Preparation of activated carbon electrode for capacitive deionization based on PTFE emulsion spraying technology

Capacitive Deionization (CDI) is a low energy, environmentally friendly desalination technology. In this study, PTFE activated carbon electrodes were prepared based on emulsion spraying technology and applied to CDI. In this article, resistivity, contact angle, specific surface area was tested. Combined with scanning electron microscope(SEM) and cyclic voltammetry(CV), the influence of KH550 dosages (2 g, 4 g, 6 g, 8 g) and layers of spraying (1–6 layers) on electrode performance was investigated. Coupling reagent KH550 played a role to enhance the adhesion of PTFE, and bridge activated carbon to form path for electron together with PTFE. When 4 g KH550 is added, a continuous conductive path was achieved, so the electrode exhibit good conductivity, with a resistivity of 7.65 Ω/cm. As layer increasing, more active carbon, the adsorbent, were joined together by binder, PTFE and KH550. Therefore, the specific surface area and capacitance increased. When 4 layers were sprayed, the electrode obtained a better specific capacitance, 0.564 F/cm2, but the mass transfer resistance became higher. Electrode, prepared by 4 g KH550 and 3 layers, was used for desalination. For low-concentration brine, salt removal rate and charge efficiency were 8.849 mg/g and 46.75%, respectively. This research provides a simple route for the preparation of activated carbon electrodes for the preparation of CDI, which was easy to expand production. The prepared electrode has great application potential in brackish water desalination.