Insights

Near-infrared Spectroscopy (NIRS) Offers a Path to Economical Plastics Recycling

By Ahmed Korayem - Product Marketing Lead

Plastics recycling represents a massive and growing business, with global market revenue set to rise to $40 billion in 2026, up from $28 billion in 2020. However, concerns have arisen over the economics of plastic recycling given the high costs associated with the processing of the materials. One of major cost components is the sorting process—a labor-intensive job often conducted manually.

Sizeable workforces can be required to sort items based on the type of plastic resin used to create the item. On the other hand, the price of recycled plastics has fallen during the past two years. As a result of the high cost and lower prices, recycling has become a less profitable business. With global plastic recycling set to double from 2015 to 2050, profitability will become an increasingly important issue during the coming years.

The declining incentive for recycling comes at a time when minimizing plastic waste has become an increasingly critical issue. The quantity of plastic waste flowing into the world’s oceans is expected to triple during the next 20 years—unless drastic measures are undertaken to reduce pollution.

In response to this issue, innovators have sought to reduce the cost of sorting plastics, offering solutions that employ technologies ranging from visual systems to x-rays to observe and classify different types of plastic. However, a new approach has arrived that promises a cost-effective and efficient alternative to labor-intensive systems: near-infrared spectroscopy (NIRS). NIRS can detect the unique spectral responses of different material chemistries, allowing to serve as the basis of automated systems that can separate plastics by resin type.

This technology can be affordable and simple, allowing deployment not only in sorting and recycling centers—but also could be integrated into handheld devices suitable for use at sites that generate large quantities of recycled materials. Future versions of the technology could even be used in homes, allowing consumers to sort their plastic recyclables on their own.

Sorting Out Plastic Sorting

Before the actual recycling process can begin, plastics are commonly sorted according to their resin type. Such sorting processes are essential to producing top-quality, high-purity recycled material.

In the past, plastic recyclers have used the resin identification code (RIC), a method of categorization of polymer types that can be seen in the familiar numerical labels commonly seen on plastic packages. Today, most recyclers identify the resin using sorting systems ranging from manual sorting and picking of plastic materials to mechanized, automated processes that use detection technologies to identify specific types of plastic.

Such detection techniques include visual sensing, wherein a sorting system uses a camera or another light sensor to detect the color of plastics to identify what type of plastic they are composed of. However, the visual approach has shortcomings, with this technique unable to detect the actual resin composition of plastics.

  

NIRS Offers a Superior Alternative

In contrast to the other approaches for automated detection of plastic resin types, NIRS observes the wavelength signature of specific resins to distinguish them from one another.

Unlike visual sensing, NIRS does not perceive visible color to distinguish between different types of plastic. Instead, NIRS operates at infrared wavelengths where the material’s response to light is unique for each material. When a light is shined upon various plastics, different types of resin reflect the light back with certain patterns. Using artificial intelligence and data analysis algorithms, these patterns can be discerned. This approach supports a high degree of accuracy no matter what the color of the plastic is.

NIRS in Action

NIRS is a proven technique for plastic sorting and it is already being employed at recycling operations, including at materials recovery facilities (MRF), which receive, sort and prepare recyclable materials. At MRFs, NIRS detectors are placed above conveyor belts containing plastic recyclables. The NIRS systems can detect the specific wavelengths of certain polymers, allowing automated sorting to be conducted.

However, conventional implementations require expensive NIRS detection hardware that limits the deployment of the technology to larger recycling operations that can afford the cost. For NIRS to achieve its potential to improve sorting and cut recycling costs, the affordability and utility of the technology must be greatly enhanced.

One attractive approach to this challenge is a new implementation of NIRS from Si-Ware that is bringing down the cost of NIRS while making the technology practical for wider use in recycling operations—as well as is in new locations and with new usage models.

Making NIRS Practical

Si-Ware’s line of NeoSpectra sensors can deliver NIRS detection and analysis with a level of performance comparable to systems currently on the market. Rather than being built from distinct components, each NeoSpectra sensor is fabricated on a single microchip. This allows the sensors to take advantage of the efficiency and economy of scale inherent in semiconductor manufacturing. For the first time, NIRS can be affordable enough to be adopted by non-experts.

A study conducted by Si-Ware demonstrated that NeoSpectra sensors are highly effective in identifying plastic-resin. Testing revealed that the spectra of the most common polymers measured with NeoSpectra spectral sensor provide suitable analytical data for the correct identification of unknown polymer test samples. This validates the potential of this technology to enable fast, in-site, non-destructive, low cost, and scalable solution for plastic sorting.

NIRS Goes Far

With the capability to be integrated into affordable and portable form factors, NeoSpectra sensors have the potential to perform plastic scanning in new venues. For example, locations that generate large amounts of recyclable materials—including stadiums and restaurants. This could allow such operations to detect and sort plastics before these materials are sent off for recycling—massively improving the economics of recycling operations. With their low cost, NeoSpectra sensors could even be used in homes in the future, allowing consumers to take a personal role in promoting recycling—and again boosting the efficiency of recycling operations.

In a time when concerns over the impact of plastic waste are mounting—and the economics of recycling are being questioned—NIRS resin detection is providing the means for easier and lower-cost sorting. With the arrival of NeoSpectra sensors, NIRS technology now is promised for much more widespread use—including by consumers.