Ion Exchange of H⁺, Na⁺, Mg²⁺, Ca²⁺, Mn²⁺, and Ba²⁺ on Wood Pulp

Abstract

Ion exchange selectivity coefficients were measured for the partition of metals between solution and pulp fibers. The method accurately models the ion exchange isotherms for all cation pairs evaluated and is accurate up to approximately 0.05 molar concentrations. Selectivity coefficients were determined for calcium and magnesium with each other and with hydrogen, sodium, manganese, and barium. Measurements made at 25°, 50°, and 65°C were used to determine the enthalpy and entropy of the reactions. The data follow the expected linear free‐energy relationship. These results can be used to estimate the ion exchange selectivity coefficients for any temperature within the experimental range.

Keywords:

• Wood fiber
• pine
• ion exchange
• monovalent cations
• divalent cations
• selectivity coefficients

We thank the Georgia Traditional Industries Program in Pulp and Paper and the member companies of the Institute of Paper Science and Technology for supporting this work. Thanks to Clark Woitkovich for including funding for this effort in his grant with Georgia TIP³. Dr. Earl Malcolm and Dr. Paul Wollwage (formerly Weyerhaeuser Corp.) have been very helpful in understanding and refining the experimental approach.