles exhibited a relatively spherical and irregular surface, with a size of about 35 nm, a haematite crystal phase and a saturation magnetisation of 8.3 emu/g. The highest adsorption of methylene blue (76%) was achieved at a pH value of 6, with an optimal adsorbent quantity of 0.004 g/L and a starting concentration of 80 mg/L. The adsorption behaviour of synthesised iron oxide nanoparticles follows from Langmuir isotherm and has a maximum adsorption capacity of 49.169 mg/g. The kinetics of methylene blue dye removal using iron oxide nanoparticles followed a second-order kinetic equation. The adsorption activity of iron oxide nanoparticles showed very little change even after two regeneration cycles. Therefore, the obtained adsorbent regained its adsorption capacity with the help of the photo-Fenton process and is reusable again.