With the same method as using of Na
4P
2O
7 in the 5 th report of this series, the pH of aqueous solutions of Na
5P
3O
10 or Na
6P
4O
13 was modified by adding hydrochloric acid in order to change the stabilities of complex ions, the filter paper was saturated with this solution, ionic spots on the filter paper were allowed to migrate toward the anode or cathode by applying the direct current. When the solution was alkaline, each ion was converted into a complex ion and migrated toward the anode, and the separation was not efficient as the relative migration velocity of each ion was close to each other, while turning of the pH of the solution below 2 caused the lowering of the stability which was different for each ion and the mutual separation of them were possible. Thus, for example, Cu
2+, Cd
2+, Bi
3+, and Pb
2+, Al
3+, Fe
3+, and CrO
2-4; and Ni
2+, Co
2+ and Zn
2+ were separated in acid range. Either Na
5P
3O
10 or Na
6P
4O
13 gave different state of ionic separation than that of using Na
4P
2O
7.
With the use of the same technique as in the 5 th and 9 th report of this series, the filter paper saturated with a solution of HPO
3, (HPO
3)
3 or (HPO
3)
6 was treated with NaOH or HCl to make various pH of the solution and the migration of spots of various ions through the electrolyte between the electrodes connected with the direct current was studied. The stabilities of complex ions in HPO
3 below pH 1. 7 and in (HPO
3)
3 below pH 5. 6 were different for each ion, and the separation of the ions in these range were possible. Lowering of the pH of (HPO
3)
6 caused the decrease in stability of complex ions and, though the migration velocity toward the anode was decreased gradually, it was unsuitable for separation of ions as there were no great varriation among their mutual migration velocities. By use of HPO
3, the separation of Al
3+ and Fe
3+, Ni
2+, Co
2+ and Zn
2+; Ca
2+ and Sr
2+ (Ba
2+), as well as the separation of Ni
2+, Cu
2+ and Fe
3+; Ni
2+, Zn
2+ and Al
3+; and Ni
2+, Cd
2+ and Fe
3+ were made; (HPO
3)
3 was used for separation of Ni
2+, Co
2+ and Zn
2+; Al
3+ and Fe
3+ ; Cu
2+, Cd
2+, Pb
2+ and Bi
3+ ; Ca
2+ and Sr
2+ as well as the separation of ionic mixtures of Ca
2+, Al
3+ and Fe
3+ ; Ni
2+, Cu
2+, Sb
3+ and Fe
3+; Ba
2+, Zn
2+, Pb
2+, and Fe
3+; and Ba
2+, Co
2+, Al
3+ and Fe
3+. In the mechanism of separation of ions by use of poly-and meta-phosphoric acid, the reaction of forming a complex salt, MR, from each of these phosphoric acid, H
2R, and any ion M
2+ takes place according to the equation, H
2R + M
2+_??_MR + 2H
+. Let
K is the equilibrium constant, then the mobility of ion can be expressed by the equation, u =U × [H
+]
2/ {k[H
2R] + [H
+]
2}, where U = mobility when all dissociated into M
2+, and the mutual separation of ions are possible for those having different equiblium contant
K.
抄録全体を表示