Study On Sedimentation Of Graphene Oxide In Offshore Water Environment

Graphene oxide(GO)has unique physical and chemical properties,so in many fields has a wide range of applications.With the wide application of GO,more and more scholars began to pay attention to its environmental behavior and its impact on the ecosystem.Water environment is the ultimate goal of GO into the environment.The co-precipitation behavior of GO in water environment significantly affects its environmental behavior and its impact on the ecosystem.Therefore,it is of great significance to study the co-precipitation behavior of GO for clarifying its ecological risk.In this thesis,GO was dispersed in different water bodies.The effects of salinity,dissolved organic matter(DOM)and GO size on the cohesive behavior of GO in water environment were studied.The experimental results show that the GO dispersion prepared by sonication in water bath has good dispersion stability in deionized water.However,with the prolongation of standing time,the pH value of the dispersion system decreased significantly,and GO produced a slow coagulation phenomenon.After 48 h,the remaining rate of GO in the supernatant was 30%of the initial concentration.When GO is dispersed in natural seawater with different salinities,the GO in the dispersed system is obviously aggregated.With the increase of the salinity,the coalescence rate of GO increased rapidly and the particle size of agglomeration increased obviously.When the salinity of water reached 8-10,the coalescence rate of GO solution tended to converge rapidly This process shows a two-stage process with the increase of salinity,according to the classical colloidal stability theory.From this,the critical aggregation salinity(CCC)of 2?100 mg/L GO solution was 6.79?11.84.Compared with natural seawater,GO dispersed in different salinities of artificial seawater showed similar sinking behavior to natural seawater,and there was no significant difference in coalescence rate.However,the CCC in artificial seawater is low,suggesting that the steric hindrance of DOM in natural seawater slows down the cohesive behavior of GO.Different sizes of GO were obtained by ultrasonic pulverization and dispersed in artificial saltwater with different salinities.The smaller the size of GO in the dispersion system,the faster the rate of CO coalescence and the more obvious flocculation in the process of coagulation.Thus,due to the large number of functional groups carried on the surface of GO,GO can be uniformly dispersed in fresh water with low ionic strength,which may cause a greater exposure to organisms in freshwater bodies.In a certain salinity of water,the smaller the size of GO,the more prone to condensation phenomenon may have potential exposure to benthic organisms in water.