Oxygen nanobubbles enhanced photodegradation of oxytetracycline under visible light: Synergistic effect and mechanism

Abstract

Nanobubbles have gained much attention due to their unusual properties such as large specific surface area, surface energy and internal energy, thereby, increase the surface reaction and improve the mass transfer efficiency. The long term stability of nanobubbles and generation of reactive oxygen species enables them to address various the development of nanobubbles technology, it is anticipated to realize totally chemicals free green technology. This study provides a novel nanobubble/AOPs technology, which will be more efficient and environmental friendly and will have broad application in waste water treatment and drinking water purification.

Magnetic Photocatalyst for Wastewater Tertiary Treatment at Pilot Plant Scale: Disinfection and Enrofloxacin Abatement

“…Therefore, we can conclude that when employing higher air flows, in addition to the likelihood of higher reactive oxygen species formation which could have enhanced the overall pollutant abatement [23,48,49], it also increased the availability of the photocatalyst surface to the light and enhanced the mass transfer process through and from the particles. Hence, for the rest of experiments, air flows were 30 L/min.…”

Role of bulk nanobubbles in removing organic pollutants in wastewater treatment

“…At a concentration of 100 mM of DMPO and on the basis of a calibration curve, a total spin concentration of about 1.5 μM in the air-nanobubble system was inferred (Michailidi et al 2020 ). Wang et al ( 2020 ) used 2-propanol, benzoquinone (BQ), and NaN 3 as scavengers to trap ·OH, O 2 · − , and 1 O 2 , respectively, to identify the possible reactive species that induced the photodegradation of oxytetracycline and concluded that ·OH, O 2 · − , and 1 O 2 could coexist in nanobubble solutions, while ·OH played a predominant role in the oxidation reaction (Wang et al 2020 ). Liu et al ( 2016 ) confirmed the existence of ·OH using a sensitive fluorescent probe, APF, in oxygen-nanobubble water and quantified the amount in submicromolar order of magnitude (Liu et al 2016 ).…”

“…The post-SDBS oxidation rate was 99.8%, and the total organic compound (TOC) removal rate reached 76.8% after 24 h (Tasaki et al 2009 ). Wang et al ( 2020 ) added oxygen nanobubbles to photo-reaction system to improve the photodegradation efficiency of oxytetracycline under visible light irradiation. The results presented that the photodegradation efficiency increased to 60% in the oxygen nanobubbles water after 4 h reaction and even reached to 98% when adjust the solution pH to 11.0, while that of ordinary aeration of oxygen was only about 40%.…”

“…The results presented that the photodegradation efficiency increased to 60% in the oxygen nanobubbles water after 4 h reaction and even reached to 98% when adjust the solution pH to 11.0, while that of ordinary aeration of oxygen was only about 40%. The synergistic mechanism of oxygen nanobubble/photolysis process was attributed that oxygen nanobubbles provided both dissolved oxygen and ROS to the reaction system, and during the photoreaction process, oxygen consumption facilitated the nanobubble burst, thereby promoting the generation of ROS of which ·OH played a dominant role in the photodegradation of oxytetracycline (Wang et al 2020 ).…”

Free radical degradation in aqueous solution by blowing hydrogen and carbon dioxide nanobubbles

“…Also, the microbubbles on ozonized water indicated the presence of hydroxyl radical by the collapse of microbubble 4 . Recent papers are referred the above papers 5 and the oxygen nanobubble stability was confirmed to be pH-dependent and the collapsed oxygen nanobubble generate the free radical that induced the photodegradation of oxytetracycline 6 . When the absolute value of zeta potential of nanobubble is low, there is a possibility to collapse of nanobubble by Brownian motion and produce the free radical and also the existence of catalysts enhance the radical generation.…”