Lab-scale thermal analysis of electronic waste plastics
Wu-Jun Liu1, Ke Tian1, Hong Jiang1
1CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China.
Journal of Hazardous Materials
|March 4, 2016
Summary
This study reveals how Decabromodiphenyl ethane (DBDPE) and TBBPA in e-waste plastics decompose. Pyrolytic temperature controls bromide formation, crucial for recycling, and oxygen atoms influence PBDD/F generation.
Area of Science:
- Environmental Chemistry
- Materials Science
- Chemical Engineering
Background:
- Electronic waste (e-waste) contains brominated flame retardants (BFRs) like Decabromodiphenyl ethane (DBDPE) and tetrabromobisphenol A (TBBPA).
- Understanding the thermochemical decomposition of these BFRs is critical for managing e-waste and recovering valuable materials.
- The formation pathways of hazardous byproducts during BFR pyrolysis require detailed investigation.
Purpose of the Study:
- To experimentally determine the thermochemical decomposition pathways of DBDPE and TBBPA in e-waste plastics.
- To investigate the influence of pyrolytic temperature on the distribution and species of brominated byproducts.
- To elucidate the role of intramolecular oxygen in the formation of polybrominated dibenzodioxins and dibenzofurans (PBDD/Fs).
Main Methods:
- Utilized an online thermogravimetric-fourier transform infrared-mass spectroscopy (TG-FTIR-MS) system for real-time analysis.
- Employed high-resolution gas chromatography/high-resolution mass (HRGC-MS) spectroscopy for detailed product identification.
- Conducted pyrolysis experiments using a fixed-bed reactor to analyze liquid and solid residues.
Main Results:
- The distribution and species of generated bromides were controllable by adjusting pyrolytic temperature, vital for recycling applications.
- Bromine radicals formed during pyrolysis were captured by organic and inorganic species, remaining in the char residue.
- Intramolecular oxygen atoms were identified as pivotal in PBDD/F formation; oxygen-free BFRs yielded no PBDD/Fs, while oxygen-containing BFRs showed reduced PBDD/F formation.
Conclusions:
- The study provides a fundamental understanding of DBDPE and TBBPA decomposition mechanisms in e-waste.
- Controlling pyrolytic conditions offers a pathway for managing BFRs and potentially recycling brominated compounds.
- The presence of intramolecular oxygen significantly impacts the formation of hazardous PBDD/Fs during BFR pyrolysis.
