Distribution of HDBP in two-phase systems consisting of aqueous nitric acid, organic diluent (with or without TBP), and HDBP or its zirconium salt

Abstract

The distribution of HDBP between 0–5 M aqueous HNO3 and various solvents or solutions of acidic zirconium salt of HDBP (HDBP ZS, HDBP : Zr ratio 6–18) in the same solvents [decane, xylene, CCl4, m-nitrobenzotrifluoride (F-3), 30 vol % TBP in decane and xylene] was studied. The HDBP concentration in aqueous solutions decreases with an increase in the HNO3 concentration. At HDBP concentrations in the organic phase below 0.1 M, its distribution follows the Nernst equation; in the range 0.1–0.4 M, its concentration in the aqueous phase at a constant acidity is approximately constant; and with a further increase in the HDBP concentration in the organic phase, its concentration in the aqueous phase starts to grow again. When the organic solvent is TBP in diluent, the HDBP concentration in more concentrated HNO3 solutions decreases by almost an order of magnitude compared to the systems without TBP, whereas with water and dilute HNO3 solutions the difference from the TBP-free systems is insignificant. The presence of Zr somewhat increases the HDBP distribution ratio. The extraction of HNO3 with a solution of HDBP in xylene and CCl4 apparently involves the HDBP dimer. A mathematical description of the HDBP and HNO3 distribution between aqueous nitric acid solutions and xylene or CCl4, based on equations of chemical reactions between the components, was suggested.