부산대학교 도서관

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.memsci.2008.10.054 Byline: Ludivine Franck-Lacaze, Philippe Sistat, Patrice Huguet Keywords: Anion exchange membrane; pK.sub.a; Electrical conductivity; Water content; Confocal Raman microscopy Abstract: The paper deals with physicochemical investigations of anionic membranes in view to better understanding the proton leakage phenomenon in the treatment of acidic solutions. The membranes of interest consisted of poly (4-vinylpyridine) ionisable groups grafted on two different copolymer structures. The acidity constant of the two membranes has been determined by confocal Raman microscopy, depending on the pH of the equilibrating acidic solutions, and the nature of the acid tested. In addition the membranes were shown to exhibit an appreciable electrical conductivity and water content only in the protonated form: the values obtained can be correlated with the pK.sub.a of the ionisable groups. Calculations of the chemical composition of the membrane in equilibrium with the acidic solutions revealed that the aqueous phase inside the membrane is far less acidic than the external equilibrating solution, leading to the acidity constants in the membrane (pK.sub.a.sup.true) and another related to the solution phase (p K.sub.a.sup.apparent). This fundamental work led to the concentration range of the acidic solution to be treated: the pH of the acidic solution has to be of the order of the apparent pK.sub.a of the membrane for appreciable content of active poly (4-vinylpydinium) groups and high selectivity of the ion transport through the membrane. Author Affiliation: Institut Europeen des Membranes, UMR 5635 Universite Montpellier II- ENSCM-CNRS, CC047, Place Eugene Bataillon, F-34090 Montpellier, France Article History: Received 24 April 2008; Revised 26 September 2008; Accepted 28 October 2008