Peroxymonosulfate-enhanced photocatalysis by carbonyl-modified g-C3N4 for effective degradation of the tetracycline hydrochloride

• Published in: The Science of the total environment 2020-12, Vol.749, p.142313, Article 142313
• Main Authors: Shi, Yahui, Li, Jinsong, Wan, Dongjin, Huang, Jinhui, Liu, Yongde
• Format: Article
• Language: English
• Subjects: Carbonyl-modified g-C3N4; Peroxymonosulfate activation; Photocatalysis; TCH degradation
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.142313

In this work, carbonyl-modified g-C3N4 (CO-C3N4) is prepared through one-step calcination of the melamine-oxalic acid aggregates. The visible light-assisted photocatalytic degradation efficiency of the tetracycline hydrochloride (TCH) for CO-C3N4 is significantly enhanced by introducing the peroxymonosulfate (PMS), and the apparent rate constant is greatly increased from 0.01966 min−1 in CO-C3N4/vis system to 0.07688 min−1 in CO-C3N4/PMS/vis system. It is found that carbonyl for CO-C3N4 might offer possible reactive sites for PMS activation and collection sites of photo-generated electrons, greatly accelerating carrier's separation for PMS activation. The favorable conditions, such as the higher catalyst dosage, higher PMS amount and alkaline pH, contribute to TCH degradation. The deleterious effects of co-existing anions on the TCH degradation efficiency are ranked in a decline: H2PO4− > SO42− > HCO3− > NO3− > Cl−, and it may be affected by the type and amounts of anions and active radicals generated. The radical trapping tests and electron spin resonance (ESR) detection display that the O2−, h+, 1O2, OH and SO4− all contribute to TCH degradation. Meanwhile, possible degradation mechanism, intermediates and degradation pathway of TCH are revealed in CO-C3N4/PMS/vis system. This study will offer a new insight for constructing PMS activation with carbonyl modified g-C3N4 photocatalysis system to achieve effective treatment of organic wastewater. [Display omitted] •The carbonyl-modified g-C3N4 is synthesized via one-step calcination.•The introduction of carbonyl accelerates carrier's separation and PMS activation.•The CO-C3N4 possesses higher photocatalytic activity than g-C3N4.•The performance of CO-C3N4 is largely promoted with the addition of PMS.•O2−, h+ and 1O2 mainly contribute to TCH degradation relative to •OH and SO4−.