Efficient Removal of Anionic Radioactive Pollutant from Water Using Ordered Urea-Functionalized Mesoporous Polymeric Nanoparticle

A urea-functionalized ordered mesoporous polymeric nano particle for removing the perrhenate anion ReO4- as the surrogate of the particularly intractable anion radioactive pollutant TcO4- was demonstrated in the present study. This nanoniaterial (denoted as urea-MPN) was produced for the first time by a surfactant-directed urea-phenol-formaldehyde resol oligomers self-assembly protocol under hydrothermal condition. The obtained urea-MPN possessed the uniform nanosized spherical morphology with a 3D interconnected ordered cubic mesoporous structure. Also, the urea functional groups were succefully embedded in the polymer framework without the alteration of the molecular configuration. Meanwhile, it exhibited excellent beta radiation resistance up to 200 kGy dose. We employed the perrhenate anion ReO4- to test its potential for the removal of anionic radioactive pollutant TcO4- from water. Interestingly, the optimized urea-MPN nanocomposite achieved the high removal efficiency at a low concentration of 0.25 mM within a short contact time of 30 min. The control experimental results revealed that the short nanoscale pore channels and the hydrophobic mesopore surface facilitated the hydrogen-bonding interaction between the charge diffuse ReO4- tetrahedral oxoanion and the urea moieties in the framework of urea-MPN, accounting for the rapid and effective removal performance in pure water. Importantly, it can selectively capture ReO4- in the presence of different competitive anions including NO3-, CO32-, SO42- and PO43-. This attractive capability of this unique nanosized mesoporous polymeric sorbent will pave the way for the diverse applications in the decontamination of nuclear wastes in a more economical and sustainable manner.