The Preparation Of Carbon Nanometer Adsorption Materials Based On Multi-component Reactions And Their Applications

With the rapid development of nanoscience and nanotechnology,carbon nanomaterials(CNMs),such as graphene oxide(GO),carbon nanotubes(CNT),nano-diamond(NDs)and mesoporous carbon,etc have become one of the most popular nanomaterials.Among them,CNT and its composites have extensively explored for various applications owing to its excellent optical,chemical,electrical,mechanical,and thermal and biological properties.Moreover,CNT and its composites were deemed as potential adsorbents for removing pollutants from wastewater because of its high specific surface and unique porous structure.Nevertheless,the poor dispersion and lack of functional groups of pristine CNT have largely restricted their adsorption application.Therefore,surface modification of CNT is of great importance to improve its adsorption performance.In this thesis,a series of CNT-based composites have been fabricated through the following modification methods.The pristine CNT was first functionalized by Diels-Alder reaction(DA)or mussel-inspired chemistry.Then,different functional polymers were introduced on the surface of CNT through multicomponent reactions.Furthermore,the adsorption of Cu2+ or Eu3+ from aqueous solution by these CNT-based composites was investigated in detail.The main content of this thesis could be divided into materials preparation and adsorption experiments:1.The surface modification of CNT(a)The CNT was first modified with polydopamine(PDA)through the mussel-inspired chemistry.Subsequently,the CNT@PDA was reacted with polyethyleneimine(PEI)and paraformaldehyde via Mannich multicomponent reaction to obtain the CNT@PDA@PEI composites with better adsorption performance toward Cu2+.(b)The CNT was first reacted with furfuryl amine(FFA)through Diels-Alder(DA)reaction to obtain amino groups functionalized CNT(CNT-FFA),which was further reacted with amnio group terminating polyacrylic acid(PAA),diethyl phosphite and glutaraldehyde through the Kabachnik-Fields(KF)multi-component reaction.The resultant CNT-FFA-PAA composites with a large number of carboxyl groups could display enhanced adsorption capacity toward Eu3+.(c)The small molecule of furfural(FFL)was introduced into the CNT surface by the DA reaction to form CNT-FFL.Then the oxidized sodium alginate(OSA)could conjugate on the surface of CNT through the KF reaction using p-phenylenediamine,diethyl phosphite,OSA,and CNT-FFL as the reaction substrates.The adsorption capacity of CNT-FFL-OSA was obviously improved owing to the introduction of adsorption active sites on CNT after KF reaction.The successful preparation of the samples,such as CNT@PDA@PEI,CNT-FFA-PAA and CNT-FFL-OSA composites were confirmed by different characterization techniques,including Fourier transform infrared reflectance spectroscopy(FT-IR),Thermogravimetric analysis(TGA),Transmission electron microscopy(TEM),Scanning electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS),etc.2.Removal of pollutants from aqueous solution using CNT-based compositesThe adsorption behavior of CNT@PDA@PEI,CNT-FFA-PAA and CNT-FFL-OSA towards Cu2+or Eu3+ was examined in detail.The adsorption parameters,such as contact time,temperature,initial concentration and pH on the adsorption behavior were investigated.Meanwhile,the corresponding kinetic curve,thermodynamic curve and adsorption isotherm were calculated based on the adsorption data.The results suggest that the adsorption capacity of CNT composites have obviously increased as compared with the pristine CNT.For example,the adsorption capacity of pristine CNT(16.7 mg·g-1)towards Cu2+ was increased to 28.8 mg·g-1 for CNT@PDA@PEI composites.The adsorption capacities of CNT-FFA-PAA and CNT-FFL-OSA for Eu3+are 130.8 mg·g-1 and 103.4 mg·g-1,respectively,which is obviously greater than that of pristine CNT under the same experiment conditions.