Production of Reactive Oxygen Species by Photoactive Anthraquinone Compounds and Their Applications in Wastewater Treatment

Abstract

2-Anthraquinone sulfonate (2-AQS) was found to exhibit an abnormally high singlet-oxygen quantum yield in aqueous solution after UVA irradiation based on a widely used testing method for singlet oxygen. To discover the cause of the abnormal results, several possible reactive oxygen species were also measured in the system. Results revealed that 2-AQS and two other similar compounds produced singlet oxygen, hydroxyl radicals, and superoxide, so-called reactive oxygen species (ROS), under UVA exposure. The production of hydroxyl radical contributed to the abnormally high quantum yield. Quantifications of the ROS produced by these compounds were conducted by oxidation of p-nitrosodimethylaninline in the presence and absence of either L-histidine or superoxide dismutase. EPR results also confirmed the formation of singlet oxygen by these compounds under UVA irradiation. The influence of different exposure times on the formation of ROS was measured for all three photosensitive compounds. The effects of different additives on the production of ROS were also investigated. The results showed that some compounds traditionally known as "hydroxyl radical scavengers" instead served as hydroxyl radical "generation promoters" under UVA exposure in the system. Moreover, for the first time, these photosensitive compounds were used to degrade a textile colorant, namely, Reactive Black 5, achieving the total decoloration of this compound within 10 min.

Amplified Production of Singlet Oxygen in Aqueous Solution Using Metal Enhancement Effects

“…Singlet oxygen ( 1 O 2 ) is a reactive oxygen species that has been reported countless times in the literature as an important tool to induce oxidative damage in biological systems (24)(25)(26). As 1 O 2 is the excited form of molecular oxygen, with a finite lifetime of 10 À6 -10 À3 s in solution (27,28), and is highly reactive, it has been used in a broad range of applications including organic chemical synthesis (29)(30)(31), wastewater treatment (28,32,33) and photodynamic therapy (34)(35)(36). Interestingly, it has been shown that the metal enhancement effect is not limited to fluorescence, and enhancement of both 1 O 2 production, and phosphorescence quantum yield have been observed (12,(37)(38)(39)(40)(41)(42).…”

Photopatternable and photoactive hydrogel for on-demand generation of hydrogen peroxide in cell culture

“…Accumulated hydroperoxyl radicals then react with another of its species to form hydrogen peroxide and molecular oxygen. The details of this mechanism are much more complex than presented here and are described comprehensively elsewhere [26, 40]. A kinetic model to describe the generation of H 2 O 2 based on this reaction mechanism is proposed in equation (1).…”

Layer‐by‐layer structured gelatin nanofiber membranes with photoinduced antibacterial functions

“…The AQS could have been excited to the singlet state under UV light irradiation and then efficiently intersystem‐crossed to triplet states for diaryl ketone, which could have easily abstracted a hydrogen atom from a weak CH bond or other hydrogen donor to form a ketyl radical 28–30. The reaction of ketyl radicals with oxygen could then produce active superoxide, peroxide, and hydroxyl radicals, which were capable of degrading pollutants and inactivating bacteria.…”