Preparation Of Magnetic Carbon-polymer Nanocomposites For High-efficiency Removal Of Dyes And Heavy Metal Ions

Recently,carbon-based nanomaterials,especially graphene oxide?GO?and multi-walled carbon nanotubes?MWCNTs?have attracted tremendous attention in scientific and engineering-based field due to their high chemical/thermal stability,unique nanostructure and extraordinary electrocatalytic properties.However,the applied for water purification of GO is limited by the agglomeration,poor water dispersibility and relatively low density of surface active adsorption spots.Therefore,this thesis prepared GO with multifunctional groups by a modified Hummers method,and then MWCNTs hybridize with GO successfully by chemical-free method.The increase in interlamellar spacing may be ascribed to hybridization of the MWCNTs with GO to form a crosslinked network.Then,Fe₃O₄ magnetic nanoparticles were successfully combined with GO-MWCNTs hybrid surface by chemical co-precipitation method,after which PLL,SA and PGA were efficiently grafted onto Fe₃O₄-?GO-MWCNTs?through chemical bonding,respectively.Both of three adsorbents are found to possess unique capability for removal of dyes and heavy metal ions from aqueous solution.1.The single-layer GO with multifunction groups?hydroxyl,carboxyl and epoxy group?is prepared successfully by a modified Hummers method.XRD and TEM results showed that the layers of GO have been separated and the interlamellar spacing was 0.835 nm.2.MWCNTs hybridize with GO successfully by chemical-free method.The optimal quality ratio of GO and MWCNTs equal to 4:1.FT-IR and SEM results indicated that GO and MWCNTs has been hybridized together effectively.XRD results showed that the interlamellar spacing of GO-MWCNTs hybrid was 0.847 nm.3.Fe₃O₄ magnetic nanoparticles were successfully combined with GO-MWCNTs hybrid surface by chemical co-precipitation method.The optimal quality ratio of Fe₃O₄ and GO-MWCNTs equal to 3.2:1³.8:1.FT-IR?SEM and TGA results indicated that Fe₃O₄ has been dispersed uniformly on the surface of GO-MWCNTs through Fe-O coordinate bond.4.PLL was efficiently grafted onto Fe₃O₄-?GO-MWCNTs?through chemical bonding.FT-IR and TGA results showed that PLL has been grafted onto the surface of Fe₃O₄-?GO-MWCNTs?.This modified procedure endows PLL-Fe₃O₄-?GO-MWCNTs?nanocomposite with good solubility in water and plentiful functional groups.This adsorbentwas applied to the adsorption and separation of cationic dye methylene blue?MB?,anionic dye tartrazine and heavy metal ion Pb?II?.The results showed that the maximum adsorption capacity of PLL-Fe₃O₄-?GO-MWCNTs?for MB removal is 800 mg·g-1,for removal tartrazine is 775.19 mg·g-1and for Pb?II?removal is 1038.42 mg·g-1.5.SA was efficiently grafted onto Fe₃O₄-?GO-MWCNTs?through chemical bonding.FT-IR and TGA results showed that SA has been grafted onto the surface of Fe₃O₄-?GO-MWCNTs?.This adsorbent was applied to the adsorption and separation of MB,Cd?II?,Cu?II?and Ni?II?.The results showed that the maximum adsorption capacity of SA-Fe₃O₄-?GO-MWCNTs?for MB removal is 632.91 mg·g-1.The initial removal for all the heavy metal ion is in order Cu?II?>Cd?II?>Ni?II?.6.PGA was efficiently grafted onto Fe₃O₄-?GO-MWCNTs?through chemical bonding.FT-IR and TGA results showed that PGA has been grafted onto the surface of Fe₃O₄-?GO-MWCNTs?.This adsorbent was applied to the adsorption and separation of Cu?II?,Cd?II?and Ni?II?.The adsorption process showed to obey Langmuir adsorption model,while the kinetics of adsorption followed pseudo-second-order kinetic model.The initial removal for all the heavy metal ion is in order Cd?II?>Cu?II?>Ni?II?.