Background:
Currently, a clean environment and human health have been regarded as the most important challenges of humankind; therefore, the ability of carbon-based nanomaterials as a new type of adsorbents in the removal of various pollutants from aqueous solutions has caused the widespread attention of research groups.
Objectives:
Carbon nanosheet (CNS) and its amine-functionalized derivatives were considered to remove heavy metal ions (HMIs) (zinc(II) ion [Zn²⁺]/cadmium(II) ion [Cd²⁺]/mercury(II) ion [Hg²⁺]) from water.
Methods:
This theoretical study in the framework of density-functional theory (DFT) was performed to gain insight into the HMIs (Zn²⁺/Cd²⁺/Hg²⁺) adsorption and removal by CNS and {(NH₂)_n-CNS (n = 1 - 2)}. The calculation level was hybrid DFT methods, such as wB97XD/lanl2dz.
Results:
Based on DFT calculations, more negative chemical potential value (-1.827 eV), high global softness (0.964 eV), low highest occupied molecular orbital (NH₂)₂-CNS lowest unoccupied molecular orbital-HMI gap, and more negative adsorption energy (range: -75 to -93 kJ mol^-1) in (NH₂)₂-CNS demonstrated that this compound as a suitable adsorbent removed HMIs (Zn²⁺/Cd²⁺/Hg²⁺) from water than other nanosheets. The HMIs adsorption was confirmed by the natural bond orbital and quantum theory of atoms in molecules.
Conclusions:
The CNS and amine-functionalized structures have a good ability for HMIs (Zn²⁺/Cd²⁺/Hg²⁺) removal due to high chemical potential, electrophilicity, and adsorption energy.
Keywords:WaterContaminations,HeavyMetals,Density-FunctionalTheory,CarbonNanosheet,ElectrostaticInteractions