Universality of Tm-Doped g─C3N4 for Photocatalytic Activation of Persulfate in Organic Pollutant Degradation

With rapid industrialization and population growth, ecological environmental impacts have become increasingly prominent, with organic wastewater being particularly harmful. Traditional water treatment technologies struggle to degrade organic pollutants. Photocatalysis combined with persulfate oxidation has emerged as one of the most promising and practical advanced oxidation technologies due to its efficiency and environmental friendliness. However, this technology remains in its early stages for wastewater treatment. This study investigated the composite system of these two technologies for treating refractory organic pollutants. A single photocatalytic system was fabricated by calcining thulium-doped mesoporous g-C 3 N 4 (TMCN). Ammonium persulfate (APS) was then added to create a photocatalytic-persulfate synergistic system for degrading various dyes and antibiotics. The synergistic system significantly enhanced Rhodamine B degradation, achieving 9.8 times higher efficiency than the single photocatalytic system. Excellent degradation was also observed for tetracycline, tylosin, methyl orange, and norfloxacin. Optimal performance was achieved with 0.005% Tm doping. Cycling experiments confirmed system stability. Free radical scavenging experiments revealed the importance order: O2•-, SO4•-, h+, and •OH. Tm doping increased specific surface area, regulated band gap, extended visible light absorption, and improved photogenerated charge separation efficiency, collectively promoting enhanced photocatalytic activity.