Study of ion transport through a selective membrane

Abstract

Nowadays, the electroplating industry faces two growing concerns. The first one refers to the substitution of cyanidric raw materials, and the second one is to reduce the volume of waste generated in the process. An example of a substitute for cyanide-based compounds is an alkaline bath containing HEDP for copper plating on Zamac. Regarding the waste treatment, the electrodialysis can promote ionic separation in a solution, dispensing with phase changes and the addition of chemical compounds to the effluent. Electrodialysis allows the transport of ions through a selective membrane under the influence of an electrical field. Several variables must be evaluated in an electrodialysis process, especially when new substances are inserted into the system. The study of ion transport properties through the membrane is important because it can directly influence the efficiency of the system. The aim of this study is to evaluate two parameters related to ion transport through a heterogeneous anionic selective membrane. The swelling degree and the fraction of conductive regions of the membrane will be analyzed. To accomplish the proposed objectives, the chronopotentiometry electrochemical technique will be used, from which it is possible to determine quantitatively the fraction of conductive regions of the membrane. The influence of HEDP ions and Cu (HEDP) complexes in the swelling degree of the membrane will be evaluated. Results will be analyzed by applying the modified Sand equation and by mass loss analysis. (AU)