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Kinetics and thermodynamics of the anthraquinone-2,6-disulfonate adsorption on expanded graphite

Xiu-Yan Pang, Fei Gong, Hai-Li Ren, Ting-Ting You

Expanded graphite (EG) is a kind of important adsorbent for organic compound such as oil and dyes. We investigate the adsorption kinetic and thermodynamic characteristics of anthraquinone-2, 6-disulfonate (AQS) on EG which is prepared with 50 mesh crude graphite through chemical oxidation. We study the influence of initial AQS concentration, temperature, pH, ionic strength and EG expanded volume on the adsorption capacity ofAQS from aqueous solution. The equilibrium adsorbance is found to increase with the increase in initialAQS concentration, ionic strength and expanded volume of EG, respectively. But temperature and solution acidity do not have an obvious effect. Adsorption type of AQS on EG is type II. The adsorption isotherms can be described with Langmuir equation. Kinetic studies show that the kinetic data can be described by pseudo second- order kinetic model. Second-order rate constants and the initial adsorption rate increase with the increasing of temperature. Physical adsorption is the major adsorption of the overall adsorption process.