With the rapid advancement of modern science and technology, the damage of antibiotics to human health and ecosystem has aroused widespread concern. In this study, a Mn 0.2 Cd 0.8 S/g-C 3 N 4 type II heterojunction was prepared. The effects of different loading ratios, catalyst dosage, and pH on the photocatalytic functions of the composites were investigated. When the additive dosage of 10% Mn 0.2 Cd 0.8 S/g-C 3 N 4 was 1.20 g/ L, and the pH of the tetracycline (TC) solution was 5, the photodegradation rate of TC (10 mg/L) was 98.4% under the irradiation of visible light for 120 min. After four cycles, the photodegradation rate of 10% Mn 0.2 Cd 0.8 S/g-C 3 N 4 reached 96.8%, indicating good stability and recoverability. Furthermore, the study found that •O 2 − was the dominant active species leading to the decolorization of TC in the process of photocatalysis. Based on its excellent photodegradation rate and great cycle utilization rate, the Mn 0.2 Cd 0.8 S/g-C 3 N 4 composite provided a promising suggestion for photocatalytic degradation of antibiotics.

In this study, ternary Fe-doped CdIn2S4/g-C3N4 catalyst has been formed by a wet impregnation-calcination method and then characterized by XRD, FE-SEM, TEM, FT-IR, DRS, and photoluminescence spectra. With the experimental conditions of simulating visible-light irradiation, the photocatalytic degradation performance of methyl orange (MO) aqueous solution was studied by adding H2O2 as oxidant. After a series of characterization methods and photocatalytic activity tests on MO dye, the following conclusions were drawn: The ternary Fe-CdIn2S4/g-C3N4 heterojunction has a wider visible-light response range than that of g-C3N4 and binary CdIn2S4/g-C3N4 catalysts; the corresponding forbidden bandwidth has been narrowed. The recombination rate of carriers generated under illumination has been greatly reduced; the amount of dark adsorption has been greatly improved, which in turn promotes the progress of the photocatalytic reaction. It is speculated that its superior dark adsorption potential of the Fe-CdIn2S4/g-C3N4 is due to the positively charged Fe3+ and the negatively charged MO anionic dye, which will generate strong attraction between them.

No abstract