Synergistic Photocatalytic Oxidation and Adsorption Boost Arsenic Removal by In-Situ Carbon-Doped Tio2 and Nitrogen Deficiency C3n4 Heterojunction

The efficient removal of arsenic from wastewater is still a challenge. In this paper, a heterojunction consisted of in-situ carbon-doped TiO2 and nitrogen deficiency g-C3N4 (C/TiO2@ND-C3N4) has been constructed, which can completely oxidize As(III) (10,000 μg/L, 40 mL) to As(V) within 12 min under visible light and simultaneously adsorb total As (95.0%) with the pseudo-secondary kinetic equation, superior than in-situ carbon-doped TiO2 (75.0%) and nitrogen deficiency g-C3N4 (50.5%). The good photocatalytic oxidation and adsorption performances of C/TiO2@ND-C3N4 on As(III) removal can be attributed to the successful synthesis of heterojunction. On one hand, the building of C-O-Ti interfacial chemical bonds enable rapid electron transfer and improved the efficiency of photocatalytic oxidation. On the other hand, the decreased As(V) adsorption energy resulted from the synthesized heterojunction boost the adsorption capability of As(V), which were completed by the generation of O-As bonds with oxygen-containing functional groups on the surface of TiO2 and hydrogen bonds with high content pyrrole nitrogen derived from ND-C3N4, respectively. The results manifest that preparation of bifunctional materials with both photocatalytic oxidation and adsorption properties provides a new strategy to achieve the removal of As