The Aging Process Of Microplastics And Its Influence On The Sorption Of Pollutants

In recent years,antibiotics and heavy metals have been commonly detected in the environment as common pollutants.Methods for removing antibiotics and heavy metals in the environment include oxidation,photolysis,sorption and electrochemical methods,and sorption has been widely concerned by domestic and foreign scholars as the main removal route.Along with the extensive use of plastic products,waste plastics have entered the environment extensively.Some scholars have studied the sorption of antibiotics and heavy metals in plastics.However,the aging mechanism of microplastics and the mechanism of migration and transformation of pollutants are still unclear.Therefore,this thesis investigates the distribution and abundance of microplastics in the Weihe River basin,and simulates the aging process of typical microplastics?polystyrene,PS? under laboratory conditions,and studies the mechanism of pollutants?bacteriocin and Cd2+? sorption on aging microplastics.Leads to the following conclusions:?1?Microplastics were found in all surface water and sediment samples collected in the Weihe River,and the abundance of microplastics in surface water and sediment was relatively high,while the abundance of microplastics in the surface water samples was significantly lower than the microplastic abundance in the sediment.The results show that lower water flow velocity,flow rate and higher sand content are the main reasons for the microplastics enrichment and distribution in the Weihe River Basin.The source of microplastics in the Weihe River Basin is closely related to the surrounding agricultural production activities.?2?The aging mechanism of microplastics under ultraviolet light irradiation was explored.With the increase of aging time,aging progressed more thoroughly.The sorption kinetics and adsorption isotherm experiments show that the adsorption kinetics data of TYL and Cd²⁺ on UV-aging microplastics can be well fitted by the second-order adsorption kinetics model,and the sorption reached a dynamic equilibrium after sorption for 36 h.Sorption data can be well fitted by Freundlich model.The values of n in Freundlich model are between 0.5 and 1.The sorption is nonlinear and biased toward linear sorption.The sorption capacity of UV-aging microplastics is positively correlated with the aging time.During the same aging time,the sorption ability of UV-aging microplastics in the water is greater than the sorption capacity of UV-aging microplastics in the air,and the hydrophobic partitioning and electrostatic attraction play a leading role in the sorption process.?3?The aging mechanism of microplastics under high temperature aging conditions was explored.With the increase of aging time,aging progressed more thoroughly.The sorption kinetics and sorption isotherm experiments show that the adsorption kinetics data of TYL and Cd²⁺ on high temperature aging microplastics can be better fitted by the second-order adsorption kinetics model,including a rapid sorption in a short time,followed by a slow sorption for a long time,and sorption reached a dynamic equilibrium after 36 h.The sorption data fitted well by the Freundlich model and the value of n is between 0.5 and 1.The sorption has nonlinearity and is biased towards linear sorption.The sorption capacity of high temperature aging microplastics is positively correlated with the aging time.In the same aging time,the sorption capacity of aging microplastics in high temperature water is greater than that of aging microplastics in high temperature air.Hydrophobic partitioning and electrostatic attraction play a leading role in the sorption process.Figure 42;table 19;reference 105.