典型碳纳米材料在水中的凝聚特性比较

The comparison of aggregation characteristics of typical carbon nanomaterials in aqueous systems

以富勒烯(C_(60))和多壁碳纳米管(MWNTs)纳米颗粒悬浮液为对象,采用动态光散射技术对比研究了电解质、有机物等环境因素对其在水中凝聚和稳定性的影响.结果表明,电解质存在下,可通过压缩双电层作用使水中碳纳米材料发生凝聚反应,凝聚过程均符合经典的胶体稳定性(DLVO)理论;MWNTs较C_(60)稳定性弱、更易凝聚;两种纳米颗粒悬浮液对应的Na^+、Mg^(2+)和Ca^(2+)的临界凝聚浓度均远高于其在天然水体中的含量.Na^+和Mg^(2+)凝聚体系中,腐殖酸(HA)可通过空间位阻作用抑制凝聚发生,且对C_(60)的抑制作用更强.HA可与Ca^(2+)发生络合,强化纳米颗粒凝聚反应,并对MWNTs具有更强的强化凝聚作用.不同碳纳米材料和环境因子存在着不同的相互作用关系,将影响其在水中的稳定性.

The aggregation and stability of fullerene（C_（60）） and multi-walled carbon nanotubes（MWNTs） nanoparticle suspensions in aqueous systems were investigated using time-resolved dynamic light scattering,in presence of several electrolytes and natural organic matters.Electrolytes induced carbon nanomaterials aggregation by the mechanism of compressing the double electrode layer,which conformed to the classic colloidal stability theory（Derjaguin-LandauVerwey-Overbeek,DLVO）.In comparison to C_（60）,MWNTs were easier to aggregate and showed weaker stability because of their morphology.In Na~＋ and Mg^（2＋） solutions,humic acid（HA） could restrain the aggregation of nanoparticles by steric repulsion effect,which was more significant for C_（60）.HA could enhanced the aggregation of nanoparticles by complexing with Ca^（2＋）,and this effect was more pronounced on MWNTs.The results of this study elucidated different carbon nanomaterials had various interaction relationship with environmental factors,which would influence their stabilities in water.