Study On The Modified Reduction Of Graphene Oxide And The Adsorption Properties Of Its Composite Materials

Nowadays,the rapid development of industry has caused the ecological environment of the earth to be seriously damaged,and the problem of water pollution is particularly prominent.Water is the lifeblood of all things on earth.It moisturizes everything and feeds life.The purification of wastewater has become a hot spot in current research.There are many purification methods for dye industrial wastewater,including electrochemical flocculation,chemical oxidation,biological,ion exchange,photocatalytic degradation,adsorption and membrane filtration.Among these methods,the adsorption method is widely used because of its simple operation and low cost.Graphene oxide is a new type of carbon nanomaterial with unique physical and chemical properties,and its application in environmental protection is also endless.In order to better explore its application value as an adsorbent,in this paper,the graphene oxide was modified,reduced and composited separately,and reduced graphene oxide(Na-RGO)and Graphene oxide composite material(CAGO-4)were prepared.Their removal ability of methylene blue was also studied.Graphene oxide was prepared by the modified Hummers method.Scanning electron microscopy showed that the surface of the graphene was undulating.The infrared spectrum showed that it contained abundant oxygen-containing functional groups,and its thermal stability was analyzed by thermal weight loss.Then,the graphene oxide is modified with acid and alkali,and the reduced graphene oxide is prepared by hydrothermal method,and the sample is prepared by freeze-drying method,and S-RGO and Na-RGO are selected as the modified representative and the reduced graphene oxide according to the sample quality.A series of comparative analyses were conducted.Through a series of adsorption experiments,it was found that Na-RGO prepared by NaOH modification has better adsorption performance and high adsorption efficiency.The adsorption experimental data was fitted by a kinetic model.The Langmuir model is suitable for adsorption isotherm studies and the calculated maximum adsorption capacity can reach 740.74 mg/g.Thermodynamic studies show that the adsorption of methylene blue by Na-RGO is a spontaneous endothermic process.An easy-to-separate CAGO-4 composite was prepared by cross-linking cellulose acetate with graphene oxide by vacuum freeze-drying method.Under the condition of 323 K,the maximum adsorption amount of methylene blue on CAGO-4 composite was calculated by Langmuir model to be 374.53 mg/g,and the kinetic data was in good agreement with the quasi-second-order kinetic equation.Thermodynamic analysis shows that the adsorption process is an endothermic process.In addition,the CAGO-4 composite can be easily recycled after being washed with HCl solution,and its adsorption capacity can still reach 71% after repeated use three times.