A method for recovering silver from defective solar modules with 98% efficiency

An interdisciplinary team of chemists, metallurgists and engineers has developed a highly efficient method to extract silver from defective solar modules. Their article was published in Environmental technology and innovation.

As climate change progresses, scientists are trying to replace fossil fuels with renewable resources such as solar energy. However, the development of these technologies has brought with it new environmental problems, such as what to do with solar panels when their useful life has ended.

Previous research has shown that some components of solar panels are relatively easy to recycle. This includes the iron, steel and aluminium used to make brackets, racks and other support systems.

Unfortunately, other components are more difficult to recover, such as the silver used in electrical circuits – it must be separated from the circuits and the copper that is almost always present. As a result, these materials are rarely recycled. In this new study, a team in Italy developed a relatively inexpensive method to recover the silver used in solar panels.

This process uses a base-activated persulfate together with ammonia. This allows the persulfate to act as an oxidizing agent. During the reaction, copper oxide is formed, which acts as a protective layer and prevents the copper from leaching.

To determine the correct amounts of each material for the process, the researchers ran several reactions with different variables, such as ammonia concentration, while keeping other variables such as stirring speed and temperature constant.

After many experiments, the team found the right combination of factors – ammonia at a concentration of 0.5 M and potassium persulfate at a concentration of 0.2 moles per liter, and a reaction time of one hour. Under these conditions, the reaction leads to the separation of 85% of the silver in a sample.

The team then performed a redox electroplating process to increase the content to 98.7%. The team confirmed the enrichment of the silver particles using scanning electron microscopy.

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