Adsorption Characteristics And Mechanism Of Microplastics And Biomacromolecules

At present,microplastics have received great attention from researchers.A large number of studies have reported the adsorption of pollutants and heavy metals by microplastics.However,the adsorption characteristics of microplastics and biological macromolecules are not clear.Therefore,relevant work is urgently needed.Aging can significantly affect the physical and chemical properties of microplastics and make them show different surface characteristics from the original microplastics.Therefore,when studying the environmental behavior and biological effects of microplastics,the related effects of aging should not be ignored.In this paper,three kinds of non-degradable microplastics(polyurethane PU,polystyrene PS,polyamide PA)and two kinds of degradable microplastics(polylactic acid PLA,poly adipic acid/butanol terephthalate PBAT)were used for the adsorption of lysozyme before and after aging.PU and PBAT microplastics were selected to study their interaction with extracellular polymers(EPS),and the following conclusions were obtained:(1)The aging mechanism of non-degradable microplastics under uv irradiation and the interaction with biological macromolecules were investigated.The results of adsorption kinetics and adsorption isotherm experiments showed that the adsorption kinetics data of lysozyme on raw and uv aged microplastics could be well fitted by pseudo-second-order adsorption kinetics model,and the dynamic equilibrium was reached after adsorption for 24 h.The adsorption data of raw and aged PU,PA and PS are more suitable for Freundlich model.The adsorption capacity of the three microplastics reached the maximum at pH 5.5-7.When the ionic gradient increased from 0.5%to 2.5%,the adsorption amount of lysozyme changed slightly,but not significantly,indicating that the change of solution salinity had little influence on the adsorption of microplastics.(2)The adsorption behavior of degradable microplastics and lysozyme was studied.The results of adsorption kinetics and adsorption isotherm experiments showed that the adsorption kinetics data of lysozyme on PBAT and PLA could be well fitted by the second-order adsorption kinetics model,and the adsorption capacity of aged microplastics was higher than that of the original microplastics.For raw and aged PBAT and PLA,the Freundlich isotherm model better describes the adsorption of PBAT.PH also affected the adsorption process,and the adsorption of PBAT and PLA increased first and then decreased with the pH range from 3.0 to 11.0.The concentration of solution salt has little effect on the adsorption of biodegradable microplastics.(3)The adsorption capacity of PU,PBAT and EPS changes with time.Compared with EPS-mud,both of them have stronger adsorption on EPS-M.At the same time,aging also has a certain influence on the adsorption of EPS.Compared with the original microplastics,the adsorption amount of aging microplastics is larger.Three-dimensional fluorescence spectrum showed that the fluorescence intensity decreased with time,which once again indicated that proteins in EPS could be adsorbed on microplastics.Figure[29]Table[13]Reference[110]...