Preparation Of Magnetic Ggraphene Foam Composites And Its Application In Adsorption

The design and synthesis of new magnetic materials have important scientific significance and application value in the direction of sewage treatment and environmental remediation.This article is based on the magnetic controllability and magnetic separation stability of magnetic nanoparticles,as well as the unique structure,excellent performance?high porosity,large surface area,good stability,etc.?and low cost of three-dimensional graphene foam.The magnetic nanoparticles and the graphene foam are composited to obtain a composite material which is both magnetically responsive and has a unique porosity of the graphene foam.The magnetic graphene foam was characterized by XRD,FESEM,TEM,BET,etc.The magnetic graphene foam?MGF?materials were applied to the adsorption of two organic pollutants,phenols and dyes.The experimental data show that the composite material has good adsorption of phenols and dyes in the water system and can be recycled.The results are summarized as follows:1.MGF composites were prepared by one-pot reduction and the prepared MGF composites were characterized by SEM,TEM,TG,FT-TR and XRD.MGF composites were used as adsorbent for methylene blue.The results as follws:Fe₃O₄ is a spherical structure composed of irregular polyhedral particles and the particle size was in the range of 150 nm²00 nm.Fe₃O₄ is successfully compounded on graphene and relatively uniformly dispersed on the inner and outer surfaces of graphene.MGF has good thermal stability.MGF can achieve solid-liquid separation under external magnetic field.The adsorption capacity of the synthesized MGF for MB was determined and the results are listed as follows:MGF has good adsorption properties to MB,and the calculated maximum monolayer adsorption capacity is 194.5 mg/g when the MB concentration was 200 mg/L,the magnetic adsorbent concentration was1 g/L and the temperature was 303 K.The size of pH has a great influence on the adsorption of MGF,and the adsorption performance is best under near-neutral and alkaline conditions.MGF composites show a good recyclability and the removal rate is still 67.6%after 4 cycles.This shows that the structure of MGF composites is relatively stable and has potential commercial value in wastewater treatment.2.Using ammonia as a reducing agent,a solid Fe₃O₄/graphene foam?S-Fe₃O₄/GF?composite was synthesized by a simple hydrothermal method.The structures and properties of S-Fe₃O₄/GF were characterized by FESEM,TEM,TG,BET and VSM.The adsorption properties of S-Fe₃O₄/GF materials for five different anionic and cationic dyes were studied.The results are as follows:that graphene is a three-dimensional foam structure;Fe₃O₄ is a standard spherical structure and the particle size distribution is 460 nm⁶60 nm.The process of reducing S-Fe₃O₄/GF by GO reduction does not change the spinel structure of magnetic particles.The graphene layer is lighter and thinner,and many meshes are distributed,increasing the surface area of the material.The saturation magnetization of the S-Fe₃O₄/GF is 32.9emu/g and its specific surface area is 157 m²/g.The adsorption of the S-Fe₃O₄/GF for dyes showed that S-Fe₃O₄/GF has no specific selective adsorbability for dyes and the adsorption capacity of S-Fe₃O₄/GF for five dyes was in the order of CR>MG>MO>RB>CV.Based on the surface potentials and adsorption results,it can be inferred that in addition to the electrostatic interaction between dye molecules and magnetic particles,?-?conjugates also play a large role,namely the adsorption capacity is related to the structure of the dye molecule itself and the interaction between the composite material and the dye molecules.3.Using SiO₂ as a template,SiO₂/Fe₃O₄/C microspheres were successfully prepared by solvothermal method.Hollow Fe₃O₄/C/graphene foam was prepared by alkali etching and hydrothermal reduction with GO.Hollow Fe₃O₄/C/graphene foam?H-Fe₃O₄/C/GF?composites were characterized by TEM,FESEM,XRD,BET,etc.,H-Fe₃O₄/C/GF were used as an adsorbent for the bisphenol A?BPA?,benzenediol,2-nitro-1,3-benzenediol?NRC?.The results are as follows:The composite is obviously a three-dimensional porous material.The Fe₃O₄/C microspheres were regular spherical structures and its inner hole diameter is about 300 nm.Hollow Fe₃O₄/C microspheres are uniformly dispersed on the surface of graphene.Some of Fe₃O₄/C particles are distributed on the outer surface of graphene,and some of them are wrapped between graphene sheets,effectively preventing the reduction of the graphene oxide process.H-Fe₃O₄/C/GF has good thermal stability;the specific surface area of H-Fe₃O₄/C/GF is 201 m²/g.Adsorption results of composites show that H-Fe₃O₄/C/GF exhibits excellent adsorptivity for BPA,NRC,and dihydroxybenzene?inter-and adjacent?.The NRC has the fastest adsorption equilibrium and the strongest adsorption capacity,the adsorption capacity of catechol is greater than that of resorcinol and pH has great difference in the adsorption of two kinds of catechol,it is speculated that the chemical properties and molecular structure of the adsorbate have a great influence on the adsorption capacity.Low temperature is beneficial to the adsorption of BPA,and the other three phenols are the opposite.The synthesis of H-Fe₃O₄/C/GF solves the problem of difficulty in solid-liquid separation after adsorption,and also lays a foundation for the application of H-Fe₃O₄/C/GF in the treatment of wastewater containing phenols.