Lake sediment heterojunction photocatalytic system for PMS activation to achieve efficient antibiotic degradation: Mechanism, degradation pathway and toxicity evaluation

The resource utilization of waste had significant economic value and environmental benefits. Among them, constructing a light-driven advanced oxidation system using waste was an effective strategy for treating organic wastewater. This study constructed a lake sediment/g-C 3 N 4 heterojunction - Peroxymonosulfate (PMS) photocatalytic system. The photoelectrochemical experiments and in-situ XPS analysis demonstrated that the heterojunction formed by lake sediments and g-C 3 N 4 facilitated the separation and transfer of photogenerated carriers. The BET results indicate that the specific surface area of this heterojunction material reached 20.1595 m²/g. Furthermore, the joint activation of PMS by transition metals and heterojunctions effectively increased the concentration of reactive substances in the system. Under simulated natural light conditions, this system could degrade 92.17% of tetracycline (TC) within 30 min, and the mineralization rate could reach 71.99%, and the apparent quantum efficiency (AQE) is 0.77%. After five cycles, this system was still able to achieve a degradation rate of 78.828%. The degradation pathway of TC and the stability of its products were analyzed through LC-MS and DFT calculations. The Ecological Structure Activity Relationships (ECOSAR) simulation and plant cultivation experiments had confirmed that this system could effectively reduce the environmental risk of TC. This study focused on specific components in lake sediments and examines their roles during the photocatalytic process. This study employed more intuitive simulation or experimental methods to analyze the transfer pathways of photogenerated electrons, providing valuable insights for the subsequent development of sediment photocatalytic materials.