Construction of carbon-doped supramolecule-based g-C3N4/TiO2 composites for removal of diclofenac and carbamazepine: A comparative study of operating parameters, mechanisms, degradation pathways

An eco-friendly 2D heterojunction photocatalyst composites (BCCNT) consisting of carbon-doped supramolecule-based g-C3N4 (BCCN) layers and TiO2 nanoparticles has been fabricated via an in-situ method. Based on the SEM and XPS results affirmed that the coaction of doped carbon and supramolecule precursors lead to the different morphology of pure g-C3N4, C-doped g-C3N4 have improved the photodegradation diclofenac (DCF) and carbamazepine (CBZ). And the degradation efficiencies of DCF and CBZ could reach 98.92% and 99.77%, which were separately corresponded to 30 min (min) and 6 h (h) of LED lamp illumination. Additionally, the effects of catalysis dosage, solution pH, natural organic matter (NOM), inorganic anions (Cl-, SO42-, NO3-) and different water matrices were deeply investigated. The scavenger experiments demonstrated that center dot O-2(-), h(+) were main active species under visible irradiation. Furthermore, the photodegradation pathways of DCF and CBZ were detected by high-resolution mass spectrometry (HRMS) instruments and three, dimensional excitation-emission matrix fluorescence spectra (3D EEMs). Eventually, the possible photocatalytic mechanisms of BCCNT were proposed.