Sorting using infrared

Near-infrared Spectroscopy

Near-infrared analysis technology: this technology has been widely applied in plastic detection and identification and it is one of the fastest-growing analytical technologies as it has been used in medical applications to measure tissue oxygenation and to detect hemoglobin and myoglobin content of skeletal muscle.

The technology is accurate, nonpolluting and non-destructive and measurement is rapid without a need for surface pretreatment. The technology is used, and it identifies 18 types of plastics with an error of 3% it has been used to identify the plastic solid waste of pro ethylene and propylene. The results show that the technology itself can also identify high-density polyethylene and low-density polyethylene as well, as it exceeded the target that was set for it. Sorting system has been established by Chinese companies to classify each type of plastics with high speed using this technology (Near-infrared) as it improves data acquisition speed.

Identification system:  the system consists of a device and software in particular with a detector called IngAas to measure the wavelength of each type of surface based on the wavelength type it identifies the plastic.

The software that is required to be used is called LabVIEW for data acquisition cards. The software is programmed through MATLAB for identification algorithms. While LabVIEW is used for the graphical user interface, so it is mostly a mixture between the 2 software’s to optimize the best result. The company machine shows it identifies 97% of the plastic samples and it has an error of 3%.the table below shows the positive and negative of this technology.

Pro’s	Con’s
97% accurate	Distance between samples can affect the test
Non-pollutant	Light can create dispersion for machine
Non-destructive	It does not recognize all types of plastics
Thickness does not matter	Shredder is needed to make the particles in small

Lastly, the technology can find high potential in the future but currently preprocessing is required from the plastics to grind first and sort them. But normally sorting is always needed first before grinding but the technology itself can improve in the future for recycling/analytical purposes.

Friedrich, K. (2018). Polymer composites for tribological applications. Advanced Industrial and Engineering Polymer Research, 1(1), 3–39. doi: 10.1016/j.aiepr.2018.05.001

Andersen, L. (2015). Plastic sorting at recycling centres. doi: 10.6027/tn2015-511

https://www.youtube.com/watch?v=hZ0aINfaOtU&t=151s