Development of a simplified separation process of trivalent minor actinides from fission products using novel R-BTP/SiO₂-P adsorbents

Figures & data

Figure 1. Schematic structures of R-BTP ligands used as extractants in this study.

Table 1. Purity of the respective R-BTP extractants and adsorption capacity of the R-BTP/SiO₂-P adsorbents for Dy(III).

Type of R-BTP	Purity (%)	Capacity (mmol/g)
isohexyl-BTP	98.6	0.12 (in 3 M HNO3)
isoheptyl-BTP	97.0	0.061 (in 3 M HNO3)
cyheptyl-BTP	98.3	0.044 (in 4 M HNO3)

Table 2. Weight composition of the R-BTP/SiO₂-P adsorbents obtained by TG-DTA.

Adsorbents	H2O (%)	R-BTP extractant (%)	SDB polymer (%)	SiO2 particle (%)
isohexyl-BTP	1.0	33.2	15.0	50.8
isoheptyl-BTP	0.7	34.1	14.9	50.3
cyheptyl-BTP	1.1	34.2	14.8	49.9
Note: Atmosphere gas: O2, gas flow rate: 30 mL/min, temperature increasing rate: 1°C/min.

Figure 2. Distribution coefficients (K_d ) of RE(III) on R-BTP/SiO₂-P adsorbents in 3 M HNO₃ solution (0.1 mM RE(III), phase ratio: 0.25 g/10 cm³, contact time: 72 h, temperature: 20°C).

Table 3. Distribution coefficients (K_d ) of Am(III) and separation factors (SF) between Am(III) and Eu(III) on R-BTP/SiO₂-P adsorbents in 3 M HNO₃ at 25°C.

Adsorbents	Kd (Am) (mL/g)	SF (Am/Eu)^a
isohexyl-BTP	8500	≈210
isoheptyl-BTP	5800	700
cyheptyl-BTP	980	≈230
Note: Adsorbent: 0.5 g, HNO3: 10 mL, contact time: 3 h.
^aRatio between the values of Kd (Am) in Table 3 and Kd (Eu) in Table4 at 25°C.

Table 4. Distribution coefficients (K_d ) of RE(III) on R-BTP/SiO₂-P adsorbents in 3 M HNO₃ solution.

Adsorbents	Temperature (°C)	Y (mL/g)	Ce (mL/g)	Nd (mL/g)	Eu (mL/g)	Gd (mL/g)	Dy (mL/g)
isohexyl-BTP	25^*	2.0	0.31	–	40	–	20
	50^**	14	–	6.8	122	89	118
isoheptyl-BTP	25^*	0.44	0.11	1.8	8.0	4.8	3.9
cyheptyl-BTP	25^***	0.01	–	0.01	4.2	3.5	5.3
	50^**	4.1	–	27	42	25	27
Note: RE: 1 mM, resin: 0.5 g, HNO3: 10 mL, contact time: *1 d, **5 h, ***2 d.

Figure 3. Effects of contact time on desorption of several RE(III) ions loaded in isohexyl-BTP/SiO₂-P adsorbent with H₂O at 50°C (adsorption conditions: 1 mM RE(III), 3 M HNO₃, 50°C, 5 h).

Figure 4. Effects of γ-ray irradiation on K_d of Dy(III) with isohexyl-BTP/SiO₂-P adsorbent in 0.01 M HNO₃ solution (dose rate: ≈40 Gy/h, room temperature).

Figure 5. Effects of γ-ray irradiation on leakage of isohexyl-BTP extractant from isohexyl-BTP/SiO₂-P adsorbent to 3M HNO₃ solution (dose rate: ≈40 Gy/h, room temperature).

Table 5. Leakage of the R-BTP extractants from the R-BTP/SiO₂-P adsorbents in contact with HNO₃ solution.

Contact conditions with HNO3 solution			Concentration of leaked R-BTP extractant (M)
[HNO3]	Temperature	Period	isohexyl-BTP	isoheptyl-BTP	cyheptyl-BTP
1 M	Room temperature	1 month	2.0 × 10^–6 [1.6]	−	−
	Room temperature	1 week	1.3 × 10^–6 [1]	8.3 × 10^–7 [1]	5.9 × 10^–6 [1]
	50°C	1 week	1.0 × 10^–5 [8.1]	4.2 × 10^–6 [5.0]	8.1 × 10^–6 [1.4]
	80°C	1 week	8.5 × 10^–5 [66]	1.2 × 10^–4 [150]	3.9 × 10^–4 [66]
5 M	Room temperature	1 month	1.2 × 10^–5 [9.3]	−	−
	Room temperature	1 week	2.7 × 10^–6 [ 2.1]	6.6 × 10^–6 [8.0]	3.8 × 10^–5 [6.5]
	50°C	1 week	7.9 × 10^–4 [610]	2.4 × 10^–4 [290]	5.2 × 10^–4 [88]
Note: [ ]: Relative leaked ratio to the value in 1M HNO3, at room temperature during 1 week.

Figure 6. Elution curves of various metal ions in simulated HLLW in a column experiment using isohexyl-BTP/SiO₂-P adsorbent at 25°C (concentration of stable metal ions: 1 mM, ²⁴¹Am and ⁹⁹Tc: trace amounts, column size: φ8 mm × h150 mm, A: dead volume (3M HNO₃), B: feed solution (3M HNO₃), C: washing solution (3M HNO₃), and D: eluting solution (H₂O), flow rate: 0.25 cm³/min).

Figure 7. Elution curves of various metal ions in simulated HLLW in a column experiment using isohexyl-BTP/SiO₂-P adsorbent at 50°C (concentration of stable metal ions: 1 mM, ²⁴¹Am and ⁹⁹Tc: trace amounts, column size: φ10 mm × h120 mm, A: dead volume (3M HNO₃), B: feed solution (3M HNO₃), C: washing solution (3M HNO₃), and D: eluting solution (H₂O), flow rate: 0.25 cm³/min).

Figure 8. Estimated elution curves of Am and some FP ions using isohexyl-BTP/SiO₂-P adsorbent under temperature control (A: dead volume, B: feed soln., C: washing soln., D: eluting soln., flow rate: 0.25 mL/min, C₀ : initial concentration, C: concentration in effluent).

Figure 9. Single-column separation of MA(III) under temperature control (a simplified separation process of trivalent MA) (FP: Cs, Sr, RE, Zr, Mo, etc., RE: Y, La, Ce, Pr, Nd, Sm, Eu etc., MA: Am, Cm).

Figure 10. Leakage behaviors of isohexyl-BTP extractant in the column experiments at 25 and 50°C (A–C: 3M HNO₃, D: H₂O, flow rate: 0.25 cm³/min).