Study On Release And Aging Process Of Simulated Microplastics

Since the concept of microplastics was first proposed in Science,the natural environmental problems caused by its small particle size and high abundance have attracted extensive attention.Various plastics existing in the natural environment will release microplastics with small particle size through the action of the natural environment.Microplastics can not only release toxic and harmful substances,but also cause a certain degree of harm to the natural ecology as the carrier of other pollutants in the natural environment.In addition,the micro plastics existing in the natural environment will undergo a series of aging effects such as light,thermal radiation,physical stirring,salinity and chemical oxidation,which will change their physical and chemical properties to a certain extent.Aging can change the surface morphology of micro plastics,break them,cause surface roughness,and increase the adsorption of micro plastics to pollutants in the natural environment.The aging process will also break the polymer chain in the microplastic and release the additives contained in it,and the toxicity of the additives released by the micro plastic will endanger the growth and development of organisms.However,due to the long aging cycle of micro plastics caused by natural environmental factors,it is particularly important to find a laboratory technology that can replace natural conditions to simulate the aging of microplastics.Therefore,this paper uses laboratory conditions to simulate the release and aging of microplastics,so as to provide a feasible scheme for the follow up study of the aging of microplastics.The main research results of this paper are as follows:（1）In the experiment of simulating the release of microplastics,it is found that:Commercial plastic products release hundreds of millions of micro and nano plastics.The size of the released microplastics is usually irregular,and the large particle size microplastics are mainly concentrated in 1.5-3.5μm.The small particle size is concentrated in 0.05-0.10μm.Because the size of small particle size microplastics is too small,it is more prone to agglomeration,so the size of these aggregates is closer to a sphere.（2）When simulating the aging experiment of micro plastics,it is found that:Light conditions play a key role in the aging of micro plastics.Different aging conditions have different aging degrees of micro plastics.During the aging process,the surface morphology of microplastics will become rough and uneven,and even rupture will occur.Its particle size will also be reduced to the range of 0-100μm.Aging will also make microplastics produce hydroxyl,carboxyl and other oxygen-containing functional groups.Oligomers will also be released into the filtrate,increasing the potential risk to the environment.（3）When simulating the aging of coexisting microplastics,it is found that:PS microplastics significantly accelerated the photodegradation of coexisting PP microplastics,including faster oxidation and fragmentation.The existence of PS microplastics changed the photodegradation pathway of PP microplastics.The critical effect of PS microplastics mainly comes from the polymer itself and its released dom.OH·and ¹O₂ produced by the reaction of polymer free radical and dissolved oxygen play an important role in accelerating the photodegradation of PP microplastics,while ¹O₂plays a major role in the composite system of PS-DOM.Figure 43;Table 4;Reference 115...