Visible-Light-Sensitive SrCO₃/AgI Hybrids for Tetracycline Degradation

Abstract

The SrCO₃/AgI photocatalysts were prepared via a co-precipitation method by using SrCO₃ as a co-photocatalyst and AgI as a photo sensitizer. X-ray diffraction, field emission scanning electron microscope, X-ray photoelectron spectrometer, UV-vis diffuse reflectance spectroscopy and electrochemical impedance spectroscope were used to analyze the structure, micro-morphology, chemical compositions, optical properties and photo-generated carrier behaviors of the as-prepared samples, respectively. The photocatalytic degradation mechanism of the as-developed composites was also proposed. Analysis results show SrCO₃, an insulator, can improve the photocatalytic performances and recyclability of AgI for degrading tetracycline under visible light. As the theoretical molar ratio of Sr(NO₃)₂ to AgNO₃ increases, the degradation efficiency of the hybrids first increases and then descends. When the theoretical molar ratio of that is 1: 1, it acquires the maximum of 66.6% within 8 min. This is higher than 32.0% of pure AgI and 34.0% of SrCO₃. Moreover, after three times degradations it is 63.0%, which is higher than 13.6% of AgI. The improvement of the photocatalytic performance of the sample is attributed to the construction of hybrids. The main activated species in catalysis process are superoxide radicals.

Keywords

AgI / SrCO₃ / insulator / photocatalysts / tetracycline