Credit: Environmental technology and innovation (2024). DOI: 10.1016/j.eti.2024.103803
A multi-institutional team of chemists, metallurgists and engineers has developed a highly effective method for recovering silver from disused solar panels. Their paper is published in Environmental technology and innovation.
As climate change progresses, scientists are looking to replace fossil fuels with renewable resources, including solar energy. But the development of these technologies has brought new environmental challenges, such as what to do with solar panels once they’ve reached the end of their lifespan.
Previous research has shown that some components of solar panels are relatively easy to recycle, including iron, steel and aluminum used to make brackets, racks and other support systems.
Unfortunately, other components are harder to recover, such as silver used in electrical circuits, which must be separated from the circuits and copper that is almost always present. These materials are therefore rarely recycled. In this new study, an Italian team has developed a relatively inexpensive way to recover silver used in solar panels.
The process involves using a base-activated persulfate with ammonia. In this way, the persulfate can serve as an oxidizing agent. As the reaction proceeds, copper oxide is produced, which serves as a protective layer, preventing the copper from leaching.
To find the right amounts of each material to use in the process, the researchers ran several reactions using different variables, such as ammonia concentrations, while keeping other variables such as stirring speed and temperature uniform.
After much experimentation, the team found the right combination of factors: ammonia at a concentration of 0.5 M and potassium persulfate at 0.2 mol per liter, and a reaction time of one hour. Under these conditions, the reaction results in the separation of 85% of the silver in a sample.
The team then performed a redox electrodeposition replacement to increase the percentage to 98.7%. Using a scanning electron microscope, the team confirmed the enrichment of the silver particles.
More information:
Raffaele Emanuele Russo et al, Silver recovery from silicon solar cell waste by hydrometallurgical and electrochemical technique, Environmental technology and innovation (2024). DOI: 10.1016/j.eti.2024.103803
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