The metal-finishing and tannery industries have been under strong pressure to replace their current wastewater treatment based on a physicochemical process. The electrodialysis process is becoming an interesting alternative for wastewater treatment. Electrodialysis is a membrane separation technique, in which ions are transported from one solution to another through ion-exchange membranes, using an electric field as the driving force. Blends of polystyrene and polyaniline were obtained in order to produce membranes for electrodialysis. The produced membranes were applied in the recovery of baths from the metal-finishing and tannery industries. The parameter for electrodialysis evaluation was the percentage of chromium extraction. The results obtained using these membranes were compared to those obtained with the commercial membrane Nafion 450. 1. Introduction Over the past few decades, there has been increased concern for the preservation of water resources. Industrial activities have led to widespread heavy metal contamination of soils and natural waters. Among the various sources of water contamination, the electroplating industry stands out as one of the most important, because it generates a considerable volume of effluents containing high concentrations of metal ions and, often, high concentrations of organic matter [1]. Another aggravating factor is that the traditional process for the treatment of these effluents, not very efficient and in some cases totally inefficient, produces dangerous solid waste (electroplating sludge), which should, therefore, be disposed of in appropriate landfills. The most commonly used technology for the treatment of effluents is the physicochemical one, followed by units of biological treatment, usually consisting of activated sludge or aerated lagoon systems [2]. These conventional treatments are generally not able to reduce all the polluting parameters. Chemical Oxygen Demand (COD), chlorides, sulfates, and chromium often do not reach the required limits [3]. In this context, the leather and metal-finishing industries urge researchers to investigate new technologies for the recovery or recycling of chemical wastewater [4]. Because of their toxicity, these effluents cannot be rejected without pretreatment in the environment [5, 6]. Membrane technology has become increasingly attractive for wastewater treatment and recycling [7]. The main advantage of a membrane process is that concentration and separation are achieved without changing the physical state or using chemical products. Because of their modularity,
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