水中C60纳米颗粒的稳定性研究

以两种C60纳米颗粒悬浮液为对象,研究贮存时间、pH、电解质和有机物等因素对其稳定性的影响.结果表明,溶剂替换法制备的C60纳米颗粒(C60/son)稳定性优于延时搅拌法(C60/aq),可长时间保持稳定;pH升高可使C60纳米颗粒稳定性增强;电解质投加可使C60纳米颗粒的|ζ|减小、粒径增大,促进凝聚的发生;水中C60纳米颗粒凝聚过程可分为慢速凝聚和快速凝聚两个阶段,符合经典胶体稳定性(DLVO)理论.C60/son的临界凝聚浓度:NaCl 321 mmol·L-1、KCl 316 mmol·L-1、MgCl29.6 mmol·L-1和CaCl26.7 mmol·L-1,C60/aq的临界凝聚浓度:NaCl 295 mmol·L-1、KCl 278 mmol·L-1、MgCl27.8 mmol·L-1和CaCl25.9 mmol·L-1,均远高于其在天然水体中的浓度;腐殖酸存在可通过空间位阻效应显著增强水中C60纳米颗粒的稳定性,这表明C60纳米颗粒可稳定存在于典型的水环境中.

Stability of C60 Nanoparticles in Aquatic Systems

The influences of storage time, pH, electrolytes and organic matters on the stability of two different suspensions of C₆₀ nanoparticles were investigated. The results showed that the C₆₀ nanoparticles prepared by solvent substitution (C₆₀/son) were more stable than that prepared by prolonged stirring (C₆₀/aq), and kept stable for a period of time. Higher pH enhanced the stability of C₆₀ nanoparticles. The presence of electrolyte made a dramatic decrease in the surface zeta potential and an increase in the particle size. The aggregation process of C₆₀ nanoparticles exhibited slow and rapid regions, which was found to be consistent with the classic Derjaguin-Landau-Verwey-Overbeek (DLVO) theory of colloidal stability. The critical coagulation concentration (CCC) values of C₆₀/son, obtained from the intersection of the interpolated lines through the slow and fast regions, were estimated as 321 mmol·L^-1 NaCl, 316 mmol·L^-1 KCl, 9.6 mmol·L^-1 MgCl₂ and 6.7 mmol·L^-1 CaCl₂. The CCC values of C₆₀/aq were estimated as 295 mmol·L^-1 NaCl, 278 mmol·L^-1 KCl, 7.8 mmol·L^-1MgCl₂ and 5.9 mmol·L^-1CaCl₂, which were much higher than their concentrations in natural waters. The presence of humic acid enhanced the stability of C₆₀ nanoparticles, which was attributable to steric repulsion. Therefore, C₆₀ nanoparticles will keep relatively stable in typical aquatic environments.