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全氟烷基类物质热解和脱氟机理研究进展
A review on pyrolysis and defluorination mechanisms of perfluoroalkyl substances(PFASs)
【摘要】 全氟烷基类物质(PFASs)因其高化学稳定性,广泛应用于工业领域及日常生活。其具有较高的生物毒性和持久性,已经成为全球关注的典型持久性有机污染物。PFASs中高稳定的碳氟键,使其难以被常规方法彻底降解。热解技术凭借其对C—F和C—C键的高效裂解能力和较低的运行成本,成为降解PFASs的重要途径和方法。总结了PFASs自身理化性质(官能团和链长)和反应条件(温度、气氛和助催剂)对PFASs热解的影响,发现官能团自身热稳定性越低,PFASs热解温度越低;链长增加,PFASs的热解温度降低;随着温度上升,PFASs的降解效率和脱氟率增加,PFASs热解时间越短;氧气和水蒸气会加速PFASs的氧化分解;活性炭和铝/铜氧化物通过吸附作用降低PFASs的热解温度,促进PFASs低温分解;钙/钠基助催剂能提高PFASs的脱氟率,减少挥发性有机氟产物的生成。此外,总结了PFASs热解的反应路径,主要包括头端官能团脱除、碳链断裂、短链全氟碳和无机氟化物生成3个阶段。并指出彻底无害化处理PFASs需要继续深入揭示PFASs降解的分子动力学机制、优化助催剂、控制短链全氟碳的产生。该综述可为处理含PFASs的固废提供理论依据与技术支持,实现PFASs的无害化目标。
【Abstract】 Perfluoroalkyl substances(PFASs) are widely used in industrial fields and daily life due to their high chemical stability. They exhibit high biological toxicity and persistence and have become a typical persistent organic pollutant with global concern. The highly stable carbon-fluorine bonds in PFASs make them difficult to degrade completely by conventional methods. Pyrolysis technology has become an important approach for degrading PFASs due to its efficient cracking of C—F and C—C bonds and low operating cost. This review summarizes the effects of PFASs’ intrinsic physical and chemical properties(functional groups and chain lengths) and reaction conditions(temperature, atmosphere, and catalysts) on their pyrolysis. It was found that the lower the thermal stability of the functional group itself, the lower the pyrolysis temperature of PFASs; similarly, longer chain lengths also resulted in lower pyrolysis temperatures. As the temperature increased, the degradation efficiency and defluorination rate of PFASs improved, and the required pyrolysis time decreased. Oxygen and water vapor were observed to accelerate the oxidative decomposition of PFASs. Activated carbon and aluminum/copper oxides reduced the pyrolysis temperature of PFASs through adsorption, thereby promoting low-temperature decomposition. Calcium/sodium-based catalysts improved the defluorination efficiency of PFASs and reduce the formation of volatile organic fluorine products. Furthermore, this review outlines the reaction pathways of PFASs pyrolysis, which mainly include three stages:removal of head functional groups, carbon chain scission, and the formation of short-chain perfluorocarbons and inorganic fluorides. Finally, this paper emphasizes that achieving complete and harmless treatment of PFASs requires further in-depth exploration of the molecular dynamics mechanisms underlying PFASs degradation, optimization of catalysts, and control of the formation of short-chain perfluorocarbons. This review aims to provide a theoretical basis and technical support for the treatment of PFASs-containing solid waste, ultimately achieving the goal of harmless treatment of PFASs.
【Key words】 perfluoroalkyl substances; pyrolysis mechanisms; defluorination efficiency; influencing factors; reaction pathways;
- 【文献出处】 环境工程 ,Environmental Engineering , 编辑部邮箱 ,2025年08期
- 【分类号】X592
- 【下载频次】9