The partition of uranyl nitrate between water and organic solvents. Part 6. Salting-out by a second nitrate

Abstract

The partition laws developed in earlier papers can be extended to cover systems containing a second nitrate insoluble in the organic phase. This leads to measurements of the activity coefficient of uranyI nitrate in the mixed solutions. Supplementary information is available from solubilities and ion exchange. It is found that the activity coefficients obey the Harned rule, despite extensive association between the uranyl and nitrate ions. This enables us to apply the cross-differentiation relations to calculate the activity coefficient of the second nitrate.The results at ionic strengths up to 5 m show that the larger the activity coefficient of the second nitrate, the greater is its salting-out power. At higher ionic strengths ion association dominates the picture and enables us to give a qualitative explanation of the shapes of the various curves obtained.

Cation Effect of Chloride Salting Agents on Transition Metal Ion Hydration and Solvent Extraction by the Basic Extractant Methyltrioctylammonium Chloride

“…As already proposed by other authors: the extraction efficiency of a metal ion by solvating extractants is closely related to the activity coefficients of the cations of the salting agent. 26 , 27 However, it is advisable to consider the activity coefficients of the extractable metal complexes directly. These activity coefficients are influenced by the hydration of the cation of the salting agent, given the anion is the same in all comparisons.…”

“… 20 , 24 , 25 Some studies have already been performed, predicting salting effects on the extraction of metal ions from nitrate media by solvating extractants. 26 , 27 These studies link salt activity coefficients to the extraction efficiency of a metal ion by a solvating extractant. However, they are unable to explain the observed effects when nitrate salts of di- and trivalent cations are used or when the ionic strength is higher than 5 molal .…”

“…Although the effects of metal complexation on solvent extraction of metals are rather well understood, the underlying principles governing the salting effects on solvent extractions are not completely clear yet. ,, Some studies have already been performed, predicting salting effects on the extraction of metal ions from nitrate media by solvating extractants. , These studies link salt activity coefficients to the extraction efficiency of a metal ion by a solvating extractant. However, they are unable to explain the observed effects when nitrate salts of di- and trivalent cations are used or when the ionic strength is higher than 5 molal .…”

Activity coefficients of mixed electrolytes from liquid-liquid partitioning measurements

“…A very familiar form of eq 7 is revealed when activity coefficients are removed and aHL(o) is replaced by its concentration. The equation is usually given in logarithmic form as log 73 = log KOfin(KA/KUL)n + n(pH) + n log [HL(o)j (8) This relation was first derived by Kolthoff and Sandell26 and is very useful in characterizing LLPE stems. In the present context, plots of log 73 vs. pH for different values of HL(o) allow the selection of conditions where 73 is small, e.g., 0.01-0.05, so that the assumptions cited above can be satisfied.…”

Extraction of Uranyl Butyrate by Organic Solvents. Distribution and Rate of Transfer in Continous Countercurrent Spray Extraction Column.

“…The distribution of uranyl nitrate between water and various organic solvents and its continuous countercurrent extraction in spray, packed, wetted-wall, and pulse columns have been studied by many workers (1)(2)(3)(4)(5)(6)(7)(8). The distribution study for this salt shows that the extraction capacity of solvents rapidly falls off with decrease in concentration and and is very poor at the dilute end.…”