Comparison of the Disinfection Effects of Vacuum‐UV (VUV) and UV Light on <i>Bacillus subtilis</i> Spores in Aqueous Suspensions at 172, 222 and 254 nm

Wang, Ding; Oppenländer, Thomas; El-Din, Mohamed Gamal; Bolton, James R.

doi:10.1111/j.1751-1097.2009.00640.x

Cited by 90 publications

(62 citation statements)

References 34 publications

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“…The efficacy of KrCl exciplex lamps (222 nm) was demonstrated earlier for inactivation of E. coli cells [1, 2] and a number of pathogenic microorganisms in water [3]. According to the data in [4], a KrCl exciplex lamp is the most effective for inactivation of Bacillus subtilis spores compared with a Xe 2 exciplex lamp (172 nm) and a low-pressure mercury lamp (254 nm). The bactericidal effect of XeI exciplex lamps (253 nm) was studied for the same spores [5].…”

Section: Introductionmentioning

confidence: 92%

Impact of scattering of UV radiation from an exciplex lamp on the efficacy of photocatalytic inactivation of Escherichia coli cells in water

2012

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UDC 535.36We have used integrating-sphere UV spectroscopy to study scattering of radiation from an XeBr exciplex lamp (282 nm) by nanoparticles of a photocatalyst (TiO 2 ) and Escherichia coli CN13 cells. We have demonstrated that we must take into account scattered radiation in calculating the UV doses for disinfection of water in the presence of suspended TiO 2 particles. We have established that using the absorption intensities for the water to be disinfected in the dose calculation, obtained without taking into account the intensity of scattering of the radiation, leads to the actual dose exceeding the calculated dose by 5.2% to 69.4%. Total inactivation of the cells (from the absence of colony-forming units (CFU) after incubation of the irradiated aqueous suspension) was achieved at a UV radiation dose of 30 and 40 mJ/cm 2 and TiO 2 concentration of 0.25 and 0.10 g/L. The optimal concentration of TiO 2 in water determined was 0.25 g/L, which corresponds to the maximum concentration of hydroxyl radicals and the rate of their formation.

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Section: Introductionmentioning

confidence: 92%

Impact of scattering of UV radiation from an exciplex lamp on the efficacy of photocatalytic inactivation of Escherichia coli cells in water

2012

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“…Interestingly, although without O 3 bubbling, the excimer/TMiP reactor shows the highest k 1 among reactors. We ascribed the results to reactive species and oxidative intermediates generated by VUV photolysis of water as mentioned by Oppenländer et al [24][25][26][27][28]. Hydroxyl radicals and other reactive species are formed by VUV photolysis of water and can directly react with organics due to their strong oxidation potentials.…”

Section: Test Methods For Evaluation Of the Water Purification Abilitymentioning

confidence: 99%

Synergistic Water-Treatment Reactors Using a TiO2-Modified Ti-Mesh Filter

Ochiai

Masuko

Tago

et al. 2013

Water

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Abstract:The recent applications of a TiO 2 -modified Ti-mesh filter (TMiP™) for water purification are summarized with newly collected data including biological assays as well as sewage water treatment. The water purification reactors consist of the combination of a TMiP, a UV lamp, an excimer VUV lamp, and an ozonation unit. The water purification abilities of the reactor were evaluated by decomposition of organic contaminants, inactivation of waterborne pathogens, and treatment efficiency for sewage water. The UV-C/TMiP/O 3 reactor disinfected E. coli in aqueous suspension in approximately 1 min completely, and also decreased the number of E. coli in sewage water in 15 min OPEN ACCESSWater 2013, 5 1102 dramatically. The observed rate constants of 7.5 L/min and 1.3 L/min were calculated by pseudo-first-order kinetic analysis respectively. Although organic substances in sewage water were supposed to prevent the UV-C/TMiP/O 3 reactor from purifying water, the reactor reduced E. coli in sewage water continuously. On the other hand, although much higher efficiencies for decomposition of organic pollutants in water were achieved in the excimer/TMiP reactor, the disinfection activity of the reactor for waterborne pathogens was not as effective as the other reactors. The difference of efficiency between organic pollutants and waterborne pathogens in the excimer/TMiP reactor may be due to the size, the structure, and the decomposition mechanism of the organic pollutants and waterborne pathogens. These results show that a suitable system assisted by synergy of photocatalysts and other technologies such as ozonation has a huge potential as a practical wastewater purification system.

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“…This precludes the very low transmittance in quasicollimated photo-reactors in air, due to the short penetration of VUV light in air of ∼50 mm. To solve this problem VUV collimated photo-reactors in a N 2 atmosphere have been recently reported [38,39]. This study reports for the first time in a detailed, systematic and comprehensive way the effect of 185/254 nm mercury resonance lines and separately the effect of the 185 nm line on the photo-Fenton mediated MB degradation in solution.…”

Section: Introductionmentioning

confidence: 96%

Accelerated methylene blue (MB) degradation by Fenton reagent exposed to UV or VUV/UV light in an innovative micro photo-reactor

Qiang

Pulgarín

et al. 2016

Applied Catalysis B: Environmental

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a b s t r a c tThis study presents the accelerated discoloration/degradation of methylene blue (MB) in solution by Fenton reagent under exposure to ultraviolet (UV) or Vacuum-UV/UV (VUV/UV) light in an innovative micro photo-reactor. The MB degradation was kinetically faster when using VUV/UV light at 254/185 nm compared to UV-irradiation at 254 nm. Oxidative radicals produced by the photo-Fenton process were identified with appropriate scavengers. The addition of benzoquinone (BQ) at millimolar (mM) concentrations to MB solutions precluded completely the MB photo-induced bleaching, while tert-butanol hindered to a lesser extent the MB degradation suggesting that HO 2 • was the predominant intermediate leading to MB degradation. The VUV/UV micro photo-reactor comprised mercury resonance lines at 185 and 254 nm. The photon percentages absorbed by water were estimated to be 16.8% at 254 nm and 78.3% at 185 nm by water, while those absorbed by H 2 O 2 were 0.9% and 2.2%, correspondingly. The solution parameters affecting the features of MB degradation, such as MB, Fe, and H 2 O 2 concentrations, were explored and reaction mechanism was proposed. The lifetimes of • OH and HO 2 • were estimated to be 2 ns and 0.38 s under an optimized solution with 0.016 mM MB, 0.147 mM H 2 O 2 and 0.05 mM Fe 3+ . Moreover, an estimation of the mean free paths of these radicals in solution provided the evidence that it was the radical lifetimes and mean-free paths, not their oxidation potentials that controlled the MB degradation kinetics. This study shows the potential of this VUV/UV assistant photo-Fenton process for the degradation of diluted organic compounds in aqueous solution.

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Comparison of the Disinfection Effects of Vacuum‐UV (VUV) and UV Light on Bacillus subtilis Spores in Aqueous Suspensions at 172, 222 and 254 nm

Cited by 90 publications

References 34 publications

Impact of scattering of UV radiation from an exciplex lamp on the efficacy of photocatalytic inactivation of Escherichia coli cells in water

Impact of scattering of UV radiation from an exciplex lamp on the efficacy of photocatalytic inactivation of Escherichia coli cells in water

Synergistic Water-Treatment Reactors Using a TiO2-Modified Ti-Mesh Filter

Accelerated methylene blue (MB) degradation by Fenton reagent exposed to UV or VUV/UV light in an innovative micro photo-reactor

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