Effect of ultrasonic treatment on tin recovery from decommissioned displays in sulphuric, hydrochloric, and methanesulphonic acid solutions

The study investigates the physicochemical patterns of tin leaching from the surface of glass substrates from decommissioned displays in hydrochloric, sulphuric, and methanesulphonic acids. The effects of acid concentration (0.1–1.0 N), duration (10–60 min), temperature (298–353 K), and ultrasonic treatment intensity (UST) (120–300 W/cm 2 ) on leaching performance were evaluated. It was demonstrated that ultrasonic treatment positively impacts sulphuric acid leaching of tin, increasing its recovery by 14–16 %. However, during leaching in hydrochloric and methanesulphonic acid solutions, UST led to a reduction in tin recovery to 28 % and 1.7 %, respectively, due to acid decomposition under ultrasound. The partial reaction orders for tin leaching in HCl, H 2 SO 4 , and CH 3 SO 3 H were determined to be 0.8, 1.4, and 1.1, respectively, and changed to 1.5, 1.1, and 0.3 under ultrasound for the corresponding acids. An increase in temperature from 298 K to 333 K significantly improved tin recovery in sulphuric and hydrochloric acids. However, raising the temperature to 353 K led to a decrease in tin ion concentration after 10–20 min, likely due to tin hydrolysis and precipitation. The calculated apparent activation energies of tin oxide dissolution in HCl solutions were 40.4 kJ/mol without UST and 22.9 kJ/mol with UST. For H 2 SO 4 , the apparent activation energy was 4.0 kJ/mol, increasing to 29.0 kJ/mol under ultrasonic treatment. Therefore, the study showed that tin leaching from glass substrates of decommissioned displays proceeds in a kinetic regime when HCl is used and in a diffusion regime in H 2 SO 4 solutions, with ultrasonic treatment facilitating the transition to a mixed regime.