Upcycling 6PPD from tire waste
A recent paper in Nature Chemical Engineering from the University of Delaware details a new method for decontaminating waste tires to mitigate the effects of toxic additives on the environment.
The tire additive, N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine, also known as 6PPD, has been shown to transform into the highly toxic quinone form, leading to the acute morbidity of several aquatic species. As of now, tires are not disposed of in a manner that considers the fate of 6PPD. Pyrolysis is one upcycling strategy for end-of-life tires to generate carbon black and liquid pyrolysis oil. In this work, Najmi et al. detail how 6PPD survives harsh pyrolysis conditions that contaminate the resulting oil.
Using solvent extraction as a decontamination strategy, 6PPD was effectively isolated from waste tires. Solvent screening was done on several common solvents to determine their efficacy for 6PPD extraction. By leveraging COSMO-RS, experimental results were confirmed using theoretical calculations. Specifically, the extraction efficacy was shown to correlate well with the 6PPD solubility as determined by COSMO-RS. The findings here demonstrate several key takeaways in the quest for sustainable upcycling of tire waste.
Najmi S., Bhalode P., Baker-Fales M., Vance B.C., Selvam E., Yu K., Zheng W., Vlachos D.G. End-of-life tire decontamination from 6PPD and upcycling. Nat Chem Eng 1, 1-11 (2024).
