Preparation of a novel TiO2-graphene 3D framework material for efficient adsorption-photocatalytic removal of micro-organic contaminants from water

Micro-organic contaminants (MCs) have become potential source of aqueous environmental micro-pollution and TiO2 based 3D framework materials show great superiority for effectively overcoming the mass transfer resistance of MCs. Herein, a novel TiO2-graphene 3D framework material (3D TiO2/rGO) was prepared by rapid freezing-drying followed by high temperature hydrogen reduction, in which TiO2 nanowires (TiO2 NWs) and graphene oxide (GO) nanosheets were used as precursors and no organic components and templates were added. The as-prepared 3D TiO2/rGO exhibited significantly enhanced adsorption-photocatalytic activity for low concentration ethenzamide, one of the representative MCs in water. When the adsorbent dosage was 7.5 mg/150 mL, the removal rate of 500 ppb ethenzamide attained 98.5% in 60 min and the photocatalytic rate was 2.2 times of pristine TiO2 NWs and 17.4 times that of TiO2/GO under UV light irradiation, respectively and 99.8% ethenzamide was eliminated in 3 min and the photocatalytic rate was 1.89 times that of pristine TiO2 NWs and 2.83 times that of TiO2/GO under VUV light irradiation, respectively. The joint action of h+, •OH, •O2− and oxygen vacancies contributed to the photocatalytic removal of MCs and the as-prepared TiO2 based 3D framework material shows great potential for highly efficient removal of MCs from water.