Film-pore diffusion modeling for sorption of azo dye on to exfoliated graphitic nanoplatelets

Exfoliated graphitic nanoplatelets (xGnPs) have been utilized as a potential adsorbent for toxic textile dye Acid Orange 7 (acid dye). The effects of major variables governing the efficiency of the process, such as temperature, initial dye concentration and pH are studied. The kinetic measurements have been used for determining the specific rate constant, confirming the applicability of pseudo first-order rate expression. Plausible mechanism of ongoing adsorption process involved is obtained by carrying out kinetic measurements. To identify whether the ongoing process is particle diffusion or film diffusion, the treatments given by Boyd and Reichenberg have been employed. The influence of different factors on the adsorption of Acid Orange 7 from solution is explained in terms of electrostatic interaction by considering the dye species and the surface character of the xGnPs. The developed system for the removal of acid dye is found to be very useful, economic, rapid and reproducible.