Quaternary phosphonium modified cellulose microsphere adsorbent for ⁹⁹Tc decontamination with ultra-high selectivity

Decontamination of radioactive TcO₄^- from nuclear wastes is increasingly crucial for spent nuclear fuel reprocessing and environmental remediation. In the presence of a large excess of competitive anions, the selective separation of TcO₄^- is a major challenge for adsorbents. Herein, by using pre-radiation induced grafting polymerization, we have modified economical and environmentally friendly cellulose microspheres to obtain quaternary phosphonium decorated TcO₄^- adsorbents with an ultra-high selectivity, designated CMS-g-VBPPh₃NO₃. The prepared materials show adsorption capacities of 251 mg g^-1 (for the surrogate Re). The selective factor against NO₃^- in 0.5 mol kg^-1 HNO₃ is as high as 168, showing excellent anion-exchange selectivity towards TcO₄^-. Moreover, CMS-g-VBPPh₃NO₃ was packed in column for treating simulated acidic waste solutions containing Cs, Sr, Eu, Zr, Ru, U and Re, and it showed excellent Re separation performance. Tracer amount of ^99mTc experiments showed that comparing to ReO₄^-, CMS-g-VBPPh₃NO₃ has a better adsorption selectivity for TcO₄^-.