Abstract:

Chlorinated organophosphate flame retardants (Cl-OPFRs), a new type of pollutant, are widely detected in environment and has resistant to degradation, easy-migratory and biological toxicity. Tris(2-chloroethyl) phosphate (TCEP) with the highest detection rate in environment was chosen as the target pollutant in this study, and a composition adsorbent (named S/ZVI-N₁) that prepared by zero-valent iron sulfide and Novosphingobium tardaugens was used as research material, to explore the removal performance and degrading pathway of TCEP by the S/ZVI-N₁. The results showed that the removal of TCEP by S/ZVI-N₁ fitted to the quasi-first-order kinetic equation and Langmuir model, which indicated this process was a physical adsorption of monolayer primarily and the R² of quasi-second-order kinetic equation also proved the chemical adsorption. The removal rate of TCEP by S/ZVI-N₁ was 58.9% after 12h, which was higher significantly than that by Novosphingobium tardaugens or S/ZVI only (biodegradation rate was 32.95% and S/ZVI removal rate was 31.2%). The analysis of degradation products indicated that the decomposition of TCEP by S/ZVI-N₁ was more thorough than that by ZVI alone. This proved there was synergistic reaction between the S/ZVI and Novosphingobium tardaugens to remove TCEP, and the optimal conditions of TCEP removal was pH 5—7 and 30—35℃. The intermediates analysis could deduce two degradation pathways of TCEP by S/ZVI-N₁, that one was the C—Cl bond broken down by S/ZVI and another was O—P bond broken down by Novosphingobium tardaugens, and the final products were triethyl phosphate (TEP) and H₃PO₄, which meant the completely degradation of TCEP.

Key words: chlorinated organophosphate flame retardants, composited adsorbent, bio-degradation, zero-valent iron sulfide, degradation pathway, tris(2-chloroethyl) phosphate

摘要：

氯代有机磷阻燃剂（chlorinated organophosphate flame retardants，Cl-OPFRs）已在环境中被广泛检出，由于其稳定、易迁移及具有生物毒性，因此已成为不可忽视的新兴有机污染物。本文选择环境中检出率较高的磷酸三(2-氯乙基)酯[tris(2-chloroethyl) phosphate，TCEP]为研究对象，以硫化零价铁（S/ZVI）和TCEP耐受降解菌（缓生新鞘氨醇菌，Novosphingobium tardaugens，N₁）为研究材料，制备S/ZVI-微生物复合吸附剂（S/ZVI-N₁），并对其去除TCEP的性能和降解途径进行探究。结果显示，S/ZVI-N₁对TCEP的去除符合准一级动力学方程和Langmuir模型，表明该过程主要为单分子层的物理吸附作用，且根据准二级动力学方程的相关系数可知，在反应过程中同样存在化学吸附过程，S/ZVI-N₁作用于TCEP 12h，去除率达58.9%，显著高于仅依靠Novosphingobium tardaugens的去除率（32.9%）和仅依靠S/ZVI的去除率（31.2%）。产物分析表明，S/ZVI-N₁作用下TCEP较单独零价铁（zero-valent iron，ZVI）作用下降解更彻底，证明复合吸附剂中S/ZVI和Novosphingobium tardaugens之间存在协同作用，其最佳的反应条件为pH 5~7和30~35℃。微观分析显示，微生物和S/ZVI均参与了TCEP的降解。通过产物分析推导，S/ZVI-N₁对TCEP主要有2条降解途径，分别为S/ZVI主导的C—Cl键断裂和Novosphingobium tardaugens主导的O—P键断裂，最终生成磷酸三乙酯（triethyl phosphate，TEP）和磷酸（H₃PO₄）。

关键词: 氯代有机磷阻燃剂, 复合吸附剂, 微生物降解, 硫化零价铁, 降解途径, 磷酸三(2-氯乙基)酯