Synthesis Of Functionalized Graphene Oxide Composites For Pollutant Adsorption

Human activities lead to a large number of pollutants discharged into the environment.The pollutants cause a serious threat to human health through the various ways including food chain into the human body.Among them,the water pollution caused by various toxic chemicals such as heavy metals and organic chemicals from industrial activities is particularly prominent.Therefore,the preparation of highly efficiency adsorbents for the removal of heavy metal and organic pollutants in water has always been an attractive research topic.Graphene oxide(GO)has lamellar structure,large specific surface area,good uniform dispersion,and a large number of oxygen-containing functional groups on the surface,which promotes its application as a support material for the preparation of composite materials.In this paper,three kinds of functionalized GO composites had been prepared.A large number of characterization analyses and static adsorption experiments of pollutants on these three kinds of functionalized GO composites had been carried out.The main contents of this paper were as follows:(1)?-cyclodextrin decorated GO composites(?-CD-GO)was prepared using an in-situ aggregation treatment,and used to adsorb inorganic heavy metal ion(i.e.,Pb(II))and organic pollutant(i.e.,1-naphthol)from water environment.The static adsorption experiments of pollutants on as-prepared ?-CD-GO were studied as a function of various factors.The adsorption kinetic data of Pb(?)and 1-naphthol on?-CD-GO followed a pseudo-second order model,indicating that chemisorption is the main rate limiting factor.The maximum adsorption capacities of ?-CD-GO toward Pb(II)and 1-naphtholon the basis of the Langmuir model was 149.56 and 207.66 mg·g-1 at 303 K,respectively.The combined results of macroscopic experiments and microscopic characterization indicated that the primary adsorption mechanisms of Pb(?)on ?-CD-GO were the surface compexation and electrostatic attraction,and the?-? interactions mainly contributed to the adsorption of 1-naphthol on(3-CD-GO.The findings can provide a novel thought for the elimination of Pb(?)and 1-naphthol from wastewater.(2)The effective combination of dopamine(DA)and oxime containing molecule can significantly improve the adsorption performance.In order to characterize the role of the mass ratio of DA to oxime containing molecule in improving the adsorption performance,novel polydopamine/salicylaldoxime functionalized magnetic graphene oxide(MGO-PDA/oxime)with different mass ratios of DA to salicylaldoxime(i.e.,1:0.5,1:1,1:2,and 1:4)were synthesized successfully via rapid one-step polymerization.It was found that the mass ratios of DA to salicylaldoxime influenced the thickness of polymer shell,functional groups,crystallinity,surface charge,and consequently adsorption capacity of composites.According to the results of staticexperiments,MGO-PDA/oxime with DA/salicylaldoxime of 1:2(i.e.,MGO-PDA/oxime-2)showed the best performance for Pb(?)removal with the maximum adsorption capacity of 261.55 mg·g-1.The adsorption of Pb(?)on MGO-PDA/oxime-2 was fast and pH-and temperature-dependent.The remarkable Pb(?)adsorption efficiency,easy separation and good reusability imply that MGO-PDA/oxime-2 can be regarded as a suitable material in heavy metal pollution cleanup.(3)A novel magnetic GO adsorbent was fabricated successfully by the layer-by-layer assembly of GO and ZIF-8 on the magnetic ferroferric oxide particles(Fe3O4@GO@ZIF-8).The physical and chemical properties of composites were fully investigated by various characterization techniques.The results showed that Fe3O4@GO@ZIF-8 exhibited a high saturation magnetization value,a large specific surface area,and very rich functional groups.The effects of time,pH,initial concentration and temperature on adsorption performance of Fe3O4@GO@ZIF-8 towards As(?)and As(?)were also explored.And the results of static experiment showed that Fe3O4@GO@ZIF-8 exhibited fast reaction kinetics and excellent adsorption capabilities.Based on Intra-particle diffusion and XPS analysis,the adsorption of As(?)and As(?)on Fe3O4@GO@ZIF-8 was attributable to the surface complexation and electrostatic interaction.Additionally,Fe3O4@GO@ZIF-8 showed excellent recyclability and structural stability.These findings demonstrate the potential of Fe3O4@GO@ZIF-8 in the adsorption and separation of arsenic-rich wastes.In conclusion,three kinds of GO nanocomposites had excellent removal performance and recycling value,which has important theoretical significance for the development and design of highly efficient adsorption materials.