Research on Electrodialytic Processes

Dear Colleagues,

Electrodialysis is a mature separation technique in which ions migrate through electromembranes that are selective to cations or anions. Due to its versatility, electrodialysis has become a multifunctional process that is applied in several fields, such as seawater desalination, the treatment of various industrial wastewaters, as well as the production of food, medicines, biopolymers, ultrapure water, acids, and alkali. The main advantages of electrodialytic processes include their ability to extract and recover valuable components and the fact that, in most situations, it is not necessary to add reagents to the solution for treatment. On the other hand, the costs of ion exchange membranes and energy consumption are relatively high, besides the maintenance to mitigate the negative effects caused by fouling phenomena. Therefore, to ensure the economical and technical viability of electrodialytic processes, it is crucial that studies are carried out in order to 1) develop new membranes that are more selective to certain types of ions and present lower electrical resistance and costs (monopolar, bipolar, mosaic, amphoteric, monovalent selective ones, etc.), 2) develop new spacer configurations to promote turbulence at the membranes and intensify the ion transfer rate, 3) propose new layouts that reduce the total resistance of the system, 4) evaluate methods to mitigate fouling occurrence and 5) membrane cleaning procedures that extend their lifespan, 6) evaluate the impact of over-limiting mechanisms on membranes and the practical viability of operating the separation processes at over-limiting current regimes, and 7) propose hybrid processes that overcome the limitations faced in each of the processes when operated separately, among other things. This Special Issue serves as a platform gathering all recent advances in the broad scope of electrodialytic processes: Articles, case studies, reviews, and communications are welcome and are held in high regard.

Dr. Kayo Santana Barros
Prof. Dr. Valentín Pérez-Herranz
Guest Editors

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• electrodialysis
• electro-electrodialysis
• electrodialysis with bipolar membrane
• electrodialysis reversal
• fouling
• concentration polarization at electro membranes
• electroconvection

Title: Development of Cationic Poly (2,6-Dimethyl-1,4-Phenylene Oxide) Sulfonate Membranes for Electrodialysis
Authors: J. F. CORTE; V. D. Jahno; M. A. S. Rodrigues; A. M. Bernardes; F. Celso
Affiliation: Feevale University, Novo Hamburgo, Brazil; Federal University of Rio Grande do Sul, Porto Alegre, Brazil; Federal University of Pelotas, Pelotas, Brazil
Abstract: Electrodialysis is a water and wastewater treatment process that removes ions from a solution through ion exchange membranes under action of a electric field. Such process promotes a high quality of treated effluent without the need of chemicals. This article aimed to develop cation exchange membranes by sulfonation of Poly (p-phenylene oxide). Membranes were produced by two steps: (1) PPO was sulfonated using sulfuric acid as sulfonating agent; (2) cationic membranes were casted from solution of n-methyl pirrolidone. The membranes were characterized by FTIR, TGA, water swelling, IEC and ionic conductivity. Membranes were applied in a laboratory electrodyalisis system, and performance was compared to commercial membranes. It was possible to obtain membranes with two degrees of sulfonation, with 17.4% and 42.3%. Membranes presented, respectively, IEC of 1.4 mmol/g and 2.6 mmol/g and water swelling of 20% and 44.9%, while ionic conductivity varied from 0.2 x 10-3 S/cm to 1.4 x 10-2 S/cm. The membranes showed sodio extraction around 65%, while commercial membrane HDX100 reached 46.4%. These results indicate that membranes developed are promising to be applied in electrodialysis systems, since showed higher performance than the commercial one.