removal of heavy metal ions from water using functionalized carbon nanosheet: a density-functional theory study

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+]/cadmiu(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.