Transformation Product Formation upon Heterogeneous Ozonation of the Tire Rubber Antioxidant 6PPD (N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine)

• DOI: 10.1021/acs.estlett.2c00187
• Publication Date: 2022-04-12T16:37:28Z
• Authors: Ximin Hu; Haoqi Nina Zhao; Zhenyu Tian; Katherine T. Peter; Michael C. Dodd; Edward P. Kolodziej
• Keywords: Molar mass

Transformation products (TPs) originating within tire tread wear particles (TWPs) are likely pervasive contaminants of roadway environments although their formation, fate, and risks poorly characterized. Here, we investigated TP formation occurring during heterogeneous reaction gas-phase ozone with the common rubber antioxidant 6PPD (N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine); exposures included both pure compound TWP rubbers. Oxidative transformation occurred ozonation (∼360 ppbv), up to 81% mass reacting over 6 h. Conversion 6PPD-quinone (6PPDQ)─a recently reported highly toxic TP─was confirmed at a 9.7% molar yield for 0.95% present TWPs, representing minima these time scales conditions. Leveraging high-resolution spectrometry, identified 19 probable 6PPD-derived TPs in ozonated samples, underscoring diverse from this antioxidant. By screening environmental nine were detected runoff. The data confirm that when antioxidants react ozone, as intended, they form release various surrounding environments.