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NOTES CHLORIDE UPTAKE BY ION-EXCHANGE MEMBRANES IN DIFFERENT CHLORIDE SOLUTIONS BY N. KRISHNASWAMY Division of Plastics and Polymers, National Chemical Laboratory of India, Poona, India Received Auoust 17, 1064
In an earlier communication' the method of preparation of synthetic cation-exchange membrane discs has been described along with their Dolman diffusion properties in sodium chloride solutions. It was decided to extend the study to different salt solutions in order t o observe the effect of ionic charge, ionic size and valency on the Donnan diffusion properties of the cation-exchange membranes. For this purpose Disc 63 (a phenolsulfonic acid-formaldehyde condensation product) and Permionic CR-51 (sample obtained from Ionics Inc., U.S.A., with their Bulletin No. 1) were chosen and this note describes the results obtained in sodium chloride, barium chloride and hydrochloric acid solutions. Experimental The membranes were completely converted to the sodium, barium and hydrogen forms for estimation of the chloride uptake a t different external concentrations of sodium chlo-
ride, barium chloride and hydrochloric acid, respectively. The amount of chloride absorbed was determined by the procedure described earlier.' In the acid cycle the acidity was determined by titration with standard sodium hydroxide solution.
Results From the dimensions of the membranes measured in the different solutions the concentration of chloride absorbed by the resin phase ( N A ) was calculated. Figure 1 shows the relationship between the normality of chloride absorbed ( N A ) and the external chloride concentration (Next). Figure 2 reveals the variation of the ratio N A / N , , ~ with the external concentration Next for the two samples in different solutions. 0.8
0.7 5
0.6 0.5 J
3
2 0.4
-1
\
J
2 0.3
2
0.2 0.1 2.0
0 0
1.0
2.0
3.0
3.6
Next-
Fig. ~ . - N A / N , , ~us. N e x t : 1, CR 51 in NaCl. 2, CR 51 in HCI; 3, CR 51 in BaCI2; 4, Disc 63 in N a b ; 5, Disc 63 in HCI; 6, Disc 63 in BaC12.
1.5
It is seen that the chloride uptake in barium chloride solution by- both the samples differs from the chloride absorbed in sodium chloride and hydrochloric acid solutions. Thus, curves 3 and 6 in Fig. 2 are seen to differ from the others and the trend of these two curves in the dilute concentration range (up to 1.0 N ) indicates less of variation in chloride uptake by changing the external concentration. Further work is in progress with other salt solutions of alkali and alkaline earth metals to evaluate the Donnan diffusion characteristics.
2 1.0
0.5
T H E DENSITY OF n-OCTANE AND &,2,3,3TETRAMETHYLBUTANE AT LOW TEMPERATURES
0 Next.
Fig. 1.-Relationship betwee normality of chloride absorbed ( N A ) and the external cfloride concentration ( N e x t ) in different solutions: 1, CR 51 in NaCl; 2, CR 51 in HCI; 3, CR 51 ip BaC12; 4, Disc 63 in NaC1; 5, Disc 63 in HCI; 6, Disc 63 in BaC12. (1) N. Krishnaswamy, J . Sci. Ind. Res. (India), 13B, 7 2 2 (1954).
BY G. J. ROTARIU,D. W. FRAGA AND J. H. HILDEBRAND Department of Chemistry and Chemical Engineering, Universitu 01 California, Berkeley, California Received August 16, 1964
The measurements here reported were made in order to extend to low temperatures the compari-
