Effects of Microplastics Aging on Soil Phosphorus Adsorption Behavior

CUI Jiahui; GAO Liangmin; ZHANG Jinxin; JIN Xincheng; WU Yufan; YUAN Menghang; LU Hansong; WEI Feiyan

doi:10.19672/j.cnki.1003-6504.0808.23.338

Abstract：As a new type of pollutant with adsorption capacity,the adsorption of microplastics to pollutants in the environ-ment can aggravate their environmental pollution.Three microplastics,polyethylene(PE),polystyrene(PS),and polyvinyl chloride(PVC)were aged by UV irradiation for 120 days to investigate the effect of aging on adsorption of phosohorus by mi-croplastics in water and soil environments.The results showed that the aging process caused a large number of folds,frag-ments,and grooves on the surface of microplastics,and significantly increased their specific surface area and the number of oxygen-containing functional groups.Compared with the original plastic,phosphorus adsorption capacity of aged micro-plastics increased,indicating that the aging process improved the adsorption capacity of microplastics.The phosphorus adsorp-tion behavior of microplastics before and after aging conforms to the quasi-secondary kinetic model(R2＞0.964),which indi-cated that the phosphorus adsorption on microplastics before and after aging was mainly chemisorption.The microplastics be-fore and after aging were more consistent with the Langmuir isothermal adsorption model(R2＞0.964),which indicated that the phosphorus adsorption on each microplastic was mainly monolayer adsorption.The effect of pH on phosphorus adsorption on microplastics was significant.The unit phosphorus adsorption amount of unit microplastics before and after aging showed a'U-shaped'trend with increasing pH,and the adsorption amount of microplastics after aging was higher than that before ag-ing.The phosphorus adsorption capacity of the soil microplastic system increased with the increase of the percentage of micro-plastics added to the soil,but it was limited.The phosphorus sorption capacity of the soil microplastic system was increased but limited,compared with the phosphorus sorption capacity of the original microplastic aging microplastic,but not signifi-cantly,and did not differ significantly according to the type of microplastic.