Synthesis and characterization of carbon nitride for oxidation of nitrite ions under UV irradiation

Abstract

Nitrite ion (NO2 -) is an important targeted analyte that is widely exists in environment and industry, and can cause serious hazards to human health. In this work, metal-free carbon nitride photocatalyst was accomplished for oxidation of NO2 - under UV light irradiation. The carbon nitride was successfully synthesized through a thermal polymerization technique by using urea as the precursor. X-ray diffractometer (XRD), Fourier transform infra red (FTIR), diffuse reflectance UV-visible (DR UV-Vis), and fluoresence spectrocopies were used to analyze the prepared material. The XRD pattern showed two diffraction peaks at 2?? of 13.10 and 27.3° which were corresponding to the in-planar repeating units and graphitic structure, respectively. The FTIR spectrum for carbon nitride shows four important bands namely v(N-H), v(C=O), v(C-N heterocyclic) and v(1,3,5-triazine). From the DR UV-Vis spectra, it shows the presence of p-p* and n-p* electronic transitions, which were attributed from the C=N, C=O and C-N chromophores. In addition, only one emission peak was observed at 455 nm from the fluorescence spectrum. The performance of the carbon nitride was then investigated as the heterogeneous catalyst for oxidation of NO2 - under UV light irradiation for 1 hour. The percentage conversion of NO2 - to NO3 - was determined to be 15%, indicating that the carbon nitride can act as a potential heterogeneous photocatalyst for the oxidation process.