- Mechanism and kinetics of Rh(IV) radiation-chemical reduction in HNO 3 solutions
-
Reduction of Rh(IV) in γ-irradiated and nonirradiated solutions of HNO3 (0.3-3.0 M) was studied. In both systems, Rh(IV) is completely reduced to Rh(III). The reduction rates in nonirradiated solutions amount to 50-90% of rates in irradiated so
- Vladimirova,Khaperskaya
-
-
Read Online
- The formation of a neptunium(V)-chromium(III) complex. Kinetics and equilibria in perchlorate solutions
-
A value for the equilibrium quotient Q = [Np(V)·Cr(III)]/[Np(V)][Cr(III)] of 2.62 ± 0.48 at 25° has been determined spectrophotometrically. Values of ΔH = -3.3 ± 0.6 kcal, and ΔS = -9.0 ± 1.9 e.u. have been determined. The rates of formation and aquation of the complex Np(V)·Cr(III) have been measured. The complex is also formed by the reduction of Np(VI) with Cr(II).
- Sullivan, James C.
-
-
Read Online
- Highly selective separation of individual platinum group metals (Pd, Pt, Rh) from acidic chloride media using phosphonium-based ionic liquid in aromatic diluent
-
An effective solvent extraction-based method has been developed to recover individual platinum group metals (PGMs) (i.e. Pd, Pt and Rh) with high purity from acidic chloride media using phosphonium-based ionic liquid Cyphos IL 101 ([P66614]+Cl-) diluted in xylene used as a model of industrial diluents such as SOLVESSO 150. The system showed the selective co-extraction of Pd(ii) and Pt(iv) from a feed solution containing 100 mg L-1 Pt(iv), 55 mg L-1 Pd(ii), and 25 mg L-1 Rh(iii) in HCl via an anion exchange mechanism, leaving Rh(iii) in the raffinate. A McCabe-Thiele diagram demonstrated the quantitative extraction of Pd(ii) and Pt(iv) with 0.6 g L-1 [P66614]+Cl- with two counter-current stages at an organic/aqueous (O/A) phase volume ratio of 3/2 at 298 K. The stoichiometry of complexes formed in the organic phases was determined using Job's method and further characterized by 1H, 13C, 31P NMR and UV-vis spectroscopy. More importantly, a two-step stripping strategy was successfully adapted to treat the loaded organic phases with low aggressive media NaSCN and thiourea/HCl for the selective recovery of Pt(iv) and Pd(ii), respectively, with high purity >99.9% (w). Three counter-current stages are required for the quantitative stripping of Pt(iv) with 0.1 mol L-1 NaSCN at an O/A ratio of 3, whereas the total stripping of Pd(ii) with 0.01 mol L-1 acidic thiourea requires only one stage at an O/A ratio of 5. A series of extraction-stripping processes of up to 5 cycles indicated a possible recirculation of regenerated solvent without loss of performance. Simulated experiments in continuous modes suggest that phosphonium-based ionic liquid such as Cyphos IL 101 can be advantageously used as extractant to recover individually Pd, Pt and Rh from acidic chloride feed solutions as those encountered in the PGM's recycling industry.
- Nguyen, Viet Tu,Lee, Jae-Chun,Chagnes, Alexandre,Kim, Min-Seuk,Jeong, Jinki,Cote, Gérard
-
p. 62717 - 62728
(2016/07/13)
-
- The reduction of cobalt(III) by neptunium(V) and the neptunium(V)-chromium(III) complex
-
The rate law for the reaction Np(V) + Co(III) = Np(VI) + Co(II), from 5 to 25° in perchloric acid-lithium perchlorate solutions of constant ionic strength, is -d[Np(V)]/dt = k′[Np(V)] [Co(III)] where k′ = k0e-β[H+]. Under the same co
- Sullivan, James C.,Thompson, Richard C.
-
p. 1795 - 1798
(2008/10/08)
-