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[Display omitted] • The 1O 2 -mediated advanced oxidation processes (AOPs) have significant potential in wastewater treatment. • The physical and chemical properties, and reaction characteristics of 1O 2 are summarized. • 1O 2 can be produced by many pathways including direct catalytic and energy-assisted activation. • Multiple mature detection methods of 1O 2 are collected in this review. • The existing deficiencies and improvements of 1O 2 -mediated AOPs are discussed. Advanced oxidation processes (AOPs) have been widely used in contaminants decomposition to reduce their harm. Especially, the singlet oxygen (1O 2)-mediated AOPs have been considered a promising decontamination method due to their good ability to resist water matrix in actual wastewater treatment. However, there are still some doubts about the important role of 1O 2 in wastewater treatment. Therefore, it is necessary to comprehensively summarize the characteristics, detection methods, and generation pathways of 1O 2 based on the latest research. In this review, various characteristics of 1O 2 are comprehensively summarized, including its molecular structure, orbital energy, lifetime in solvents, reaction characteristics and reaction pathways. Next, the generation pathways of 1O 2 including catalytic ozonation, hydrogen peroxide, persulfate, periodate, photocatalysis, electrochemical, and peracetic acid activation systems are summarized. Additionally, 1O 2 can be detected by various methods such as fluorescence probes, chemiluminescence probes, quenching tests, electron paramagnetic resonance, deuterium oxide experiments, and product analysis. The combination of multiple detection methods can improve accuracy of 1O 2 detection. Finally, the existing deficiencies and improvements in mechanism exploration, detection means and practical application of 1O 2 are also contained. It is expected that this review can provide new inspiration for subsequent research on 1O 2 -mediated AOPs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A heterogeneous catalytic system of NaBiO 3 for PMS without light irradiation was investigated. • Both radical (SO 4 −• and •OH) and non-radical (1O 2) were contributed to BPAF degradation. • The contribution rate of 1O 2 , · SO- 4, and · OH was calculated as 80.4%, 8.7%, and 9.9%, respectively. It has been shown previously that the NaBiO 3 (NBO) could efficiently photocatalytically degrade organic contaminants because of its excellent photocatalytic property. In this study, we proposed a heterogeneous catalytic system of NBO for peroxymonosulfate (PMS) without light irradiation. The results showed that NBO/PMS exhibited excellent performance toward bisphenol AF (BPAF) degradation and mineralization. The effectiveness of the NBO/PMS system was also investigated in different multicomponent systems. The effects of initial pH, NBO dosages, and PMS concentration for BPAF degradation were also investigated. Radical quenching experiments combined with electron spin resonance analysis indicated that singlet oxygen (1O 2) was the main reactive oxygen species, and · SO 4 - and · OH– radicals participated in the process. X-ray photoelectron spectroscopy revealed the main catalytic mechanism: lattice oxygen (O vac) was extruded during the transformation of Bi(V) to Bi(III) to form and activate oxygen (O*), and the generated O* between the [BiO 6 ] regular octahedral layers reacted with PMS on the NBO surface to form 1O 2. Based on the results of the Bi element, it is suggested that the activation process proceeded through electron transfer from NBO to PMS. The stability of NBO and applicability of the NBO/PMS system in a natural water environment were explored. This work provides a novel approach to PMS activation and the potential use of NBO for the decontamination of organic pollutants. [ABSTRACT FROM AUTHOR]

[Display omitted] • An effective way for treating high-salinity organic wastewater was developed. • CuO/MXene nanocomposite was prepared to activate PMS for carbamazepine degradation. • CuO/MXene/PMS system presented > 95.88% removal of carbamazepine within 20 min. • The inhibition of inorganic anions was conquered by CuO/MXene/PMS system. • 1O 2 was identified as dominant ROS and its contribution was verified. The degradation of organic contaminants via traditional radical-dominated advanced oxidation processes (AOPs) under high salinity conditions was limited due to side reactions between coexisting inorganic anions and radicals. Herein, a nonradical oxidation process via peroxymonosulfate (PMS) activation by CuO/MXene for treating high-salinity organic wastewater was developed. Rapid removal efficiency of target pollutant carbamazepine (CBZ) was significantly enhanced to 95.88% within 20 min by CuO/MXene under high salinity conditions (NaCl, 200 mM), compared to the efficiency of 4.30% exhibited by PMS alone. Besides, CBZ maintained a higher removal efficiency of > 81.04% in complex highly saline wastewater composed of eight common inorganic anions. Radical quenching experiments and electron paramagnetic resonance (EPR) analysis confirmed that radical and nonradical oxidation processes were involved in the catalytic process. However, singlet oxygen (1O 2) was identified as the primary reactive species, and its contribution rate to CBZ degradation was > 73.58% in a wide pH range (3.0-9.0). The oxygenated functional groups and the interaction between CuO/MXene and PMS facilitated the production of 1O 2. The degradation pathway was proposed based on the detection of intermediates. This work provided a new inspiration for the decontamination of organic contaminants under high salinity conditions via a nonradical oxidation process. [ABSTRACT FROM AUTHOR]