Electrochemical Detection of Free Chlorine in Ballast Water Management System

Abstract

Ballast water, which is seawater taken onboard ships to ensure stable and maneuverable sailing, can pose a significant threat to marine ecosystems and human health when discharged owing to the presence of undesirable organisms. To mitigate this risk, ballast water treatment methods such as electrochlorination are employed, where oxidants such as hypochlorite are generated to effectively eliminate marine microorganisms. The effectiveness of an electrochlorination-based ballast water management system (BWMS) depends on the maintenance of optimal concentrations of total residual chlorine (TRC). However, excessive levels of free chlorine (Cl) can result in corrosion and environmental damage, rendering the accurate monitoring of TRC levels crucial for the safe discharge of ballast water. This review focuses on recent advancements in electrochemical sensors for free Cl measurement in BWMS. The process of free Cl generation, techniques for electrochemical detection, and factors influencing sensor performance are elucidated. In addition, materials and strategies for improving the performance of the sensors are described. Finally, perspectives on the current issues and future challenges that must be overcome to effectively utilize electrochemical detection in BWMS are discussed, thereby offering new directions for advancing this technology.