Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China.
Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China.
Sci Total Environ. 2021 Apr 10;764:142889. doi: 10.1016/j.scitotenv.2020.142889. Epub 2020 Oct 14.
The pervasiveness of microplastics, which can absorb pollutants, has a certain impact on pollutant migration in natural waters. Differences in functional groups, such as the hydroxyl group, of pollutants will affect their adsorption on microplastics. In this study, the adsorption of phenanthrene (PHE) or its monohydroxy derivatives, including 1-hydroxyphenanthrene (1-OHP), 2-hydroxyphenanthrene (2-OHP), 4-hydroxyphenanthrene (4-OHP), and 9-hydroxyphenanthrene (9-OHP), on polyvinyl chloride (PVC, measured mean particle size = 134 μm) microplastics was studied. The adsorption efficiency of PHE was shown to be higher than that of either of OHPs. A better fit for pseudo-second-order and Freundlich isotherm models was obtained, indicating different binding sites on the surface of PVC microplastics. The adsorption processes of PHE and OHPs on PVC microplastics were demonstrated to be exothermic and spontaneous. Combined with FT-IR analysis, theoretical calculation, and comparative adsorption experiments, hydrophobic interaction was the dominant mechanism during the adsorption process. In contrast, electrostatic repulsion, CH/π interaction, and halogen bonding played a minor role, to an extent, in the adsorption of PHE/OHPs on PVC microplastics. These findings indicate the influence of the hydroxyl group on adsorption and improve the understanding of interactions between PVC microplastics and PHE/OHPs.
微塑料的普遍性使其能够吸附污染物，这对自然水中污染物的迁移具有一定的影响。污染物的功能团（如羟基）的差异会影响其在微塑料上的吸附。在这项研究中，研究了多氯代烃（PVC，平均粒径为 134μm）微塑料对菲（PHE）或其单羟基衍生物（包括 1-羟基菲（1-OHP）、2-羟基菲（2-OHP）、4-羟基菲（4-OHP）和 9-羟基菲（9-OHP））的吸附作用。结果表明，PHE 的吸附效率高于 OHPs。准二级和 Freundlich 等温模型的拟合效果更好，表明 PVC 微塑料表面存在不同的结合位点。证明了 PHE 和 OHPs 在 PVC 微塑料上的吸附过程是放热和自发的。结合 FT-IR 分析、理论计算和对比吸附实验，表明在吸附过程中疏水相互作用是主要机制。相比之下，静电排斥、CH/π 相互作用和卤键在 PHE/OHPs 在 PVC 微塑料上的吸附中只起到次要作用。这些发现表明了羟基对吸附的影响，提高了对 PVC 微塑料与 PHE/OHPs 之间相互作用的理解。
