Preparation And Performance Of Functionalized-Graphene-Cement-based Composite Materials(FGNC)

Along with the growth of vehicle emissions and unlimited emissions of industrial wastewater,all these things make much more existence of heavy metal ions in lakes and rivers,not only leading to serious damage for environment,but also threatening human health.Therefore,effective adsorbents for removal of heavy metal ions in waste water have been became a hot spot in scientific research.In recent years,many researchers at home and abroad studied on the graphene and its composites used for wastewater treatment research.All of these studies showed the graphene and its composite materials has a good prospect of development into adsorbent materials with great academic value.However,all the graphene and its composites has apparent disadvantages of poor adsorption capacity,low removal percentage,low yield and recyclability.This paper adapted functional way to improve hydrophilic and increase the specific surface area,due to the introduction of oxygen containing functional groups,such as hydroxyls?-OH?,carboxyls?-COOH?,and epoxide group?-O-?etc.oxygen-containing functional groups.Bunches of FGNps adsorption experiments adapted Cu²⁺ as adsorbate and adsorption performance and mechanism of FGNps are revealed in analysis;The researches of functionalized graphene-cement-based composite materials?FGNC?was studied and the adsorption performance of Cu²⁺ and Pb²⁺ was tested.Besides,the mechanical property of FGNC and reinforcing and toughening mechanisms of FGNps was stated.The research results are illustrated as following:?1?By functional method used in paper,the FGNps were attained via treatment of H2SO4 and H3PO4.Through FTIR?AFM?BET?SEM-EDS etc.testing technologys,the results showed that the thick layer of graphene shaped into the thin film,with theirs large specific surface area reached up to834.05m2/g and lower ratio carbon to oxygen.And the surface of FGNps was covered by large amount of oxygen containing functional groups,which offered adsorption sites for heavy metal ions.?2?Adsorption performance of FGNps: FGNps can remove Cu²⁺ from solution effectively with excellent adsorption capacity under the different conditions of varied solution pH,outside temperature,initial concentration of Cu²⁺ and contact time.And the adsorption-desorption experiments result showed that FGNps removal rates can reach 70.2% after adsoportion-desorption test five times,so that FGNpsps showed thiers outstanding adsorption performance.?3?The rational content of FGNps can improve the mechanical properties of cementbased-composite materials?FGNC?,but they will have an impact on the workability?characterized by plastic viscosity?.With FGNpsps content increased,the compressive strength of FGNC increases and then decreases,up to maximum compressive strength 41.8 MPa.Compared to the controlled sample,the compressive strength of FGNC increases by 37.5% at the FGNps content of 0.03 wt.%;The impact strength increased with FGNpsps content increases,the impact strength reached maximum of 9.9 cm·kg with 58.9% improvement at FGNps content of 0.04 wt.%;Contrast to the plastic viscosity value of graphene-cement mortar,cement mixture of FGNps and sonicated FGNps is small obviously,proved that the cement mixture of FGNps has better dispersion effect.It also suggested that ultrasound method is an effective way to disperse FGNps in solution or cement.?4?FGNC possess better adsorption property.For instance,at the condition of pH=7,the initial concentration of heavy metals(Cu²⁺ and Pb²⁺): 100mg/L,outside temperature of 10?,20?and 30?,the FGNC removal percentage of Pb²⁺ reached to 11.5%,10.7% and 11.4%,respectively.And removal percentage of Cu²⁺ are 11.60%0,9.97% and 12.46%,compared to the controlled samples.?5?The toughening and strengthen mechanism of FGNps: FGNps have a special regulating effect on cement hydrations.With the increase of content of FGNps,C-S-H and some hydrates gathered into neatly arranged big blocks,and the pores and cracking size are reduced for the reason that mechanical properties improved.?6?The adsorption mechanism of FGNC included: physical adsorption,crystal and intercellular replacement and double decomposition reaction.With incorporation of FGNps,the more C-S-H and CH generated the more specific surface area and adsorption sites of hydration products.Using the SEM-EDS test,the results revealed that the types and distribution of metal complexing compounds.