Nitrogen-grafted activated carbon for removing nitrate from water

Abstract

Nitrate (NO3~) and nitrite (NO2~) ions are ubiquitous in the environment and considered hazardous to humans. The primary health hazard from drinking water containing NO3~ occurs when it is transformed to NO2~ in the digestive system (Robillard et al., 2006). Currently nitrate is removed from water using polymer anion exchangers. However, this process is expensive and requires a lot of brine (NaCl) for the exchanger regeneration. Alternative physicochemical methods such as reverse osmosis are expensive and inefficient. The proposed research aims to develop anion-selective nitrogen-containing activated carbon, NGAC that can be regenerated electrochemically and does not require concentrated brine for regeneration. The key to the selectivity of the NGAC is achieved by the deposition of N-bearing conductive polymers or other species such as polypyrrole, polyaniline, pyridinium, quaternary ammonium, etc. onto the AC surface. Our preliminary results indicate that the polypyrrole charge can remain stable through multiple redox cycles (at least 50).