Study Of The Synthesis Of Graphene-based Composite Materials And The Removal Performance For Water Contaminants

Environmental crisis is a major problem faced by today’s society.The vigorous development of urbanization and industrialization process lead to a large number of organic compounds and metal pollutants being dumped into the water environment,resulting in increasingly serious water pollution.Because these pollutants are bioaccumulative and non degradable,they seriously affect the balance of ecosystem and human health and safety.The key pollutants include organic and inorganic substances.Among them,organic pollutants include some representative substances,such as toxic dye rhodamine B and antibiotic tetracycline,which have strong biological toxicity and harm,causing major diseases in human body.In addition,inorganic pollutants mainly refer to toxic metals,which often exist in the water environment in the form of ions,such as lead ions and arsenic ions.They are representative substances of heavy metals and metalloids in recent years,which also cause toxicological effects on human body at low concentrations,thus becoming a persistent threat to human beings and the earth’s ecosystem,Therefore,metal ions can also be selected as the target pollutant.Water treatment technologies such as catalysis and adsorption are often used to remove key pollutants in water,which is a research hotspot in recent years.The key to the breakthrough lies in the synthesis and application of new materials,so as to solve the problem of environmental pollution and promote the healthy development of industry.Among them,graphene and its composites,as effective catalytic carriers and adsorption materials,show significant effects in water treatment,but there are some problems in practical application,such as limited reaction activity and difficult separation.Therefore,the research use bismuth oxide and clay mineral to modify graphene to form composite materials with enhanced photocatalytic activity and adsorption performance.In the research,three relatively new graphene based composites were prepared,and comprehensive characterization analysis and catalytic degradation（adsorption）performance of pollutants in water environment were carried out,which strengthened the understanding of catalytic mechanism and expanded the research scope of our research group.Main research results are as follows:（1）Silver oxide/bismuth tungstate heterostructure incorporated reduced graphene oxide（ABW-RGO）was synthesized by hydrothermal reduction method.XRD,XPS,FE-SEM,HR-TEM and UV-DRS were used to explore the structural and morphological characteristics of the composite,and the effect of different contents on the photocatalytic degradation of tetracycline was studied.The results showed that the TC degradation efficiency was over 95.3%in 40min,and the rate constant was 0.096 min^-1.ABW-RGO had high removal efficiency to many kinds of organic pollutants.In addition,XRD and XPS analysis confirmed the formation and stability of Z-scheme structure,which can be reused.After degradation,the total organic carbon removal rate was 48.6%,and the mineralization degree was high and there was basically no intermediate residue.The composite photocatalyst has a great application prospect in the treatment of organic pollutants and environmental remediation under complex conditions.（2）The magnetic nanoparticles were loaded on the surface of graphene oxide by chemical precipitation method and combined with bismuth tungstate to prepare functional magnetic composite（BWO-MGO）.The composite was characterized by XPS,TEM,FT-IR,PL and VSM,and applied for visible-light photocatalytic degradation of dye pollutant（Rhodamine B）.The degradation performance of prepared samples was evaluated under different catalyst dosage,pollutant concentration and p H value.Under visible light irradiation,the degradation rate of RB dye reached 98.5%in 40 min,which was almost completely degraded.Moreover,the key roles of superoxide and hydroxyl radicals in heterojunction were confirmed by ESR analysis and active species capture.The spent catalyst can be separated and recovered rapidly,which showed good recycling performance and optical stability.The results confirmed that BWO-MGO has excellent photocatalytic properties that can be applied to the industrial degradation of organic pollutants.（3）Graphene oxide-supported organic montmorillonite composite（GO-OM） were prepared by ultrasonic assisted method.The composite material was characterized by FT-IR,FE-SEM,XPS,TGA and N₂-BET techniques,and its adsorption for heavy metal and metalloid pollutants（lead and arsenic）in aqueous solution were investigated.In the binary system,the adsorption capacity of GO-OM for Pb（II）and As（V）were 183.93 mg/g and 104.17 mg/g respectively.The treatment process was conformed to Langmuir isothermal model and pseudo-second-order kinetic model,and the reaction was also spontaneous and endothermic.The adsorption mechanism is mainly electrostatic attraction and complexation,and the functional groups on the surface have synergistic effect with the interlayer active ions.The composite sorbent has revealed good performance on a variety of heavy metal ions,which is expected to be widely used in wastewater treatment of the actual production.Several photocatalytic and adsorptive functional materials were synthesized in this study,which have advantages of high efficiency,simple operation and cost saving.These composites are suitable for the treatment of a variety of target pollutants,and provide valuable reference for industrial production process.