An investigation through the validation of the electrochemical methods used for bipolar membranes characterization

- Three kinds of heterogeneous bipolar membranes differing in their monolayers properties, were prepared.
- Three kinds of electrochemical methods were used to characterize the bipolar membranes.
- Two sorts of electrodialysis with bipolar membranes were carried out and the important variables of the electrodialysis were calculated.
- The comparison between the results of the electrodialysis with those of electrochemical techniques confirmed their reliability.
- Effect of the functional and structural properties of the bipolar membranes on their efficiency was investigated.

Four types of bipolar membranes (BMs) with different structural properties were subjected to various electrochemical methods including current-voltage curve, (CVC) chronopotentiometry, and impedance spectroscopy, to be characterized in terms of selectivity, energy consumption and the water splitting capability. Then the bipolar membranes were used in two kinds of electrodialysis modules, lab scale and pilot unit, for acid and base production. The produced acid and base were analyzed to calculate the product purity, energy consumption and current efficiency of each bipolar membrane electrodialysis (BMED). The results obtained with electrodialysis coincided with those of electrochemical methods, indicating that even though the electrochemical methods are rather fast and easy to perform, they are quite reliable. Furthermore the impact of structural properties of each BM on its efficiency was investigated. It was figured out that the reinforcing of a heterogeneous BM improves its properties while the increase in the ion exchange resin content on each layer of the heterogeneous BMs was not resulted in any significant enhancement of BM properties. The investigated homogenous membrane showed higher selectivity and less energy consumption compared to the heterogeneous BMs.

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