The large-scale application of electrochemical softening technology is severely hindered by its high investment cost due to the limitation of precipitation rate. In view of this question

an ultrasonic-assisted reactor with flat electrodes was employed for the softening treatment of circulating cooling water

and its softening performance was systematically investigated. The results show that

ultrasonic assistance accelerated the mass transfer process of scaling ions

thus made the precipitation rate rise without restriction as the current density increased. A high precipitation rate of 39 g/(m~2·h) could be obtained at the current density of 140 A/m~2 and ultrasound intensity of 1.8 W/cm~2.When the ultrasound intensity was larger than 2.5 W/cm~2

the precipitation rate would not be significantly improved. The diameters of the precipitates arranged loosely on the cathode surface were much smaller under ultrasonic condition than that of silent condition

which was conducive to the improvement of precipitation rate and removal of precipitates. Moreover

scale inhibitors should not be used together with ultrasonic assistance ascribed to their negative effect on precipitation reaction process. After 10 cycles of experiments

the average precipitation rate exhibited no obvious fluctuation

indicating that the ultrasound-assisted electrochemical reactor showed good operation stability. The conclusions provide valuable reference for improving electrochemical softening performance in circulating cooling water.