The Performance Of G-C₃N₄ In Removal Of Ammonia And Disinfection Of Vibrio Splendidus

g-C₃N₄ is a new kind of semiconductorphotocatalyst, which only consists of two metal-free elements: C and N. By using melamine as precursor, this experiment fabricated a Single Layer g-C₃N₄（SL g-C₃N₄） by calcined and ultrasonic process. SEM, TEM, AFM, XRD and UV-visible diffuse reflectance spectra were used to characterize the properties of SL g-C₃N₄. Then we determined the performance of SL g-C₃N₄ in removal of ammonia and disinfection of Vibrio splendidus under visible light.（1） The g-C₃N₄ fabricated in this experiment was presented as typical 2-dimension nano structure and had some folds as well as irregular bends. It was partly transparent under the electron beam. According to TEM, the sample of g-C₃N₄ had 2-dimension and micro structure; AFM indicated 1² μm of size, 0.5 nm of thickness and the single layer structure of g-C₃N₄. XRD of g-C₃N₄ showed there was a characteristic peak at 2θ=27.5o, which corresponded 002 crystal face. The UV-visible diffuse reflectance spectra showed g-C₃N₄ could absorb part of UV and visible light and the bandgap was about 3.0 eV.（2） Using SL g-C₃N₄ as photocatalyst, which had an excellent photocatalytic activity for total ammonia nitrogen（TAN） removal from water. The results demonstrated that the optimal quantity of SL g-C₃N₄ was 0.20 g·mL-1. In this experimented condition, over 80% of TAN（initial concentration 1.50 mg·L-1） could be removed in 6 h under Xe lamp irradiation（195 mW·cm-2）. Comparing with acidic and neutral conditions, alkaline one was more efficient in the removal reaction. The investigation suggested that the major oxidation product was NO3--N.In addition, according to 6 re-used experiments, SL g-C₃N₄ exhibited good photocatalytic stability in aqueous solution.（3） Using SL g-C₃N₄ as photocatalyst, the disinfection of Vibrio splendidus was performedunder the visible light irradiation. When the initial cell density of Vibrio splendidus was 1×10-7cfu·mL-1and the concentration of SL g-C₃N₄ was 0.20 g·L-1 in water, cell densityof Vibrio splendidus decreased about 2.3 log unit after 90 min irradiation（30 mW·cm-2）. This indicated that the SL g-C₃N₄ had the capability for disinfection of Vibrio splendidus.