Influence Of Natural Organic To Diffusion And Aggregation Of Carbon Nanotube In Aquatic Systems

With amount of production and use of Carbon nanotubes(CNTs),it has inevitably been discharging or leaking into the water environment.Existing research shows that because of the great affinity adsorption and adsorption capacity,CNTs easily become the carrier of persistent toxic pollutants in the environment,which can affect human health through drinking water and aquatic organisms.It is also able to produce toxicity to the microorganisms,aquatic organisms and human cells,which has negative environmental effects.Therefore,it is important to study the environmental behavior and the law of diffusion and aggregation of CNTs materials in the water.This project selects CNTs as the object and focuses on the analysis of the effects of electrolyte,natural organic and other factors on the condensation and diffusion of CNTs in the water,providing a theoretical basis for understanding the diffusion and migration of carbon nano material in water environment.The main results are as followed:(1)Electrolyte and natural organic also can induced the aggregation of CNTsand the process conforms to the classical DLVO theory.MWNTs(Multi-walled nanotubes)are more quickly and more increase on size;The greater the outside diameter of CNTs are,the lower critical coagulation concentration will be,and more easily the aggregation will occur.With the increase of outside diameter of carbon nanotube,the ?potential and particle size change more obviously.FA can inhibit the aggregation function of CNTs in wate.Inhibiting effect wuold be weakened with the increase of the nanotube diameter.HA can promote the aggregation function between CNTs and Ca2+ by complexing bridging function,which can lead to inhanced aggregation.(2)MWNTs adsorption of FA and HA both conform with the Langmuir adsorption isotherm model,which shows that surface adsorptions are closer to chemical monolayer adsorption process,and MWNTs have better adsorption effect of HA.The increase of ionic strength can promote the MWNTs adsorption of NOM.The promote of Ca2+ on the adsorption is more obvious than the promote of the Mg2+.(3)Under the action of electrostatic repulsion NOM can effectively dispersed into MWNTs particles in the water environment.The suspension quantity of MWNTs in NOM will increase with the increase of concentration of organic matter.HA has better disaggregation effect on MWNTs in lower concentration of organic matter,while FA has better disaggregation effect on MWNTs in higher concentration of organic matter.As the growth of standing time,there will be a small amount of precipitation and sedimentation from MWNTs dispersed in water.More obvious Inhibition effect of disaggregation is showed in higher the ionic strength.The increase of ionic strength can effectively inhibit the diffusion of MWNTs in the HA.(4)Disaggregation effect ofdosing MWNTs particles directly into natural water samples is worse than dosing MWNTs suspension.The hgiher concentration of MWNTs in SDS-MWNTs suspension,the better disaggregation effect of MWNTs in natural water samples.Compared with the blank water sample,|?| potential of natural water samples will rise when dosing MWNTs particles directly and reduce when dosing MWNTs suspension.Aggregation occurs more easily with higher MWNTs concentration in suspension dosing into natural water samples.