Graphene oxide encapsulated in alginate beads for enhanced sorption of uranium from different aquatic environments

Removal of Uranium from Aqueous Solution and Simulated Seawater Using a Mixed Matrix Membrane Fabricated by Cyclophosphazene and Triazine-Based Inorganic–Organic Hybrid Material

“…As per the above-mentioned discussion on the speciation of uranium with pH, the most abundant species U­(VI) exist within the pH range of 5–7. − Therefore, the adsorptive removal of U­(VI) is expected in the pH range of 5–7. Aqueous uranium solution (5 ppm of 50 mL) was used to carry out the batch adsorption experiment as it is considered the maximum concentration of uranium present in groundwater. − The effect of pH has a strong impact on the adsorption of uranium ions. At lower pH (<4) and higher pH (>8), the influences of H + and OH – ions are more, which further affects the removal efficiency of targeted pollutants.…”

“…Numerous adsorbents such as metal–organic frameworks (MOFs), , covalent organic frameworks (COFs), , graphene, g-C 3 N 3 , ,, POPs, , mesoporous silica, and activated carbons , have been reported for the adsorption of uranium. However, the widespread concerns of metal leaching and trace metal residues are major problems in metal-based adsorbents.…”

“…15−18 The chemistry of uranium in an aqueous solution is quite interesting. Below pH of 4, the dominant species is UO 2 2+ , and pH of above 7, it can easily combine with OH − and CO 3 2− to form different ionic and neutral species such as [UO 2 CO 3 15,16 Within the pH range of 5−7, the most dominating form of uranium present in the aqueous solution is the cationic species [(UO 2 ) 3 (OH) 5 ] + . 14−18 The hexavalent uranium U(VI) is considered as the most commonly available species found in the aqueous solution.…”

“…However, there are several limitations associated with the nuclear energy consumption like availability of radioactive elements, effluent management, extraction of nuclear fuel, and their utilization. , Nearly 4 billion tons of uranium is present in the ocean, which can provide an ample amount of energy to compensate for the energy problem. − However, an extremely low concentration of uranium in the seawater with other interfering ions/organisms causes some unavoidable major challenges . Uranium most commonly exhibits U­(III), U­(IV), U­(V), and U­(VI) oxidation states, among which U­(VI) is most abundant in the aqueous environment. − The chemistry of uranium in an aqueous solution is quite interesting. Below pH of 4, the dominant species is UO 2 2+ , and pH of above 7, it can easily combine with OH – and CO 3 2– to form different ionic and neutral species such as [UO 2 CO 3 ], [(UO 2 ) 2 CO 3 (OH) 3 ], [UO 2 (OH) 2 ], [UO 2 (OH)] + , [UO 2 (OH) 4 ] 2– , [UO 2 (CO 3 ) 2 ] 2– , [UO 2 (OH) 3 ] − , [UO 2 (CO 3 ) 3 ] 4– , and [(UO 2 ) 3 (OH) 7 ] − . , Within the pH range of 5–7, the most dominating form of uranium present in the aqueous solution is the cationic species [(UO 2 ) 3 (OH) 5 ] + . − The hexavalent uranium U­(VI) is considered as the most commonly available species found in the aqueous solution.…”

Optimization of hybrid polymer preparation by ex situ embedding of waste Fe/Mn oxides into chitosan matrix as an effective As(III) and As(V) sorbent

“…This can be achieved by dispersion of metal oxide particles in the solution of the polymer, followed by its precipitation (occurring as a consequence of pH change or cross-linking) resulting in impregnation of the used matrix. Natural polymers such as alginate, chitosan, or modified cellulose, due to their availability, low-cost, and easy processing, are often used as the supporting materials (Wang and Chen 2014; Basu et al 2015; Lee et al 2017; López-García et al 2017; Basu et al 2018; Kumar et al 2018; Ociński et al 2019). Special attention has been focused on the use of chitosan in the formation of hybrid sorbents, owing to its high reactivity and beneficial physical properties.…”