Niobium MXene Modified Carbon Felt Electrode for the Removal of Cr ⁶⁺ From Metal Bearing Wastewater Through Capacitive Deionization

ABSTRACT In this study, a novel Niobium MXene (Nb 2 CT x ) coated carbon felt (CF) electrode was introduced as a cathode to improve the performance of capacitive deionization (CDI) for the removal of hexavalent chromium (Cr 6+ ) from Cr 6+ metal bearing wastewater. The Nb 2 CT x MXene was synthesized by etching out the Al layer from the Nb 2 AlC MAX phase and characterized. The cyclic voltammetry (CV) analysis shows highest current response for Nb 2 CT x coated CF electrode compared to the bare CF, suggesting larger surface area and electrochemically active sites. CDI performance was analysed using two configurations, symmetric (CF||CF) with bare CF used both for the anode and the cathode and asymmetric (CF||Nb 2 CT x ) with bare CF as the anode and Nb 2 CT x coated CF as the cathode. The removal efficiency of Cr 6+ was studied under various parameters including applied voltage, pH, and initial concentrations of Cr 6+ . The CF||Nb 2 CT x exhibits a remarkable removal efficiency of 94.58% for Cr 6+ at a lower applied potential of 1.5 V within an hour at pH 2, highlighting the energy conservation aspect. This enhanced efficiency in the CF||Nb 2 CT x can be attributed to the superior adsorption capacity of the Nb 2 CT x MXene‐coated cathode, as Nb 2 CT x MXene offers a higher specific surface area, better electrical conductivity, and structural stability, facilitating the effective removal of Cr 6 + . To the best of our knowledge, this is the first report on Nb 2 CT x MXene based CDI system for the removal of Cr 6+ from metal bearing wastewater in comparison to other MXene based systems reported till date. Additionally, the CF||Nb 2 CT x system showed 87.8% removal efficiency even after eight cycles, highlighting the durability of electrode for long‐term CDI applications. The findings highlight the potential of Nb 2 CT x MXene electrode‐based CDI systems for energy‐efficient and sustainable heavy metal remediation in wastewater treatment applications.