Researchers Recycle Copper from Solar Panels into Useful Nanoparticles

By Muhammad OsamaReviewed by Laura ThomsonAug 2 2024

In a recent article published in Catalysts, researchers highlighted a new method for recycling copper from waste solar panels and converting it into copper oxide nanoparticles (CuONPs) using an eco-friendly synthesis approach.

They aimed to demonstrate how copper can be fully recovered and transformed into CuONPs for potential medicinal uses. This method underscores the value of electronic waste as a source of valuable metals and their transformation into useful nanomaterials for biomedical and environmental applications.

Solar Energy as an Important Renewable Source

Solar energy reduces greenhouse gas emissions and dependence on fossil fuels. However, solar panels last only 25 to 30 years and eventually become waste. By 2050, end-of-life solar panels are expected to total 78 million tons, posing challenges for waste management and environmental protection due to their toxic materials and valuable metals.

Copper, the second-most-important metal after silver, is crucial for its high electrical conductivity and market demand. It is used in wiring and electrical connections within solar panels, making up about 0.6% of the weight of crystalline silicon (c-Si) solar panels. Therefore, recovering copper from waste solar panels is crucial for the long-term sustainability of its supply and minimizing the environmental impact of electronic waste.

Novel Solution for Recovering Copper From Solar Panels

This paper proposes a novel method for recovering copper from old decommissioned solar panels and transforming it into CuONPs. CuONPs have a high surface area and unique properties compared to bulk materials. They can be used in various applications, including catalysis, sensors, environmental cleanup, and drug delivery. The method consists of two steps: leaching and synthesis.

First, nitric acid was used to dissolve copper from the wires in waste solar panels, producing a blue copper nitrate solution. In the synthesis step, a green approach was used with Piper nigrum fruit extract (black pepper) to create CuONPs. Piper nigrum has potential antibacterial, antioxidant, and anticancer properties. The extract's phytochemicals, including polyphenols, terpenoids, and piperine, helped reduce and stabilize the CuONPs. The synthesis was indicated by a color change from blue to dark brown, almost black.

Research Findings

The researchers characterized the CuONPs using various techniques: energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), zeta potential analysis, and inductively coupled plasma atomic emission spectroscopy (ICP-OES). These analyses confirmed that the CuONPs were pure, crystalline, stable, and spherical.

TEM measured the average size of the CuONPs at 26 nm, and the zeta potential was -34.3 mV, indicating stable dispersion. FTIR showed that biomolecules from the Piper nigrum were on the CuONPs’ surface, acting as natural capping agents to prevent clumping. XRD revealed characteristic peaks corresponding to a face-centered cubic structure and the (111) plane. ICP-OES measured the copper concentration in the leachate at 19,000 ppm from 10 grams of copper wires.

The study tested the antibacterial activity of the CuONPs against E. coli and S. aureus using a well-diffusion method. The CuONPs were effective against both bacteria, with greater inhibition and larger zones observed for E. coli than S. aureus. The antibacterial action resulted from Cu ions penetrating bacterial cell walls, causing damage, oxidative stress, generation of reactive oxygen species, and DNA disruption, leading to cell death.

Applications

The research demonstrated that copper can be fully recovered from waste solar panels and converted into valuable CuONPs. These nanoparticles have several potential uses. Due to their high surface area and reactivity, they can act as catalysts in various reactions, such as oxidation, reduction, and decomposition. Owing to their unique optical and electrical properties, they can also be used as sensors for detecting gases like hydrogen, ethanol, and carbon monoxide.

CuONPs can also help in environmental cleanup by removing organic pollutants and heavy metals from water and soil through adsorption and photocatalytic processes. In biomedical applications, they can assist in drug delivery and wound healing and act as antibacterial agents due to their biocompatibility, stability, and pathogen-targeting ability.

Conclusion

The novel method effectively recycled copper from waste solar panels and converted it into useful CuONPs. This approach is simple, eco-friendly, cost-effective, and scalable, using a natural plant extract as a reducing and stabilizing agent.

The CuONPs were pure, crystalline, stable, and well-dispersed with a spherical shape. They also exhibited antibacterial activity against common bacterial strains, indicating potential uses in medicine and environmental cleanup.

The researchers highlighted the importance of recycling solar panel waste and the advantages of green synthesis for producing nanoparticles. They recommended optimizing the synthesis process, evaluating the toxicity and environmental impact of CuONPs, and developing standardized characterization techniques to enhance their performance, ensure safety, and support sustainable applications in various fields.

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