High performance of amidoxime/amine functionalized polypropylene for uranyl (VI) from aqueous solution

Amidoxime-based adsorbents are widely investigated as the main adsorbent in the recovery of uranium from seawater. However, the adsorption rate and loading capacity of such adsorbents should be further improved due to the economic viability consideration. In this paper, the adsorption properties of amidoxime-based adsorbent were enhanced through the cografting of amino groups. The acrylonitrile (AN) and glycidyl methacrylate (GMA) were firstly cografted onto polypropylene fibers by preirradiation grafting technique. Then the cografted fibers were treated with ethylenediamine to convert GMA to amino group, following treated with hydroxylamine to convert AN groups to amidoxime (AO) group. Fourier transform infrared spectroscopy, scanning electron microscopy and contact angle measurement were used to characterize the structure of the adsorbent. The results showed that the amidoxime and amino groups had been successfully grafted onto the polypropylene fibers. For AO fiber, high adsorption rate was observed within the first 30 min and the plateau value of 42.3% uranium loading (0.0904mg/g) was reached at around 30 min. The AO/amine fibers exhibited a higher adsorption rate. The adsorption equilibrium for AO/amine fiber was attained within 20 min, resulting in the adsorption of 93.3% uranium loading (0.191mg/g). Additionally, AO/amine fibers can avoid pH reducing for better adsorption efficiency.