Uranium sorption on oxyhydroxide minerals by surface complexation and precipitation

Adsorption of Low-Concentrated U(VI) on a Preferable Crystalline Boehmite (γ-AlOOH) in Alkaline Conditions

“…The adsorption capacities of the different adsorbents are listed in Table S3 (Supporting Information). Among the adsorbents reported in Table S3, eight adsorbents (γ-AlOOH, UiO-66-PO-Ph), phosphate rock apatite (PRA), chitosan-modified phosphate rock (CPR), Na-attapulgite, zeolite NaY, aerated zone soil, and P–C4 (PPN-6-CH 2 P + (C 4 H 9 ) 3 Cl – ) were used to adsorb U­(VI) at different conditions. ,,,,,,, The maximum adsorption capacities of UiO-66-PO-Ph, Na-attapulgite, and phosphate rock apatite (PRA) were 111.9, 0.19, and 0.2021 mg/g to U­(VI) ions in pH 3, pH 4.4, and pH 3.88, respectively. ,, The maximum adsorption capacities of zeolite NaY and CPR for U­(VI) ions at pH 2.5 were 14.05 and 8.06 mg/g, respectively. , Aerated zone soil showed the maximum adsorption capacity of 1.98 mg/g at pH 7, with the U­(VI) content of 10 mg/L, 24 h, 298 K . Compared to the six reported adsorbents, γ-AlOOH showed a higher U­(VI) adsorption capacity of 19.8 mg/g in alkaline solution than those of other adsorbents.…”

“…To date, there are various methods for separating U­(VI) ions from aqueous solution, mainly involving adsorption, − solvent-extraction, − chemical precipitation, , membrane separation, , and so on. For example, Wang et al showed that the sorption capacity of boehmite for U­(VI) was 2.78 mg/g (pH 5 ± 0.1). de Moraes et al stated that the removal yield of U­(VI) via hematite was nearly 100% in slightly acidic mine wastewaters (pH = 6).…”

“…To date, there are various methods for separating U(VI) ions from aqueous solution, mainly involving adsorption, 9−12 solvent-extraction, 13−16 chemical precipitation, 17,18 membrane separation, 19,20 and so on. For example, Wang et al 11 showed that the sorption capacity of boehmite for U(VI) was 2.78 mg/ g (pH 5 ± 0.1). de Moraes et al 21 stated that the removal yield of U(VI) via hematite was nearly 100% in slightly acidic mine wastewaters (pH = 6).…”

Adsorption-photoreduction behaviors and mechanisms of layered double hydroxide loaded on uranium(vi) removal

“…At a pH of 6.0–8.0 (stage II), the gradual appearance of negatively charged U( vi ) species (UO 2 ) 3 (OH) 7 − , UO 2 (OH) 3 − and UO 2 (OH) 4 2− increased the electrostatic attraction and the –OH group on the surface of NiAl and ZnNiAl could complex with UO 2 2+ , as well as the UO 2 CO 3 precipitate was formed owing to CO 3 2− intercalation (urea pyrolysis). 34,35 At a pH > 8.0 (stage III), the concentration of OH − increased and the surface of NiAl and ZnNiAl was negatively charged, therefore, the adsorption capacity decreased due to electrostatic repulsion. Subsequently, the effects of different concentrations of NaNO 3 (0001, 0.01, and 0.1 mol L −1 ) on U( vi ) adsorption were investigated.…”

“…At a pH of 2.0-6.0 (stage I), U(VI) presented as positive species of UO was formed owing to CO 3 2− intercalation (urea pyrolysis). 34,35 At a pH > 8.0 (stage III), the concentration of OH − increased and the surface of NiAl and ZnNiAl was negatively charged, therefore, the adsorption capacity decreased due to electrostatic repulsion. Subsequently, the effects of different concentrations of NaNO 3 (0001, 0.01, and 0.1 mol L −1 ) on U(VI) adsorption were investigated.…”