Co-precipitation synthesis of non-cytotoxic and magnetic cobalt ferrite nanoparticles for purging heavy metal from the aqueous medium: Pb(II) adsorption isotherms and kinetics study

Owing to unique physical and chemical properties, nanostructured magnetic materials have proved their efficacy in treating heavy metals from the aqueous system. In this study, oleic acid-coated cobalt ferrite is synthesised by the co-precipitation method for the remediation of Pb(II) ions from an aqueous solution. The synthesised CoFe2O4@OA was characterised by various analytical techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FT-IR) and dynamic light scattering (DLS). The non-cytotoxic behaviour of CoFe2O4@OA suggests it a risk-free adsorbent for the aquatic environment. The mechanism of adsorption reveals that electrostatic interaction, inner-sphere complex formation within Pb(II) ions and CoFe2O4@OA are responsible for the removal. The kinetics experiment followed the pseudo-second-order model with a regression coefficient (R-2) of 0.999. In the isothermal study, equilibrium data were well tuned with the Langmuir isotherm model with a maximum adsorption capacity of 16.7 mg g(-1). The desorption experiment with a series of acid (HCl, HNO3) and alkali (NaOH, KOH) solvents informs the high dependency of desorption efficiency on the solvent type and concentration. Pb(II) ions removal efficiency using 0.5M HCL and 0.6M NaOH was attainted 98% and 82%, respectively, after three cycles. Thus, CoFe2O4@OA maintains sustainable development by reusing and saving the aquatic ecosystem by eliminating Pb(II) ions.