Singlet oxygen generation in light-assisted peroxymonosulfate activation by carbon nitride: Role of elevated crystallinity

Chen，Beizhao1; Liu，Xun1; Liu，Bei1; Han，Qi1; Li，Li1; Wang，Li1; Shu，Yufei1; Zang，Linlin1; Zhu，Wenlei2; Wang，Zhongying1

2023-04-01

10.1016/j.chemosphere.2023.138112

CHEMOSPHERE   Impact Factor & Quartile

0045-6535

1879-1298

Carbon nitride (CN) is an emerging 2D non-metal semiconductor material that could be used in photocatalysis and advanced oxidation processes (AOPs) for pollutants degradation. The radical-induced degradation by CN in photocatalysis or photo-assisted AOPs was widely reported in previous studies. Nevertheless, how the non-radical degradation by CN materials could be achieved under irradiation is neither well understood nor controlled. In this work, crystalline carbon nitride (CCN) was synthesized via a facile molten-salt method, and used to activate peroxymonosulfate (PMS) under visible light (>420 nm) to selectively and efficiently degrade tetracycline (TC). Compared to the traditional polymeric carbon nitride (PCN), CCN was found to be a superior PMS activator with the assistance of visible light, which was ascribed to the increased crystallinity of CN tri-s-triazine units and the increased number of catalytic sites, thereby optimizing the photoelectric properties. The activation performance could be further improved by copper loading, with TC degradation rate nearly six times more than that of PCN. EPR trapping and quenching tests showed that singlet oxygen (O) was the dominant reactive oxygen species in the CCN/PMS/visible light system, attributing to the increased graphitic N sites and formation of electron-deficient C in C–N bonding between neighboring tri-s-triazine units upon crystallinity elevation in CCN. In contrast to the conventional radical-based photocatalysis and AOP processes, the visible light-assisted non-radical AOP degradation was highlighted for the selectivity and the remarkable resistance to the impacts of background inorganic anions or natural organic matter (up to 10 mg/L) in the actual water matrix. This work revealed the O generation mechanism by CN-based materials under the joint assistance of visible light illumination and crystallinity elevation, and its excellent removal performance demonstrates the great potential of CCN-based materials in the practical wastewater treatment.

Crystalline carbon nitride Non-radical Photodegradation PMS activation Singlet oxygen

SCI

English

First ; Corresponding

National Natural Science Foundation of China["22076075","22176086"]

Environmental Sciences & Ecology

Environmental Sciences

WOS:000944181400001

PERGAMON-ELSEVIER SCIENCE LTD

ENVIRONMENT/ECOLOGY

2-s2.0-85148366902

Scopus

1.School of Environmental Science and Engineering,Southern University of Science and Technology,Shenzhen,518055,China
2.State Key Laboratory of Pollution Control and Resource Reuse,School of the Environment,Nanjing University,Nanjing,Jiangsu,210000,China

Chen，Beizhao,Liu，Xun,Liu，Bei,et al. Singlet oxygen generation in light-assisted peroxymonosulfate activation by carbon nitride: Role of elevated crystallinity[J]. CHEMOSPHERE,2023,321.

Chen，Beizhao.,Liu，Xun.,Liu，Bei.,Han，Qi.,Li，Li.,...&Wang，Zhongying.(2023).Singlet oxygen generation in light-assisted peroxymonosulfate activation by carbon nitride: Role of elevated crystallinity.CHEMOSPHERE,321.

Chen，Beizhao,et al."Singlet oxygen generation in light-assisted peroxymonosulfate activation by carbon nitride: Role of elevated crystallinity".CHEMOSPHERE 321(2023).