College of Natural Resources and Environment, Joint Institute for Environmental Research & Education, South China Agricultural University, Guangzhou, 510642, China.
Jiangmen Agricultural and Rural Affairs Bureau, Jiangmen, 529000, China.
Environ Pollut. 2021 Dec 15;291:118120. doi: 10.1016/j.envpol.2021.118120. Epub 2021 Sep 6.
Polyethylene (PE) and polypropylene (PP) microplastics (MPs), as carriers, can bind with pesticides, which propose harmful impacts to aqueous ecosystems. Meanwhile, carbofuran and carbendazim (CBD), two widely used carbamate pesticides, are toxic to humans because of the inhibition of acetylcholinesterase activity. The interaction between two MPs and two pesticides could start in farmland and be maintained during transportation to the ocean. Herein, the adsorption behavior and mechanism of carbofuran and carbendazim (CBD) by PE and PP MPs were investigated via characterization and density functional theory (DFT) simulation. The adsorption kinetic and thermodynamic data were best described by pseudo-second-order kinetics and the Freundlich models. The adsorption behaviors of individual carbofuran/CBD on both MPs were very similar. The CBD adsorption rate and capacity of PE and PP MPs were higher than those of carbofuran. This phenomenon explained the lower negative effects of DOM (oxalic acid, glycine (Gly)) on CBD adsorption relative to those of carbofuran. The presence of oxalic acid and Gly decreased the PE adsorption by 20.40-48.02% and the PP adsorption by 19.27-42.11%, respectively. It indicated the significance of DOM in carbofuran cycling. The adsorption capacities were negatively correlated with MPs size, indicating the importance of specific surficial area. Fourier transformation infrared spectroscopy before and after adsorption suggested that the adsorption process did not produce any new covalent bond. Instead, intermolecular van der Waals forces were one of the primary adsorption mechanisms of carbofuran and CBD by MPs, as evidenced by DFT calculations. Based on the zeta potential, the electrostatic interaction explained the higher adsorption CBD by MPs than carbofuran.
聚乙烯（PE）和聚丙烯（PP）微塑料（MPs）作为载体，可以与农药结合，对水生生态系统造成有害影响。同时，两种广泛使用的氨基甲酸酯类农药克百威和多菌灵（CBD）由于乙酰胆碱酯酶活性的抑制对人体有毒。两种 MPs 和两种农药之间的相互作用可能始于农田，并在运输到海洋的过程中得以维持。在此，通过表征和密度泛函理论（DFT）模拟研究了克百威和多菌灵（CBD）在 PE 和 PP MPs 上的吸附行为和机制。吸附动力学和热力学数据最好用伪二级动力学和 Freundlich 模型来描述。单独的克百威/CBD 在两种 MPs 上的吸附行为非常相似。PE 和 PP MPs 对 CBD 的吸附速率和容量均高于克百威。这种现象解释了 DOM（草酸、甘氨酸（Gly））对 CBD 吸附的负面影响相对低于克百威的原因。草酸和 Gly 的存在分别降低了 PE 吸附的 20.40-48.02%和 PP 吸附的 19.27-42.11%。这表明 DOM 在克百威循环中的重要性。吸附容量与 MPs 尺寸呈负相关，表明比表面积的重要性。吸附前后傅里叶变换红外光谱表明，吸附过程未产生任何新的共价键。相反，根据 DFT 计算，分子间范德华力是 MPs 吸附克百威和 CBD 的主要吸附机制之一。基于zeta 电位，静电相互作用解释了 MPs 对 CBD 的吸附高于克百威。
