Supramolecular self-assembled carbon nitride for the degradation of tetracycline hydrochloride

Graphitic carbon nitride microspheres photocatalyst (CN-MCA) was prepared through supramolecular self-assembly with post-heating treatment, which starts from the combination of the raw materials melamine and cyanuric acid. The as-prepared samples were characterized in detail by X-ray diffraction, Fourier transform infrared spectroscopy, new high-resolution field-emission scanning electron microscopy, specific surface areas analysis, UV–Vis diffused reflectance spectrum, photoluminescence spectrum, and thermal analysis. The structural characterization results reveal that the as-prepared CN-MCA has the same chemical structure as CN-M, but appears as microspheres with nanoporous surfaces. Compared to the CN-M, CN-MCA microspheres exhibit higher specific surface areas, stronger optical absorption and lower PL intensity, which allow more active sites, more effective visible-light harvesting and more efficient migration rate of photogenerated charge. Consequently, we observed that CN-MCA microspheres exhibit higher photocatalytic activity in the photodegradation of tetracycline hydrochloride under visible light irradiation. Moreover, the degradation efficiency of tetracycline hydrochloric acid under 2 h of visible light irradiation was 80.54% when the dosage of CN-MCA was 1.0 g/L; the initial concentration of the tetracycline hydrochloride solution was 10 mg/L; and the initial pH was 7.