Weathering Microplastics And Their Sorption Behavior With Typical Antibiotics

As plastic waste spreads throughout the world in human activities,the problem of microplastic pollution has arisen at the historical moment.Microplastics are very easy to adsorb organic pollutants.After being ingested by organisms into the environment,the threats of the mixture are gaining more and more attention.The weathered microplastics have undergone a series of changes in their surface morphology,crystallinity,hydrophilicity and other characteristics,and their adsorption behavior with pollutants will change accordingly.Complex environmental conditions can also interfere with its adsorption performance.Therefore,the research conducted study on the surface and interface behavior characteristics between microplastics and antibiotics,also analyzed various typical weathering characteristics of microplastics,and deeply discussed the adsorption mechanism of weathered microplastics and antibiotics.The major findings of this study are as follows:1.Research on the surface behavior of different microplastics and tetracycline in aqueous solutionTaking tetracycline(TC)as a typical antibiotic to study its adsorption behavior on the surface of a variety of original microplastics,the common polyethylene(PE)is the main research object.The results of isothermal adsorption experiments show that TC has the largest adsorption capacity in PE,among PE,polystyrene(PS)and polyvinyl chloride(PVC).As the particle size of PE continues to decrease,the adsorption capacity of TC increases significantly.Various metal ions affect adsorption differently;changes in ionic strength of the solution will not significantly alter the adsorption process.The superficial properties of the microplastics and the presence of other ions in the aqueous solution have an effect on the adsorption of TC.2.Study in PS before and after Fenton weathering and its surface and interface behavior changes with CIPThe Fenton immersion method was used to accelerate the simulation of the weathering process of microplastics in nature,and the surface and interface behavior of weathered microplastics and the hydrophilic antibiotic ciprofloxacin(CIP)were discussed.The results had shown that the weathered PS had reduced crystallinity,increased functional groups containing oxygen at the surface,and cracks appear on the surface,which made it more susceptible to be weathered.The surface of PS becomes rough and hydrophilic,which facilitates the adsorption of hydrophilic antibiotics.The results of the adsorption experiments show that the CIP adsorption capacity onto the PS after alteration is approximately twice that of the original PS.The adsorption behavior of CIP onto weathered PS particles will be affected by various environmental conditions(salinity,p H,humic acid,sea water)and weakened.3.Research on the weathering process of PLA and its surface and interface behavior with TCThe degradable plastic polylactic acid(PLA)was weathered by indoor and outdoor methods.The degradation process of PLA under conventional conditions was studied,and the surface and interface behavior with antibiotics after weathering was studied.The study found that the weathering characteristics of PLA under normal conditions is similar to those of PS.Its surface becomes rough,and even cracks appear,which all lead to the improvement of its ability to adsorb antibiotics.The weathered PLA also has poor thermal stability,resulting in the fusion and agglomeration of certain fine particles,so that the specific surface area does not change significantly.The study also found that the composition of oxygen-containing functional groups on the weathered PLA has changed.The hydrophilic functional groups have increased,and the contact angle has also decreased significantly.Therefore,the adsorption capacity of PLA after weathering on TC is considerably increased compared to that before weathering,and the potential ecological risks of both will also increase accordingly.The research results presented in this chapter provide research insights and basis on for the into biodegradable plastic methods.