Phenol removal from aqueous phase by adsorption on activated carbon prepared from paper mill sludge

A new activated carbon was synthesized using paper mill sludge as a low cost waste material. It was employed to remove phenol from aqueous solution in the concentration range of 0–60 mg/l and temperature range of 25–45°C. The adsorbent characteristics were determined by different analyses such as BET, FTIR, and SEM. The effects of pH, adsorbent dosage, initial phenol concentration, contact time, and temperature on phenol adsorption were investigated. The maximum adsorption capacity of 15.04 mg/g was obtained at optimum condition. The equilibrium experimental data were analyzed by several model isotherms. The best-fitted adsorption models were found to be in the order: Langmuir–Freundlich > Freundlich > Langmuir. The kinetics of phenol adsorption was investigated using different kinetics models. Experimental kinetic data were well described by the pseudo-second-order model. It was found that the temperature had negative impact on the phenol removal. Thermodynamic parameters such as Gibbs free energy, the enthalpy, and the entropy changes were determined. The results indicated that phenol adsorption process was spontaneous, exothermic, and controlled by physical sorption mechanism. Finally, the results revealed that the paper mill sludge can be employed as a promising raw material in terms of economical and technical aspects for the removal of contaminants from wastewaters.