Sulfur doped carbon quantum dots loaded hollow tubular g-C3N4 as novel photocatalyst for destruction of Escherichia coli and tetracycline degradation under visible light

Microbial contamination and antibiotic pollutions diffusely exist in wastewater system, and contaminated water poses a threat to public health. Therefore, there is a need to effectively remove biohazard and antibiotic contamination from wastewater systems. In this paper, sulfur doped carbon quantum dots (S-CQDs)/hollow tubular g-C3N4 photocatalyst (HTCN-C), prepared via ultrasonic assisted synthesis strategy, was regarded as an efficient catalyst for the degradation of antibiotic (tetracycline) and destruction of a typical Gram-negative bacterium (Escherichia colt) in imitated wastewater system. The unique structures of hollow tubular g-C3N4 and loading of modified carbon quantum dots enhanced electron transfer and charge separation, leading to a significant improvement in photocatalytic efficiency. Benefiting from these merits, the optimized catalysts (HTCN-C(2)) exhibited superior performance with a reaction rate of 0.0293 min(-1) for tetracycline (TC) degradation and 99.99% destruction of Escherichia coil under visible-light irradiation. Moreover, the characterization of UV-Vis diffuse reflectance spectra, photoluminescence technique, transient photocurrent responses and electrochemical impedance spectroscopy also verified the good optical and electrochemical properties of resultant samples. Our current work indicates that HTCN-C has great potential in degradation of antibiotic and destruction of bacterium for practical wastewater treatment.