Efficient and robust selective defluorination through capacitive deionization: Application of MOF-based Ti/N-doped activated porous carbon

Elimination of fluoride pollution in water is the key to improving the water quality. However, the traditional defluorination methods all have defects such as unsatisfactory results and complicated operation. In this study, we proposed an electrosorption method and prepared a Ti/N metal organic framework derived porous carbon electrode for efficient CDI defluorination. The experimental results showed that the prepared titanium-based porous carbon composites possessed better electrochemical activity and more efficient electrosorption capacity compared with the original materials. The electrosorption capacity of TiNC at 1.2 V was 33.99 mg F- g-1 in an initial solution of 50 mg F- L-1 within 2 h. We further analyzed the electrosorption behavior using adsorption kinetics and isotherm models, from which we can see that chemisorption played an important role in adsorption process. Finally, we elaborated fluoride electrosorption mechanism from the perspectives such as ligand exchange and electrostatic attraction. This study provides a new strategy for the defluorination technology.