Arsenic removal from water/wastewater using adsorbents—A critical review

More than 1000× uranium exists in the oceans than exists in terrestrial ores. With nuclear power generation expected to increase over the coming decades, access to this unconventional reserve is a matter of energy security. With origins in the mid-1950s, materials have been developed for the selective recovery of seawater uranium for more than six decades, with a renewed interest in particular since 2010. This review comprehensively surveys materials developed from 2000–2016 for recovery of seawater uranium, in particular including recent developments in inorganic materials; polymer adsorbents and related research pertaining to amidoxime; and nanostructured materials such as metal–organic frameworks, porous-organic polymers, and mesoporous carbons. Challenges of performing reliable and reproducible uranium adsorption studies are also discussed, as well as the standardization of parameters necessary to ensure valid comparisons between different adsorbents.

Materials for the Recovery of Uranium from Seawater

Preparation and applications of ion exchange membranes by radiation-induced graft copolymerization of polar monomers onto non-polar films

Chelating polymers and related supports for separation and preconcentration of trace metals.

Uranium is the main source for nuclear energy but also one of the most toxic heavy metals. The current methods for uranium removal from water present limitations, such as narrow pH operating range, limited tolerance to high salt concentrations, or/and high cost. We show here that a layered sulfide ion exchanger K2MnSn2S6 (KMS-1) overcomes these limitations and is exceptionally capable in selectively and rapidly sequestering high (ppm) as well as trace (ppb) quantities of UO22+ under a variety of conditions, including seawater. KMS-1 can efficiently absorb the naturally occurring U traces in seawater samples. The results presented here reveal the exceptional potential of sulfide-based ion-exchangers for remediating of uranium-containing wastes and groundwater and for extracting uranium from the sea.

Layered Metal Sulfides Capture Uranium from Seawater

The preparation of the macroreticular chelating resins containing 'hydrazide groups by the hydrazinolysis of macroreticular methyl methacrylate-divinylbenzene copolymer with h ydrazine hydrate was carried out and adsorption of metal ions on these resins was tested.It was found that the hydrazinolysis of these copolymers was accompanied by the formation of carboxyl groups in an early stage of the reaction and the carboxyl groups thus formed converted into hydrazide groups during a subsequent reaction at a high temperature. The good chelating resins were prepared by the hydrazinolysis of macroreticular copolymer for 5 9 hours at 175°C. This copolymer was obtained with the following compositions: methyl methacrylate 90-95% (volume), divinylbenzene 5-10% (volume) and isooctane 50% (volume) per the monomer. As the chelating resins had a few carboxyl groups, the adsorption of CA2+ occurred at higher pH values than 4. But the chelating resins exhibited selectivity for certain metal ions, which was liable to form ammine complexes, and showed a special high affinity toward Hg2+ or Cu2+ at lower pH values than 4. The separation of the certain metal ions could easily be carried out by varying the pH; the adsorption of these metal ions was scarcely influenced by other ion, e. g., K+ or Na+.

https://www.jstage.jst.go.jp/article/nikkashi1972/1977/6/1977_6_888/_pdf

Preparation of Macroreticular Chelating Resins Containing Hydrazide. Groups and Adsorption of Metal Ions on Them

Autorecycling oxidation of alcohol by pyridodipyrimidine bound to crosslinked polystyrenes

Chelating resins containing a macrocyclic ligand, 1, 4, 8, 11-tetraazacyclotetradecane-5, 7-dione, were prepared by ligand reactions with two different crosslinked copolymer beads of the macroreticular type: chloromethylated styrene- divinylbenzene (RCS) and glycidyl methacrylate-divinylbenzene (RG) copolymers. Although both resins have nearly equal amounts of the fixed ligand, the RG-based resin (RGD) shows a much higher uptake of Cu(II) than does the RCS- based resin (RCSD). This indicates that the complexing ability of the fixed ligand is strongly influenced by copolymer matrices. A further detailed study of RGD revealed that the characteristics of RGD include high selectivity toward Cu(II) and a rapid elution rate of Cu(II) with an aqueous solution of strong acid. The usefulness of RGD in the separation of Cu(II) has been demonstrated by means of column operation.

Hiroaki Egawa

Papers

Preparation of Macroreticular Chelating Resins Containing Hydrazide. Groups and Adsorption of Metal Ions on Them

Autorecycling oxidation of alcohol by pyridodipyrimidine bound to crosslinked polystyrenes

Chelating Resins Containing 1,4,8,11-Tetraazacyclotetradecane-5,7-dione Based on Crosslinked Copolymer Beads of the Macroreticular Type.

Effect of additives on photocrosslinking of poly(2, 3‐epithiopropyl methacrylate)

Photocrosslinking of poly(2,3‐epithiopropyl methacrylate) and its copolymers