Reverse permeation of salicylate ion through cellulose membrane.

The reverse permeation of salicylate ion and the effect of bovine serum albumin on the permeation were studied in a sodium salicylate-sodium oxalate-water system. In passive transport the permeation flux of an ion is expressed by the linear combination of the two terms which represent the concentration and electric potential gradients. Because the mobility of the sodium ion is greater than the oxalate ion, salicylate ion moves against the concentration gradient, and follows the electric potential gradient in the initial stage of permeation. The reverse permeation of salicylate ion through a cellulose membrane was accelerated with a high concentration ratio of oxalate to salicylate ions and reached a maximum value after 10 hr in the absence of bovine serum albumin. After reaching a maximum value, the salicylate ion permeated along the concentration gradient. The maximum concentration efficiency was 11.2%. In the presence of bovine serum albumin, the reverse permeation of salicylate ion reached a maximum value after 3 hr.