Shift in Mass Transfer of Wastewater Contaminants from Microplastics in the Presence of Dissolved Substances.
Shift in Mass Transfer of Wastewater Contaminants from Microplastics in the Presence of Dissolved Substances.
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DOI：
10.1021/acs.est.7b02664
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发表时间：
2017-10
影响因子：
11.4
通讯作者：
Sven Seidensticker;C. Zarfl;O. Cirpka;Greta Fellenberg;P. Grathwohl
中科院分区：
文献类型：
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作者：
Sven Seidensticker;C. Zarfl;O. Cirpka;Greta Fellenberg;P. Grathwohl
在水性环境中，疏水性有机污染物通常与颗粒相关联。除了天然颗粒，微塑料也引起了公众的关注。污染物从这些颗粒中的释放取决于质量传递，无论是在含水边界层中还是通过颗粒内扩散。这些机制控制的传质动力学取决于分配系数，颗粒大小，边界条件和时间。我们已经开发了一个半分析模型，占这两个过程，并进行了批量实验的典型废水污染物（菲，tonalide，和二苯甲酮）在不同的溶解有机物浓度的解吸动力学，这改变了微塑料和水之间的整体分区。最初，传质是外部主导的，而最后，颗粒内扩散控制释放动力学。在典型的批实验（有限浴）的边界条件下，解吸加速增加分配系数的颗粒内扩散，而它成为独立的分配系数，如果膜扩散盛行。相反，在现场条件下（无限浴），污染物的释放控制的颗粒内扩散不受影响的化合物的分区，而外部的传质减慢，增加吸附。我们的研究结果清楚地表明，在批量实验中观察到的吸附/解吸时间尺度可能不会被转移到现场条件下，没有一个适当的模型占双方的传质机制和具体的边界条件在手。
In aqueous environments, hydrophobic organic contaminants are often associated with particles. Besides natural particles, microplastics have raised public concern. The release of pollutants from such particles depends on mass transfer, either in an aqueous boundary layer or by intraparticle diffusion. Which of these mechanisms controls the mass-transfer kinetics depends on partition coefficients, particle size, boundary conditions, and time. We have developed a semianalytical model accounting for both processes and performed batch experiments on the desorption kinetics of typical wastewater pollutants (phenanthrene, tonalide, and benzophenone) at different dissolved-organic-matter concentrations, which change the overall partitioning between microplastics and water. Initially, mass transfer is externally dominated, while finally, intraparticle diffusion controls release kinetics. Under boundary conditions typical for batch experiments (finite bath), desorption accelerates with increasing partition coefficients for intraparticle diffusion, while it becomes independent of partition coefficients if film diffusion prevails. On the contrary, under field conditions (infinite bath), the pollutant release controlled by intraparticle diffusion is not affected by partitioning of the compound while external mass transfer slows down with increasing sorption. Our results clearly demonstrate that sorption/desorption time scales observed in batch experiments may not be transferred to field conditions without an appropriate model accounting for both the mass-transfer mechanisms and the specific boundary conditions at hand.