Fe3O4-4,4′-biphenyldicarboxaldehyde superparamagnetic-nanomaterial for the high-efficiency removal of 9-phenanthrol: experimental combined with DFT investigations

Abstract

Owing to the more significant health and environmental risks of 9-phenanthrol (9-PROL) compared to phenanthrene, it is imminent to solve the 9-PROL pollution issue. Herein, Fe₃O₄-0.75-4,4′-biphenyldicarboxaldehyde (Fe₃O₄-0.75BIPHENY) was synthesized via a silane coupling reaction and condensation reaction and employed as an efficient nanocomposite for the removal of 9-PROL. The magnetic core provided the possibility for its fast and convenient separation and the aromatic rings on the BIPHENY shell contributed to improving the capturing ability of 9-PROL molecules via the formation of π–π interactions. Multiple characterization techniques were employed to obtain a comprehensive understanding of the prepared magnetic adsorbents. Fe₃O₄-0.75BIPHENY not only exhibited an excellent adsorption performance towards 9-PROL, but also showed a relatively excellent regeneration performance. The homogeneous surface of Fe₃O₄-0.75BIPHENY provided adsorption sites for the adsorption of 9-PROL molecules, which adhered in monolayer molecular form. Importantly, density functional theory calculations provided novel deep insights into the most possible adsorption bonding mode and verified that π–π interactions existed in the offset stacking form. Furthermore, the visible electrostatic potential and energy orbital distribution plots demonstrated the validity of the adsorption reaction and stability of a specific configuration. This study provides guidance for the assembly of novel magnetic nanocomposites for alleviating traditional and secondary pollution caused by polycyclic aromatic hydrocarbons.