Removal of radioactive palladium based on novel 2D titanium carbides

A series of MXene materials with high specific surface areas was obtained by HF treatment of MAX materials at 25 °C, 35 °C and 45 °C, named MXene-25, MXene-35 and MXene-45, respectively. These materials exhibited excellent ability to remove Pd2+ from HNO3 aqueous solution due to their large specific surface area and wide layer spacing, especially for the materials prepared at higher temperature. Adsorption experiments indicated that these adsorption behavior better fitted the Langmuir model, with the maximum adsorption capacity of Pd2+ being 184.56 mg g−1, 163.82 mg g−1, and 118.86 mg g−1 for MXene-45, MXene-35 and MXene-25, respectively; this is higher than for most other inorganic adsorbents, and is attributed to the wide layer d-spacing and large surface area. Moreover, these materials can retain high selectivity for Pd2+ in simulated nuclear wastewater, and thermodynamic analysis revealed that low temperatures benefit adsorption of Pd2+. Remarkably, MXene-45 exhibits excellent regeneration performance and reusability, with no obvious loss after five cycles of adsorption. The present results suggest that 2D MXene materials are promising adsorbents for removing radioactive palladium from radioactive wastewater.