Porous carbon flow-electrode derived from modified MOF-5 for capacitive deionization

Abstract

Flow electrode capacitance deionization technology (FCDI) has drawn an increasing interest as a new strategy for desalination. In this paper, we demonstrated the possibility of porous carbon flow-electrode derived from modified MOF-5 by graphene oxide (C-MOF@G) for capacitive deionization. After adding graphene oxide (GO) as a supporting frame, the prepared C-MOF@G with porous structure remarkably enhanced the specific surface area as high as 933.72 m2/g, which was approximately 3.1 times than that of common MOF-5 derived carbon (C-MOF) in the absence of GO. The complex pore structure was conductive to strengthening ion migration and diffusion. This result exhibited a distinct contrast with commercial activated carbon (AC). At an applied voltage of 1.2 V, a flow rate of 20 mL/min, a carbon content of 4 % and 1 g/L NaCl, C-MOF@G exhibited the remarkable desalination rate of 68.4 μg/cm2/min, accounting for the values being 1.8 and 8.7 times than that for C-MOF and AC. Meanwhile, the desalination energy consumption and efficiency kept relatively stable after the five continuous desalinations cycling. Then this modified MOF-5 derived carbon as flow-electrode will provide a new candidate for the FCDI system, which makes the desalination process much more economical and efficient in the future.