Table 2.

Enthalpies of reactions involving uranyl peroxide compounds

NaUT, LiUT, and KUT (and studtite) formation with peroxide:
UO2(c) + 4Na+(aq) + 4H2O2(l) + 7H2O(l)⇌Na4[UO2(O2)3] ∗ 9H2O(c) + 4H+ΔH = -352.3 (A)
UO2(c) + 4Li+(aq) + 4H2O2(l) + 8H2O(l)⇌Li4[UO2(O2)3] ∗ 10H2O(c) + 4H+ΔH = -307.7 (B)
UO2(c) + 4K+(aq) + 4H2O2(l) + 7H2O(l)⇌K4[UO2(O2)3] ∗ 9H2O(c) + 4H+ΔHM = -133.4 (C)
NaUT, LiUT, and KUT formation without peroxide:
UO2(c) + 4Na+(aq) + 11H2O(l) + 2O2(g)⇌Na4[UO2(O2)3] ∗ 9H2O(c) + 4H+ΔH = 37.9 (D)
UO2(c) + 4Li+(aq) + 12H2O(l) + 2O2(g)⇌Li4[UO2(O2)3] ∗ 10H2O(c) + 4H+ΔH = 82.5 (E)
UO2(c) + 4K+(aq) + 11H2O(l) + 2O2(g)⇌K4[UO2(O2)3] ∗ 9H2O(c) + 4H+ΔH = 256.8 (F)
U60 formation without peroxide:
60UO2(c) + 40Li+(aq) + 20K+(aq) + 274H2O(l) + 60O2(g)⇌Li40K20[UO2(O2)(OH)]60 ∗ 214H2O(c) + 60H+(aq)ΔH = -7592.3 (G)
U60 formation from LiUT, KUT, and studtite:
10Li4[UO2(O2)3] ∗ 10H2O(c) + 5K4[UO2(O2)3] ∗ 9H2O(c) + 45UO2(O2) ∗ 4H2O(c)⇌Li40K20[UO2(O2)(OH)]60 ∗ 214H2O(c) + 81H2O(l) + 15O2(g)ΔH = -4374.3 (H)
Uranyl oxyhydrate formation from uranyl peroxides:
UO2(O2) ∗ 4H2O(c)⇌UO3 ∗ 2H2O(c) + 2H2O(l) + 0.5O2(g)ΔH = -17.0 (I)
Na4[UO2(O2)3] ∗ 9H2O(c) + 3UO2(c)⇌4Na(UO2)O(OH)(c) + 7H2O(l)ΔH = -493.7 (J)
Na4[UO2(O2)3] ∗ 9H2O(c) + 5UO2(c) + O2(g) + 2H+(aq)⇌Na2[(UO2)3O2(OH)3]2 ∗ 7H2O(c) + 2Na+(aq)ΔH = -844.7 (K)
1/60Na40K20[UO2(O2)(OH)]60 ∗ 214H2O(c) + 2UO2(c) + 14/15H2O(l) + 1/2O2(g) = 1/3Na2[(UO2)3O2(OH)3]2 ∗ 7H2O(c) + 1/6K2[(UO2)3O2(OH)3]2 ∗ 7H2O(c)ΔH = -243.6 (L)
(For clarity, reaction L has been normalized to one mole U)

All values in kJ/mol; c = crystal, l = liquid, g = gas, aq = aqueous solution. For clarity, the peroxo groups are shown in blue.