Application of pitch-based multi cavity carbon microsheets in capacitive deionization removal of NO3–

Abstract

Capacities deionization (CDI) denitrification technology has attracted considerable attention, and electrode materials with nitrate adsorption properties have become a research hotspot. In this study, a multi cavity carbon microsheets (MCCM-5) was prepared using a hard template method and low-cost nitrated pitch as a carbon source. The results of the electrosorption experiments showed that the material had an excellent capacity of NaNO3 (45 mg g−1). Furthermore, although the actual specific surface area and specific capacitance of MCCM-5 are lower than those of hierarchical porous carbon materials (HPCM-1), MCCM-5 exhibit lower diffusion and charge-transfer resistances, resulting in a better denitrification performance. The adsorption capacity of MCCM-5 for NaNO3 was twice that HPCM-1 and 11.8 times that of commercial activated carbon, which is superior to the material properties reported thus far. Our analysis indicated that the material combined the advantages of both a layered structure and hierarchical pores. First, the uniformly distributed hierarchical pores in the layered structure enhanced the ion concentration potential. Second, the layered structure provided good ion diffusion channels, thereby increasing the effective adsorption area of the material. DFT calculation shows that the carbon cavity structure enriched in the material shows a stronger adsorption capacity for NO3–, which can promote the electron transfer process during NO3– adsorption. This study shows that a precise regulation of the carbon material structure can be achieved by adjusting the size of the template material and carbonization conditions to obtain a higher adsorption capacity and provides a new idea for the structural optimization of electrode materials.