Exploring Uranyl/Salicylate/Hematite Binary and Ternary Complexes by Attenuated‐Total‐Reflection Infrared Spectroscopy

Abstract

Attenuated‐total‐reflection infrared technique was utilized to investigate the binding mechanisms in uranyl/salicylate/hematite binary and ternary systems at the molecular scale. Uranyl has been found to adsorb onto hematite surfaces in an outer‐sphere mode, similar to uranyl/maghemite system, whereas the desorption process is much longer than the latter which is probably due to different surface structures of the two minerals. Salicylate, as a good analogue of humic acid and other ortho‐hydroxo aromatic acids, binds with the surface mainly through complexation of the carboxylic group with the surface. In the cosorption system of uranyl/salicylate, at a sub‐micromolar concentration onto hematite, only weak interactions are deduced from the shifts of salicylate characteristic peaks. The increasing amount of salicylate have significant influences upon uranyl species and would release uranyl from the surface. The ternary complexes were found for both systems, and the possible structures were predicted through DFT calculations. The results of the present study could provide some information on the organic ligand influences on the uranyl sorption process, especially for the ortho‐hydroxo acromatic acids, such as humic acid.

Synthesis of sandwich-like Mn3O4@reduced graphene oxide nano-composites via modified Hummers' method and its application as uranyl adsorbents

“…11). The FTIR spectrum of the Mn 3 O 4 @G after four cycles adsorption experiments and washed by dilute HNO 3 shows new characteristic peaks at 920 cm −1 and 1020 cm −1 in the fingerprint region associated with the vibration of O=U=O, compared with the FTIR spectrum of the initial Mn 3 O 4 @G powders [26] (Fig. 12).…”