Magnetic-assisted strategy for performance enhancement of flow-by capacitive deionization

Abstract

Capacitive deionization is an environment friendly electro-sorption desalination technology that has broad application prospects in high-efficiency seawater desalination and brackish water purification. However, the insufficient ion separation performance and desalination capacity restrict the large-scale application of capacitive deionization with flow-by structure. Since the separation of cations and anions is intensified via the synergetic manipulation of the electric field force and Lorentz force, a magnetic-assisted strategy was proposed to enhance the performance of capacitive deionization. The effects of magnetic field strength and layout on the desalination performance of capacitive deionization were experimentally investigated. The results confirmed the feasibility of performance enhancement via the effect of the magnetic field. The performance of capacitive deionization under a vertical magnet layout was increased by 25.2 % at a magnetic field strength of 0.33 T, compared to that without a magnetic field. However, the deionization performance decreased when the magnetic field strength was further increased to 0.45 T, which indicates the existence of a critical magnetic field strength. Benefitting from the superposition of magnetic fields, the horizontal layout of magnets can provide a stronger average magnetic field than the vertical layout. This study provides insights into a new design of flow-by capacitive deionization.