Making precious metals cheap: A sonoelectrochemical – Hydrodynamic cavitation method to recycle platinum group metals from spent automotive catalysts

Platinum group metals, such as Pd and Pt, found in three-way catalyst converters were recycled a two-step method: hydrodynamic cavitation followed by sonoelectrochemical dissolution. High shear forces obtained using convergent nozzle with throat diameter of 0.2 mm, feeded plunger pump at pressure 60 MPa. Cavitating submerged jets acted locally on the water dispersed waste catalyst. As-obtained samples analyzed scanning electron microscopy transmission microscopy. Electron initial sample showed that round shaped Pt nanoparticles randomly distributed Al 2 O 3 matrix. Cavitated show two zones which partially completely separated from cordierite. The separates cordierite leading to an apparent increase concentrations 9% 34% respectively. Conventional electrochemistry dissolution 20% 1 h. To further accelerate dissolution, sonotrode operating 20 kHz 75 W was placed inside electrochemical cell order mass transport obtain high rates. Indeed, results 40% available can be just In absence conventional less than 10% is recovered cost analysis 10 EUR per g 5 times smaller their current market price.