Generation Characteristics of Long-Lived Active Species in a Water Falling Film DBD Reactor
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Generation Characteristics of Long‑Lived Active Species in a Water Falling Film DBD Reactor Kefeng Shang1,2 · Ning Wang1,3 · Wenfeng Li1,3 · Nan Jiang1,2 · Na Lu1,2 · Jie Li1,2 · Yan Wu1,2 Received: 7 April 2020 / Accepted: 18 August 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Water falling film dielectric barrier discharge (WFFDBD) has been widely studied for water treatment, due to its good performance on production of active species, mass transfer of active species from gas phase into liquid phase, and therefore the degradation of pollutants. However, few studies have focused on the production characteristics of active species of WFFDBD. In this paper, the formation characteristics of hydrogen peroxide, ozone and nitrate ions in a WFFDBD reactor powered by bipolar pulsed generator were studied under different electric discharge time, peak pulse voltage, power–frequency, air flow rate, water circulation flow rate, pH value and conductivity. The results show that the concentrations of hydrogen peroxide, ozone and nitrate ions increased with the peak pulse voltage, power supply frequency and water circulation flow rate, but the inputted air flow rate presented different effect on the production of active species. Moreover, the increase in pH value and conductivity led to a decrease in the concentration of hydrogen peroxide, while nitrate ion increased with the water pH value and conductivity. The p-nitrophenol degradation result indicates that both ozone and hydrogen peroxide contribute to its degradation possibly via their reaction into hydroxyl radical. Keywords Dielectric barrier discharge · Water falling film reactor · Active species · Hydrogen peroxide · Ozone · Nitrate ions
Introduction Organic compounds in wastewater are concerned worldwide due to their severe threats to the environment and human health [1]. Non-thermal plasma (NTP) technology, as one of highly efficient AOPs, produces various physical and chemical effects, such as pyrolysis, UV * Kefeng Shang [email protected] 1
Key Laboratory of Industrial Ecology and Environmental Engineering, MOE of China, Dalian 116024, China
2
School of Electrical Engineering, Dalian University of Technology, Dalian City 116024, China
3
School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
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Plasma Chemistry and Plasma Processing
photolysis, electrohydraulic cavitation, as well as a formation of active species including radicals (H·, O·, .OH) and molecular species (H2O2, O3, etc.) [2]. Recently, NTPs have attracted increasing attentions to organic wastewater treatment [3–12], due to its excellent performance of organic pollutant degradation, simple operation process and less production of secondary pollutants. Non-thermal plasma can be produced in gas phase [13], liquid phase [5] and hybrid gas–liquid phase [14] for gas/water treatment. Electrical discharges in two-phase medium can increase the gas–liquid boundary surface area and enhances t
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