Determination of optimum conditions in electrodialytic processes for brine production from seawater

In this thesis, the performance of electrodialytic methods to be used in the production of brine from seawater for chlor alkali process were analysed with the parameters such as membrane type, electrical potential applied and feed concentration. In electrodialysis (ED) and electrodeionization (EDI) processes, real seawater, sample seawater and sodium chloride solutions with different concentrations were used for feed solutions. Both type of membranes as charge selective and monovalent selective were used in experiments. Ion chromatography was used to analyse the concentrations of ions in solution. In the first step of study, called purification, undesired bivalent ions were removed from feed solution; in the following step, called enrichment, the aim was to concentrate sodium chloride in the solution purified. Purification performance is evaluated by selectivity, whereas enrichment performance by specific power consumption, flux and recovery. While ED as electrodialytic method and monovalent selective membrane as membrane type were found to be more successful than the others in the purification step, there was neither electrodialytic method nor membrane to be distinguished for all kinds of feed solutions in the enrichment step.