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A density functional theory calculation for revealing environmentally persistent free radicals generated on PbO
Jianzhong Wu1, Yun Liu2, Jia Zhang3
1MGI of Shanghai University, Xiapu Town, Xiangdong District, Pingxiang City, Jiangxi, 337022, PR China.
Chemosphere
|May 14, 2020
Summary
1,2-dichlorobenzene forms the most persistent environmentally persistent free radicals (EPFRs) on lead oxide particles, posing greater health risks. Understanding EPFR formation is crucial for environmental protection and health assessments.
Area of Science:
- Environmental Chemistry
- Toxicology
- Materials Science
Background:
- Organic precursors on metal oxides form environmentally persistent free radicals (EPFRs).
- EPFRs in particulate matter are significant for health risk assessment and environmental protection.
- Lead oxide (PbO) is a common component in particulate matter.
Purpose of the Study:
- To characterize EPFRs formed from different organic precursors on PbO particles.
- To investigate the formation processes and decay kinetics of these EPFRs.
- To assess the health implications of EPFRs derived from various precursors.
Main Methods:
- Experimental determination of EPFR characteristics and formation.
- Gas chromatography-mass spectrometry (GC-MS) for precursor identification.
- Density functional theory (DFT) calculations for adsorption energy analysis.
- Oxidative-stress investigations to evaluate radical reactivity.
Main Results:
- Phenol formed phenoxyl radicals at 230°C.
- Monochlorobenzene and 1,2-dichlorobenzene yielded phenyl and chlorobenzene radicals, respectively.
- Radical decay followed the order: chlorobenzene radical (4 d) > phenyl radical (3 d) > phenoxyl radical (2 d).
- 1,2-dichlorobenzene exhibited high adsorption energy on PbO, contributing to chlorobenzene radical persistence.
- Chlorobenzene radical generated more reactive oxygen species, indicating higher oxidative stress.
Conclusions:
- 1,2-dichlorobenzene generates more persistent EPFRs on PbO particles.
- The persistence and reactivity of EPFRs correlate with potential health impacts.
- Findings offer new insights into assessing health risks associated with organic and oxide-containing particulate matter.
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