An Experimental Investigation of Electrodialysis with Bipolar Membranes Long-run Performances with Real Solutions from Saltworks

Abstract

Electrodialysis with Bipolar Membranes (EDBM) is a promising process to produce acidic and basic solutions that are important in circular treatment chains. However, there is a lack of knowledge regarding the long-run performance of EDBM units fed multi-ionic solutions. This study aims to fill this gap by performing a long-run test, via an innovative feed and bleed configuration, with real brines coming from Trapani (Italy) saltworks and pre-treated to remove Mg and Ca. A laboratory EDBM unit with 5 triplets with an active membrane area of 100 cm2 was used. The results show that a steady-state concentration of 0.44 mol/L on average of OH- and H+ (in the form of NaOH and HCl) was reached in both acid and base outlet solutions, respectively, with a maximum deviation of 2 %. Stable performances were observed with a current efficiency of 69 % and 56 % and specific energy consumption of 1.78 kWh/kg and 2.19 kWh/kg on average for base and acid, respectively. These results demonstrate the potential of EDBM processes to maintain competitive and efficient performance.