Preparation of modified microtubule Carbon nitride and its photocatalytic performance
GAO Feng, WANG Jin, DOU Meng-meng, GAO Bo-ru, XU Juan, HUO Kai-li, WANG Xiao-yue, LUO Heng, LIANG Zi-han
Beijing Key Laboratory of Typical Pollutant Control and Water Quality Assurance, School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China
Abstract：Hexagonal microtubule carbon nitride (MTCN-x) with layered stacking structure was prepared by hydrothermal-calcination method by melamine and solid phosphite H3PO3, where x represents the mass ratio of phosphite to melamine. Its structure, morphology, and photochemical properties were characterized using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy(XPS), scanning electron microscope (SEM), transmission electron microscope (TEM), nitrogen adsorption-desorption isotherms (BET), fluorescence spectroscopy (PL) and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). The results showed that the doping of phosphorus suppressed the growth of catalyst grains, reduced the energy gap, increased the response range of visible light and its utilization, inhibited the recombination of photoelectron and hole effectively and improved the photocatalytic performance significantly. The degradation rate of ciproloxacin (CIP) and tetracycline (TCL) for 10min was 99.7% and 97.8%, respectively. The degradation rate constants were 10.5 and 6.8 times of those by pure g-C3N4 (BCN), respectively. The modified MTCN-1.2 exhibited better photocatalytic degradation performance than MTCN-0 and BCN. At the same time, the effects of pH, catalyst dosage, humic acid concentration on photocatalytic degradation of antibiotics were investigated, The results showed that the best pH values for CIP and TCL degradation were 5 and 9, respectively. The high dosage of catalyst and the increase of HA concentration would lead to the decrease of photocatalytic efficiency. The results of free radical capture experiment proved that superoxide radical(×O2-)and hole (h+) play a leading role in the catalytic system.
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