Magnetic Fe3O4/CeO2/g-C3N4 composites with a visible-light response as a high efficiency Fenton photocatalyst to synergistically degrade tetracycline

•Preparation of Fe3O4/CeO2/g-C3N4 composites by a one-step hydrothermal method.•Fe3O4/CeO2/g-C3N4 composites are a high-efficiency green catalyst and easily separated.•The Fe3O4/CeO2/g-C3N4 composites can reduce iron leaching.•The removal rate of tetracycline by Fe3O4/CeO2/g-C3N4 is 2.45 times that of tetracycline by Fe3O4/CeO2. Magnetic Fe3O4/CeO2/g-C3N4 (FCG) composites with a visible-light response were successfully synthesized and characterized as a heterogeneous Fenton-like catalyst for tetracycline hydrochloride (TCH) degradation. The optimal mass ratio, pH value, catalyst addition, H2O2 concentration, and temperature were explored. Photodegradation studies showed the best activity when the mass ratio of the composite was 1:0.75:0.75 (F1C0.75G0.75) and the removal rate of TCH by F1C0.75G0.75 reached 96.63% after 180 min. The first order kinetic constant of the reaction system was 0.0533 min−1. According to the test of free radical scavenger and metal leaching tests, the Fenton-like degradation of TCH by F1C0.75G0.75 composite was analyzed. g-C3N4 effectively reduced the leaching of Fe and the location where TCH was attacked by hydroxyl radicals was mainly on the surface of the catalyst. The reusability of the F1C0.75G0.75 composites was also studied after five cycles.