Intraparticle diffusion of cadmium and zinc ions during adsorption from aqueous solution on activated carbon

The adsorption isotherms of cadmium(II) and zinc (II) onto activated carbons were obtained in a batch adsorber. The concentration decay data were obtained in a rotating basket adsorber and were interpreted by a mathematical model, which takes into account the adsorption rate, external mass transport and intraparticle diffusion. The results showed that the overall rate of adsorption of Cd(II) and Zu(II) was mainly controlled by the intraparticle diffusion which was solely due to pore volume diffusion. The contribution of the external mass transport resistance was negligible. The effective pore volume diffusivities of Cd(II) and Zn(II) were predicted reasonably well using the ionic diffusivity of the metal and the void fraction and tortuosity of activated carbon. © 2005 Society of Chemical Industry.

Activated carbon; Adsorption rate; Heavy metal; Intraparticle diffusion Activated carbon; Adsorption isotherms; Cadmium; Concentration (process); Decay (organic); Ions; Mathematical models; Zinc; Adsorption rates; Batch adsorbers; Concentration decay; Ionic diffusivity; Diffusion; activated carbon; cadmium; zinc ion; heavy metal; adsorption; aqueous solution; article; concentration (parameters); controlled study; diffusion; isotherm; mathematical computing; mathematical model; statistical analysis; statistical significance

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