Simple construction of core- shell MnO2@ TiO2 with highly enhanced U( VI) adsorption performance and evaluated adsorption mechanism

The adsorption remediation of radioactive contamination from wastewater is scientifically and economically important. In this work, titanium dioxide-modified manganese dioxide (MnO2@TiO2) was prepared by immobilizing crystalline anatase titanium dioxide (TiO2) on the surface of alpha manganese dioxide nanowire (MnO2). The base material MnO2 nanowire acted as a physical template for the guest TiO2, and the formed MnO2@TiO2 composite exhibited a highly uniform core-shell nanorod structure. The MnO2@TiO2 composite was investigated as an efficient adsorbent for the removal of U(vi) from aqueous solution. In the same system, MnO2@TiO2 exhibited a much higher maximum adsorption capacity (105.3 mg g(-1)) for U(vi) as compared with MnO2 (13.3 mg g(-1)), showing that the performance of the surface-modified MnO2 was greatly improved. The fitting results for kinetic and isothermal models manifested that U(vi) ion adsorption by MnO2@TiO2 involved monolayer chemisorption. Characterization before and after adsorption was performed and the results compared and analyzed carefully, with the conclusion that there might be three kinds of interactions between U(vi) and MnO2@TiO2 during the adsorption process, namely inner-sphere surface complexation, chemical precipitation, and electrostatic interaction. The low-cost, facile fabrication method and efficient performance endow the adsorbent MnO2@TiO2 with a high potential for U(vi) removal from actual wastewater.