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| Effects of the coexistence of biochar and microplastic in different particle sizes on phenanthrene sorption |
| Received:August 07, 2021 |
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| KeyWord:biochar;microplastic;coexistence;sorption;dissolved organic carbon;polycyclic aromatic hydrocarbon |
| Author Name | Affiliation | | CHI Jie | School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China | | XING Haiwen | School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China | | ZHANG Haitong | School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China | | TONG Yindong | School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China |
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| Abstract: |
| Biochar and microplastics normally coexist in the environment, and the interactions between them can influence their sorption of organic pollutants. In this study, polyethylene(PE) and wheat straw biochar(BC) with particle size ranging between 0.85~2.00 mm and 0.11~0.18 cm were selected and named as LPE, SPE, LBC, and SBC, respectively. The properties of these particles were characterized. The concentration and composition of dissolved organic carbon in the equilibrium solution was determined, and the phenanthrene sorption behavior in response to single or mixed particles was studied. The results showed that there were significant differences in the total specific surface area, pore structure, and contents of the surface functional groups between particles of different sizes. The total specific surface area of SBC(216.32 m2·g-1) was approximately 100 times as much as that of LBC(2.31 m2·g-1). The average pore diameter of LBC(8.92 nm) was approximately 4 times as much as that of SBC(2.28 nm). The total specific surface area of SPE(0.17 m2·g-1) was as much as double of that of LPE(0.07 m2·g-1). As expected, the peak intensity of -OH vibrations in SBC(3 400 cm-1) was stronger than that in LBC and the peak intensity of the -CH2 vibrations was stronger in SPE than in LPE. The sorption isotherms demonstrated that phenanthrene sorption on particles, fit well with the Freundlich model(R2>0.94).The sorptive ability(lg Kf) of a single particle of phenanthrene, was in the order of SBC>SPE>LPE>LBC. When BC and PE microparticles coexist, the lg Kf value was higher than what was predicated by the sum of the independent sorption values of BC and PE, indicating that the sorption of phenanthrene on mixed particles does not occur independently; meanwhile, the concentration and aromaticity of dissolved organic carbon was largely reduced. Additionally, concentration of dissolved organic carbon was negatively correlated with the lg Kf value. These results all suggest that phenanthrene sorption on different particles is affected not only by the surface properties of the particles, but also by the amount of dissolved organic carbon present. |
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