Process intensification of the electrodialysis metathesis for calcium bromide preparation: Effects of key influencing factors and phenomena of water migration

Calcium bromide, a high-value bromine resource, is widely used in the industrial synthesis processes and mercury removal from flue gas. However, there are some problems in traditional preparation methods for calcium bromide, such as long processing time, environmentally unfriendly and so on. To address these challenges, an electrodialysis metathesis (EDM) process was developed in this study to prepare high value-added calcium bromide using sodium bromide and calcium chloride as the raw materials. In order to obtain calcium bromide with high purity and improve the economic efficiency of the EDM process, the key influencing factors were investigated. Furthermore, the water migration during EDM was analyzed, and potential prospects of reducing apparent water flux volume by lowering temperature, current density, and the concentration difference between the dilute chamber and the concentrated chamber within an appropriate range. As a result, a calcium bromide product with a purity higher than 99 % was obtained with no Cl- detected. Mass fraction of Na+ was found to be 0.016 %, meeting the standards required by the industry. This method provides a new perspective and a good guide for the efficient preparation of highly valued bromine resources.