Bipolar Membrane Electrodialysis For Binary Salt Water Treatment: Valorization Of Type And Concentration Of Electrolytes

The bipolar membrane electrodialysis (BMED) system has been receiving intense attention recently due to its simultaneous desalination and acid and base production. In this study, in addition to salt water recovery, the BMED system was used for the generation of hydrochloric acid (HCl), ammonia (NH3 center dot H2O), and sodium hydroxide (NaOH) from a binary salt mixture of 1.12 M ammonium chloride (NH4Cl) and 0.51 M sodium chloride (NaCl) solutions. The main aim of the study is to evaluate the effects of type and concentration of anolyte and/or catholyte solutions (electrolytes) on desalination, feed solution conductivity, acid and base formation from salt, and product purity. Sulfuric acid (H2SO4), sodium sulfate (Na2SO4), NaCl, and NaOH are used as the electrolytes, and three different concentrations (0.05, 0.075, 0.1 M) were tested for all types of electrolytes. The results of the study indicate that 0.05 M H2SO4 is the most effective electrolyte with respect to the desalination and product (acid and base)-based conversion. Higher concentrations of electrolytes result in higher process performance as well as lower product impurity.