A Research On The Co-transport Of Iron,Manganese Ions And Graphene Oxide In Porous Media

Graphene oxide(GO),as a new type of carbon nanomaterials,is widely used in medical,chemical and other fields.GO entering water or soil environment may cause unknown environmental risks.Iron(Fe)and manganese(Mn)are common metal trace elements in groundwater and soil environment.When Fe,Mn and GO exist in water at the same time,their migration and transformation in porous media are likely to have interactive effects.Therefore,it is necessary to study the synchronous migration and interaction mechanism of the above complex pollutants in porous media.In this paper,natural quartz sand was used as porous media,and a porous media filtration system was established.GO was prepared by improved Hummer's method.The co-migration of Fe,Mn ions and GO in porous media was studied.By fitting and analyzing the concentration of pollutant effluent,the changing rules of the penetration curves of Fe,Mn and GO in porous media were obtained.By testing the effluent quality of sand column with different height,the migration rates of Fe,Mn and GO in porous media under different conditions were obtained.By analysing SEM,FTIR and XPS images of the filter material,the morphological changes of Fe and Mn was informed,and the changes of GO surface functional groups was illustrated,and the influence mechanism of these changes on the migration of pollutants in quartz sand column was inferred.The main research results are as follows:(1)Under the condition of being alone,GO was difficult to be intercepted in the sand column,showing strong migration ability.When Fe,Mn and GO coexist,the intercept capacity of quartz sand column for Fe,Mn and GO was improved to different extents when the above pollutants were present alone.Fe(III)/Fe(II)in water could significantly enhance the interception effect of quartz sand column on GO,and the effect of Fe(II)was more obvious.While Mn had little effect on the migration of GO in quartz sand column.(2)Under the Fe&Mn&GO combined pollution condition,by comparing the breakthrough curves of different Fe forms,the formation of floc size and the solution zeta potential,the process of transforming Fe(II)into Fe(III)could promote the interception efficiency of quartz sand column on GO,Fe,Mn.(3)The interception effect of quartz sand column on GO,Fe and Mn was affected by the change of solution pH.Under the condition of GO&Fe(III)& Mn(II)condition,the quartz sand column had the best GO interception effect at pH=6.0.Under the condition of GO&Fe(II)&Mn(II)condition,the effect of solution pH change on the ability of quartz sand column to intercept GO was not obvious.(4)The results of SEM,FTIR,XPS and other characterizations showed that the presence of GO could enhance the oxidation of Fe(II)and Mn(II)in the filtration system by means of electron transfer,promote the growth of flocs,and strengthen the combination of GO and Mn oxides and Fe oxides.The combination allowed the contaminants to be more easily intercepted in the quartz sand column.