A new imidazolium-based polymeric ionic liquid gel with high adsorption capacity for perrhenate

Abstract

A new imidazolium-based polymeric ionic liquid (PC₂vimBr) gel was prepared by γ-radiation induced polymerization and crosslinking of 1-vinyl-3-ethylimidazolium bromide and a functional crosslinker 3,3′-divinyl-1,1′(1,6-hexanediyl) diimidazolium dibromide. A high gel fraction of ca. 95% could be achieved under 40 kGy, and the equilibrium degree of swelling and mechanical properties could be adjusted by crosslinker content and absorbed dose. The highest fracture compressive strength of PC₂vimBr could be as high as 0.21 MPa. PC₂vimBr could strongly adsorb perrhenate (ReO₄⁻) with an adsorption capacity as high as ca. 8.6 × 10² mg g⁻¹ (Re/gel), following a Langmuir model by an ion exchange mechanism, which was confirmed by IR and XPS. Competitive adsorption with the electrolytes or sodium dodecyl benzene sulfonate showed that the PC₂vimBr gel has good efficiency for ReO₄⁻ removal from a low concentration of electrolyte solution or laundry waste water. Considering ReO₄⁻ is the natural analogue of TcO₄⁻, PC₂vimBr may be used in decontamination of low level wastes such as laundry wastes. Interestingly, PC₂vimBr would shrink strongly after adsorbing ReO₄⁻, which is meaningful for volume reduction of radioactive wastes.