摘要
研究目的:腐殖酸(HA)对富勒烯(C60)粉末的悬浮作用以及pH、离子强度对HA-C60悬浮性能的影响。创新要点:研究水质条件对C60悬浮性能的影响。研究方法:测定C60粉末在HA溶液中的zeta电位,水力学粒径和悬浮浓度;HA存在下,C60悬浮体系的zeta电位与水力学粒径随pH的变化及C60悬浮体系团聚动力学随离子强度的变化。重要结论:HA对C60粉末起到一定的分散作用,但不能使其长时间稳定悬浮于水中。当pH<4时,C60水悬液开始沉淀;而当HA存在时,C60水悬液在pH 3–11范围内都保持稳定,这是由于HA吸附于C60表面,通过静电排斥和空间位阻作用,促进C60分散悬浮。C60水悬液的稳定性随盐离子价位和浓度升高而降低。HA会抑制Na+对C60水悬液的脱稳作用;但高价离子Ca2+和La3+存在时,HA与C60之间会发生桥联从而促进C60水悬液脱稳沉淀。
Natural organic matter （NOM） has a profound effect on the colloidal stability of discharged C60 nanoparticles in the water environment, which influences the environmental behaviors and risks of C60 and therefore merits more specific studies. This study investigates the effects of humic acid （HA）, as a model NOM, on the aqueous stabilization of C60 powder and the colloidal stability of a previously suspended C60 suspension （aqu/nC60） with variations of pH values and ionic strengths. Our results reveal that HA could disperse C60 powder in water to some degree, but was unable to stably suspend them. The aqu/nC60 could remain stable at pH〉4 but was destabilized at lower pH values. However, the colloidal stability of aqu/nC60 in the presence of HA was insensitive to pH 3-11, owing to the adsorption of HA onto nC60 and the increased electrosteric repulsions among nC60 aggregates. The colloidal stability of aqu/nC60, with and without HA, decreased as we increased the valence and concentration of the added cations. HA was found to mitigate the destabilization effect of Na＋on the colloidal stability of aqu/nC60 by increasing the critical coagulation concentration （CCC） of Na＋, while HA lowered the CCCs of Ca2＋and La3＋probably by the bridging effect of nC60 with HA aggregates formed through the intermolecular bridging of the HA macromolecules via cation complexation at high concentrations of cations with high valences.
基金
Project supported by the National Natural Science Foundation of China(No.21337004)
the National Basic Research Program(973)of China(No.2014CB441104)
the Zhejiang Provincial Natural Science Foundation of China(No.LR12B07001)
the Specialized Research Fund for the Doctoral Program of Higher Education(SRFDP)(No.20130101110132)
the Fujian Provincial Natural Science Foundation of China(No.2014J01053)
the Fundamental Research Funds for the Central Universities(No.2014FZA6009),China
关键词
富勒烯
腐殖酸
胶体稳定性
天然有机质
纳米材料
Fullerene, Hurnic acid, Colloidal stability, Natural organic matter, Nanomaterial
