PVP-Assisted SiO2 Templates for g-C3N4 Photocatalyst in Acetaminophen Removal Under Simulated Solar Light Irradiation

Metal-free polymeric semiconductor graphitic carbon nitride (g-C3N4) was synthesized via thermal polycondensation using cyanamide with PVP as a medium, using SiO2 nanospheres as sacrificial templates to suppress bulk agglomeration. Structural analysis using X-ray diffraction (XRD) confirmed the conservation of the g-C3N4 structure, while diffuse reflectance UV-Vis spectroscopy (DRS) showed that there is a slight change in optical absorption, modifying the band gap energy of g-C3N4 with the addition of SiO2. Transmission electron microscopy (TEM) evidenced the formation of interconnected porous architectures, facilitating charge migration. Photocatalytic activity was evaluated under simulated solar irradiation using acetaminophen (ATP) as a model pharmaceutical pollutant. Kinetics experiments demonstrated that the sample containing 7% SiO2 nanospheres achieved 65% degradation for 180 min. The best photocatalytic performance is attributed to the pore volume, which favors better adsorption, facilitating the degradation of acetaminophen. The participation of different reactive species during the photocatalytic degradation of ATP was determined. Experiments with scavenger agents indicate that the photogenerated holes are the predominant oxidizing reactive species. These results highlight the potential of g-C3N4 modified with SiO2 nanospheres as an efficient photocatalyst for the degradation of emerging contaminants, thus advancing sustainable water treatment technologies.