地膜源微塑料PE对除虫脲的吸附动力学研究

Adsorption Kinetics of Diflubenzuron by Mulch-derived Microplastic PE

聚乙烯(PE)农用地膜在环境中容易脆化和分解成微塑料(MPs),越来越多的研究表明MPs可以吸附有机污染物,这可能会影响它们的分布和生物利用度。除虫脲等农药在农田蔬菜中广泛使用,其可能与MPs长期共存于环境中,存在潜在的环境和人身安全风险。因此,探究除虫脲与PE农用地膜微塑料的吸附行为,是农药与微塑料共暴露风险评估的基础。该文对除虫脲和PE微塑料的吸附过程进行了系统的批量吸附实验,对影响微塑料吸附能力的环境因素进行了评价,并对其吸附机理进行探讨。结果表明,除虫脲能被PE MPs吸附,在80 min达到吸附平衡,平衡吸附量可达84.89μg/g。当PE MPs为10 g/L时对除虫脲吸附量最高,1μg/mL除虫脲初始浓度条件下,随pH值在3~6范围内增加,除虫脲的吸附能力先增加后趋于稳定。0.05%~3.5%盐度范围内,高盐浓度不利于PE MPs对除虫脲的吸附。拟二级模型更适合描述PE MPs对除虫脲的吸附动力学过程,这说明吸附过程除了吸附于表面位置外,还涉及了传质和颗粒内扩散。综上分析表明,探究其他农药与MPs之间吸附过程及影响因素是必要的。

Polyethylene(PE)agricultural mulch is prone to embrittlement and decomposition into microplastics(MPs)in the environment.More and more studies have shown that MPs can absorb organic pollutants,which may affect their distribution and bioavailability.Pesticides such as diflubenzuron are widely used in field vegetables,which have potential environmental and personal safety risks.They may coexist with MPs in the environment for a long time,resulting in pollution to the ecosystem.Therefore,it is helpful to explore the adsorption behavior of diflubenzuron and PE microplastics from agricultural plastic mulching film for the risk assessment of co-exposure of pesticides and microplastics.In this study,a batch adsorption experiment was carried out to systematically study the adsorption process of diflubenzuron and PE microplastics,and the environmental factors affecting the adsorption capacity of microplastics were evaluated,and the adsorption mechanism was discussed.The results showed that diflubenzuron could be adsorbed by PE MPs and reached the equilibrium adsorption capacity of 84.89μg/g in 80 min.The dosage of 10 g/L PE MPs will be determined as the most effective dosage for the adsorption of insecticide.Under the initial concentration of 1.0 mg/L of insecticide,the adsorption capacity of insecticide increases first and then becomes stable with the increase of pH value in the range of 3~6.In the salinity range of 0.05%~3.5%,high salt concentration is not conducive to the adsorption of PE MPs for diflubenzuron.The pseudo-second-order model is more suitable to describe the kinetic process of PE MPs adsorption on diflubenzuron,which indicates that the adsorption process involves mass transfer and intra-particle diffusion in addition to the adsorption on the surface.It is necessary to investigate the adsorption processes between other pesticides and MPs and their influencing factors.