Shao Xuechun, Zhang Qi, Liang Weiyu, Gong Kailin, Fu Mengru, Saif Sadia, Peng Cheng, Zhang Wei
State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China.
Department of Environmental Sciences, Kinnaird College for Women, Lahore 54000, Pakistan.
Mar Pollut Bull. 2023 Jan;186:114492. doi: 10.1016/j.marpolbul.2022.114492. Epub 2022 Dec 18.
The adsorption, desorption, and their influence factors of Cr(VI) by microplastics (MPs) in the solution was investigated in this study. The results demonstrated that UV aging promoted adsorption, while the increase of salinity and natural organic matter (NOM) inhibited adsorption. The particle size affected the total Cr(VI) active adsorption sites on MPs, while the pH changed the electrostatic force. The Cr(VI) adsorption by MPs conformed to the pseudo-first and pseudo-second order kinetic models, and was monolayer and inhomogeneous. SEM-EDS, XPS and ATR-FTIR analyses demonstrated that the physical adsorption dominated the adsorption process. Especially, the highest adsorption capacity of Cr(VI) by polyamide (PA) MPs was attributed to their hydrophilic amide groups. However, Cr(VI) was only released from PA MPs, of which desorption rate followed the sequence of seawater (79.5 %) > fresh water (66.6 %) > deionized water (34.8 %). Thus, PA MPs might be non-negligible environmental vectors for the transport of Cr(VI).
本研究考察了溶液中微塑料（MPs）对Cr(VI)的吸附、解吸及其影响因素。结果表明，紫外线老化促进吸附，而盐度和天然有机物（NOM）的增加抑制吸附。粒径影响了MPs上Cr(VI)的总活性吸附位点，而pH值改变了静电力。MPs对Cr(VI)的吸附符合准一级和准二级动力学模型，且为单层不均匀吸附。扫描电子显微镜-能谱（SEM-EDS）、X射线光电子能谱（XPS）和衰减全反射傅里叶变换红外光谱（ATR-FTIR）分析表明，物理吸附主导了吸附过程。特别是，聚酰胺（PA） MPs对Cr(VI)的最高吸附容量归因于其亲水性酰胺基团。然而，Cr(VI)仅从PA MPs中释放，其解吸率顺序为海水（79.5%）>淡水（66.6%）>去离子水（34.8%）。因此，PA MPs可能是Cr(VI)传输中不可忽视的环境载体。
