Enhanced capacitive deionization performance using Mn-doped activated carbon electrodes for energy-efficient brackish water desalination

Abstract

Capacitive deionization (CDI) has emerged as a promising alternative for brackish water desalination due to its low energy consumption and operational simplicity. However, the performance of CDI is highly dependent on the properties of the electrode materials. In this study, Mn-doped activated carbon (Mn-AC) electrodes were synthesized and evaluated for enhanced ion removal efficiency in CDI systems. The Mn doping process was optimized using hydrothermal synthesis with varying KMnO 4 precursor concentrations. Structural characterization via X-ray diffraction, Fourier transform infrared, scanning electron microscopy and elemental mapping confirmed successful Mn incorporation, while thermogravimetric analysis demonstrated improved thermal stability. Electrochemical studies, including cyclic voltammetry and chronoamperometry, revealed that Mn-AC electrodes exhibited higher specific capacitance and superior ion adsorption capacity compared with pristine activated carbon. The CDI performance was evaluated at different applied voltages and NaCl concentrations, demonstrating a significant increase in electrosorption capacity with optimized Mn doping. The highest electrosorption capacity was achieved at +1.2 V with 0.1 M NaCl, where Mn-AC exhibited a 33% higher adsorption efficiency than pristine AC. These findings highlight the potential of Mn-AC as an efficient electrode material for high-performance CDI applications, providing a sustainable and scalable solution for water desalination.