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

Abstract

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) 1 H 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.

Multi-Analytical Approach to Characterize the Degradation of Different Types of Microplastics: Identification and Quantification of Released Organic Compounds

“…As shown in Figure 5 , all photo-aged PET microplastic samples present additional small signals between 0 and 4 ppm, which can be due to the presence of CH and CH 2 signals close to ketones, aldehydes, and carboxyl functional groups, as it will be discussed in Section 3 . Among these proton signals, some show either an increase or a decrease in relative intensity, thus indicating changes occurring to the PET macromolecular structure as a result of photo-induced degradation [ 27 , 29 , 37 ].…”

“…Multi-analytical approaches which include NMR spectroscopic techniques [ 24 , 27 ] are thus expected to provide a more solid understanding of the chemical nature of microplastics, a better chemical identification of different microplastic types [ 21 , 28 ] and, as presented in this work, to identify minor compounds released from microplastics during degradation [ 29 , 30 ].…”

A stochastic dynamic mass spectrometric diffusion method and its application to 3D structural analysis of the analytes

“…MS protocols are compulsory in environmental research (Spiteller, 1981), agricultural sciences and food science and technology, including the area of methodological development of MS methods for food control (Wu & Prior, 2005). MS methods have found application in the field of energetics (Ramirez-Pradilla et al, 2019), as well as in the field of environmental protection implementing new cleanup technologies (Kumar et al, 2018). An enormous amount of research effort has also been focused on the field of the chemistry of natural products.…”