Effect of ionic strength on ion exchange equilibrium between cationic membranes and K+/Na+, K+/Li+ and Na+/Li+ binary systems

• Published in: Desalination and water treatment 2010-10, Vol.22 (1-3), p.265-270
• Main Authors: Hannachi, Ch, Guesmi, F., Marzouk, I., Hamrouni, B.
• Format: Article
• Language: English
• Subjects: Applied sciences; Binary system; Drinking water and swimming-pool water. Desalination; Exact sciences and technology; General purification processes; Ion exchange membrane; Ionic strength; Isotherms; Pollution; Selectivity coeffi cients; Wastewaters; Water treatment and pollution
• ISSN: 1944-3986; 1944-3994; 1944-3986
• DOI: 10.5004/dwt.2010.1838

Ion exchange membranes are receiving considerable attention and are successfully applied for desalination and for treating industrial effl uents. They are effi cient tools for the concentration or separation of food and pharmaceutical products containing ionic species. Extensive work has been reported on synthesis, characterization, properties and applications of these membranes. In this work ion exchange isotherms for the binary Na+/K+, Li+/K+, and Li+/Na+ were established at various ionic strengths, using CRP cationic membrane. All experiments were carried at 25°C, by setting the ionic strength in the range of I = 0.1–1.5 mol · l–1. All the results given by this membrane were compared with those obtained, in the same conditions, with CMX membrane. For the two membranes, up to ionic strength 1.5 mol · 11 affinity order was: KK+ > Na+ > Li+. Selectivity coefficients KK+Na+ KK+Li+ KNa+Li+ for homogenous CMX membrane were greater than those determined for heterogeneous CRP membrane. For low ionic strength till I = 0.2 mol · 11,these selectivity coefficients decrease strongly and tend asymptotically to unity for higher values of I. The product of selectivity coefficients KNa+Li+ · KK+Na+ · KLi+K+ were always close to unity.