Application of Calixarenes as Macrocyclic Ligands for Uranium(VI): A Review

Table 7

Extraction of UO₂²⁺ from nitric acid solutions into 𝑚-NBTF by phosphorylated calixarenes. Distribution coefficients 𝐷^a.

Entry	Extraction agent	Nitric acid concentration (M)					Reference
		0.1	0.3	1	3	6
1	11	0.24	0.32	0.49	0.23	0.15	[52]
2	12	7.5	3.1	1.69	1.22	0.84	[52]
3	22	21	16.8	12.1	8.6	4.0	[52]
4	𝐓𝐎𝐏𝐎^b	8.3	5.9	1.23	0.19	0.09	[52]

^aD: distribution coefficient, D = [UO₂²⁺]_org/[UO₂²⁺]_aq.
^bTOPO: trioctyl phosphine oxide.