Preparation Of Three-dimensional Graphene And Its Adsorptive Property

With the rapid development of the dye industry, a large number of dye wastewater discharge to the water environment, brought serious threat to human life and health.Adsorption method for low-cost, high efficiency etc. advantages get more and more attention.Graphene with great theoretical specific surface area, have been widely applied in the adsorption, however, graphene has a problem in proning to reunite, improve the adsorption performance of graphene get more and more attention from researchers. In this paper,graphene as the research target, prepared three-dimensional structure of graphene(r GO) and layered double hydroxides/graphene(LDH/r GO) by hydrothermal reduction and freeze drying method, without light conditions, the adsorption reaction of dye solution in order to investigate the adsorption performance, the main points as the following:(1) Graphene oxide(GO) dispersion was prepared by a modified Hummers’ method.The study involves preparing r GO used GO as a precursor and prepared by hydrothermal reduction and freeze drying method. The structural and properties of three-dimensional graphene were characterized by X ray diffraction(XRD), Fourier infrared spectrometer(FT-IR), Scanning electron microscopy(SEM), Energy dispersive spectrum(EDS), BET surface area measurement(BET) showed that the prepared r GO has a three-dimensional porous structure. The adsorptive property was evaluated with rhodamine B(Rh B) as the model substance, the influence of contact time, mass of adsorbent, p H were tested;experimental results show that maximum adsorption quantity and removal rate of Rh B reached 16.55 mg/g and 82.75% under the conditions of adsorbent dosage was 0.5 g/L, Rh B concentration was 10 mg/L and the p H value was 4, adsorption reaction reached adsorption equilibrium at 300 minutes. The adsorption can be described by a pseudo-second-order rate equation and Langmuir adsorption isotherm. We compared adsorptive property of graphite and r GO, the removal rate were 16.17% and 82.75%, r GO has better adsorption effect, and is more suitable for adsorption of pollutants in aqueous solution.(2) Layered double hydroxides(LDH) was prepared by coprecipitation method,layereddouble hydroxides/graphene(LDH/r GO) prepared by hydrothermal reduction and freeze drying methods. The structural and properties of LDH/r GO were characterized by XRD,FT-IR, SEM, EDS, BET showed that the prepared LDH/r GO has a three-dimensional porous structure. The adsorptive property was evaluated with cationic dye Rh B and anionic dye reactive brilliant blue(KN-R) as the model substance, the influence of conditions for Rh B and KN-R adsorption, including different mass ratio, time, p H of aqueous solution, adsorbent dose were investigated. Experimental results show that mass ratio of LDH/r GO is 3(LDH/r GO-2)has best adsorption effect for Rh B and KN-R; optimum adsorption conditions of LDH/r GO-2adsorbed Rh B included that Rh B concentration was 10 mg/L, adsorbent dosage was 0.5 g/L and p H of solution value was 6; optimum adsorption conditions of LDH/r GO-2 adsorbed KN-R included that KN-R concentration was 30 mg/L, adsorbent dosage was 0.5 g/L, p H of solution value was 7 and temperature was 20 ℃. Adsorption reaction of Rh B and KN-R reached adsorption equilibrium at 210 minutes, and maximum adsorption quantity were 19.80mg/g and 56.73 mg/g, removal rate were 99% and 94.56%. The adsorption of Rh B and KN-R can be described by a pseudo-second-order rate equation and Langmuir adsorption isotherm.Adsorptive property of LDH/r GO-2 better than r GO, the combination of LDH and r GO was beneficial to improve the adsorption performance r GO. We have know that LDH/r GO-2 has efficient, fast, and convenient adsorption effect, reaction conditions are easy, has better adsorption effect on cationic dye(Rh B) and anionic dye(KN-R).