Enhanced photocatalytic removal of antibiotics over graphitic carbon nitride induced by acetic acid post-treatment

Being a kind of eco-friendly and low-cost metal-free photocatalyst, graphitic carbon nitride (g-C3N4) shows a great potential in antibiotic wastewater treatment. However, the uncompetitive photocatalytic performance limited its practical applications. In this study, carbonyl (C=O) is introduced on the terminal amino group of gC(3)N(4) (G-CN) via a condensation reaction in acetic acid solution under 80 degrees C of oil-bath stirring (HAC-CN). After the post-treatment of acetic acid, the photocatalytic degradation efficiency of antibiotics over HAC-CN is significantly enhanced with the quasi-first-order rate constants of 0.0120 min(-1), 0.0086 min(-1), and 0.0058 min 1 for tetracycline hydrochloride (TC), sulfamethoxazole (SMZ), and ciprofloxacin (CPFX), respectively, which are 1.50, 1.50, and 1.99 times those over G-CN. The characterization and analysis indicate that C=O might offer more collection sites for photogenerated electrons to facilitate the separation of photogenerated electron-hole pairs. Combined with the calculation of the conduction band and valence band of HAC-CN, and the active species detection tests, h(+),center dot OH,center dot O-2(-), and O-1(2) contribute to the TC degradation, especially center dot O-2(-) and O-1(2) is the dominant oxidized radical. This work provides a facile method for non-metal modification of g-C3N4 to achieve efficient photocatalytic degradation potential of antibiotic and other organic wastewater.

Automated summary

In this study, carbonyl groups (C=O) were introduced onto the graphitic carbon nitride (g-C3N4) through a condensation reaction in acetic acid solution, resulting in enhanced photocatalytic degradation efficiency of antibiotics in wastewater. The introduction of carbonyl groups provided more collection sites for photogenerated electrons, facilitating the separation of electron-hole pairs and improving the photocatalytic performance.