Boosting the photocatalytic activity of g-C 3 N 4 via loading bio-synthesized Ag 0 nanoparticles and imidazole modification for the degradation and mineralization of fluconazole.

The emergence of fluorinated organic compounds in the pharmaceutical, agrochemical, and textile industries has led to a potential increase in the environmental issues and health problems. Herein, a modified heterojunction of bio-synthesized Ag nanoparticles (Ag ⁰ NPs) immobilized on imidazole-modified graphite carbon nitride (Im/g-C ₃ N ₄ ) as a suitable support (Ag ⁰ /Im/g-C ₃ N ₄ ) was hydrothermally synthesized and studied for the photocatalytic removal of the most widely used antifungal organo-fluorine compound-fluconazole (FCZ). The optical properties were thoroughly investigated in the present study, and it was observed that the proposed modification to g-C ₃ N ₄ has led to the shifting of conduction and valance band edge position (for g-C ₃ N ₄ , -0.73 and 1.54 eV and for ICA, -1.14 and 1.28 eV), narrowing of band gap energies, i.e., 2.01 eV, and reduced charge recombination rate. The external and internal surface morphologies were scrutinized through FE-SEM and HR-TEM analyses. Functionalities and potential crystallinity were investigated using FTIR and XRD techniques. The elemental state and composition of the composite were analyzed via XPS. The obtained results substantiate the intended modifications in the ICA composite. The photocatalyst Ag ⁰ /Im/g-C ₃ N ₄ (ICA) was able to degrade 95.74% of FCZ with a high degradation rate (k ₁ ) of 0.0289 min ^-1 within 2-h of the solar illumination experiment. The overall degradation process was observed to be governed by a pseudo-first-order kinetic model. Detailed parameters such as effects of ions, pH (optimized pH 4, highest degradation rate k ₁ =0.039 min ^-1 ), dissolved organic matter (DOM), and optimization of catalysts dosage were studied. The major reactive oxygen species (ROS) was identified as super-oxide radicals (O ₂ ^●- ). The HR-MS and COD-TOC analysis were used to evaluate the degradation and mineralization of FCZ forced by ICA catalysts. The ICA catalyst was found to be stable and reusable for up to five cycles suggesting towards its potential towards the mitigation of environmental pollutants.
(© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)