| Work Detail |
Researchers in India have demonstrated a wet chemical process to recover high-purity silicon from end-of-life solar panels, which they used to fabricate functionalized silica nanoparticles. Tests on the processed nanoparticles into anti-corrosion coatings showed a corrosion protection efficiency of 99.5%, which they say is 200 times lower corrosion rate compared to uncoated silica nanoparticles. Researchers in India have demonstrated a wet chemical process to recover silicon material from dismantled end-of-life (EoL) solar panels. To validate the usefulness of the recovered silicon, the scientists produced functionalized silica nanoparticles, which were then used as anti-corrosion coatings on a polymer. Test results showed a corrosion protection efficiency of 99.5%, which they say is about 200 times lower than uncoated silica nanoparticles. The scientists noted that their simple wet-chemical process for recycling EoL panels focused on aluminum back-face field (Al-BSF) type panels because most current and future EoL panels will be of this type. “We have demonstrated an efficient, environmentally friendly, sustainable and circular economy-oriented strategy to manage the growing EoL solar panel waste streams worldwide,” Parveen Saini, corresponding author of the research, told pv magazine . “It was a challenge to recover silicon solar cells encapsulated between top and bottom ethylene vinyl acetate (EVA) polymer sheets, without incinerating the EVA.” The team used solvents for the EVA removal step, which posed another challenge to overcome: avoiding the loss of the medium or solvents used and their subsequent regeneration for reuse. According to the research, the recovered cells underwent successive chemical treatments to selectively etch away various layers, such as the top silver contacts, top anti-reflective coatings, and bottom aluminum contact layer. Component materials such as silicon cells, glass cover, connecting wires, and polymer layers were then removed to expose the bare silicon wafer. Its purity exceeded 99.9%. Recognizing that the recovered silicon could not be reused to make solar silicon, the team decided to use it to fabricate silica nanoparticles, optical-grade hydrophilic silica nanoparticles with optimized functionalization. The team used ground silicon powder as a precursor for the synthesis of silica nanoparticles, which was processed by chemical functionalization into silica nanoparticles (SNPs) and hydrophobic silica nanoparticles (HSNPs) in a three-step process. SNPs and HSNPs were then characterized by structural, morphological, optical and spectroscopic techniques. HSNPs were used as anti-corrosion coatings and “significantly” outperformed conventional coatings based on either a simple polymer matrix or uncoated nanoparticle-filled polymer composites. According to the team, the corrosion inhibition efficiency was 99.5% and the corrosion rate was about 200 times lower than that of the uncoated silica nanoparticle-filled polymer coating. The performance was attributed to the nanoparticles ability to minimize water absorption and effectively prevent corrosive agents from reaching the substrate. The research is described in “ A facile waste-to-wealth approach for synthesis of functionalized silica nanoparticles from end-of-life solar panel waste for technological applications,” published in Resources, Conservation and Recycling . The HSNP recovery process has already attracted attention outside of academia. “Both the corrosion and specialty coatings industries have been interested in recovery and reuse,” Saini explains. Looking ahead, the research team aims to scale up and adapt the nanoparticle process by redesigning it – or reducing the steps – to better fit existing value chains and intended applications. Work is also underway on “converting these particles into industrially useful end products,” Saini explains. The researchers were from the Academy of Scientific and Innovative Research (AcSIR), CSIRs National Physical Laboratory and the University of Delhi. |
