紫外老化前后聚氯乙烯微塑料对氮元素的吸附研究

Study on the adsorption of nitrogen by polyvinyl chloride microplastics before and after ultraviolet aging

氮素是农业面源污染的主要污染源之一,而水环境中的微塑料和氮素间存在相互作用,从而会对环境造成影响甚至产生扩大农业面源污染的环境风险,为探究自然环境中微塑料与氮素的相互作用行为,本文进行了聚氯乙烯(PVC)微塑料紫外老化前后对氮素的模拟吸附实验。所得结论如下:PVC微塑料对氮素存在吸附作用,且紫外老化作用明显增强PVC微塑料对氮素的吸附能力,同时老化时间越长吸附能力越强。聚氯乙烯微塑料颗粒对氮素的吸附可用准二级动力学方程很好的拟合,且在24h左右时接近吸附饱和。此外,Langmuir和Freundlich吸附等温模型对该吸附过程均表现出较好的拟合度,表明微塑料对氮素的吸附过程包含多种方式,为单层物理吸附和多层化学吸附相结合的过程。

Nitrogen is one of the main pollution sources of agricultural non-point source pollution,and there is interaction between microplastics and nitrogen in water environment,which will affect the environment and even increase the environmental risk of agricultural non-point source pollution.In order to explore the interaction behavior between microplastics and nitrogen in natural environment,the simulated adsorption experiment of nitrogen by polyvinyl chloride(PVC)microplastics before and after ultraviolet aging was carried out in this paper.The conclusion is as follows:PVC microplastics can adsorb nitrogen,and the ultraviolet aging can obviously enhance the adsorption capacity of PVC microplastics to nitrogen,and the longer the aging time is,the stronger the adsorption capacity is.The adsorption of nitrogen on PVC micro-plastic particles could be well fitted by pseudo-second-order kinetic equation,and the adsorption was close to saturation at about 24h.In addition,Langmuir and Freundlich adsorption isotherm models showed good fitting for the adsorption process,indicating that the adsorption process of nitrogen on microplastics included multiple modes,which was a combination of monolayer adsorption and multilayer adsorption.