Study On Removal Of Pollutants In Water By Sulfide-modifed Nanoscale Zero-valent Iron/graphene Aerogel Composite

With the development of industrialization,the pollution of water bodies is becoming more and more serious,and the repair technology of polluted water bodies is also receiving more and more attention.Among them,organic pollutants can hardly be degraded by traditional water treatment methods due to their persistence,refractory degradation,and strong carcinogenic and teratogenic properties.Therefore,the treatment of organic pollutants has always been a difficult problem in the field of water treatment.Since the advent of nanometer zero-valent iron?nZVI?,its extremely strong activity and universality for the treatment of pollutants,especially for chlorine-containing organic hydrocarbons,have a strong ability to dechlorinate organic pollutants,which can degrade organic pollutants into low toxicity.Metabolites of small molecules,at the same time,it also has a catalytic degradation effect on dye wastewater,mineralizing dye wastewater into carbon dioxide and water,which has caused widespread concern.However,nZVI has the problems of easy oxidation,easy agglomeration,and poor reactivity.Therefore,nZVI needs to be modified to enhance its stability and dispersion.In this paper,the liquid phase reduction method is used to sulfide nZVI,and the sulfide-modified nZVI is loaded on a three-dimensional graphene sheet with high electron transfer efficiency and easy recovery?S-nZVI/GA?.A series of characterization methods were used to analyze the structure and performance of the composite materials;S-nZVI/GA and simulated wastewater containing trichloroethylene?TCE?,Rhodamine B?RhB?reaction batch experiments to study S-nZVI/GA reactivity.The main conclusions reached are as follows:?1?SEM and TEM characterization results show that S-nZVI has a clear core-shell structure,which is clustered together in a chain shape.After being loaded on GA,S-nZVI nanoparticles are evenly dispersed in the sheet structure of GA.The BET test shows that the specific surface area of S-nZVI/GA is about 14 times that of S-nZVI.Through the results of electrochemical tests,it can be concluded that S-nZVI/GA has the smallest impedance and the best electron transmission efficiency.?2?S-nZVI/GA has a good removal effect on TCE in simulated wastewater.S-nZVI/GA can remove 95%of TCE in 50 minutes,and pure S-nZVI is only 75%in120 minutes.And as the initial pH and temperature of the solution increase,the TCE removal rate also gradually increases.According to the kinetic simulation,it is concluded that the removal of TCE by S-nZVI/GA conforms to the quasi-first-order kinetic model.?3?S-nZVI/GA not only has a good removal effect on TCE,but also has a good catalytic degradation effect on RhB pollutants in simulated wastewater by activating persulfate?PS?.S-nZVI/GA can remove 99%of RhB in 10 minutes.And as the initial pH value of the solution increases,the degradation efficiency of RhB gradually decreases;co-existing ions can inhibit the degradation of RhB;through the cycle experiment,we can know that S-nZVI/GA has good recycling performance,free radical capture The experiment can conclude that the main free radical responsible for the degradation of RhB is SO₄·^-.In summary,the S-nZVI/GA synthesized in this paper has the advantages of high reactivity,good recycling performance,and easy recovery.It provides a new idea for removing organic pollutants in water.