title: How pulse modes affect proton-barriers and anion-exchange membrane mineral fouling during consecutive electrodialysis treatments.
abstract: Mineral fouling of cation-exchange membrane (CEM) was recently reduced by pulsed electric fields (PEFs) during the electrodialysis (ED) of solutions containing high Mg(2+)/Ca(2+) ratios. However, a fouling layer appeared on the diluate side of anion-exchange membrane (AEM) once the pause lapse surpassed certain duration. Recent studies presented a multilayer mineral growth on CEM, but the case of AEM needs yet to be cleared. The current study reveals the mechanisms involved in AEM fouling growth when applying pulse modes of current in comparison with dc current. The results showed that dc current generated steady proton barriers given by water splitting at AEM interfaces that impeded fouling on both membrane sides. The higher frequency of PEF ratio 1 (Ton/Toff=10s/10s) acted removing completely an initial mineral deposit on the concentrate side of AEM, keeping it clean after two and three consecutive runs. Particularly, an undesirable brucite layer was formed on the AEM-diluate side for longer pause lapses as for a PEF ratio 0.3 (Ton/Toff=10s/33.3s) current regime. This structure caused violent water splitting resulting in amorphous magnesium hydroxide formation and consequently in fouling precipitation on the concentrate side during a third run through current exaltation.
authors.affiliation: Institute of Nutraceuticals and Functional Foods (INAF) and Dairy Research Center (STELA), Department of Food Sciences and Nutrition, Pavillon Comtois, Université Laval, Sainte-Foy, QC, Canada G1V 0A6.
authors.forename: Nicolás
authors.initials: N
authors.lastname: Cifuentes-Araya
authors.affiliation: Institut Européen des Membranes, UMR 5635, Université Montpellier 2, ENSCM, CNRS, CC047, 34095 Montpellier Cedex 5, France.
authors.forename: Gérald
authors.initials: G
authors.lastname: Pourcelly
authors.affiliation: Institute of Nutraceuticals and Functional Foods (INAF) and Dairy Research Center (STELA), Department of Food Sciences and Nutrition, Pavillon Comtois, Université Laval, Sainte-Foy, QC, Canada G1V 0A6. Electronic address: Laurent.Bazinet@fsaa.ulaval.ca.
authors.forename: Laurent
authors.initials: L
authors.lastname: Bazinet
mesh_terms: D000838:Anions / Q000737:chemistry; D003956:Dialysis; D055664:Electrochemical Techniques; D010316:Particle Size; D011522:Protons; D013499:Surface Properties
chemical_list: D000838:Anions; D011522:Protons