Role of turbulent flow and gas bubbles in enhancing mass transfer in batch electrocoagulation: A brief review

• Published in: Desalination and Water Treatment
• Main Author: Niza N.M.; Emmanuel M.I.; Shadi A.M.H.; Yusof M.S.M.; Kamaruddin M.A.
• Format: Article
• Language: English
• Published: Desalination Publications 2019
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068662662&doi=10.5004%2fdwt.2019.24327&partnerID=40&md5=95e751265f52d18095b77e1fec4a36fa

Electrocoagulation (EC) has now become a popular choice in wastewater treatment owing to its easy operation, low sludge production and small quantity of chemicals used. Electrocoagulation is an electrochemical method that involves the release of active coagulant precursors (usually aluminium or iron cations) from corroded sacrificial anodes in a solution with the simultaneous formation of hydroxyl ions and hydrogen gas at the anode and cathode, respectively. The conventional design of the electrodes in an EC cell, however, does not take into consideration the impact of electrode passivation. It has been shown that the accumulation of hydrogen bubbles around the electrodes will result in a high internal resistance between the electrodes and will hinder the transfer of ions, which eventually, the efficiency of the EC cell will be reduced. While providing an extensive review of electrocoagulation, the main focus of this paper has been to highlight recent works on EC cells such as investigations into the geometry of electrodes and the utilization of gas bubbles to improve the removal efficiency. Interestingly, the improvements have not only been shown to have had a strong influence on the mass transfer of the EC cell but have also indirectly reduced the impact of passivation and the accumulation of bubbles on the electrodes. The roles of agitation through mechanical stirring and gas bubbles in enhancing mass transfer during electrocoagulation have also been discussed in this paper. © 2019 Desalination Publications. All rights reserved.