Adsorption of pollutant cations from their aqueous solutions on graphitic carbon nitride explored by density functional theory

Safdari, F ; Sharif University of Technology | 2018

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  1. Type of Document: Article
  2. DOI: 10.1016/j.molliq.2018.03.114
  3. Publisher: Elsevier B.V , 2018
  4. Abstract:
  5. In this study, adsorption of important pollutant cations on the surface of graphitic carbon nitride (g-C3N4) was investigated by density functional theory. The calculations indicated that N6 cavity surrounded by triazine units is the most probable adsorption site on this surface. The structural optimizations also predicted a planar surface for Cr3+, and Ni2+/g-C3N4 systems while the structure of the surface for other systems indicated a considerable distortion with strong dependency on the cation size. Also, g-C3N4 surface exhibited the high adsorption energies for Cr3+, As3+, and Sb3+ ions in the gas phase. However, formation energies of the metal-aquo complexes of these cations indicated that only adsorption of Sb3+, As3+, Pb2+, Hg2+ and Cd2+ cations from the aqueous solution is favorable in a thermodynamic point of view, in such a way that efficiency of adsorption obeys a Sb3+ > As3+ > Pb2+ > Hg2+ > Cd2+ trend. Moreover, time-dependent density functional calculations indicated “metal to ligand charge transfer” vertical excitations for Cr3+/g-C3N4 structure, and “ligand to metal charge transfer excitations” for Hg2+/g-C3N4, Cd2+/g-C3N4, As3+/g-C3N4, and Sb3+/g-C3N4 systems, which indicates the potential of these systems for future use in variety fields of nanotechnology and catalysis. © 2018 Elsevier B.V
  6. Keywords:
  7. Adsorption ; Carbon nitride ; Charge transfer ; Ligands ; Nitrides ; Pollution ; Positive ions ; Solutions ; Structural optimization ; Adsorption energies ; Adsorption site ; Formation energies ; Graphitic carbon nitrides ; Ligand-to-metal charge transfers ; Metal to ligand charge transfers ; Time-dependent density functional calculations ; Vertical excitation ; Density functional theory
  8. Source: Journal of Molecular Liquids ; Volume 260 , 15 June , 2018 , Pages 423-435 ; 01677322 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/pii/S0167732218301788