Ultra-stable 3D pyridinium salt-based polymeric network nanotrap for selective TcO/ReO capture via hydrophobic and steric engineering.

Selective capture of radioactive TcO from highly alkaline nuclear waste is highly desirable for environmental remediation and waste disposal. However, the combined features of adsorbents with excellent chemical stability and high capture selectivity for TcO have not yet been achieved. Herein, we report an ultra-stable 3D pyridinium salt-based polymeric network (TMP-TBPM) nanotrap with remarkable radiation, acid and base stability for selective capture of ReO via hydrophobic engineering and steric hindrance, a non-radioactive surrogate of TcO. The batch capture experiments show that TMP-TBPM has high capture capacity (918.7 mg g) and fast sorption kinetics (94.3 % removal in 2 min), which can be attributed to the high density of pyridinium salt-based units on the highly accessible pore channels of 3D interconnected low-density skeleton. In addition, the introduction of abundant alkyl and tetraphenylmethane units into the 3D framework not only greatly enhanced the hydrophobicity and stability of TMP-TBPM, but also significantly improved the affinity toward TcO/ReO, enabling reversible and selective capture of TcO/ReO even under highly alkaline conditions. This study exhibits the great potential of 3D pyridinium salt-based polymeric network nanotrap for TcO/ReO capture from highly alkaline nuclear waste, providing a new strategy to construct high-performance cationic polymeric sorbents for radioactive wastewater treatment.