Scientific Results

Miniaturized Near-Infrared (MicroNIR) Spectrometer in Plastic Waste Sorting

Year: 2019

Authors: Rani M., Marchesi C., Federici S., Rovelli G., Alessandri I., Vassalini I., Ducoli S., Borgese L., Zacco A., Bilo F., Bontempi E., Depero L.E.

Autors Affiliation: Univ Brescia, Dept Mech & Ind Engn, Via Branze 38, I-25123 Brescia, Italy; Consorzio Interuniv Nazl Sci & Tecnol Mat INSTM, I-50121 Florence, Italy; ABCS Srl Sci Instruments & Mat Sci, Viale Regina Giovanna 37, I-20129 Milan, Italy; Univ Brescia, Dept Informat Engn, Via Branze 38, I-25123 Brescia, Italy; CNR, INO, Unit Brescia, I-25123 Brescia, Italy

Abstract: Valorisation of the urban plastic waste in high-quality recyclates is an imperative challenge in the new paradigm of the circular economy. In this scenario, a key role in the improvement of the recycling process is exerted by the optimization of waste sorting. In spite of the enormous developments achieved in the field of automated sorting systems, the quest for the reduction of cross-contamination of incompatible polymers as well as a rapid and punctual sorting of the unmatched polymers has not been sufficiently developed. In this paper, we demonstrate that a miniaturized handheld near-infrared (NIR) spectrometer can be used to successfully fingerprint and classify different plastic polymers. The investigated urban plastic waste comprised polyethylene (PE), polypropylene (PP), poly(vinyl chloride) (PVC), poly(ethylene terephthalate) (PET), and poly(styrene) (PS), collected directly in a recycling plastic waste plant, without any kind of sample washing or treatment. The application of unsupervised and supervised chemometric tools such as principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) on the NIR dataset resulted in a complete classification of the polymer classes. In addition, several kinds of PET (clear, blue, coloured, opaque, and boxes) were correctly classified as PET class, and PE samples with different branching degrees were properly separated.

Journal/Review: MATERIALS

Volume: 12 (17)      Pages from: 2740-1  to: 2740-13

KeyWords: urban plastic waste; near-infrared (NIR) spectroscopy; chemometrics; principal component analysis (PCA); partial least squares-discriminant analysis (PLS-DA); circular economy
DOI: 10.3390/ma12172740

Citations: 2
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