Column studies on the removal of chromium, lead, and Arsenic (Cr6+, Pb+2, and As3+) ions using graphene coated iron oxide (GCIO) as efficient nanoadsorbents.

The efficient graphene coated iron oxide (GCIO) nanoadsorbent was prepared for removal of various ions, viz., Cr(VI), Pb(II), and As(III), by coating graphene onto the iron oxide surfaces taken as a base material. The as-prepared nanoadsorbent was further characterized by several analytical techniques such as Fourier transform infrared (FTIR) spectroscopy, energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Raman spectroscopy, Differential scanning calorimetry (DSC), and Zeta-potential measurements, respectively. These techniques provided valuable information about the nanoadsorbent and confirmed the interactions between Cr6+, Pb2+, and As3+ ions and the nanoadsorbent. The effect of concentration of adsorbate solution, contact time between adsorbate–adsorbent, and flow rate of adsorbate were studied using a sensitive, simple, and selective spectrophotometric method that enabled quantification of Cr6+, Pb+2, and As3+ ions, respectively. Various modeling of breakthrough curves was applied for monitoring progress of the adsorption process and the results showed that the three metal ions followed second order kinetic model thus confirming that GCIO is an excellent, effective, and economic adsorbent. [ABSTRACT FROM AUTHOR]