Kinetic and equilibrium characterization of phenols adsorption onto a novel activated carbon in water treatment

The present study envisages the use of an aquatic plant material, water hyacinth to prepare a novel activated carbon for the removal of phenol, p-chlorophenol and p-nitrophenol from simulated wastewaters by adsorption process. The effect of pH, contact time, initial concentration of adsorbate and temperature on removal process was investigated. The maximum removal of phenols from their aqueous solutions occurred at pH 6.0. The applicability of the intraparticular mass transfer diffusion kinetic model in each case of phenol, p-chlorophenol and p-nitrophenol was studied separately at different concentrations and temperatures. Kinetic parameters as a function of concentration and temperature were evaluated to predict the nature of adsorption. The adsorption process was found to be exothermic and the adsorption of phenols was found to follow the order: p-nitropherol > p-chlorophenol > phenol. Equilibrium adsorption data were correlated with Langmuir, Freundlich and Redlich-Peterson adsorption isotherm models. Freundlich isotherm model was found applicable to represent the adsorption data for all three adsorbates. The maximum adsorption capacity of activated carbon was found to be 1.20, 1.28 and 1.35 mmol/g for phenol, p-chlorophenol and p-nitrophenol respectively. Adsorbed phenols on activated carbon were recovered (91.5-96.3%) using 0.05 M sodium hydroxide. The petroleum refinery industry wastewater sample was treated by activated carbon to demonstrate its efficiency in removing phenols from wastewaters.