Understanding the sorption mechanisms for organophosphate flame retardants (OPFRs) on impervious surfaces is important to improve our knowledge of the fate and transport of OPFRs in indoor environments. The sorption processes of semivolatile organic compounds (SVOCs) on indoor surfaces are heterogeneous (multilayer sorption) or homogeneous (monolayer sorption). In this study, we adopted simplified Langmuir isotherm and Freundlich isotherm in a dynamic sink model to characterize the sorption dynamics of OPFRs on impervious surfaces such as stainless steel and made comparisons between the two models through a series of empty chamber studies. The tests involve two types of stainless steel chambers (53-L small chambers and 44-mL micro chambers) using tris(2-chloroethyl)phosphate (TCEP) and tris(1-chloro-2-propyl)phosphate (TCPP) as target compounds. Our test results show that the dynamic sink model using Freundlich isotherm can better represent the sorption process in the empty small chamber. Micro chamber test results from this study show that the sink model using both simplified Langmuir isotherm and Freundlich isotherm can well fit the measured gas-phase concentrations of OPFRs. We further applied both models and the parameters obtained to predict the gas phase concentrations of OPFRs in a small chamber with an emission source. Comparisons between model predictions and measurements demonstrate the reliability and applicability of the sorption parameters.

了解有机磷阻燃剂（OPFR）在不透水表面上的吸附机理对于提高我们对室内环境中OPFR的结局和运输的了解非常重要。室内表面上的半挥发性有机化合物（SVOC）的吸附过程是非均质的（多层吸附）或均质的（单层吸附）。在这项研究中，我们在动态水槽模型中采用简化的Langmuir等温线和Freundlich等温线来表征OPFRs在不透水表面（如不锈钢）上的吸附动力学，并通过一系列空腔研究对这两种模型进行了比较。测试涉及使用三（2-氯乙基）磷酸酯（TCEP）和三（1-氯-2-丙基）磷酸酯（TCPP）作为目标的两种类型的不锈钢腔室（53-L小腔室和44-mL微型腔室）化合物。我们的测试结果表明，使用Freundlich等温线的动态吸收模型可以更好地表示空小室中的吸附过程。这项研究的微室测试结果表明，使用简化的Langmuir等温线和Freundlich等温线的水槽模型可以很好地拟合OPFR的气相测量浓度。我们进一步应用了模型和获得的参数来预测带有排放源的小室中OPFR的气相浓度。模型预测和测量之间的比较证明了吸附参数的可靠性和适用性。这项研究的微室测试结果表明，使用简化的Langmuir等温线和Freundlich等温线的水槽模型可以很好地拟合OPFR的气相测量浓度。我们进一步应用了模型和获得的参数来预测带有排放源的小室中OPFR的气相浓度。模型预测和测量之间的比较证明了吸附参数的可靠性和适用性。这项研究的微室测试结果表明，使用简化的Langmuir等温线和Freundlich等温线的水槽模型可以很好地拟合OPFR的气相测量浓度。我们进一步应用了模型和获得的参数来预测带有排放源的小室中OPFR的气相浓度。模型预测和测量之间的比较证明了吸附参数的可靠性和适用性。