Beijing Research Center for Agricultural Standards and Testing, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China.
Beijing Research Center for Agricultural Standards and Testing, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China; College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
Environ Pollut. 2019 Nov;254(Pt A):112927. doi: 10.1016/j.envpol.2019.07.095. Epub 2019 Jul 20.
Biodegradable plastics have been introduced and widely used as a promising alternative to traditional nondegradable plastics. However, the differences in sorption behavior of pesticides on nondegradable and biodegradable microplastics has been insufficiently studied. Here, four types of nondegradable [polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polypropylene (PP)] and two types of biodegradable [polylactic acid (PLA), polybutylene succinate (PBS)] microplastics were selected to investigate the sorption mechanism of fipronil based on their sorption kinetics and isotherms. The results indicated that the sorption rates of PLA and PBS were much higher than those of PE, PP, PVC and PS and that the sorption capacities of fipronil on microplastics followed the order of PBS > PLA > PP > PE > PS > PVC. The sorption kinetics followed a pseudo-second-order kinetics model (R = 0.953-0.998) for all tested microplastics. External mass transport and intraparticle diffusion were the main rate controlling steps of the sorption of fipronil on microplastics. Furthermore, isotherm results indicated that a Langmuir model provided the best fit for fipronil sorption on PE, PS, PVC and PP (R = 0.997-0.999), while a Freundlich model was the most appropriate model for PLA and PBS (R = 0.998-0.999). The presence of surface O-containing functional groups and the spatial arrangement of rubbery domains are likely to affect the sorption process. The results from this work suggest that microplastics, especially biodegradable ones, may play an important role in the fate and transport of pesticides, and their effects on soil organisms (e.g., earthworms) require further investigation.
可生物降解塑料作为传统不可降解塑料的一种有前景的替代品已经被引入并广泛使用。然而，对于不可降解和可生物降解微塑料对农药的吸附行为差异的研究还不够充分。在这里，选择了四种不可降解的（聚乙烯（PE）、聚苯乙烯（PS）、聚氯乙烯（PVC）、聚丙烯（PP））和两种可生物降解的（聚乳酸（PLA）、聚丁二酸丁二醇酯（PBS））微塑料，基于吸附动力学和等温线来研究氟虫腈的吸附机制。结果表明，PLA 和 PBS 的吸附速率远高于 PE、PP、PVC 和 PS，氟虫腈在微塑料上的吸附容量依次为 PBS>PLA>PP>PE>PS>PVC。吸附动力学对所有测试的微塑料都遵循拟二级动力学模型（R=0.953-0.998）。外部质量传输和颗粒内扩散是氟虫腈在微塑料上吸附的主要速率控制步骤。此外，等温线结果表明，Langmuir 模型最适合氟虫腈在 PE、PS、PVC 和 PP 上的吸附（R=0.997-0.999），而 Freundlich 模型最适合 PLA 和 PBS（R=0.998-0.999）。表面含 O 官能团的存在和橡胶状区域的空间排列可能会影响吸附过程。这项工作的结果表明，微塑料，特别是可生物降解的微塑料，可能在农药的命运和迁移中发挥重要作用，它们对土壤生物（例如蚯蚓）的影响需要进一步研究。
