Equilibrium and Kinetic Modeling for the Adsorption of Three Phenolic Compounds onto Cement Kiln Dust

Phenolic compounds; classified as priority pollutants by Environmental Protection Agency (EPA), exist widely in many of the industrial effluents such as those from oil refineries, coal tar, plastics, leather, paints, pharmaceutical and steel industry. In the present study, cement kiln dust (CKD) was investigated as an adsorbent for three phenolic compounds (o-cresol, o-chlorophenol and o-nitrophenol). Equilibrium and kinetics properties of the adsorption process were studied. The experimental data was found to best fit Langmuir model. Also, the results have been proven the favorability of cement kiln dust for removal of the phenolic compounds with chemisorption to be the mechanism of adsorption. The maximum adsorption capacity was found to be 100 mg/g for o-cresol, 167 mg/g for o-chlorophenol and 125 mg/g for o-nitrophenol. The adsorption process was found to be rapid for the three adsorbates. The equilibrium was attained faster in case of o-nitrophenol compared with the other two compounds. The film diffusion was found to control the adsorption process.