Co-deposition Of Carbon Nanotubes With NZnO And Co-transport Of Carbon Nanotubes With Oxytetracyclinein In Water Soil Meidia

The wide use of nanomaterials in life and industry lead to the concentrations,species gradually increases in the environment,its environmental effect has been widely concerned.In recent years,we found that the nanomaterials often the coexistence in various nanomaterials with the growing variety of nanomaterials into the environment,and the coexistence of nanomaterials and will have a strong impact on other nanomaterials' and other organic contaminants's environmental behavior.At present,the study about co-deposition of various nanometer materials and co-transport of pollutants with nanomaterials in the environment is less,the mechanism about co-deposition and co-transport is not clear.Therefore,we studied the behavior and mechanism of co-deposition of oxidized-multiwalled carbon nanotubes(o-MWCNTs)with nano-ZnO(nZnO)in nature water first,and then,we studied the behavior and mechanisms about co-transport of o-MWCNTs and oxytetracycline(OTC)in saturated porous media under different solution pH and ionic strength conditions.The results of this study will help to master the carbon nanotube effects on deposition and transport behavior and mechanism of other coexisting nanomaterials and organic pollutants in environment,and to provide important theoretical basis about recognize and evaluate the environmental risks of carbon nanotubes accurately.The main research results are as follows:(1)The existence of natural colloid significantly inhibits the homoaggregation between nZnO-nZnO and enhances the suspension stability of nZnO in natural waters.In the membrane natural water(within natural colloid),the high concentration o-MWCNTs enhances the suspension stability of nZnO in the natural water body,while the low concentration o-MWCNTs promotes the nZnO subsidence,which may be attributed to the complex mechanism between nZnO,o-MWCNTs and natural colloidal,and the further research is needed.In the membrane natural water(without natural colloid),the addition of o-MWCNTs significantly enhances the suspension stability of nZnO in natural waters,and the higher the concentration of o-MWCNTs,the more obvious the effect of promoting the suspension stability of nZnO.This is consistent with the regularity of aggregation of particles,the aggregates size and aggregation rate decreased with the addition of o-MWCNTs.(2)In the test of three ionic strength(0.1mM,1.0mM and 10mM)and three pH(3.0,5.5 and 8.5)conditions,the existence of the OTC significantly increased the transport of o-MWCNTs in quartz sand column,so that o-MWCNTs' relocation rate increased by more than 20%.The promotion mechanism of OTC to o-MWCNTs in quartz sand:on the on hand,the OTC in o-MWCNTs and quartz sand surface adsorption will reduce o-MWCNTs and quartz sand surface hydrophobic,reduce the o-MWCNTs on the surface of quartz sand adsorption deposition;on the other hand,OTC will compete with o-MWCNTs quartz sand surface adsorption sites.(3)The influence of o-MWCNTs on the transport behavior of OTC in quartz sand column is related to pH of electrolyte solution,under the conditions of three kinds of ionic strength(0.1mM,1.0mM and 10mM)and three pH(3.0,5.5 and 8.5).At pH of 5.5,neutral zwitterions is the dominate species,compared with the OTC individual transport,the coexistence of o-MWCNTs and OTC promotes the transport of OTC in quartz sand column.This is because the existence of o-MWCNTs can compete OTC in quartz sand column adsorption position point at this time,thus promotes the OTC transport.At pH of 3.0 and 8.5,positive and negative zwitterions is the dominate species,there is no significant difference in the transport of OTC in the coexistence of o-MWCNTs and OTC.The experiment of changing the sequence of leaching shows that o-MWCNTs is difficult to compete with the adsorption sites of the surface of quartz sands at this time.