The structure and adsorption properties of the modified coke powder

The chemical modification of coke powder by HNO₃ was reported in this paper. The structure and composition of the coke powder were analyzed using scanning electron microscope (SEM), X-ray photoelectron spectroscopy(XPS), X-ray diffraction (XRD). The effect of the HNO₃ concentration on the adsorption capability as well as the adsorption kinetics of the modified coke powder was investigated. In the modification, the coke powder was etched and oxidized in HNO₃ solution, resulting in an increase in specific surface area and formation of large numbers of oxygen-containing function groups. The adsorption property of the modified coke powder by HNO₃ (50% vol.) was optimum. The adsorption capacity of the modified coke powder to methylene blue increased during 200 min and kept subsequently constant. The adsorption process could be modeled by Longmuir or Freundlich adsorption isotherm equation and had a good correlation with the Ho´s second-order rate equation.