**2.1 Sample preparation**

The chemical composition of the recycled aluminum alloy is shown in **Table 1** [6]. Before each measurement, the aluminum allow surface preparation of these discs for electrochemical tests was the following: the discs were first ground with 400 through 4000 grit SiC papers and then polished with diamond down to 6 μm and followed by 1 μm alumina – 30% chrome oxide suspension, and finishing with 5% oxalic acid solution. Later, each polished sample was rinsed with acetone and put in an ultrasonic cleaner for 10 min. Subsequently, it was rinsed with milliQ water (with a conductivity of 0.7 μs/cm) and ethyl alcohol and finally dried under a hot air flow. The contact area with the culinary media is 3.46 cm<sup>2</sup> .
