Interaction of uranium(VI) with titanate nanotubes by macroscopic and spectroscopic investigation

Recently, titanate nanotubes (TNTs) have attracted more and more attention in multidisciplinary areas because of their unique tube structure and many outstanding physicochemical properties. This work examined the interaction of U(VI) with TNTs as a function of water quality factors such as reaction time, medium pH, ionic strength, solid content, humic acid (HA) or fulvic acid (FA) by a combined macroscopic and spectroscopic investigation. The results indicated that the U(VI) interaction was dependent on ionic strength under acidic medium, while U(VI) interaction was independent on ionic strength under alkaline medium. Combined with the spectroscopic investigation, it is revealed that outer-sphere surface complex and inner-sphere surface complex can occur simultaneously during U(VI) interaction with TNT sample. Besides, for the first time, we found a positive role of HA and FA in U(VI) interaction with TNTs at low pH values, whereas we observed a negative role of HA and FA in U(VI) interaction with TNTs at high pH values. Results indicated that TNTs can be used as an excellent adsorbent for capturing U(VI) from aqueous environments. Considering the low cost of TNTs, we can conclude that TNTs show great application potential in the disposal and remediation of U(VI)-contaminated wastewaters and groundwater.