Removal of nitrate from aqueous solution using modified granular activated carbon

Abstract

In this study, a commercial granular activated carbon was modified with sodium hydroxide followed by a cationic surfactant to increase its efficiency for nitrate removal from water. Physicochemical properties of untreated activated carbon and treated activated carbons were characterized in the terms of FTIR spectroscopy, N2 adsorption-desorption, and SEM analyses. The surface properties of ACs were determined by N2-adsorption isotherm data and modeled with several mathematical models. The results showed that the combination of two treatments could improve the nitrate removal efficiency, which is mainly attributed to the modification by cationic surfactant, while the porous volume and specific surface area did not seem to play an important role in the nitrate uptake. In batch experiments, the influence of several operating parameters on the nitrate adsorption capacity was investigated including solution pH, adsorbent dosage, contact time, initial nitrate concentration, temperature and competing ions. Small continuous column test was performed to investigate the feasibility of using each adsorbent. Results of this study suggest that using two-step treatment can be a promising method to enhance the efficiency of activated carbon for nitrate removal from water.