Utilization of peanut shells for the fabrication of high-performance activated carbon electrodes in capacitive deionization

Capacitive deionization (CDI) has emerged as an effective method for seawater desalination owing to its low energy consumption and high efficiency, with the development of cost-effective and high-performance electrodes being a key focus. In this study, porous activated carbon derived from peanut shells was prepared using the chemical activation method with varying ratios of potassium hydroxide. The resulting materials were characterized and tested to investigate the effects of different potassium hydroxide ratios on their pore structure and electrosorption properties. The biochar obtained at a mass ratio of 4 for KOH to activated carbon (PSAC4) exhibited the highest specific surface area (3032.26 m 2 g −1 ). Additionally, PSAC4 demonstrated excellent electrochemical performance with a capacitance of 182.39 F g −1 (5 mV s −1 ) and a charge transfer resistance of 0.46 Ω. PSAC4 demonstrated a salt adsorption capacity of 22.40 mg g −1 (at 1.2 V and 500 mg L −1 NaCl), exhibiting an average salt adsorption rate of 14.93 mg g −1 min −1 and maintaining 19.36 mg g −1 (86%) adsorption capacity after 20 cycles of adsorption/desorption, thereby highlighting the potential of peanut shell activated carbon as a high-performance electrode for capacitive deionization.