Sustainable synthesis of emerging bio-based magnetite nanoparticles for efficient removal of Cr(VI) from groundwater

A facile, one-pot, rapid and cost-effective green synthesis approach is adopted for synthesis of spherical magnetite nanoparticles (Fe3O4) using Averrhoa carambola leaf extract for removal of Cr(VI). The polar biomolecules of leaf extract act as non-toxic surfactants and as reducing as well as stabilizing agents. The morphological, structural and optical properties of bio-based magnetite nanoparticles were characterized by FESEM, XRD, FT-IR, UV-VIS DRS and Raman analysis. The batch biosorption of Cr(VI) was investigated at different experimental limits such as contact time, temperature, pH, adsorbent dose and metal concentration. The experimental data was well fitted to Langmuir adsorption isotherm and found to follow linear pseudo-second-order kinetics. The maximum biosorption efficiency of bio-based magnetite nanoparticles was recorded 99.34% and can be reused proficiently upto 7 cycles. The mechanism for role of biomolecules in synthesis of nanoparticles along with the mechanism for biosorption of Cr(VI) over bio-based magnetite nanoparticles were discussed. The bio-based magnetite nanoparticles can be effectively used for removal of Cr(VI) from groundwater in contaminated areas.