Mesopore dominated capacitive deionization of N-doped hierarchically porous carbon for water purification

Under the global shortage of freshwater resources, capacitive deionization (CDI) has attracted widespread attention as an efficient and energy-saving water purification technology. Herein, N-doped hierarchically porous carbons (NPCs) with micro-meso-macropore, excellent specific capacitance (194.75 F g(-1)), large specific surface area (1903.0 m(2) g(-1)), high mesoporous content, and fast ion transport capability were prepared by the pyrolysis of polyacrylonitrile using nano-silica and ZnCl2 as pore-making agents. As CDI electrode materials for desalination and heavy metal adsorption, the optimized NPC-0.75 electrode delivered a maximum electrosorption capacity of 19.61 mg g(-1) at the optimum operating parameters (1.2 V, 10 mL min(-1), 500 mg L-1 NaCl) and an excellent regeneration performance after continuous electrosorption-desorption cycles. The structure-activity relationship analysis indicated that the mesopore dominates the CDI performance of NPCs in water. In addition, NPC-0.75 electrode showed a high removal capacity for Cu2+ (36.3 mg g(-1)), Cd2+ (30.02 mg g(-1)) and Pb2+ (21.5 mg g(-1)) in water. This study provides new insight into the design of high-efficiency porous carbons toward the CDI from water.

Automated summary

N-doped hierarchically porous carbons with excellent adsorption capacity and fast ion transport capability were prepared and used as CDI electrode materials for efficient removal of heavy metal pollutants from water.