Study on the kinetics and mechanism of ultrasonic-microwave synergistic enhancement for leaching indium from zinc oxide dust.

This study investigates the ultrasonic-microwave synergistic intensive leaching of indium from zinc oxide dust and compares it with conventional leaching, single ultrasonic leaching, and microwave leaching. Additionally, the temperature rise behavior of zinc oxide dust in a sulfuric acid system is examined. The results demonstrate that ultrasonic-microwave co-leaching significantly reduces leaching time compared with conventional leaching and improves the leaching rate of indium compared with single ultrasonic leaching and microwave leaching. The optimal process conditions for ultrasonic-microwave synergistic leaching are determined to be an ultrasonic power of 200 W, microwave power of 200 W, leaching time of 30 min, sulfuric acid concentration of 180 g L⁻¹, and liquid to solid ratio of 8:1. Under these conditions, the leaching rates of indium, zinc, aluminum, and iron are 91.25, 97.69, 74.57, and 48.62%, respectively. In contrast, under the same conditions, the leaching rates of indium and zinc by single ultrasonic leaching were 89.01 and 94.12%, respectively, and the leaching rates of indium and zinc by single microwave leaching were 88.59 and 95.59%, respectively. These findings indicate a synergistic effect of ultrasound and microwave. The accuracy of the single factor optimization experiment results was verified using the response surface analysis method to optimize the experimental conditions. The results indicated that the single factor optimization experiment was accurate. Studies in chemical kinetics studies demonstrated that the leaching of indium is primarily influenced by ultrasound microwave power and sulfuric acid concentration. Additionally, the leaching process is governed by chemical reactions. Arrhenius diagram was used to plot the (1/W–lnK) and (ln[H₂SO₄] − lnK) diagrams. The reaction coefficient for ultrasound-microwave is − 7.5, and the reaction order for sulfuric acid is 0.815. The chemical kinetic models are: 1 − (1 − x)^1/3 = exp(− 4.12 − 7.5/W).t, 1 − (1 − x)^1/3 = exp(− 4.654 + 0.815ln[H₂SO₄]).t. The mechanism of ultrasonic-microwave synergistic enhancement for leaching indium from zinc oxide dust was elucidated. This research introduces a novel method for indium leaching, which holds significant theoretical and practical implications. Future research should focus on enhancing the amplification technology of ultrasonic-microwave leaching equipment. [ABSTRACT FROM AUTHOR]