Construction of heterojunction of C ₃ N ₅ /TiO ₂ loaded with recycled construction micropowder for photocatalytic degradation of sulfamethazine and mechanism analysis

In this study, the recycled construction powder (RCP), a solid waste byproduct of the construction industry, is employed as a carrier to develop the RCP/C 3 N 5 /TiO 2 heterojunction through the heterojunction construction strategy for photocatalytic degradation of sulfamethazine (SMZ). Formation of a Z-type heterojunction between C 3 N 5 and TiO 2 on RCP/C 3 N 5 /TiO 2 broadens the spectral absorption range and effectively enhances the separation of photogenerated electron-hole pairs, contributing to photocatalytic degradation of SMZ. Under the synergistic effect of the electric field in the Z-type heterojunction and the RCP induced dipole field, the efficient separation of photogenerated electrons and holes is realized, and the photocatalytic efficiency is improved. The generated active radicals, such as ·O 2 ⁻ and ·OH are generated, which degrade SMZ into small inorganic molecules. Under visible light irradiation, the RCP/C 3 N 5 /TiO 2 heterojunction achieves efficient degradation of SMZ with a degradation removal of 97.40%. Impurity ions have a relatively minor impact on the degradation process of the SMZ. The photocatalytic degradation process of SMZ conforms to the Z-type charge transfer mechanism. Furthermore, the RCP/C 3 N 5 /TiO 2 heterojunction exhibits excellent recyclability. This study realizes the resource utilization of solid waste, effectively reduces the cost of catalyst preparation, conforms to the concept of “treating waste with waste”, and provides an effective strategy for dealing with antibiotic pollution.