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Theoretical Study of Adsorption of Organic Pollutants on Polypyrrole with Density Functional Theory (DFT)

Rezaee, Mozafar | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54306 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Rahman Setayesh, Shahrbanoo
  7. Abstract:
  8. Phenolic compounds, which are one of the most dangerous compounds for the environment, are present in many effluents of various industries such as petrochemicals and pharmaceuticals, and the need to eliminate these compounds is increasingly felt. In this study, adsorption of three compounds of para-chlorophenol, para-nitrophenol and hydroquinone on polypyrrole adsorbent in the form of neutral, charged, copolymer with polyaniline and phosphorus-doped have been investigated using density functional theory (DFT). Calculations are performed at two levels of b3lyp/6-31+G(d,p) and wb97xd/631+G(d,p) for two different orientations of adsorbate molecules that the correlation-exchange function wb97xd shows a more negative adsorption energy for the adsorption of these compounds. The effect of the solvent has been investigated with the conductive polarizable continuum model (CPCM). Due to the inhibition of rotation of adsorbent and adsorbate molecules in the solvent phase, the adsorption energy is less negative compared to the gas phase. Charged polypyrrole has a more negative adsorption energy due to the electrostatic interactions contribution. The adsorption energy for polypyrrole-polyaniline copolymer is more negative than the adsorption energy of phosphorus-doped polypyrrole. Evaluation of energy level changes of HOMO and LUMO orbitals, hardness, chemical potential, softness, electrophilicity, dipole moment, charge transfer by Muliken method and natural bonding orbitals, adsorption energy, density of states diagrams, molecular electrostatic potential, intermolecular distances and non-covalent interaction analysis has been performed. Using the wb97xd correlation-exchange function, more band gap energy and hardness and more negative chemical potential are calculated. For charged polypyrrole, the band gap energy is lower and the electrophilicity is higher. Molecular electrostatic potential maps show more active sites in the polypyrrole-polyaniline copolymer adsorbent, which causes the adsorbent to interact more with the adsorbates and the adsorption energy to be more negative. Analysis of non-covalent interactions shows more van der Waals interactions between adsorbent and adsorbate in the wb97xd correlation-exchange function compared to the b3lyp
  9. Keywords:
  10. Adsorption ; Density Functional Theory (DFT) ; Polypyrrole ; Phenolic Compounds ; Phosphorus Doped Polypyrrole ; Polypyrrole-Polyaniline Copolymer ; Organic Pollutant

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