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Abstract: To better understand the nanoparticle (NP) transport in the environment, the agglomeration and sedimentation of Al₂O₃, SiO₂, and TiO₂ NPs were evaluated after being treated with bovine serum albumin (BSA) and a commercial humic acid (HA). The morphology of NP agglomerates was examined through a transmission electron microscope (TEM), and the agglomeration kinetics was evaluated using established time-resolved dynamic light scattering techniques. BSA treatments decreased the hydrodynamic diameters (d _H) of the three NPs in both NaCl and CaCl₂ electrolytes due to their steric repulsive forces caused by the BSA globular architecture. The treatments using HA induced the smallest d _H of NPs in NaCl electrolyte, but the largest d _H of NPs was found in CaCl₂ electrolyte, because the HA bound to each other via calcium complexation and thereby enhanced the NP agglomeration. The zeta potentials of NPs were not the dominant factor to affect agglomeration. The NP sedimentation kinetics were studied through measuring the suspension optical absorbance. It was shown that the BSA treatments retarded the sedimentation in most situations; however, HA treatments accelerated the sedimentation greatly in CaCl₂ electrolyte, which was consistent with the measured changes in the d _H values. The smallest d _H of HA-treated NPs in NaCl electrolyte did not result in the lowest sedimentation rate, which indicated that the agglomeration size was not the only factor to affect the NP sedimentation.

腐殖酸和牛血清蛋白对氧化物纳米颗粒团聚和沉降行为的影响

研究目的：比较牛血清蛋白和腐殖酸对Al2O3、SiO2和TiO2三种纳米颗粒团聚与沉降行为的影响，并讨论其影响机制。
创新要点：纳米颗粒团聚物直径的增大能引起其沉降速度的加快，但小的水动力学直径并不一定导致低的沉降速度，说明团聚直径不是决定纳米颗粒沉降的唯一因素。
研究方法：通过透射电镜观察纳米颗粒团聚物的形态；采用动态光散射技术研究纳米颗粒的团聚动力学；最后通过测量悬浊液的光学吸收来研究纳米颗粒的沉降动力学。
重要结论：牛血清蛋白处理降低了三种纳米颗粒在NaCl和CaCl2中的水动力学直径，原因是牛血清蛋白的球状结构能够引起颗粒间的空间位阻斥力。腐殖酸处理导致纳米颗粒的水动力学直径在NaCl中最小，而在CaCl2中最大（图4），原因是腐殖酸能通过钙的配位作用彼此连接，从而促进了纳米颗粒的团聚。牛血清蛋白减缓了纳米颗粒的沉降；然而腐殖酸在CaCl2中明显加大了纳米颗粒的沉降速度（图5），与其水动力学直径的增大一致。腐殖酸处理的纳米颗粒在NaCl中水动力学直径最小，但沉降速度却不是最低。
纳米颗粒；团聚；沉降；牛血清蛋白；腐殖酸

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