Aminomethylpyridine isomers functionalized cellulose microspheres for TcO/ReO uptake: Structure-properties relationship and their application in different aquatic systems.

Technetium-99 (Tc) is a long-lived radioactive nuclide that poses great threat to environment, hence selective removal of Tc from aquatic system is always an issue. Aminomethylpyridine (AMP) equipped with pyridine and amino, is a promising receptor for TcO and its surrogate ReO, thus it is of interest to explore and understand the structure-properties relationship of ReO adsorption related to n-AMP structure that differ in amino methyl position. In this work, three n-AMP functionalized cellulose microspheres (n-AMPR, n = 2, 3, 4) were synthesized and employed for TcO/ReO uptake. The effect of aminomethyl position on adsorption properties of n-AMPR for ReO were investigated and compared. Adsorption kinetics and adsorption isotherm showed that adsorption speed and adsorption capacity were in order of 3-AMPR > 2-AMPR > 4-AMPR. DFT calculation verified that the adsorption of ReO by n-AMPR was attributed to electrostatic interaction and hydrogen bonding interaction, the order of adsorption abilities of n-AMPR was due to that steric effect and hydrogen bond collaborated in stabilizing n-AMPR-ReO complexes. The column experiments demonstrated that 3-AMPR can be selectively remove ReO from simulated groundwater. More importantly, Tc column experiments showed that 3-AMPR had a better ability for actual radioactive TcO.