Scheutz Charlotte, Dote Yutaka, Fredenslund Anders M, Mosbaek Hans, Kjeldsen Peter
Institute of Environment & Resources, Building 115, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
Environ Sci Technol. 2007 Nov 15;41(22):7714-22. doi: 10.1021/es0707409.
Chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs) have been used as blowing agents (BAs) for foam insulation in home appliances and building materials, which after the end of their useful life are disposed of in landfills. The objective of this project was to evaluate the potential for degradation of BAs in landfills, and to develop a landfill model, which could simulate the fate of BAs in landfills. The investigation was performed by use of anaerobic microcosm studies using different types of organic waste and anaerobic digested sludge as inoculum. The BAs studied were CFC-11, CFC-12, HCFC-141b, HFC-134a, and HFC-245fa. Experiments considering the fate of some of the expected degradations products of CFC-11 and CFC-12 were included like HCFC-21, HCFC-22, HCFC-31, HCFC-32, and HFC-41. Degradation of all studied CFCs and HCFCs was observed regardless the type of waste used. In general, the degradation followed first-order kinetics. CFC-11 was rapidly degraded from 590 microg L(-1) to less than 5 microg L(-1) within 15-20 days. The degradation pattern indicated a sequential production of HCFC-21, HCFC-31, and HFC-41. However, the production of degradation products did not correlate with a stoichiometric removal of CFC-11 indicating that other degradation products were produced. HCFC-21 and HCFC-31 were further degraded whereas no further degradation of HFC-41 was observed. The degradation rate coefficient was directly correlated with the number of chlorine atoms attached to the carbon. The highest degradation rate coefficient was obtained for CFC-11, whereas lower rates were seen for HCFC-21 and HCFC-31. Equivalent results were obtained for CFC-12. HCFC-141b was also degraded with rates comparable to HCFC-21 and CFC-12. Anaerobic degradation of the studied HFCs was not observed in any of the experiments within a run time of up to 200 days. The obtained degradation rate coefficients were used as input for an extended version of an existing landfill fate model incorporating a time dependent BA release from co-disposed foam insulation waste. Predictions with the model indicate that the emission of foam released BAs may be strongly attenuated by microbial degradation reactions. Sensitivity analysis suggests that there is a need for determination of degradation rates under more field realistic scenarios.
氯氟烃（CFCs）、氢氯氟烃（HCFCs）和氢氟烃（HFCs）已被用作家用电器和建筑材料中泡沫绝缘材料的发泡剂（BAs），这些发泡剂在使用寿命结束后被填埋处理。本项目的目的是评估填埋场中发泡剂的降解潜力，并开发一个能够模拟发泡剂在填埋场中归宿的填埋场模型。该研究通过使用不同类型的有机废物和厌氧消化污泥作为接种物进行厌氧微观研究来进行。所研究的发泡剂有CFC - 11、CFC - 12、HCFC - 141b、HFC - 134a和HFC - 245fa。还进行了考虑CFC - 11和CFC - 12一些预期降解产物归宿的实验，如HCFC - 21、HCFC - 22、HCFC - 31、HCFC - 32和HFC - 41。无论使用何种类型的废物，所有研究的CFCs和HCFCs都观察到了降解。一般来说，降解遵循一级动力学。CFC - 11在15 - 20天内迅速从590微克/升降解至低于5微克/升。降解模式表明依次产生HCFC - 21、HCFC - 31和HFC - 41。然而，降解产物的产生与CFC - 11的化学计量去除不相关，这表明还产生了其他降解产物。HCFC - 21和HCFC - 31进一步降解，而未观察到HFC - 41的进一步降解。降解速率系数与连接在碳上的氯原子数直接相关。CFC - 11获得了最高的降解速率系数，而HCFC - 21和HCFC - 31的降解速率较低。CFC - 12也得到了类似的结果。HCFC - 141b也发生了降解，其降解速率与HCFC - 21和CFC - 12相当。在所研究的HFCs中，在长达200天 的运行时间内的任何实验中均未观察到厌氧降解。所获得的降解速率系数被用作一个现有填埋场归宿模型扩展版本的输入，该扩展版本纳入了来自共同处置的泡沫绝缘废物的随时间变化的发泡剂释放。该模型的预测表明，发泡剂释放的排放可能会因微生物降解反应而大幅减弱。敏感性分析表明，需要在更符合实际现场的情景下确定降解速率。
