Thermochemical emission and transformation of chlorinated paraffins in inert and oxidizing atmospheres. (October 2017) - Xin, Shanzhi
Abstract: Chlorinated paraffins (CPs) generally function as flame retardants and plasticizers in various materials. They are most likely to be processed by thermal processes during the entire life cycle. However, data on the formation and emission of CPs during thermal processes are still not fully understood. In this study, we simulated industrial thermal processes to investigate the emission of medium-chain chlorinated paraffins (MCCPs) and short-chain chlorinated paraffins (SCCPs) using commercial CP52 as the feedstock. We found that CP52 decomposed very easily at 210–320 °C. The decomposition of CPs generated large quantities of MCCPs and SCCPs. These remained in the residue at low temperature (∼200 °C) and were gradually released into the gas phase at higher temperatures. MCCPs and SCCPs were not detected in either the residue or the gas phase when the temperature exceeded 400 °C. However, considerable concentrations of aromatic and chlorinated aromatic hydrocarbons (Cl-PAHs) were identified in the gas phase, and they were formed as the amount of SCCPs and MCCPs decreased. Cl-PAHs were dominated by low-chlorinated chlorobenzenes, polychlorinated biphenyls, and polychlorinated naphthalenes. Oxygen promoted the release and decomposition of SCCPs in the gas phase. The results of the present study revealed the release of MCCPs and SCCPs and their synergistic emission with Cl-PAHs when CPs were subjected to heat. This work may also provide data for developing multiple techniques to control the emission of CPs and Cl-PAHs. Graphical abstract: Highlights: CP52 was decomposed by a one-step process at 210–330 °C with ∼92 wt% weight loss. SCCPs gradually released into the gas phase and decomposed completely at temperatures >400 °C. Thermal decomposition of CP52 generated high concentrations of PAHs and Cl-PAHs. PAHs and Cl-PAHs were dominated by 2- to 5-ring and mono-CBz, PCBs, and PCNs, respectively.