同位素分析对有机磷酸酯类阻燃剂化学氧化降解过程的机理研究

Organophosphate ester (OPE) flame retardants are commonly applied in many consumer products and resisted degradation, resulting in their widespread distribution in multi-environment matrices. Considering potential adverse effects have been observed in animals exposed to OPE flame retardants. Therefore, developing efficient and safe methods for removing OPE flame retardants is urgent. Conventionally, concentration of reactants and identification of degradation products are routinely analyzed to evaluate degradation pathways. However, this approach often has large uncertainties because of the influence of physical processes (such as dilution, volatility), and challenges of detecting unknown products. Thus, compound-specific stable isotope analysis (CSIA) is used in offsetting the deficiencies. CSIA is based on breaking chemical bond kinetics with variation abundance of stable isotope when moving from reactant to transition state, and isotope fractionation essentially allows a glimpse at transition states. With these backgrounds, in-depth analysis transformation mechanisms of OPE flame retardants is planned. The purpose of the present study is to clarify the OPE flame retardants oxidation degradation pathways via isotope fractionation effects; characterise the influence of environmental factors on isotope fractionation via simulating anions and humic acids; establish an isotope fractionation model to diagnostically evaluate OPE flame retardants degradation in the field. This study will provide basic theoretical and technical support for OPE flame retardants prevention, control and treatment.

有机磷酸酯类（OPEs）阻燃剂因使用量大且不易降解导致环境多介质检出率高，已对环境造成危害，如何去除成为当务之急。目前，对此类物质的降解研究主要在浓度变化和依据产物鉴定结果间接推导降解路径。但同一降解产物可能由不同降解机理产生，此外受稀释、挥发等环境因素的干扰使待测物浓度降低造成消除的假象，所以传统方法具有局限性。单体稳定同位素分析（CSIA）通过检测待测物中稳定同位素的变化特征量化降解路径，可为降解反应提供直接证据弥补了传统方法的不足。本研究拟采用CSIA对OPEs阻燃剂化学氧化降解中的同位素进行检测，获得碳、氢同位素分馏效应，结合降解反应动力学和降解产物的鉴定结果，推导降解路径阐明降解机理；模拟阴离子和腐殖酸的存在，探究环境因素对同位素分馏的影响特征；以自然水体为反应介质研究降解反应，建立应用CSIA评估污染物环境归宿的方案。本研究将为该类物质的防控和治理提供重要的理论依据和技术支撑。

有机磷酸酯类阻燃剂（OPFRs）已成为溴系阻燃剂的替代品，近年来使用量不断增加，环境多介质检出率高。同时毒理学研究表明，OPFRs可破坏内分泌系统，产生神经毒性、生殖毒性和发育毒性，对人类健康构成威胁，因此如何高效去除该类污染物已成为当务之急。基于此，本项目选取含氯烷基OPFR和烷基OPFR的代表物质，即三(2-氯乙基)磷酸（TCEP）和三正丁基磷酸（TnBP）作为研究对象，完成阴离子参与的过硫酸盐（PS）活化体系对该类物质的降解实验。①采用探针法和模型法相结合，定量揭示了阴离子存在于PS体系中自由基的生成转化规律。②室内模拟阴离子参与的PS体系对TCEP和TnBP的降解，从量化自由基稳态浓度的角度出发，深入探讨了自由基氧化对同位素分馏的影响机制，验证了单体稳定同位素分析（CSIA）应用于实地自由基化学污染修复的可行性。值得注意的是，若介质中存在HCO3−时，CSIA需要对产生的CO3−•引起重视。③选择自然水体作为介质参与降解实验，获得水体的理化性质、TCEP和TnBP降解速率以及同位素分馏系数，结合室内模拟自由基调控的实验结果，采用数学统计分析，建立CSIA在OPFRs环境归宿评估的应用方案，为后续PS体系降解污染物的实地应用提供理论支撑。