The Preparation Of Graphene Aerogels And Its Adsorption Of Tetrabromobisphenol A

Graphene was widely used as an adsorbent in water for organic pollutants adsorption removal because of its high specific surface area,excellent mechanical strength.Due to the strong ?-? stacking and van der Waals force between the two-dimensional graphene sheets,graphene was easy agglomerated in the aqueous solution,reduc tion its own specific surface area,limited the adsorption properties of graphene.In addition,graphene adsorbent as a nano-materials existence of practical problems in the separation of difficult problems.Three-dimensional graphene aerogels were macromolecules of nanometer graphene,which effectively solved their problem of agglomeration and effective separation in aqueous solution,and had good mechanical properties,fine uniform pore structure and large specific surface area,was one of the hot spots of adsorbent research.In this study,the graphene aero gels S-RGA were prepared by self-assembly of NaHSO3 chemical reduction GO,greatly improved the problem of graphene agglomeration and separation,and S-RGA had a uniform three-dimensional network pore structure which nano-graphene sheets didn't possess.These fine uniform pores not only ensured a sufficiently large specific surface area but also provided a large amount of adsorption sites for adsorbing contaminants in water,while reduced the spatial steric hindrance of pollutants from the surface into the internal channels of the adsorbent,provided more convenient conditions for adsorption.A large flaky graphene aerogels C-RGA were prepared by self-assembly of steam heat from NaHCO3 as bubble additive.graphene aerogels RGA were prepared by hydrothermal reduction of GO at 180?.The prepared samples were characterized by SEM,XPS,BET,XRD and so on.The adsorption experiment of MO was investigated.The results of SEM analysis showd that the C-RGA prepared by NaHCO3 was a huge lamellar structure.the thickness of the sheet increases as the reaction temperature increases,the higher the reaction temperature,the more serious the stacking between the layers.However S-RGA and RGA have a 3D network pore structure,S-RGA had a more uniform and fine pore structure with pore size distribution between several hundred nanometers and several microns.The specific surface area of S-RGA was 98.37 m2/g and the pore volume was 0.34 cm3/g.The adsorption experiments of MO with different graphene aerogels showed that the adsorption capacity of C-RGA was poor and the S-RGA adsorption efficiency was the best.The adsorption experiments of S-RGA on TBBPA in water show that at the initial concentration of TBBPA of 0.25 mg/L,the adsorption capacity of S-RGA to TBBPA increased first and then decreased with the amount of adsorbent,when the concentration of S-RGA was 15 mg / L,the adsorption capacity was the largest.At pH> 7,the TBBPA was gradually ionized into a negatively charged ion state,while the surface charge of S-RGA was negative,so the adsorption capacity decreased with the increase of p H under the action of electrostatic repulsion.In the range of(0.25-1 mg/L)of TBBPA,the adsorption capacity of S-RGA increases with the initial concentration.And the adsorption kinetics at different concentrations were consistent with pseudo-second-order kinetics and intra-particle diffusion model.The adsorption isotherm model showed that the adsorption process was in accordance with Langmuir adsorption isotherm model,and its maximum Langmuir adsorption capacity was 128.37 mg/g.The adsorption capacity of S-RGA decreases with the increase of temperature,Adsorption thermodynamic model analysis showd that the adsorption process was spontaneous and exothermic.In addition,the S-RGA was found to have only a slight loss of adsorption capacity after five cycles,and still had 93.17% of the initial adsorption capacity.S-RGA surface and the interior were made of graphene sheet,had a very rich ? electron field,TBBPA benzene ring structure can also provide ? electrons.Therefore,S-RGA can effectively provide the adsorption site for TBBPA by ?-? interaction,a good pore size can cause TBBPA to enter the interior from the outside and increase its adsorption capacity.Through the EDS mapping element distribution analysis,in the S-RGA internal filled with Br elements,proving that TBBPA was successfully inhaled into its interior.The adsorbed S-RGA was characterized by FTIR,it can be deduced that the main adsorption mechanism was the ?-? interaction between S-RGA and TBBPA.