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 π-π interaction, reduce the light-shielding effect and improve separation of photogenerated carriers effectively. Meanwhile, the N-TiO 2 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 and improve photocatalytic activity. The degradation pathway of phenanthrene was proposed based on intermediates analysis and density functional theory calculations. This work helps to reveal the relationship between the adsorption-photodegradation and the photoinduced hydrophilicity.