Kinetic models based on analysis of the dissolution of copper, zinc and brass from WEEE in a sodium persulfate environment

• Cu, Zn, and brass leaching in a persulfate environment was investigated.
• Leaching rate increases with the increase of temperature and Na2S2O8 concentration.
• Three models which describe the leaching process have been developed.
• Assumed the formation of porous layer during leaching decrease the model error.
• All developed models have been validated based on measurements.

The purpose of this study is to provide an accurate kinetic description for the dissolution process of metals found in WEEE, such copper, zinc, and brass, using persulfate as a leaching oxidant. The factors affecting the performance and efficiency of the leaching process, such as stirring speed, persulfate concentration and temperature were separately investigated. It was observed that the leaching rate of the metals increased with the increase of temperature and persulfate concentration. We propose three models which accurately describe the variation in the surface of the solid for two kinds of geometries, a rectangular block, in the case of pure zinc dissolution, and a cylindrical rod for pure copper and brass dissolution. The apparent activation energy for the leaching of pure copper and zinc has been evaluated using Arrhenius expression and has been determined to be 5.2 × 104 J mol−1 for copper and 3.5 × 104 J mol−1 for zinc, in the range between 30 and 60 °C. The third model which describes the dissolution of brass has provided the best results.