Green Synthesis of Magnetite Nanoparticles Using Catha Edulis Plant Leaf Extract for Removal of Hexavalent Chromium from Aqueous Solution and Antibacterial Application

Abstract

Hexavalent Chromium pollution in aquatic environments is a serious problem for living organisms and public health. In addition, the emergence of drug resistant bacterial strains has become a threat to human health. A number of researches are being carried out to address the problem and minimize chromium related pollutions and also search for alternative metal based antibacterial treatments. In this study Magnetite (Fe3O4) Nanoparticles synthesized using Catha edulis plant leaf extract were investigated as adsorbent for Cr(VI) removal from aqueous solutions and also as antibacterial agent. The synthesized NPs were characterized by using X-ray diffraction (XRD) spectroscopy, Fourier Transforms Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Ultraviolet-visible (UV-Vis) spectroscopy, and thermal analysis (TGA-DTA). The XRD result revealed that the phase structure of Fe3O4 NPs was cubic face-centered with crystallite sizes of 12.1 nm, 14 nm, and 9 nm for metal to plant extract ratios of 1:1, 2:1, and 1:2 NPs respectively. UV-vis DRS confirmed band gap energy of synthesized NPs was found to be ranging from 2-2.5 eV. The batch adsorption experiment was used to evaluate the efficiency of the adsorbent by varying the different parameters such as pH (3-10), adsorbent dose (250mg – 1250mg), initial concentration of adsorbate (20mg/L - 60mg/L), and contact time (20-100 min) at room temperature. The concentrations of Cr(VI) were measured using ultraviolet-visible (UV-Vis) spectrophotometry with 1, 5 diphenylcarbazide at 540 nm. Cr(VI) removal efficiency of Fe3O4 was found to be 98.6% from an aqueous solution at the initial concentration of 20 mg/L. The experimental data were best fitted to the Freundlich adsorption isotherm model (R2 = 0.98341). Moreover, the mechanism of adsorption was in good agreement with pseudo 2nd order kinetics (R2=0.98188). The results suggested that the biosynthesized Fe3O4 nanoparticles have the potential for the removal of hexavalent chromium ions. In addition to this, the synthesized Magnetite (Fe3O4) Nanoparticles were evaluated for antibacterial activity by the disk diffusion method and 100μg/mL concentrations of Fe3O4 NPs (1:2) showed better activity against S. aureus with a zone of inhibition of 12 mm followed by S. pyogen and E.coli with zone of inhibition of 11 mm in both cases.