Water reclamation and chemicals recovery from a novel cyanide-free copper plating bath using electrodialysis membrane process

Abstract

One of the industrial concerns is to change procedures into sustainable and cleaner processes. In electroplating, researches have been developed to replace toxic materials for safer alternatives. Cyanide salts are toxic compounds used as complexing agents in alkaline baths. This work focused in a cyanide-free copper alkaline bath developed for copper coating onto zinc alloys. Electrodialysis was evaluated to obtain a concentrated solution from a model rinsing water and simultaneously to treat the effluent for further reuse. Membrane properties after electrodialysis were analyzed, before and after cleaning procedures. Deposition tests were performed using electrolytes containing the recycled inputs and the coatings were analyzed. As results, a solution 5 to 6 times more concentrated than the initial one was obtained. The average demineralization was 90% and the percent extraction of ions was higher than 80%. Interactions between the organic acid and the exchange groups may affect membrane properties. Nevertheless, FTIR analyses and the applied cleaning procedures showed that bonds between phosphorus and quaternary amine may be reversible. Both cleaning procedures presented similar performance and partially restored the membrane properties. The concentrate could be added to the copper bath to compensate eventual drag-out losses without affecting the quality of the coatings.

Electrodialysis Applications in Wastewater Treatment for Environmental Protection and Resources Recovery: A Systematic Review on Progress and Perspectives

“…Despite various ionic complexes formed as the pH was changed, diluate and concentrate products were suitable for recycle in the bath and rinsing processes, respectively (maximum recovery of 99.7% for Cu, 94.4% for organic acid). Further experiments again achieved high recoveries, and pieces of electroplated Zamak alloy exhibited good-quality coatings [189]. However, AEMs properties were worsened (electrical resistance and limiting current), likely because of interactions between organic acids or their chelates and fixed groups.…”

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

“…For constructing the chronopotentiograms, current pulses were applied for 300 s. Then, the relaxation process was allowed to proceed for 100 s before the next pulse was applied. These durations were chosen based on previous work [37,39]. The current-voltage curves in the chronopotentiometric step were obtained from the steady-state polarization voltage of the membranes (potential drop) corresponding to each current pulse.…”

“…The concentration of the working solution was based on the electrodeposition bath tested by Almeida et al [8,9]. We here used a closed system configuration of electrodialysis for performing concentration tests, for obtaining a concentrated solution rich in cations and anions, and a diluted solution [36,37]. The ED configuration was chosen based on the possibility of replacing a portion of desalted solution with a portion of a new solution with the same initial content of components and the recovery of metals from the concentrated solution in the electrodeposition bath.…”

Membrane processes

“…Scarazzato, Panossian, Tenório, Pérez‐Herranz, and Espinosa (2018) developed a cyanide‐free copper alkaline bath for copper coating. The membrane test suggested 90% demineralization and greater than 80% ion extraction.…”