Application of titanium suboxide electrode in electrochemical polarity reversal descaling-filtration crystallization coupling system

Abstract

In the electrochemical (EC) polarity reversal descaling, frequent polarity reversal shortens the electrode's service life, and the large amount of scale peeled off from the cathode can impact the quality of the effluent. To overcome these challenges, this study proposes a periodic polarity reversal electrochemical descaling process coupled with a filtration crystallization (FC) system. Both the anode and cathode utilize titanium suboxide (Ti4O7) electrodes to remove hardness ions from circulating cooling water (CCW). The unique oxygen vacancy structure of Ti4O7 electrodes allows for an extended electrode lifespan which is 2.5 times electrode lifespan under the constant current supply mode through periodic polarity reversal. In comparison to mesh electrodes, plate electrodes exhibit higher water treatment efficiency and scale detachment ability. The optimal descaling efficiency of 17–20 % was achieved at a current density of 8 mA·cm−2 and a flow rate of 2.7 L·h−1. After operating for 420 min and then reversing the polarity, the scale detachment reaches 90.2 % within 20 min of polarity reversal. By coupling the electrochemical process with a filtration crystallization system filled with artificial zeolites, the overall hardness removal of the system can be increased to 25.5 %–27.3 %. Furthermore, the system maintains good treatment performance even after 20 cycles. This study innovatively applies the Ti4O7 electrodes to electrochemical polarity reversal descaling, providing a reference for the development of related descaling technologies.