Crown ether-type organic composite adsorbents embedded in high-porous silica beads for simultaneous recovery of lithium and uranium in seawater

Abstract

The syntheses of crown ether-type organic composite adsorbents embedded in high-porous silica beads for simultaneous recovery of lithium and uranium in seawater have been achieved and the adsorption behavior of lithium and uranium on the composite adsorbents has been examined in several types of original seawater in the wide temperature and pH ranges. As a result, the composite adsorbents composed of benzo-15crown-5 (BC15) and benzo-18-crown-6 (BC18) showed the top-class maximum adsorption capacities for lithium [6.5 mg / g (BC15), 11 mg / g (BC18)] and uranium [12 mg / g (BC15), 4.2 mg / g (BC18)].

Removal of lithium and uranium from seawater using fly ash and slag generated in the CFBC technology

“…8 ), it was found that (UO 2 ) 11 (CO 3 ) 6 (OH) 12 2− is probably the major form of U ion in the Sea of Japan in the pH range 7.7–9.0. 19 During the experiments in seawater, an anion exchange reaction between the U ions and the dissociated anions of the adsorbents probably took place. According to the diagram presented in Fig.…”

“…The mixed solution of U( vi ) ions was used without removing the elements because seawater originally contains them in lower concentrations. 19 Fly ash and slag were used in these studies as adsorbents. The materials were generated in one of the sewage treatment plants located in Poland and formed as a result of municipal sewage sludge incineration in the CFBC technology.…”

“…Seawater contains around 4.5 billion tons of U in its reserves, which may be sufficient to power the world's nuclear reactors for around 13 000 years. 19 . 16,[19][20][21] As with lithium, it is also possible to recover U from seawater using an adsorption process.…”

“…19 . 16,[19][20][21] As with lithium, it is also possible to recover U from seawater using an adsorption process. A number of adsorbents capable of binding U ions exist, including the following: inorganic substances, 22 polymers, 23 atom transfer radical polymerization prepared adsorbents (ATRPAs), 24 mesostructured organosilica-phosphonate hybrids, 25 highly porous and stable metal-organic frameworks (MOFs), 26 benzimidazole-functionalized 2-D COF, 27 nanostructured carbons (NCs), 28 genetically-engineered proteins and their associated materials (HAGEPs), 29 metal silicate nanotubes 30 and many others.…”

“…Seawater contains around 4.5 billion tons of U in its reserves, which may be sufficient to power the world's nuclear reactors for around 13 000 years. 19 Uranium can exist in seawater in the following chemical neutral and anionic forms: Mg 2 [UO 2 (CO 3 ) 3 ], Ca 2 [UO 2 (CO 3 ) 3 ], Ca[UO 2 (CO 3 ) 3 ] 2− , UO 2 (CO 3 ) 3 4− , (UO 2 ) 11 (CO 3 ) 6 (OH) 12 2− and (UO 2 ) 2 CO 3 (OH) 3 − . 16,19–21 As with lithium, it is also possible to recover U from seawater using an adsorption process.…”