Interaction Mechanism Between Microplastics And Soil Media

In 2011,"microplastic pollution"was listed by the United Nations environment programme(UNEP)as a new crisis and challenge facing mankind.Therefore,"microplastics"(particle size<5mm)have attracted the attention of many researchers.Due to the wide use of all kinds of plastic products in the world and the improvement of people's living standards,its demand is increasing.After entering the environment(soil),a series of complex physical and chemical reactions take place and form fine particles,which accumulate in the soil environment and pollute the soil,ultimately threatening the ecological environment and human health.At present,domestic and foreign researchers have made some progress in the research on microplastics,but it is mainly limited to the pollution of Marine microplastics,and few researchers have studied the migration and transformation mechanism of microplastics in the soil environment.In this study,polystyrene(PS)was taken as the research object.This study respectively studied the influence of microplastics on soil adsorption of Tylosin(TYL),the adsorption behavior of soil from different regions on microplastics,and the reaction mechanism of iron oxide and microplastics.The main achievements of this paper are as follows:1.The main research on the adsorption of Tylosin on soil after micro-plastics enter the soil:at 36h,the adsorption of Tylosin in soil samples and micro-plastic-soil complexes tends to be in equilibrium;The Lagrangian pseudo-second-order kinetics is suitable for the fitting of adsorption data of antibiotics by soil and microplastic-soil composite system;It is better to fit the adsorption isotherm data by linear and Freundlich equations;Adsorption is inversely proportional to pH value and ionic strength.The adsorption of antibiotics on the composite system is greater than that on the soil,which proves that the addition of microplastics is conducive to the migration of antibiotics to the solid phase,reduces the mobile phase of antibiotics and reduces the ecological risk of antibiotics.2.The adsorption mechanism of different soils on micro-plastics was studied.The test results show that:the adsorption kinetic curves of micro-plastics in different soils all showed an inverted"L"shape.The adsorption kinetics of microplastics on five different soils are similar.The adsorption mainly occurred in the first 3 hours,and the Lagrangian pseudo-second-order kinetic model can fit the adsorption data well,R~2>0.99;Linear and Freundlich models can better fit the adsorption isotherm data;the adsorption is affected by the pH and ionic strength in the environment.3.The adsorption kinetics of iron oxides on microplastics showed an inverted"L"shape,and the adsorption reached equilibrium within 3 hours.The adsorption kinetics could be well fitted by Lagrangian pseudo-second-order kinetics,and the adsorption process mainly occurred on the surface of iron oxides.The adsorption isotherm can be well fitted by Langmuir model.The adsorption capacity of microplastics on iron oxides decreases with the increase of pH value and increases with the increase of ionic strength.Figure[25]Table[9]Reference[109]...