Bromination effect of polybrominated diphenyl ethers on the graphyne surface on enhanced adsorption characteristics using density functional theory study

Among various techniques for treating polybrominated diphenyl ethers (PBDEs), adsorption and removal methods using carbon materials are widely applied to remove and decompose organic pollutants with high efficiency. Of many carbon allotropes, theoretically developed graphyne has numerous promising applicabilities for its strong carbon chemical bond, large conjugate system, good chemical stability, and excellent electrical conductivity. To evaluate the PBDE removal capability of graphyne as an adsorbent, we investigated the adsorption properties of ten PBDE species on graphyne using the density functional theory calculation. Furthermore, we analyzed the correlation between the hydrophobicity and adsorption characteristics of PBDEs and found that the adsorption energy increased with the hydrophobicity and the bromination number, indicating a linear relationship for only seven samples. In BDE154, BDE183, and BDE209, however, this linearity was not clearly found because when the bromine groups of the PBDE structures were located at 6,6′, two phenyl rings repelled each other to limit adsorption. From a water solvation model, graphyne also indicated a high adsorption capacity of PBDEs. It is worth noting that graphyne is considered to be a suitable material for PBDE adsorption, and the adsorption reaction may vary depending on the structural characteristics and hydrophobicity of the PBDEs.