Polystyrene sulfonate coated activated graphene aerogel for boosting desalination performance using capacitive deionization

Abstract

Capacitive deionization (CDI) has proven to be a cost-effective and environmentally friendly desalination process. However, the high salt adsorption capacity is hampered by the poor surface wettability of the electrode materials and a lack of charge in the surface electrode. Despite its unique chemical and physical properties, pure reduced graphene oxide is still far from the expected potential desalination performance. In this work, graphene aerogel (GA) and activated graphene aerogel (AGA) with an ultrahigh specific surface area were successfully synthesized. The AGA was functionalized using a charged polystyrene sulfonate (PSS) and utilized as a negative electrode for the asymmetric CDI configuration cell. The synthesized charged PSS-activated graphene aerogel (PSS-AGA) achieved outstanding hydrophilic behavior, a high specific surface area (1401.53 m2/g), and a typical specific capacitance of 178F/g, furthermore excellent capacitance retention of 97.2 % over 5000 cycles. The salt adsorption capacity of the fabricated electrodes is evaluated by conducting a single-pass mode (SP-Mode) experiment under various conditions. The fabricated PSS-AGA//AGA asymmetric cell configuration delivers an exceptional salt adsorption capacity of 26.33 mg/g, excellent charge efficiency of 88 % with low energy consumption at 1000 mg/L, and full regeneration with long-term stability.