Interfacial kinetics regulation and electrochemical optimization in ultrasonic-induced sponge cadmium nucleation

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• The cadmium cementation efficiency reaches 99.23 % at optimal conditions. • The grade of sponge cadmium obtained by ultrasonic method increased by 23.11 %. • The apparent activation energy decreases by 21.34 kJ/mol under ultrasonic. • Ultrasound induced the release of 89.8 % of dissolved oxygen and prevented the redissolution of cadmium. • The reduction peak potential is positively shifted by 0.299 V and current density increases by 0.053 A/cm 2 . The cementation method has become the dominant method for recovering cadmium from copper-cadmium slag leach solution due to its low cost and safety features. However, the conventional method has several limitations, including low zinc powder utilization, low sponge cadmium purity, and an extended production cycle. These limitations primarily stem from zinc powder agglomeration and the subsequent coverage of zinc particles by the product layer. In this study, the ultrasonic-enhanced zinc powder cementation process is proposed. Ultrasonic effectively dissociates the agglomeration and accelerate the reaction rate, improving the utilization of zinc powder and the grade of sponge cadmium. The cadmium cementation efficiency and the grade of sponge cadmium are increased by 24.56 % and 23.11 %. Kinetic experiments reveal that ultrasonic reduced the apparent activation energy by 21.34 kJ/mol. Moreover, the reduction potential exhibits a positive shift from −2.731 V to −2.432 V (vs. SCE). The current density increases from 0.146 A/cm 2 to 0.199 A/cm 2 . The self-corrosion potential reduces from −1.411 V to −1.453 V (vs. SCE). Simple economic analysis indicates that the benefits under ultrasonic method are significantly higher than conventional method. This work provides new insights into the application of ultrasonic in the recovery of cadmium from copper-cadmium slag.