Mycosynthesis of iron oxide nanoparticles using manglicolous fungi isolated from Indian Sundarbans and its application for the treatment of chromium containing solution: Synthesis, Adsorption isotherm, Kinetics and Thermodynamics study

Abstract The study describes mycosynthesis of iron oxide nanoparticles (IO-NPs) synthesized using manglicolous fungi isolated from Indian sundarbans which subsequently used for the treatment of Cr(VI) from synthetic waste water. Cell Free Filtrate (CFF) of 5 isolated fungi was screened to identify their potentiality to hydrolyze the mixture of FeCl2 and FeCl3 salts for the production of IO-NPs. The extracellular bio-reduction was observed by changes in the colour of CFF which was monitored by analysing the reaction mixture in UV-Vis Spectrophotometer. The bio-synthesized particles were characterised by Fourier transform infrared (FTIR) spectroscopy for determining the involvement of fungal proteins with iron-nanoparticle. The shape of IO-NPs was found to be spherical as confirmed by Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM). Size of the IO-NPs was found to be ranging between 2-16 nm. Energy Dispersive spectroscopy (EDS) analysis was performed during FESEM and TEM study to confirm the presence of elemental Fe in the sample. Selected Area Electron Diffraction (SAED) and X-Ray Diffraction (XRD) pattern confirmed the elemental and crystalline nature of mycosynthsized IO-NPs. The IO-NPs studied in Vibrating Sample Magnetometer (VSM) at different temperature showed superparamagnetic property. Batch studies were conducted for the treatment of Cr (VI) containing solution in different experimental conditions like adsorbent dose (0.2-1 g/L), pH (2-8) and temperature (293-313 K). The data recorded were subjected to different isotherm and kinetic model. Langmuir isotherm model and Pseudo second order kinetic model was determined as best fitted isotherm and kinetic model respectively. The removal mechanism of Cr(VI) from synthetic waste water by IO-NPs was found to be chemisorption in nature, where IO-NPs showed 4.623 mg/g of adsorption capacity. Thus the present study demonstrates a novel approach where mycosynthesized IO-NPs had shown effective result for the treatment of waste water.