厦大英文报告

1、1,Reporter: Chen Yuehao Major: Environmental Engineering Research supervisor: Ouyang Tong,Fabrication of novel magnetic chitosan grafted with graphene oxide to enhance adsorption properties for methyl blue,2,Contents,Introduction,Materials and Methods,Results and Discussion,Conclusions,3,First Part,

2、4,Methyl Blue （1/4）,Dye Wastewater,Methyl Blue,5,Chitosan（2/5）,Chitosan,Chitosan is a linear polysaccharide, which is made by deacetylation of chitin. And it has a number of commercial and possible biomedical applications due to its biodegradability, biocompatibility and renewability.,6,Magnetic Chi

3、tosan（3/5）,It is difcult to be separated and recovered except by high speed centrifugation and lter.,powdery chitosan,Magnetic Chitosan (MC): attaches chitosan to the surface of magnetic particles.,7,Graphene oxide（4/5）,Graphene oxide has the advantages of large theoretical surface area, high mechan

4、ical strength, rich functional groups, non-toxic and inexpensive.,graphene oxide,8,Experimental objectives（5/5）,（1）Explore and prepare magnetic chitosan-graphene oxide (MCGO) composite bio-adsorbent with higher adsorption capacity and excellent separation properties. （2）Methyl blue (MB) with large a

5、nd complicated structures was selected as model pollutant to evaluated the adsorption characteristics of MCGO under laboratory conditions.,9,Second Part,10,Preparation of MC and MCGO（1/3）,FeCl24H2O and FeCl36H2O are used to make magnetic particles.,Add magnetic particles and glutaraldehyde to chitos

6、an acetic acid solution.,Wash the precipitate until pH was about 7, and dry it.,Use the modied Hummers method to prepare GO, and activate the carboxyl groups of GO,MC,Add 0.1 g MC to the activated GO solution. After ultrasonic dispersion for 10 min, the mixed solution was stirred for 2 h.,MCGO,Wash

7、the precipitate until pH was about 7, and dry it,11,Adsorption experiments（2/3）,（1）All batch adsorption experiments were performed on a SHA-C shaker with a shaker speed of 150 rpm until the system reached equilibrium.,（2）Typically, a 25 mL solution of known MB concentration and 0.015 g of MCGO were

8、added into 100 mL glass asks and then shook under 30 0.2.,（3）At the completion of preset time intervals, the bio-adsorbents were collected by the aid of a magnet.,12,Adsorption experiments（3/3）,Residual MB concentration in supernatant was measured by using a spectrophotometer. The Absorbance is maxM

9、B = 610 nm.,Q: adsorption quantity; E: adsorption rate; C0: the initial concentration; Ce: the equilibrium concentration; V: the volume of MB solution, in liters; W:the weight of the MCGO used, in grams.,13,Third Part,14,SEM（1/10）,Fig. 1. SEM images of GO (A) and MCGO (B).,GO：the sheet-like structur

10、e with large thickness, smooth surface, and wrinkled edge.,The MCGO has a much rougher surface, revealing that many small magnetic chitosan had been assembled on the surface of GO layers with a high density.,The BET surface area: 392.5 m2/g; The pore volume: 0.3852 cm3/g; The average of the pore siz

11、e distribution is 2.587 nm. The average particle size is 200 nm.,mesoporous material,15,FTIR（2/10）,Fig. 2. IR spectra of GO (A) and MCGO (B).,C-O-C,C-OH,C-C,C-O (COOH),O-H,Fe3O4,C-O (NHCO),16,XRD（3/10）,Fig. 3. XRD pattern of pure Fe3O4 (A), magnetic chitosan (B) and MCGO (C).,The XRD analysis result

12、s of pure Fe3O4, magnetic chitosan and MCGO were mostly coincident. It indicates the existence of iron oxide particles(Fe3O4), which has magnetic properties and can be used for the magnetic separation.,17,pH（4/10）,Fig. 4. Effect of pH on the adsorption capacity (initial concentration, 200 mg/L; temp

13、erature, 303 K; contact time, 60 min). Black points: Qe versus initial pH values; red points: equilibrium pH values versus initial pH values.,The optimum pH range for MB adsorption onto MCGO bio-adsorbents is 4.56.5.,18,Adsorption kinetics（5/10）,The pseudo-rst-order kinetic model,Qe: adsorption quan

14、tity at equilibrium, in mg/g; Qt: adsorption quantity at time t, in mg/g; K1: the rate constant of adsorption (min1); t: time, in min.,The pseudo-second-order kinetic model,19,Adsorption kinetics（6/10）,Fig. 5. Pseudo-rst-order kinetic plots for the adsorption of MB (A), and pseudo-second-order kinet

15、ics for adsorption of MB (B) (pH 5.3, temperature: 303 K).,Table 1 Adsorption kinetic parameters of MB onto MCGO.,20,Adsorption isotherm（7/10）,Fig. 6. The linear dependence of Ce/Qe on Ce (pH, 5.3; temperature, 303 K; contact time, 60 min).,The adsorption process is mainly monolayer adsorption on th

16、e surface.,The Langmuir adsorption isotherm model,21,Temperature（8/10）,Fig. 7. Vant Hoff plots for the adsorption of MB onto MCGO,The negative value of H shows exothermic nature of adsorption process. The adsorption was favored at lower temperature and MB molecules were orderly adsorbed on the surfa

17、ce of MCGO. The negative value of G indicates that the adsorption reaction was spontaneous at 303, 313 and 323 K.,Table 2 Thermodynamic parameters at different temperatures.,Vant Hoff equation,22,Desorption experiments（9/10）,Fig. 8. Effect of recycling adsorbents on MB adsorption (pH, 5.3; initial c

18、oncentration, 200 mg/L; temperature, 303 K; contact time, 60 min).,The 0.5 mol/L NaOH is the optimum eluent.,Table 3 The desorption percentages of HCl, NaOH and H2O (Concentration, 0.5 mol/L).,23,最大吸附量（10/10）,Table 4 Maximum adsorption capacities for the adsorption of MB onto various adsorbents.,24,Fourth part,25,Conclusions（1/1）,（1）Prepare the MCGO composite bio-adsorbent with higher adsorption