Enhanced Selective Electrosorption of Nitrate from Wastewater by Controllably Doping Nitrogen into Porous Carbon with Micropores.

The biological NO 3 - removal process might be accompanied by high CO 2 emissions and operation costs. Capacitive deionization (CDI) has been widely studied as a very efficient method to purify water. Here, a porous carbon material with a tunable nitrogen configuration was developed. Characterization and density functional theory calculation show that nitrogenous functional groups have a higher NO 3 - binding energy than Cl - , SO 4 2- , and H 2 PO 4 - . In addition, the selectivity of NO 3 - is improved after the introduction of micropores by using the pore template. The NO 3 - ion removal and selectivity of MN-C-12 are 4.57 and 3.46-5.42 times that of activated carbon (AC), respectively. The high NO 3 - selectivity and electrosorption properties of MN-C-12 (the highest N content and micropore area) are due to the synergistic effect of the affinity of nitrogen functional groups to NO 3 - and microporous ion screening. A CDI unit for the removal of nitrogen from municipal wastewater was constructed and applied to treat wastewater meeting higher discharge standards of A (N: 15 mg L -1 ) and B (N: 20 mg L -1 ) ((GB18918-2002), China). This work provides new insights into enhanced carbon materials for the selective electrosorption of wastewater by CDI technology.