Insight into UV-induced simultaneous photocatalytic degradation of Ti3C2Tx MXene and reduction of U(VI).

With the development of MXene as the efficient adsorbent for U(VI), the tendency of MXene coming into contact with U(VI) in wastewaters increases. Motivated by UV light irradiation applied in wastewater treatments, the UV light induced photochemical co-transformation of Ti3C2Tx MXene and U(VI) is studied. To clarify the role of U(VI) induced Ti3C2Tx aggregation in phototransformation of Ti3C2Tx, the aggregation kinetics of Ti3C2Tx in the presence of various valent radioactive ions are investigated, obtaining the critical coagulation concentrations (CCC) of Ti3C2Tx for Cs+, Sr2+, UO22+, Eu3+, and Th4+. Besides, the colloidal stability of UV-induced Ti3C2Tx as a function of standing time is discussed. The results show that the aggregation behavior of Ti3C2Tx induced by radioactive ions follows the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and the Schulze-Hardy rule. The UV irradiation will change the physicochemical properties and colloidal stabilities of Ti3C2Tx. Furthermore, the degradation of Ti3C2Tx can be accelerated by UV irradiation and further promoted by the presence of U(VI). The removal of U(VI) is highest in the case of Ti3C2Tx combined with UV irradiation via adsorption and reduction. This study provides an example demonstrating that the simultaneous transformation of Ti3C2Tx (adsorbent) and U(VI) (adsorbate) to mild toxic components.