Decorating UiO-66-NH2 crystals on recyclable fiber bearing polyamine and amidoxime bifunctional groups via cross-linking method with good stability for highly efficient capture of U(VI) from aqueous solution

Although polyacrylonitrile fiber (PANF) and metal-organic frameworks (MOFs) have been extensively investigated to remove U(VI) from water, their practical applications are seriously hindered by the relatively low stability of PANF in acidic solution and great difficulty of separating MOFs nanoparticles from solution, beside that, little attention is paid to the fabrication of MOFs and PANF composite materials (MPCMs) with excellent adsorption capacity for U(VI). Herein, we report the synthesis of novel MPCMs by decorating different concentrations of UiO-66-NH2 crystals onto polyamine and amidoxime groups functionalized PANF (PA-AO-PANF) through cross-linking method for U(VI) extraction. The characterization results reveal that the combination of PA-AO-PANF and UiO-66-NH2 crystals endows MPCMs with excellent separation ability, large surface area, good stability and plentiful surface functional groups, which contributes to good selectivity and enhanced adsorption performance. Consequently, the obtained UN-PA-AO-PANF-2 shows the maximum uptake capacity of 441.8 mg/g and equilibrium uptake time of 30 min towards U(VI). Besides, the U(VI) uptake ability and structure of UN-PA-AO-PANF-2 are well preserved after ten adsorption-desorption cycles. With these outstanding properties, the adsorbent has great potential for the capture of U(VI) from aqueous solutions. Importantly, this work provides a cost-effective and efficient way to construct extremely stable MPCMs hybrid fibers.