Stable and high-flux polyacrylonitrile/hafnium phosphonate nanofibrous membranes for efficient removal of actinides from strong acidic solutions

Tetravalent metal (e.g., Zr4+, Hf4+) phosphonate frameworks featuring remarkable chemical and radiolytic stabilities have been newly utilized as high-performing adsorbents for actinide in harsh solutions. Nevertheless, the practical applications have been impeded by the as-synthesized powder form that is not compatible with continuous actinide recovery or removal. Herein, we incorporate hafnium phosphonate (HfP) fine powder into polyacrylonitrile (PAN) via a simple and economical electrospinning technique, engendering a stable and hy-drophilic nanofibrous membrane with the first-rank permeate flux for the potential treatment of a large volume of actinide-containing wastewater. This composite membrane can capture more than 90% Th(IV) at ppm level and 95% Pu(IV) and 90% Np(V) at tracer amount level in strong acidic solutions, which retains the excellent adsorption efficacy of HfP powder. Besides, it has a breakthrough volume larger than 880 mL for Th(IV) and 760 mL for U(VI) at the ppb level under a high permeate flux of 785 +/- 11.2 L center dot m-2 center dot h-1, representing one of the top nanofibrous membranes for the dynamic removal of actinides. This work will pave an avenue for fabricating highly efficient and stable adsorptive membranes, which are promising candidates for capturing actinides from large-volume of acidic nuclear wastewater.

Automated summary

Tetravalent metal phosphonate frameworks are utilized as high-performing adsorbents for actinide in harsh solutions, but their practical applications are hindered by the as-synthesized powder form. By incorporating hafnium phosphonate fine powder into polyacrylonitrile via electrospinning, a stable and hydrophilic nanofibrous membrane is created with excellent adsorption efficacy for actinides in large-volume acidic nuclear wastewater.