The Effect Of Natural Organic Matters On The Stability Of C₆₀Nanoparticles In Aquatic Systems

The mass production and use of C60 will inevitably lead to these materials be released to the water environment as a potential new pollutant,which have a significant impact on the ecological environment.The stability of C60 nanoparticles as the objective of this paper to be investigated under different types and molecular weight of natural organic matters and another type of carbon nanomaterials in water environment.Main research contents and results of this paper were as foliowes.(1)Aggregation kinetics of C60 nanoparticlesThe size of C60 nanoparticles in the stable suspension prepared by toluene solvent-exchange method was about 120nm.C60 nanoparticles had a high negative zeta potential and was stable in water.Adding electrolytes induced aggregation of C60 nanoparticles through acompressing electric double layer.The aggregation process of C60 nanoparticles exhibited slow and rapid regions.High counter-ions are in favor of promoting the aggregation of C60 nanoparticles.HA enhanced the stability of C60 in water due to steric repulsion.However,the complexing-bridging between humic acid molecule and Ca2+ caused enhanced aggregation.Changing the dosing sequence of HA and electrolytes affected the agglomeration process of C6o nanoparticles significantly.(2)The influence of NOM on the aggregation of C6o nanoparticles in waterThe aggregation process of C60 nanoparticles still exhibited slow and rapid regions in the presence of different organic matters.In the presence of HA and TA,C6o nanoparticles aggregated faster than in the presence of FA.The complexing-bridging among HA and FA and Ca2+ would cause enhanced aggregation.Ca2+ reached the rapid regions faster than Mg2+.FA enhanced the stability of C60 nanoparticles.Compared with Mgig,the decreasesu aggregation with NOM and Ca2+was weaker.In presence of larger molecular weight organic matters,C60 nanoparticles became more negative and more stable,while the smaller molecular weight organic matters had litter influence.Compared with C60 in water,dosing HA and FA strengthened the dispersion of C60 while TA weakened the dispersion.By their corresponding zeta potential can be seen that the dispersion mechanism had certain relevance with electrostatic interactions.The |?| is greater and the size of C60 is smaller.Under the static state,the size and potential of particles in water did not change over time.The larger molecular weight organic matters strengthened the dispersion of C6O nanoparticles,while the smaller molecular weight organic matters enhanced aggregation.The zeta potential and size of nanoparticles in suspension under the condition of original NOM and<100kDa did not change over time;while the size of nanoparticles under the condition of<10okDa,<1kDa decreased slightly,and the dispersion was strengthened.(3)Heteroaggregation between C60 and MWNTsThe heteroaggregation between C60 and MWNTs exhibited slow and rapid regions.In the slow region,adding C60 would lower the growth rate of particle size in mixture with the same concentration of Ca2+ and decreased the aggregation.With the concentration of C60 increased,the inhibition became more obvious.HA increased the aggregation rate of particles in water and caused enhanced aggregation.The enhanced aggregation became more obvious with the concentration of HA increased.For this phenomenon,there might be more complex interaction between HA,C60,MWNTs and CaCl2,such as adsorption bridging role.