Microwave discharge electrodeless lamps (MDELs). VI. Performance evaluation of a novel microwave discharge granulated electrodeless lamp (MDGEL)—Photoassisted defluorination of perfluoroalkoxy acids in aqueous media

Horikoshi, Satoshi; Tsuchida, Akihiro; Sakai, Hideki; Abe, Masahiko; Serpone, Nick

doi:10.1016/j.jphotochem.2011.05.007

Cited by 21 publications

(14 citation statements)

References 21 publications

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“…A mercury-free MDEL device has also been proposed. 10 The penetration depth of the 185 nm radiation in water is shorter than the 254 nm wavelength, and the 185 nm light irradiance decreases by ca. To resolve this problem, in another study we included a tungsten wire to improve the ignition efficiency of the MDELs.…”

Section: Introductionmentioning

confidence: 99%

Microwave discharge electrodeless lamps (MDELs). Part IX. A novel MDEL photoreactor for the photolytic and chemical oxidation treatment of contaminated wastewaters

Horikoshi

Tsuchida

Shinomiya

et al. 2015

Photochem Photobiol Sci

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This article reports on the fabrication and enhanced performance of a novel microwave discharge electrodeless lamp (MDEL) consisting of a three layered cylindrical structure that was effective in the remediation of wastewater containing the 2,4-D herbicide and the near total sterilization of bacteria-contaminated pond water (E. coli and other microorganisms) through photolysis with the emitted vacuum-UV (185 nm) and UVC (254 nm) light from the MDEL and through chemical oxidation with reactive oxygen species (ROS) produced by the photolysis of dioxygen and air oxygen through one of the photoreactors. The flow rates of the 1.0 L contaminated waters were 0.6 and 1.2 L min(-1). The integrated UV/ROSO2 and UV/ROSair methods used to carry out the degradation of 2,4-D and sterilization processes were more effective than either the UV method alone or the ROSO2 and ROSair methods for short time periods (5 or 8 min). At a lower flow rate, 79% of 2,4-D was degraded by the UV/ROSO2 method and 55% by UV/ROSair after 8 min. At a faster flow rate of 1.2 L min(-1), degradation of 2,4-D in 1.0 L volume of water was 84% and 77% complete by the UV/ROSO2 and the UV/ROSair method, respectively, after 8 min of irradiation. The number of kills of E. coli bacteria was nearly quantitative (98 and 99%) by the UV/ROSO2 and UV/ROSair methods after treating the contaminated water for 5 min. The decrease of total viable microorganisms in pond water was 90% and 80% after 5 min of microwave irradiation at a flow rate of 1.2 L min(-1) by the integrated methods UV/ROSO2 and UV/ROSair, respectively. The rate of flow of oxygen gas through the photoreactor impacted the extent of degradation and the related dynamics of the 2,4-D herbicide.

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Section: Introductionmentioning

confidence: 99%

Microwave discharge electrodeless lamps (MDELs). Part IX. A novel MDEL photoreactor for the photolytic and chemical oxidation treatment of contaminated wastewaters

Horikoshi

Tsuchida

Shinomiya

et al. 2015

Photochem Photobiol Sci

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“…Small size microwave discharge granulated electrodeless lamps (MDELs) were constructed using vacuum-UV transparent synthetic quartz as the envelope and a mixture of Hg and Ar as the gas-fills [54]. Dimensions of the devices were 10 mm (length) by 5 mm (external diameter)—see Figure 11a.…”

Section: Microwave Discharge Electrodeless Lampmentioning

confidence: 99%

Section: Microwave Discharge Electrodeless Lampmentioning

confidence: 99%

Coupled Microwave/Photoassisted Methods for Environmental Remediation

Horikoshi

Serpone

2014

Molecules

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Abstract:The microwave-induced acceleration of photocatalytic reactions was discovered serendipitously in the late 1990s. The activity of photocatalysts is enhanced significantly by both microwave radiation and UV light. Particularly relevant, other than as a heat source, was the enigmatic phenomenon of the non-thermal effect(s) of the microwave radiation that facilitated photocatalyzed reactions, as evidenced when examining various model contaminants in aqueous media. Results led to an examination of the possible mechanism(s) of the microwave effect(s). In the present article we contend that the microwaves' non-thermal effect(s) is an important factor in the enhancement of TiO2-photoassisted reactions involving the decomposition of organic pollutants in model wastewaters by an integrated (coupled) microwave-/UV-illumination method (UV/MW). Moreover, such coupling of no less than two irradiation methods led to the fabrication and ultimate investigation of microwave discharged electrodeless lamps (MDELs) as optimal light sources; their use is also described. The review focuses on the enhanced activity of photocatalytic reactions when subjected to microwave radiation and concentrates on the authors' research of the past few years.

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“…Microwave (MW)-enhanced TiO 2 photocatalysis using MW-discharged electrodeless lamps (MDELs) as the light source has attracted increasing attention for improving the degradation efficiency of various organic pollutants in aqueous and atmospheric environments [ 26 , 27 , 28 , 29 , 30 , 31 ]. Studies have demonstrated that the irradiation of MW on TiO 2 could form hot spots in the photocatalysts, which could increase the surface defects on TiO 2 and improve the production of additional charge carriers and trap sites to enhance the photocatalytic degradation rate of pollutant [ 32 , 33 ].…”

Section: Introductionmentioning

confidence: 99%

Microwave-Enhanced Photolysis of Norfloxacin: Kinetics, Matrix Effects, and Degradation Pathways

Liao

Sharma

et al. 2017

IJERPH

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Degradation of norfloxacin (NOR) was studied using a combination of microwave and UV irradiation methods (MW/UV process). Remarkable synergistic effect was found between MW and UV light. The removal rate with the MW/UV process was much faster than that with UV light irradiation only. Degradation of NOR followed second-order kinetics and ~72% of NOR could be removed in the first 5 min of MW/UV reaction. Influence of inorganic ions (cations (K+, Mg2+, Ca2+, Cu2+) and anions (Cl−, SO42−, NO3−, CO32−)), humic acid (HA) and surfactants (cation, anion, and non-ionic) on the degradation of NOR by the MW/UV process was investigated. Among the ions, Cu2+ and NO3− ions inhibited the degradation of NOR. The presence of HA and surfactants in water showed a slight inhibition on the NOR removal. Furthermore, the NOR degradation in the MW/UV process was primarily caused by the ·OH-photosensitization steps. Seven intermediates formed by the oxidation of NOR were identified and three reaction pathways were proposed. Removals of NOR in tap water (TW), synthetic wastewater (WW), river water (RW), and seawater (SW) were also studied, which demonstrated that the MW/UV process was an effective oxidation technology for degrading fluoroquinolone antibiotics in different water matrices.

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Microwave discharge electrodeless lamps (MDELs). VI. Performance evaluation of a novel microwave discharge granulated electrodeless lamp (MDGEL)—Photoassisted defluorination of perfluoroalkoxy acids in aqueous media

Cited by 21 publications

References 21 publications

Microwave discharge electrodeless lamps (MDELs). Part IX. A novel MDEL photoreactor for the photolytic and chemical oxidation treatment of contaminated wastewaters

Microwave discharge electrodeless lamps (MDELs). Part IX. A novel MDEL photoreactor for the photolytic and chemical oxidation treatment of contaminated wastewaters

Coupled Microwave/Photoassisted Methods for Environmental Remediation

Microwave-Enhanced Photolysis of Norfloxacin: Kinetics, Matrix Effects, and Degradation Pathways

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