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Treatment of Cyanide-Free Wastewater from Brass Electrodeposition with EDTA by Electrodialysis: Evaluation of Underlimiting and Overlimiting Operations

1
Department of Chemical Engineering, University of São Paulo (USP), Av. Professor Lineu Prestes, 580, Bloco 18–Conjunto das Químicas, São Paulo–SP 05434-070, Brazil
2
IEC Group, ISIRYM, Universitat Politècnica de València–Spain, Camí de Vera s/n, 46022, P.O. Box 22012, E-46071 València, Spain
3
Department of Materials Engineering, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, Porto Alegre 91501-970, Brazil
*
Author to whom correspondence should be addressed.
Membranes 2020, 10(4), 69; https://doi.org/10.3390/membranes10040069
Received: 16 March 2020 / Revised: 6 April 2020 / Accepted: 8 April 2020 / Published: 11 April 2020
Growing environmental concerns have led to the development of cleaner processes, such as the substitution of cyanide in electroplating industries and changes in the treatment of wastewaters. Hence, we evaluated the treatment of cyanide-free wastewater from the brass electroplating industry with EDTA as a complexing agent by electrodialysis, aimed at recovering water and concentrated solutions for reuse. The electrodialysis tests were performed in underlimiting and overlimiting conditions. The results suggested that intense water dissociation occurred at the cathodic side of the commercial anion-exchange membrane (HDX) during the overlimiting test. Consequently, the pH reduction at this membrane may have led to the reaction of protons with complexes of EDTA-metals and insoluble species. This allowed the migration of free Cu2+ and Zn2+ to the cation-exchange membrane as a result of the intense electric field and electroconvection. These overlimiting phenomena accounted for the improvement of the percent extraction and percent concentration, since in the electrodialysis stack employed herein, the concentrate compartments of cationic and anionic species were connected to the same reservoir. Chronopotentiometric studies showed that electroconvective vortices minimized fouling/scaling at both membranes. The electrodialysis in the overlimiting condition seemed to be more advantageous due to water dissociation and electroconvection. View Full-Text
Keywords: electrodialysis; chronopotentiometry; ion-exchange membrane; overlimiting current; water dissociation electrodialysis; chronopotentiometry; ion-exchange membrane; overlimiting current; water dissociation
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MDPI and ACS Style

Barros, K.S.; Scarazzato, T.; Pérez-Herranz, V.; Espinosa, D.C.R. Treatment of Cyanide-Free Wastewater from Brass Electrodeposition with EDTA by Electrodialysis: Evaluation of Underlimiting and Overlimiting Operations. Membranes 2020, 10, 69.

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