Abstract: 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.

腐殖酸对富勒烯C60的悬浮作用

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pH3-11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。
富勒烯；腐殖酸；胶体稳定性；天然有机质；纳米材料

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