ATR-FTIR Spectroscopy Combined with Chemometric Methods for the Classification of Polyethylene Residues Containing Different Contaminants

Low density polyethylene (LDPE) and high (HDPE) are the principal plastics present in solid plastic waste found out as main components of microplastics marine terrestrial environments. Currently, efforts have been made to develop new effective methods ensure identification separation waste, ensuring necessary purity obtain quality economically competitive recycled products. In this contribution, we investigated usage Fourier-Transform Infrared Spectroscopy Attenuated Total Reflection mode (ATR-FTIR) combined with Principal Component Analysis (PCA), Linear Partial Least Squares Regression by Intervals (iPLS-R) Competitive Adaptive Weighted Sampling (CARS/PLS-R) chemometric classify determine compositional fraction pristine mixtures HDPE LDPE from São Paulo, Brazil. Here, 3D PCA plots were not classifying different polyethylenes their polymer blends using three Components (PC), but 2D diagrams PC1 PC3 presented promising performance for purpose. The iPLS-R presents best predictive ability than CARS/PLS-R content HDPE/LDPE blends. However, presence contaminants (in 5 wt%), such silicon dioxide (SiO2), calcium carbonate (CaCO3), polypropylene (PP), poly(ethylene terephthalate) (PET), reduces potential models tools sorting industrial recycling processes.