Development of a new approach based on midwave infrared spectroscopy for post-consumer black plastic waste sorting in the recycling industry


  1. Rozenstein, O.
  2. Puckrin, E.
  3. Adamowski, J.
Corporate Authors
Defence Research and Development Canada, Valcartier Research Centre, Quebec QC (CAN);Institute of Soil, Water and Environmental Sciences, Rishon LeZion (ISRAEL) Agriculture Research Organization;McGill University, Ste-Anne-de-Bellevue (CAN) Department of Bioresource Engineering
Waste sorting is key to the process of waste recycling. Exact identification of plastic resin and wood products using Near Infrared (NIR, 1–1.7 µm) sensing is currently in use. Yet, dark targets characterized by low reflectance, such as black plastics, are hard to identify by this method. Following the recent success of Midwave Infrared (MWIR, 3–12 µm) measurements to identify coloured plastic polymers, the aim of this study was to assess whether this technique is applicable to sorting black plastic polymers and wood products. We performed infrared reflectance contact measurements of 234 plastic samples and 29 samples of wood and paper products. Plastic samples included black, coloured and transparent Polyethylene Terephthalate (PET), Polyethylene (PE), Polyvinyl Chloride (PVC), Polypropylene (PP), Polylactic acid (PLA) and Polystyrene (PS). The spectral signatures of the black and coloured plastic samples were compared with clear plastic samples and signatures documented in the literature to identify the polymer spectral features in the presence of coloured material. This information was used to determine the spectral bands that best suit the sorting of black plastic polymers. The main NIR-MWIR absorption features of wood, cardboard and paper were identified as well according to the spectral measurements. Good agreement was found between our measurements and the absorption features documented in the literature. The new approach using MWIR spectral features appears to b
plastic recycling;infrared spectroscopy
Report Number
DRDC-RDDC-2017-P129 — External Literature
Date of publication
01 Dec 2017
Number of Pages
Reprinted from
Elsevier / Waste Management, no. 68, 2017, p. 38 44
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