Thermodynamics of Extraction of Nitric Acid by Tri-n-Butyl Phosphate—Hydrocarbon Diluent Solutions: III. Comparison of Literature Data
Nuclear science and engineering
I - Some of the published data on the extraction of nitric acid from aqueous solutions, containing 5 5 M acid, by tributyl phosphate-hydrocarbon diluent solutions were tested for their agreement w z h a mathematical description presented i n Part 1. I n a l l cases the agreement of the literature data with this description ranged from adequate to very good, thereby adding support to the interpretation of the parameters of the equation i n terms of the equilibrium . . constant, Kf, for the
... , Kf, for the extraction reaction and the two activity coefficients y ' and y ' The T T N' form of the mathematics suggests that TBP and TBPsH20 are indistinguishable i n t h e~r reaction with H N O 3 and that y ' i s an approximate mean molar activity coefficient of these two i n the T water-saturated system; similarly, y! i s an approximate mean molar activity coefficient of the two species TBP-HN03 and TBP!&O~ eH20. The quantity K C y ' has a value of -1.5 i n 1 J molar units for di luent-free ' TBP; its extrapolated value i n the pure dl luent Amsco 125-82, or odorless kerosene, i s -0.23, while its value i nn-hexane i s -0.27. NOTICE T h i s document contains information of a preliminary nature and was prepared primarily for internal use a t the Oak Ridge National Laboratory. I t i s subject to revision or correction and therefore does not represent a final report. The information i s not to be abstracted, reprinted or otherwise given public dissemination without the approval of the O R N L patent branch, L e g a l and Information Control Department. The purpose of this report i s to summarize literature data on the extraction of nitric acid from aqueous solutions by tributyl phosphate-hydrocarbon dilluent solutions i n terms of equations similar to those previously developed, B n the first paper (1) o f this series data were presented for the extraction o f aqueous nitric acid, i n the 0-5 Mconcentration range, by tributyl phosphate-Amsco 125-82 solutions and a representation o f these data by eqs. 9 and 2, the first of which applies for a constant ratio (diluent)/(TBP), the second of which is completely general: In these and subsequent equations square brackets refer to activities, parentheses to concentrations, aq and org to aqueous and organic phases, and the superscripts m and c to molal and molar scales, respectively; YO and YO PBP "2O are !he mole fractions of PBP and H 2 0 i n water-saturated PBP-Amsco 125-82 solutions. As i n the previous report (I), the scope o f this work i s limited to aqueous solutions containing less than about 5 M -H N 0 3 , Literature data analyzed are those of Codding, Haas, and Heumann (21, -Geary (3), -Healy and Brown (4), -Oiander, Donadieu, and Benedict (51, -Savolainen (61,and Damiani and Fattore (7' 1, -The d i l uent used i n references 2, 3, and 4 was of the odo:less mineral spirits type; that o f references 5 and 6, n-hexane. Damiani and Fattore used diluent-free TBP.