Kinetics of Pb (II) adsorption on black carbon derived from wheat residue

The kinetics of Pb (II) adsorption onto black carbon (BC) has been investigated. The BC samples were characterized by the techniques of X-ray diffraction (XRD), scanning electron microscope equipped with the energy dispersive X-ray spectroscope (SEM-EDS) and Fourier transform-infrared spectroscopy (FTIR). Some characteristic parameters including specific surface area, point of zero point and surface acidity/basicity were also determined. The experimental data was analyzed using various adsorption kinetic models – pseudo-first order, the Ritchie second order, the modified second order, the Elovich and the parabolic diffusion models – to determine the best-fit equation for the adsorption of metal ions onto BC. The results show that the modified Ritchie second order equation and Elovich equation fitted the experimental data well. Also, the parabolic diffusion model fitted the experimental data well at the initial stage of adsorption (<60 min), indicating that the process of Pb (II) adsorption by BC was diffusion-controlled.