Abstract
A specially designed electrodeionization (EDI) stack was used for deep softening from simulated aqueous solutions containing low concentrations of hardness ions. Characteristics of the current–voltage ( I– V) and resistance–voltage ( R– V) curves of EDI and electrodialysis (ED) were compared at first, and then removal of Ca 2+ ions was carried out in a continuous experiment under a constant applied voltage. In order to further investigate the abilities of EDI to remove hardness without chemical regeneration, performances of different processes were compared under various experimental conditions of applied voltage, concentrate flow rate, and feed solution composition. It was shown that with feed Ca 2+ concentration of 5 mg dm −3, the dilute resistivity of 3.45 MΩ cm was obtained when under optimized operation conditions. It was also found that applied voltage and concentrate flow rate had remarkable impacts on the migration of Ca 2+ ions. A dimensionless coefficient K t was put forward to distinguish the “enhanced transfer” and “electoregeneration” mechanisms. It was found that scaling formation due to water dissociation on the membranes surface could be avoided under reasonable operation conditions. In addition, no significant influence on final hardness rejection was revealed with multi-species of feed solutions (Ca/Mg). The experimental results have demonstrated the feasibility of deep water softening by improved EDI technology.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
