Adsorption behavior of phenanthrene onto coal-based activated carbon prepared by microwave activation

Coal-based activated carbon (CAC) was prepared from coal produced in Xinjiang of China by microwave activation. CAC was characterized and used as an adsorbent for phenanthrene adsorption. The effects of temperature, adsorption time, CAC amount, initial concentration and pH value of solution on phenanthrene adsorption were studied. The adsorption rate of phenanthrene onto CAC was obtained nearly 100% with initial concentration of 100 mg/L and CAC dosage of 0.3 g at 25 degrees C. Phenanthrene adsorption was well described with the Langmuir isotherm. The pseudo-second-order model was found to more effectively explain the adsorption kinetics of phenanthrene. The lower temperature was favorable to the adsorption rate and equilibrium adsorption capacity of phenanthrene onto CAC. The thermodynamic parameters Delta H-theta, Delta S-theta and Delta G(theta) computed for phenanthrene adsorption onto CAC demonstrate the process was spontaneous, radiative, and entropically driven. Thus, CAC prepared by microwave activation could be effective for removing phenanthrene.