Recovery of uranium from seawater V. Preparation and properties of the macroreticular chelating resins containing amidoxime and other functional groups

Abstract

SynopsisWe have synthesized macroreticular chelating resins containing amidoxime groups from acrylonitrile (AN)-divinylbenzene (DVB)-alkyl acrylate, alkyl methacrylate, or vinylpyridine (VPy) copolymer beads. It was found that the chelating resin (RNMH)-containing amidoxime groups prepared from AN-DVB-methyl acrylate (MA) indicated the highest adsorption ability for uranium in seawater. Hydroxamic acid and carboxylic groups in addition to amidoxime groups were formed during the reaction of the copolymer beads with a methanol solution of hydroxylamine. The adsorption ability for uranium was greatly influenced by the physical pore structure (macropore) and the pore structure formed by the swelling(microp0re). RNMH prepared with 10 mol% of DVB and 10 mol% of MA had the highest adsorption ability and physical stability for uranium. On the other hand, improved adsorption ability for uranium was not obiserved in the case of the macroporous resins (RNPyH) prepared by the copolymerization of VPy as the basic component. After seawater was passed through the column packed with RNMH10-10 at a space velocity (SV) of 180 h-' (up-flow) for 10 days, the amount of uranium adsorbed on the resin was about 100 mg/&-R and 260 mg/kg-R. INTRODUCTIONSince atomic power is expected to play an important role in energy resources, the industrial system of uranium recovery from natural seawater, which contains approximately 4 billion tons of uranium, must be established in the near future. We have already synthesized the macroreticular chelating resins containing amidoxime1-6 and dihydroxyphosphino and/or phosphono groups,' which are highly effective for the recovery of uranium from seawater.'-" In this research, it has become apparent that the physical and chemical structure of adsorbents greatly influence the adsorption ability for uranium from seawater. In recent years there have been reports on the synthesis of some adsorbents and the application of uranium recovery from seawater (e.g., chelating resins containing dithiocarbamate groups,12 amidoxime group^,^^*^* 1,2-dihydroxyanthraquinone groups,15 and aminomethylphosphonic acid group^.'^^") In these reports, the physical and chemical structure of uranium adsorbents seems not to be well defined. In our recent study,6 the macroreticular chelating resins containing amidoxime groups with various pore structures have been prepared by using several crosslinking reagents, and the inhence of the pore structure on the adsorption ability for uranium was were washed with pure water until hydroxylamine was not released in the wash water, then were air-dried, and dried in vacuo at 40°C for 6 h. Each resin (1 g) was treated with 100 cm3 of 0.1 mol * dmP3 sodium hydroxide solution at 3OoC for 15 h (alkali treatment) or with a 100 cm3 of 1 mol . dm-3 hydrochloric acid solution at 60°C for 5 h (acid treatment). The resulting resins were washed with deionized water until the wash water became neutral and then were air-dried and dried in vacuo at 40°C for 2 h. An apparent anion and cation exchange capaci...

Chelating polymer granules prepared by radiation-induced homopolymerization. I?Kinetic study of radiation polymerization process

“…This effect becomes very important at high conversion, when most of chains are initiated by radicals generated by the polymer. (2) The polymer formed could act as a cocatalyst in the reaction, by way of "immobilized" free radicals created by chain transfer on the surface of the polymer. (3) The acceleration was caused by a reduced rate of chain termination owing to the coiled state of the growing polymer chains, the active-end chain being efficiently shielded by the precipitated polymer, thus producing an effect of steric hindrance, which should lower the general reactivity of the growing chain by a mechanism analogues to diffusion control.…”

“…A number of chelating resins containing amidoxime groups have been prepared by reacting the acrylonitrile-divenylbenzene copolymer with hydroxylamine. [1][2][3][4] Several research groups have continued this line of work, developing and testing the various kinds of adsorbents containing amidoxime groups. [5][6][7][8][9][10] In our previous work, 10,11 radiation-induced graft polymerization has been used with high efficiency to synthesize chelating filter paper with amidoxime groups.…”

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

“…The studies indicate that poly(acrylamidoximes) are the most promising candidate adsorbents for the recovery of uranium from seawater. Therefore, recent studies have been focused on the amidoxime-based adsorbent system [15][16][17][18][19][20][21].…”

Improvement in Uranium Adsorption Properties of Amidoxime-Based Adsorbent Through Cografting of Amine Group

“…Therefore, recent studies have been focused on the poly(acrylamidoximes) adsorbents. [15][16][17][18][19][20][21] However, the economic viability of recovery of uranium from seawater still critically depends on the uranium adsorption rate and loading capacity in amidoxime-based adsorbents. It is desirable that the uranium species present in seawater should be instantaneously adsorbed when it comes in contact with the surface of adsorbents.…”