Application of High-Resolution NMR and GC-MS to Study Hydrocarbon Oils Derived from Noncatalytic Thermal Transformation of e-Waste Plastics

The increases in the volumes of electronic waste have become an aggravating environmental, economic, and social health issue in recent times. This study investigates the conversion of e-waste plastics into hydrocarbon oils via noncatalytic thermal transformation followed by an in-depth characterization of these oils using diverse analytical techniques such as gas chromatography-mass spectrometry (GC-MS), Fourier transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. In particular, NMR spectroscopy is a key analytical tool utilized in this study to gain a comprehensive insight into the chemical nature of the resultant oils along with a semiquantitative investigation of the changes in their composition over a temperature range of 800-1200 °C. The one-dimensional (1D) ¹H and two-dimensional (2D) heteronuclear single-quantum correlation spectra were acquired for the oils, wherein the 2D NMR spectrum provided improved resolution of peaks to address the overlaps encountered in the 1D spectrum. The experimental results obtained from GC-MS, FTIR spectroscopy, and NMR spectroscopy were found to align well with each other. The oils produced in this study have a high calorific value of 38.27 MJ/kg and thus may find use in several applications. A detailed mechanism for the thermal degradation of styrene acrylonitrile plastics and the formation of major products is elucidated in this study.