Department of Chemistry, University of California, Irvine, CA 92697, USA.
Department of Civil, Architectural and Environmental Engineering, Drexel University, PA 19104, USA.
Environ Sci Process Impacts. 2023 Sep 20;25(9):1464-1478. doi: 10.1039/d3em00213f.
Indoor surfaces can act as reservoirs and reaction media influencing the concentrations and type of species that people are exposed to indoors. Mass accommodation and partitioning are impacted by the phase state and viscosity of indoor surface films. We developed the kinetic multi-layer model KM-FILM to simulate organic film formation and growth, but it is computationally expensive to couple such comprehensive models with indoor air box models. Recently, a novel effective mass accommodation coefficient () was introduced for efficient and effective treatments of gas-particle partitioning. In this study, we extended this approach to a film geometry with as a function of penetration depth into the film, partitioning coefficient, bulk diffusivity, and condensed-phase reaction rate constant. Comparisons between KM-FILM and the method show excellent agreement under most conditions, but with deviations before the establishment of quasi-equilibrium within the penetration depth. We found that the deposition velocity of species and overall film growth are impacted by bulk diffusivity in highly viscous films ( ∼<10 cm s). Reactions that lead to non-volatile products can increase film thicknesses significantly, with the extent of film growth being dependent on the gas-phase concentration, rate coefficient, partitioning coefficient and diffusivity. Amorphous semisolid films with > ∼10-10 cm s can be efficient SVOC reservoirs for compounds with higher partitioning coefficients as they can be released back to the gas phase over extended periods of time, while glassy solid films would not be able to act as reservoirs as gas-film partitioning is impeded.
室内表面可以作为储层和反应介质，影响人们在室内接触到的浓度和物种类型。大量的滞留和分配受到室内表面薄膜的相态和粘度的影响。我们开发了动力学多层模型 KM-FILM 来模拟有机薄膜的形成和生长，但将如此全面的模型与室内空气箱模型耦合计算成本很高。最近，一种新的有效质量滞留系数（）被引入，以有效地处理气-粒分配。在这项研究中，我们将这种方法扩展到一个薄膜几何形状，其中作为穿透深度进入薄膜、分配系数、体扩散系数和凝聚相反应速率常数的函数。KM-FILM 和方法之间的比较表明，在大多数情况下，两者吻合得非常好，但在穿透深度内达到准平衡之前，存在偏差。我们发现，在高粘性薄膜（～<10 cm s）中，物质的沉积速度和整体薄膜生长受到体扩散系数的影响。导致非挥发性产物的反应可以显著增加薄膜厚度，薄膜生长的程度取决于气相浓度、速率系数、分配系数和扩散系数。具有> ∼10-10 cm s 的非晶半固态薄膜可以作为具有较高分配系数的化合物的有效 SVOC 储层，因为它们可以在较长时间内释放回气相，而玻璃态固态薄膜则不能作为储层，因为气体-薄膜分配受到阻碍。
