Enhancement of hardness and chloride removal and reduction of Cl2 release and corrosion in electrodeionization units

In this work, two approaches were used to reduce the chlorine corrosion in an electrodeionization unit. The first approach is the adsorption of chloride ions on composite materials of Tripoli, Pozzolana, and Feldspar with layered double hydroxides. A mixed adsorption column of 15% Feldspar, 25% Tripoli, 45% Pozzolana, 15% Mg–Al LDH removed about 60% of chloride ion concentration and reduced the chlorine gas release from about 4.8–1.9 ppm. This column composition showed the best percentage removal because it contains the highest percentage of Pozzolana. The second approach is using a 60/40 w/w Tripoli/LDH filter to protect the positive electrode from the chloride ions. The porosity of the Triploi/LDH filter increases with increasing the amount of ammonium carbonate reaching a porosity of about 50% at 5 wt% ammonium carbonate. The filter prevented the chloride from reaching the positive electrode and kept the concentration at the negative electrode without change.