Fabrication Of Poly Pyrrole And Its Nanocomposites And Their Applications For Cr(Ⅵ) Adsorption

With worldwide industry developing, people in the world get great benefit frommodern civilization. However, the developing of industry also brings some terrible effectto our society, such as environmental pollution. Among various kinds of pollutions, wastewater is one kind of pollutions that gives immeasurable impact to people. People not onlycannot see beautiful scenery, but also cannot drink sweet spring water. What’s worse, wehave to bear the harm that the waste water brings to our bodies. This thesis mainly focuson how to remove the hromium contamination in water, and we have fabricate variousnanomaterials which are used as Cr(VI) remover. Polypyrrole (PPy) has been proved toexhibit great ability in Cr(VI) removal. In this thesis, all materials that we fabricated arebased on PPy. In order to increase the removal capacity of the remover, we designdifferent nanostructures, and hope these nanostructures can increase the remover’s specificsurface area.In this thesis, many methods have been used together, such as electrospinning,calcination technique, gas-phase, and liquid-phase polymerization. We have fabricatedvarious kinds PPy nanomaterials with different nanostructures, all these nanomaterialsexhibit large adsorption capacity when they are used as Cr(VI) remover. We also study theeffect of the Cr(VI) initial concentration on the Cr(VI) removal, the kinetics of Cr(VI)removal and use the Langmuir model to evaluate the experimental data. Specific researchresults are as follows:1. A reactive-template vapor phase polymerization method for preparation ofbamboo-like PPy nanotubes has been successfully demonstrated in this paper. Herein,electrospun V2O5nanofibers were chosen as templates to deposit PPy, which served as the oxidants as well. This method can provide the fabrication of PPy nanostructures moreeasily than conventional routes due to its independence of removing template, which isusually a complex and tedious experimental process. The applications of the bamboo-likePPy nanotubes for Cr(VI) ions removal in aqueous solution has been explored. Theresulting bamboo-like PPy nanotubes exhibited much higher adsorption performance thantraditional PPy nanoparticles.The equilibrium Cr(VI) adsorption capacity (qe) ofbamboo-like PPy nanotubes and PPy nanoparticles is8.324and3.763mmol/g (1.44mmol/L, room temperature), respectively. The PPy nanotubes adsorption process fits wellwith pseudo-second-order model, while the initial concentrations of Cr(VI) varied from0.62to1.95mmol/L, the pseudo-second-order rate constant (k2) decreases from0.0202to0.0025g/mmol/min. Finally, the Langmuir model was used to describe the adsorption ofCr(VI) on PPy nanotubes. The maximal adsorption capacity of Cr(VI) ions of bamboo-likePPy nanotubes was about9.281mmol/g.2. We have successfully synthesized PPy/graphene oxide (GO) composite nanosheetsby sacrificial-template polymerization method. MnO2nanosheets were chosen as asacrificial-template to deposit PPy, which served as the oxidant as well. During thepolymerization of pyrrole on surface of GO nanosheets, MnO2component was consumedincessantly. As a result, the PPy growing on the surface of GO nanosheets has themorphology of nanosheets just like the MnO2nanosheets. This method can provide thefabrication of PPy nanostructures more easily than conventional route due to itsindependence of removing template, which usually is a complex and tedious experimentalprocess. The as-prepared PPy/GO composite nanosheets exhibited an enhanced propertiesfor Cr(VI) ions removal in aqueous solution based on the synergy effect. The adsorptioncapacity of the PPy/GO composite nanosheets is about two times as large as that ofconventional PPy nanoparticles.Finally, the Langmuir model was used to describe theadsorption of Cr(VI) on PPy/GO composite. The maximal adsorption capacity of Cr(VI)ions of PPy/GO composite was about9.56mmol/g.3. We have successfully prepared magnetic adsorbent by introducing magnetite particlesinto GO/PPy nanocomposite. The resulting ternary composite not only exhibited a goodcapability for Cr(VI) adsorption in aqueous solution, but also performed high magneticsensitivity under an external magnetic field. The effect of the Cr(VI) initial concentrationon the Cr(VI) removal, was studied and the kinetic experimentrevealed that theadsorptionprocess well followed the pseudo-second-order kinetic model. The Langmuir model wasalso used to describe the adsorption of Cr(VI) on GO/Fe3O4/PPy composite. Then, the equilibrium Cr(VI) adsorption capacity data were well fitted by the Langmuir isothermmodel.The maximal adsorption capacity of Cr(VI) ions by GO/Fe3O4/PPy nanocompositeswas calculated to be about4.72mmol/g. Therefore, we have reason to believe that theas-prepared GO/Fe3O4/PPy composite nanosheets could be used as a magneticallyseparable and efficient adsorbent for the waste water treatment for Cr(VI).