Italian researchers develop novel method to recover silver from end-of-life solar cells

Researchers from Italy’s University of Camerino have developed a new method to recover silver from end-of-life solar cells, achieving an impressive recovery efficiency of 98%. This novel approach combines hydrometallurgical and electrochemical processes, which use aqueous solutions and electric currents, respectively, to extract and recover metals.

Traditional metal extraction, such as open-pit mining, can cause significant environmental damage. In contrast, metal recovery from industrial waste can reduce environmental impact and lower energy consumption, offering a more sustainable alternative to conventional methods.

Silver recovery from photovoltaic (PV) waste is challenging due to the similar reduction potentials of silver and copper. To address this, the researchers used a combination of base-activated persulfate and ammonia. This approach employs persulfate as an oxidizing agent while generating a protective copper (II) oxide layer to prevent copper leaching.

The research team conducted experiments with various parameters, including ammonia concentration, PV waste sample size, potassium persulfate concentration, and reaction time. The optimal conditions were found to be 0.5 M ammonia, 0.2 mol/L potassium persulfate, a solid-to-liquid ratio of 50 g/L, and a reaction time of 60 minutes at 25°C with a stirring rate of 300 rpm. These conditions resulted in an average silver recovery rate of 85.0±2.6%.

Although the initial recovery rate was 85%, the researchers sought to improve it by using the electrodeposition-redox replacement (EDRR) method, a technique known for recovering highly pure silver from solutions containing copper ions. By applying the EDRR approach with a pulsed electrodeposition method, they achieved a silver recovery efficiency of 98.7%.

This high recovery rate is significant because it does not require additional chemicals, making the method more competitive compared to conventional processes. The researchers believe this technique offers a sustainable and efficient way to recover silver from solar cell waste, presenting a valuable alternative to traditional metal extraction.

The study, titled “Silver recovery from silicon solar cells waste by hydrometallurgical and electrochemical technique,” was published in Environmental Technology & Innovation. It was conducted in partnership with ORIM, an Italian company specializing in metal recovery from solid waste.