Researchers in India have developed a new solar panel recycling process that converts lead into less toxic lead monoxide. It consists of three main steps: leaching, precipitation and calcination.
Researchers from India’s Center for Materials for Electronics Technology (C-MET) have developed a new process to recover lead (Pb) from photovoltaic panels at the end of their life.
“The lead recovery process outlined in our study offers a new and environmentally conscious approach to recycling waste silicon photovoltaic modules,” said the study’s lead author, Duvvuri S. Prasad, narrated pv magazine. “Unlike traditional methods that focus on recovering valuable materials, our process uniquely targets the toxic substance lead, a key component in soldering copper ribbons into solar panels.”
The lead is regained with an optimized three-step process. “The recovered lead, converted into its less toxic form as lead monoxide (PbO), demonstrates the dual benefits of environmental remediation and the creation of a commercially viable material,” Prasad added. “We rigorously analyzed the efficiency at each stage using advanced characterization techniques, providing a deep understanding of lead recovery.”
In the study “A new approach for efficient recovery of lead from photovoltaic silicon modules at the end of their life”, which was recently published in Solar energy materials and solar cellsPrasad and his colleagues explained that the process involves three steps the selective leaching of the top layer from the compound, the extraction of lead from the leachate by precipitation and the final calcination.
The selective chemical leaching of the module copper ribbons is carried out with dilute nitric acid and the separated copper ribbons are then washed with water. The precipitation technique consists of changing the pH of the leachate by adding an alkaline solution to precipitate Pb+2 ions. The calcination process converts lead into PbO at 500 C.
The group tested the proposed approach on 30 kg of material cut from the deframed polycrystalline silicon solar panels at the end of their life. It reportedly made it possible to obtain PbO with very minimal impurities. The most efficient leaching of lead from compounds was observed with 1.5 M nitric acid at 60°C.
“A total recovery rate of 70.45 was observed for obtaining Pb in its less toxic form PbO using this method,” the scientists pointed out. “Recovered PbO is useful for several applications, namely lead-acid batteries, pigments in the paint industry, ceramics and glass industries.”
“Our scalable process has been successfully validated with a 200 gram sample, underscoring the potential for large-scale implementation,” Prasad further explains. “The recovered PbO, verified for phase purity through advanced characterization techniques such as XRD and SEM-EDS, opens doors to various commercial applications. This unique approach marks an important step towards sustainable and responsible management of solar energy waste, contributing to both environmental and economic benefits.”
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