Visible-light-enhanced-hydrophilicity Promoted Adsorption-Photodegradation of Phenanthrene with Core-Shell Fe3O4@SiO2@N-TiO2 Loaded on Graphene Oxide

One kind of novel magnetically separable graphene-based titanium dioxide photocatalytic nano-adsorbents (GO-FSNTs) were prepared for the adsorption-photodegradation of phenanthrene under visible light. The GO-FSNTs displayed the high adsorption-photodegradation efficiency and 10 mg of 0.6% GO-FSNT (wt%) can remove 94.9% of phenanthrene within 4 h. The introduction of a small amount of GO enables 0.6% GO-FSNT to selectively adsorb phenanthrene through the pi-pi interaction, reduce the light-shielding effect and improve separation of photogenerated carriers effectively. Meanwhile, the N-TiO2 shell is occupied by adsorbed water molecules which can spontaneously repair lattice oxygen. Furthermore, the more hydrophilic surface of 0.6% GO-FSNT is formed by increased photoinduced hydroxyl groups under visible light during photodegradation. The photoinduced hydroxyl groups can further generate (OH)-O-center dot and improve photocatalytic activity. The degradation pathway of phenanthrene was proposed based on intermediates analysis and density functional theory calcu-lations. This work helps to reveal the relationship between the adsorption-photodegradation and the photoin-duced hydrophilicity.