A highly efficient uranium grabber derived from acrylic fiber for extracting uranium from seawater

Abstract

An amidoxime and carboxylate containing chelating adsorbent derived from acrylic fiber shows a fast adsorption rate and high uranium and low vanadium adsorption capacities in real seawater tests.

Direct uranium recovery from brine concentrate using amidoxime adsorbents for possible future energy source

“…Recently, a group at the University of Tennessee in collaboration with Oak Ridge National Laboratory achieved the highest‐ever recorded uranium adsorption of 6.56 g‐uranium/kg‐adsorbent following 56 days of seawater submersion employing amidoximated polymer adsorbents prepared by the atom‐transfer radical polymerization (ATRP) technique 36 . Moreover, Pan et al recently achieved the high uranium adsorption of 6.02 g‐uranium/kg‐adsorbent and estimated the saturation capacity of 7.73 g‐uranium/kg‐adsorbent by employing amidoxime‐ and carboxylate‐containing fiber adsorbent for 56 days of soaking in filtered natural seawater 35 . Even though the maximum adsorption achieved in the present study is only 1.39 mg/g adsorbent for 42 days of submersion, the experiments were performed at a relatively small SWRO plant with the relatively low brine concentrate discharge rate.…”

“…36 Moreover, Pan et al recently achieved the high uranium adsorption of 6.02 guranium/kg-adsorbent and estimated the saturation capacity of 7.73 g-uranium/kg-adsorbent by employing amidoxime-and carboxylate-containing fiber adsorbent for 56 days of soaking in filtered natural seawater. 35 Even though the maximum adsorption achieved in the present study is only 1.39 mg/g adsorbent for 42 days of submersion, the experiments were performed at a relatively small SWRO plant with the relatively low brine concentrate discharge rate. A larger SWRO plant with a much higher brine concentrate flow rate should result in higher adsorption.…”

“…Another crucial factor affecting the uranium adsorption capacity is the presence of vanadium ions in seawater or brine concentrate as evident in Table 1. Vanadium ions can strongly bond with the amidoxime group of adsorbents over uranium ions, 3,[33][34][35] resulting in a reduction of uranium adsorption. This also applies to other ions associated with uranium adsorption such as iron.…”

Transformation details of poly(acrylonitrile) to poly(amidoxime) during the amidoximation process

“…The conversion of PAN to PAO is fairly dependent on amidoximation conditions (such as amidoximation time, temperature and NH 2 OH concentration). 9,[17][18][19][20][21][22][23] High temperature, high NH 2 OH concentration and a long reaction time benet the diffusion of NH 2 OH from solution into the PAN matrix and enhance PAN conversion and H 2 L I formation. 13,14,21 However, because of the instability of PAO, unproper amidoximation conditions result in the degradation and decomposition of PAO.…”

“…10,13,[24][25][26] Rao et al 27,28 reported that open-chain AO and cyclic imide dioximes are the major products of PAO at low and high temperatures, respectively. Moreover, the U/V selectivity and the conversion of the ester group (-C] O) to carboxylate (-COO À ) on adsorbent surface depend on the amidoximation condition, 18 which is important for applying PAObased adsorbents. Therefore, it is necessary to characterize the transformation of PAN to PAO during the amidoximation process, which can provide pivotal information for optimizing amidoximation conditions, and then improve its adsorption capability for trace U(VI) in seawater.…”