Selective adsorption of Cs+ by MXene (Ti3C2Tx) from model low-level radioactive wastewater

This study explored whether MXene (Ti3C2Tx) could remove radioactive Cs+ from model nuclear wastewater. Various adsorption tests were performed and the physical aspects of the interaction were investigated. We varied the MXene dosage, Cs+ initial concentration, solution pH, solution temperature and exposure time. MXene adsorption exhibited very fast kinetics, based on the fact that equilibrium was achieved within 1 h. MXene exhibited an outstanding adsorption capacity (148 mg g−1) at adsorbent and adsorbate concentrations of 5 and 2 mg L−1, respectively, at neutral pH condition (i.e., pH 7). We explored Cs+ adsorption by MXene in the presence of four different ions (NaCl, KCl, CaCl2 and MgCl2) and three different organic acids (sodium oleate, oxalic acid, and citric acid). The Cs+ removal rate changed in the presence of these components; adsorption of Cs+ by MXene thus involved ion exchange, supported by both Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. We confirmed that MXene was re-usable for at least four cycles. MXene is cost-effective and practical when used to adsorb radionuclides (e.g., Cs+) in nuclear wastewater.