Influence of calcination atmosphere on Fe doped activated carbon for the application of lead removal from water

In the current work, granular activated carbon (GAC) materials doped with 5 and 10 wt% of Fe were prepared via incipient wetness impregnation method utilizing two different solvents (water and ethanol) and calcined in N2 and static air atmosphere. The prepared materials were thoroughly characterized by FE-SEM, EDS, XRD, FT-IR, XPS and BET surface area techniques. The Fe doped materials were examined for adsorptive removal of lead (Pb2+) ions from aqueous solution. According to the adsorption screening experiments, the 5 wt% Fe doped GAC impregnated in ethanol and calcined under nitrogen demonstrated the highest removal of Pb2+ ions (86.6%). The adsorption results were found consistent with the surface and porous properties of the doped GAC. The 5 wt% Fe-GAC/ethanol/nitrogen illustrated the maximum surface area (715 m2/g), the largest pore diameter and volume, and the lowest size of Fe nanoparticles. The adsorption kinetics, isotherm and thermodynamics were evaluated for the remediation of Pb2+ ions by the optimized adsorbent. The kinetic analysis outcomes found well matched with the pseudo-second order model while the isotherm results modelling were well correlated with Redlich-Peterson, Sips and Langmuir models. The Langmuir highest adsorption capacity of Pb2+ ions was 124.3 mg/g at pH 4.7 and room temperature. The process of Pb2+ ions removal by Fe modified GAC was found as endothermic and spontaneous process as confirmed by the analysis of thermodynamic adsorption parameters. It was anticipated that both chemical and physical mechanisms were participated in the adsorption process including electrostatic interactions, complexation, ion exchange and surface adsorption.