Fluorescent molecule could verify recycled content of plastic products
While many companies may claim that their products contain recycled (as opposed to 100% virgin) plastic, how can we know if they're telling the truth? According to a new study, a fluorescent molecule could blow the whistle on manufacturers who are lying.
First of all, why would companies falsely claim that they were using recycled plastic? Well, for starters, doing so might gain them some sales with eco-minded consumers. Additionally, they could avoid paying taxes that some countries are imposing on plastic products which contain little or no recycled plastic.
In order to thwart such deception, scientists at the University of Manchester looked to a food-safe molecule known as 4,4,-bis(2-benzoxazolyl) stilbene … or BBS, for short.
The researchers added small amounts of BBS to melted high-density polyethylene (HDPE), which was subsequently mixed with virgin HDPE resin in varying ratios. Their end result was a group of HPDE samples which contained anywhere from 0 to 100% simulated recycled content.
When those samples were exposed to 365-nanometer ultraviolet light, the BBS molecules within them reacted by fluorescing. It was found that the intensity, duration and color of the fluorescence varied according to the percentage of BBS-tagged HDPE within each sample.
Therefore, by measuring those parameters, it became possible to accurately gauge how much of the simulated recycled plastic was present in any one of the samples. The technology was also successfully tested on plastics such as polypropylene and PET (polyethylene terephthalate), in which it could quantify simulated recycled content as low as 10% by weight.
According to the scientists, the presence of BBS in single-use plastic products doesn't adversely affect their quality or appearance. It is hoped that ultimately, manufacturers could add the molecule to virgin plastics as they're being recycled, so their content could subsequently be measured in other products made from them.
A paper on the research was recently published in the journal ACS Sustainable Chemistry & Engineering.