Redistribution of pollutants between different solid phases occurs frequently in field and laboratory settings. Examples include the input of urban particles carrying pollutants into soils or rivers with suspended particles or passive sampling. Since multiple mass transfer mechanisms are involved and natural particles typically are very heterogeneous, modeling of sorption/desorption kinetics is challenging. Here, we present a semi-analytical model formulated in the Laplace domain to simulate pollutant redistribution kinetics in heterogeneous systems. The model accounts for a coupled process governed by intraparticle and external boundary layer diffusion, and it considers the heterogeneity of various sorbents (e.g., geometric shape, size, sorption capacity coefficient, and solid and porous particles). The model is validated against data of two batch experiments: (i) the redistribution of phenanthrene in spherical polyethylene particles of different sizes and (ii) redistribution of anthracene-d10 and phenanthrene in a heterogeneous sediment suspension with polyethylene passive samplers. It allows to explain the temporary overshooting of concentrations in the aqueous phase due to different kinetic controls of various particles involved (fast desorption vs. slow sorption) as well as initial fast kinetics followed by surprising long tailing in batch experiments. The approach is very flexible and can be used for many different scenarios.

中文翻译：

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非均相系统中污染物质量再分布（吸附/解吸）的机理建模解释了意外的慢动力学


污染物在不同固相之间的重新分布经常发生在现场和实验室环境中。示例包括将携带污染物的城市颗粒物输入到带有悬浮颗粒的土壤或河流中或被动采样。由于涉及多种传质机制，并且天然颗粒通常非常异质，因此吸附/解吸动力学的建模具有挑战性。在这里，我们提出了一个在拉普拉斯域中构建的半解析模型，用于模拟非均相系统中的污染物再分布动力学。该模型解释了由颗粒内和外部边界层扩散控制的耦合过程，并考虑了各种吸附剂的异质性（例如，几何形状、尺寸、吸附容量系数以及固体和多孔颗粒）。该模型根据两个批量实验的数据进行了验证：（i） 菲在不同大小的球形聚乙烯颗粒中的重新分布，以及 （ii） 蒽-d10 和菲在异质沉积物悬浮液中的重新分布聚乙烯被动采样器。它允许解释由于所涉及的各种颗粒的不同动力学控制（快速解吸与慢速吸附）以及初始快速动力学随后在批量实验中令人惊讶的长拖尾而导致的水相浓度暂时超调。该方法非常灵活，可用于许多不同的场景。