Sorption studies on regenerated cellulosic fibers in salt-alkali mixtures

The degrees of salt sorption were determined in lyocell and viscose fibers immersed in aqueous solutions of salt-alkali mixtures with the aim of using salt sorption as an indirect measure of changes to fiber accessibility in presence of alkali. The salt-alkali mixtures used were combinations of NaOH with NaCl or NaBr, and of KOH with KCl or KBr. In general, salt sorption in fibers increased with increase in alkali concentration up to 2 mol/l, and did not change significantly thereafter. The accessibility of Br- salts was greater than the Cl- salts, but that of the Na+ salts was greater than the K+ salts. These trends in salt sorption indicate that salt accessibility in fibers is not influenced by the size of hydrated salt ions, but by the forces of electrostatic attraction and repulsion between the charged fiber surface and salt cations and anions.