Insight into efficient removal of phenanthrene by Fe3O4-benzhydrylamine nanocomposite: A combined experimental and DFT studies

Due to the toxicity and harmful of phenanthrene (PHE) pollutant to human health and the ecosystem, it is extremely urgent to find an accessible technique to efficiently alleviate PHE contamination risk. The Fe 3 O 4 -1.5benzhydrylamine (Fe 3 O 4 -1.5BENZHY) was successfully fabricated via the silane coupling and Schiff base substitution reaction. The Fe 3 O 4 matrix facilitated the practical recycling efficiency and the aromatic nucleus of the benzhydrylamine could form π-π interaction with PHE molecular to improve adsorption performance. The benzhydrylamine loading amount and synthesis strategy could influence the adsorption capacity of the fabricated magnetic nanocomposite to some extent. Multiple characterization techniques were utilized   to assess the physical and chemical properties of the magnetic nanocomposite. The density functional theory (DFT) calculations combined with post-characterization not only revealed the π–π interaction of Fe 3 O 4 -1.5BENZHY and PHE was valid and usually existed in offset parallel stacking form, but also provided a deeper understanding of the underlying mechanism. Moreover, the stability and adsorption energy for all different configuration modes were evaluated by the LUMO-HOMO energy gap (E GAP ) and electric distribution. The Fe 3 O 4 -1.5BENZHY exhibited a homogeneous surface and PHE molecules were adsorbed in a monolayer form, its adsorption capacity (26.07 mg g −1 ) was significantly higher compared with original Fe 3 O 4 (13.28 mg g −1 ). This work helps broaden insight on the molecular binding mechanism of the adsorbent/adsorbate system and expands the modification strategies for magnetic oxide to achieve high-efficiency adsorption of hazardous polycyclic aromatic hydrocarbons.