Polymer-Supported Primary Amines for the Recovery of Uranium from Seawater

Abstract

The primary amine −CH2NH2 ligand bound to cross-linked polystyrene has a high affinity for the uranyl ion from a matrix of artificial seawater. The uranyl capacity is 14.8 mg U/gpolymer, compared to 2.34 mg U/gpolymer for a diamidoxime ligand on a polystyrene support. Secondary and tertiary amines have much lower affinities, indicating that steric effects are important to the complexation. The results with polystyrene-bound −CH2NH2 thus suggest at least a 3-fold increase in uranyl capacity (calculated on a per mole ligand basis (not per gram of polymer, in order to make the results independent of the weight of the polymer support)) and a 4-fold increase when ligands with two primary amines per ligand are utilized. An additional advantage of the primary amine over amidoxime is that it is a simpler ligand to prepare.

Surface modification of ionic liquid-spun chitin fibers for the extraction of uranium from seawater: seeking the strength of chitin and the chemical functionality of chitosan

“…24 A recent cost analysis indicated that the adsorbent comprises 43% of the total cost for extracting uranium from seawater, 25 and research has focused on lowering the cost through increasing adsorbent capacity and recycling by increasing the surface area [26][27][28] or developing alternative functional groups to amidoxime. 29,30 Even though polyethylene polymers are a major source of anthropogenic marine pollution [31][32][33] and are made from nonrenewable petroleum, there has been little emphasis on lowering the cost or environmental impact of the process by changing the sorbent backbone to a more suitable material.…”

Sequestering uranium from UO2(CO3)34−in seawater with amine ligands: density functional theory calculations

“…The primary amines showed an at least 3-fold increase in uranyl binding capacity compared to a diamidoxime ligand. Since two possible mechanisms have previously been proposed, including a coordination mechanism in which amines replace carbonates to bind to uranyl and a cation exchange mechanism in which the protonated amines bind to uranyl tricarbonate directly, 1 we also compared the relative abilities of amines and amidoxime to replace CO 3 2À in UO 2 (CO 3 ) 3…”

“…, is often viewed as a benchmark. 1 Amine-based adsorbents have also been reported to show good affinity for uranyl in aqueous solutions. [18][19][20][21][22][23][24] More importantly, the amines remain free to coordinate to uranyl effectively under seawater conditions.…”

“…18,20 Alexandratos et al reported that a primary amine on a polystyrene support shows at least a 3-fold increase in uranyl capacity compared to a diamidoxime ligand on a polystyrene support. 1 Amines have also been cografted onto amidoxime-based adsorbents to enhance the uranium adsorption rate and loading capacity. 25,26 It has been reported that the uranium loading capacity of amidoxime/amine-based polypropylene fiber is twice that of the amidoxime-based fiber.…”

Development of a new ion-exchange/coordinating phosphate ligand for the sorption of U(VI) and trivalent ions from phosphoric acid solutions

“…Our research is focused on understanding the interactions between metal ions and immobilized ligands in order to optimize both affinity and selectivity which can then lead to important applications. Studies with coordinating phosphorus-based ligands has shown how the polarizability of the phosphoryl oxygen can be varied by neighboring -OH groups which then affects affinities for divalent ions , hydrogen bonding affects the affinities of amides for lanthanides (Yang and Alexandratos, 2010), and moieties bound to the amine nitrogen affect the affinity of U(VI) from seawater through ion exchange (Sellin and Alexandratos, 2013).…”