Hyperspectral Imaging Applied to WEEE Plastic Recycling: A Methodological Approach

Abstract

In this study, the possibility of applying the hyperspectral imaging (HSI) technique in the Short-Wave InfraRed (SWIR) spectral range to characterize polymeric parts coming from Waste from Electric and Electronic Equipment (WEEE) is explored. Different case studies are presented referring to the identification of (i) plastic flakes inside a mixed waste stream coming from a recycling plant of monitors and flat screens, (ii) different polymers inside a mixed plastic waste stream coming from End-Of-Life (EOL) electronic device housings and trims, (iii) contaminants (i.e., metals) in a mix of shredded plastic particles coming from a recycling line of electrical cables, and (iv) brominated plastics in mixed streams constituted by small appliances (i.e., cathode-ray tube televisions and monitors). The application of chemometric techniques to hyperspectral data demonstrated the potentiality of this approach for systematic utilization for material characterization, quality control and sorting purposes. The experimental findings highlight the feasibility of employing this method due to its user-friendly nature and quick detection response. To increase and optimize WEEE valorization avoiding disposal in landfills or incineration, recycling-oriented characterization and/or quality control of the processed products are fundamental to identify and quantify substances to be recovered.

Strong Optical Coupling of Lattice Resonances in a Top-down Fabricated Hybrid Metal–Dielectric Al/Si/Ge Metasurface

“…A straightforward application of our metal–dielectric metasurface to wavelength-selective photodetection can make use of a parameter regime in which absorptance peaks are weakly affected by crucial fabrication tolerances, e.g., in the etching depth. A wavelength range of 1000–1500 nm could allow us to target applications such as optical detection of water stress in plants or imaging-based plastic classification and recycling . Future investigations could also focus on applications in refractive index sensing.…”

“…A wavelength range of 1000−1500 nm could allow us to target applications such as optical detection of water stress in plants 35 or imaging-based plastic classification and recycling. 36 Future investigations could also focus on applications in refractive index sensing. The presence of a continuous connecting layer, moreover, can be explored for active metasurface design if the refractive index of this layer can be varied via external gating.…”