[Removal of Nitrate from Aqueous Solution Using Cetylpyridinium Chloride (CPC)-modified Activated Carbon As the Adsorbent]

Surfactant-modified activated carbon (SMAC) was prepared by loading cetylpyridinium chloride (CPC) onto activated carbon and used as adsorbents to remove nitrate from aqueous solution. The SMAC was effective for removing nitrate from aqueous solution. The SMAC exhibited much higher nitrate adsorption capacity than that of the unmodified activated carbon. The nitrate adsorption capacity for SMAC increased with increasing the CPC loading. The adsorption kinetics of nitrate on SMAC followed a pseudo-second-order kinetic model. The equilibrium adsorption data of nitrate on SMAC could be described by the Langmuir isotherm model. Based on the Langmuir isotherm model, the maximum nitrate adsorption capacity for SMAC with CPC loading amount of444 mmol per 1 kg activated carbon was determined to be 16.1 mg x g(-1). The nitrate adsorption capacity for SMAC decreased with the increasing solution pH. The presence of competing anions such as chloride, sulfate and bicarbonate reduced the nitrate adsorption capacity. The nitrate adsorption capacity for SMAC slightly decreased with the increasing reaction temperature. Almost 95% of nitrate molecules adsorbed on SMAC could be desorbed in 1 mol x L(-1) NaCl solution. The main mechanisms for the adsorption of nitrate on SMAC are anionic exchange and electrostatic attraction. The results of this work indicate that SMAC is a promising adsorbent for removing nitrate from aqueous solution.