During the recycling of solar modules, it is imperative to recover all the toxic lead used in solder. In this experiment, acetic acid is investigated for lead leaching and electrowinning from a mixture of lead and tin. 0.0636 g of tin powder (Alfa Aesar, 325 mesh, 99.8%) and 0.0372 g of lead powder (Alfa Aesar, 100 mesh, 99.95%, atomized) were combined with 30 mL of 0.01 M acetic acid (Sigma Aldrich) and 100 μL hydrogen peroxide (Alfa Aesar, ACS, 29-33% w/w). The solution was allowed to sit for 48 hours before electrowinning to allow the hydrogen peroxide to decompose. A copper working electrode, graphite counter electrode, and silver/silver chloride reference electrode were used in a three-electrode system.

A cyclic voltammogram shows lead reduction around –0.4 V vs Ag/AgCl, and a large stripping peak around –0.05 V. There is only one set of redox peaks in the graph, indicating only lead is reduced and oxidized. EDX confirms the presence of metallic lead on the working electrode after electrowinning at –0.6 V vs Ag/AgCl for 90 minutes. Only lead is present on the working electrode surface, no tin. These results show acetic acid to be a promising leachate for the electrowinning of metallic lead from silicon solar module solder waste.