Production of the protein-based nitrogen-doped carbon quantum dots/TiO2 nanoparticles with rapid and efficient photocatalytic degradation of hexavalent chromium

Abstract

Hexavalent chromium (Cr (VI)) is a typical heavy metal ion caused numerous wastewater, and the photocatalysis is an attractive advanced treatment process for Cr (VI) removal. Biomass material bovine serum albumin and tetrabutyl titanate were used to prepare nitrogen-doped carbon quantum dots and TiO2 (N-CQDs/TiO2) nanoparticles by a facile one-step hydrothermal method. The excellent photonic conversion function of N-CQDs narrowed band gap widths of TiO2 to 2.84 eV due to the N element and the CQDs introduced to the TiO2 successfully. When the mass ratio of BSA and TiO2 was 1 and the hydrothermal reaction time was 48 h, the obtained nanoparticle can rapidly and efficiently degrade of Cr (VI) in 40 min of reaction, and the kinetic reaction rate reached 10.7 times that of pure TiO2 nanoparticles. And the Cr (VI) was reduced in 10 min by 1 mg/L nanoparticle under the pH of 2 or tartaric acid content of 1 g/L due to the electrons were transferred from N-CQDs to the TiO2 surface to achieve effective electron/hole separation and reacted with the Cr (VI) to reduce it to Cr (III). The N-CQDs/TiO2 also exhibited degradation of Congo red completely and killing of E. coli under simulated solar light.