Ag-decorated monolithic carbon sponge with porous directional frameworks for chloride removal in flow-through capacitive deionization

Abstract

The structure and composition of monolithic electrodes have offered a great advantage for the flow-through capacitive deionization (FT-CDI) process. However, developing a high-performance monolithic electrode with both high desalination capacity and favorable mechanical properties is an enormous challenge to solving the problem of water pollution. Herein, we fabricate an Ag-decorated monolithic carbon sponge (MCS) with directional pore channels (Ag@DMCS) to serve as an FT-CDI electrode by employing NH2-rich poly(m-phenylenediamine)@Fungi (PmPD@Fungi) as a matrix. Ag ions were effectively loaded onto the matrix due to the strong affinity of the NH2 for Ag. Moreover, the cold field effects through the directional ice templating allows the MCS electrodes to construct a unique porous structure with a directional arrangement, further facilitating the fluid flow through the electrode. The results indicated that the Ag@DMCS achieves a superior Cl- adsorption capacity of 68.74 mg g−1 and rapid adsorption of 0.19 mg g−1 s−1 due to the directional pore channels and the uniform loading of Ag nanoparticles. Pressure-drop tests and computational fluid dynamics (CFD) revealed that the directional pore channels in the Ag@DMCS electrodes enabled the system to lower fluid resistance and more uniform pressure distribution during the FT-CDI process. The Ag@DMCS electrode is anticipated to be a promising alternative material for extracting Cl- by the FT-CDI system.