KrCl Excimer Lamp Research Articles

Far-UVC (UV222) based photolysis, photooxidation, and photoreduction of chlorophenols using a KrCl-excimer lamp: Degradation, dechlorination, and detoxification

The KrCl-excimer lamp, emitting far-UVC light at 222 nm (UV222), offers a promising alternative to conventional UVC light at 254 nm (UV254) for the photolysis of organic pollutants and the activation of radical sensitizers. This study was aimed to investigate the efficiencies of UV222 in the treatment of halogenated aromatics, focusing on its performance in degradation, dechlorination and detoxification. Chlorophenols, representative recalcitrant and toxic halogenated aromatics, were used as target pollutants. The pathways of direct photolysis, photooxidation and photoreduction under UV222 illumination were compared. UV222 outperformed UV254 in photolyzing chlorophenols (1.4−34.1 times faster), especially protonated chlorophenols, due to substantially higher UV absorption (17.1−108.0 times) and quantum yields (2.1−3.4 times). The quantum yields of chlorophenols were influenced by the inducive electron-withdrawing effect of Cl-substitutes. Moreover, UV222 improved the dechlorination of chlorophenols to 95 % compared to 60 % by UV254. The introduction of radical sensitizer (e.g., H2O2, nitrate, and sulfite) reduced 4-chlorophenol photolysis by competing for UV222 absorption, though the sensitizers partially increased radical oxidation via generating •OH or eaq−. UV222 photolysis of 4-chlorophenol increased the toxicity by 88.6 times through forming toxic intermediates (e.g., hydroquinone and resorcinol). Notably, •OH and eaq− (i.e., UV222/H2O2 and UV222/sulfite) increased the dechlorination and •OH (i.e., UV222/H2O2) detoxified the mixture solution. Moreover, UV222 photolysis remained effective for 4-chlorophenol removal in real paper-mill wastewater, indicating the potential application of KrCl* lamp UV222.

Interventional human ocular safety experiments for 222-nm far-ultraviolet-C lamp irradiation.

The study aimed to directly assess the ocular safety of 222-nm far-ultraviolet-C (UVC) irradiation in humans, given the limited clinical trials in this area. This wavelength offers the potential for safe and effective microbial inactivation in occupied spaces, but its safety profile for human eyes requires thorough investigation. This prospective, interventional study involved five subjects aged 29-47 years, who were exposed to 222-nm UVC at doses of 22, 50, and 75 mJ/cm2. The subjects were monitored using custom-made glasses with a UV-cut filter on one eye to serve as a control. UVC irradiation was conducted using a KrCl excimer lamp, and ocular examinations were performed prior to exposure, 24 h post-exposure, and at 1, 3, and 6 months. Parameters assessed included visual acuity, refractive error, corneal endothelial density, corneal erosion scores, and conjunctival hyperemia scores. The study found no clinically significant photokeratitis or long-term eye damage across the five subjects, even at the highest dose of 75 mJ/cm2. Temporary ocular discomfort, including sensations of dryness and epiphora, was reported, but these symptoms subsided within hours after irradiation. The findings indicate that 222-nm far-UVC irradiation up to 75 mJ/cm2 does not cause "clinically significant photokeratitis" or long-term ocular damage, though it may induce temporary discomfort. This supports the safe use of 222-nm UVC for germicidal applications in occupied environments, providing a basis for revised safety guidelines.

Kinetic modeling and mechanisms of parahalogenated phenols degradation by UV222/H2O2

Advanced oxidation technology of KrCl excimer lamp activated H2O2 (UV222/H2O2) have been received widespread attention in the field of water treatment recently, due to the higher radical yield and environmentally friendly nature compared to UV254/H2O2. In this investigation, four representative parahalogenated phenols (HPs) degradation kinetic and mechanisms by UV222 alone and UV222/H2O2 were studied, respectively. The results showed that the photolysis rate constants (kobs) under UV222 followed the order of p-Chlorophenol (p-CP) > p-Fluorophenol (p-FP) > p-Bromophenol (p-BP) > p-Iodophenol (p-IP), and the degradation rate constants (kobs) by UV222/H2O2 followed the order of p-FP > p-CP > p-BP > p-IP. The molar absorption coefficient (ε222nm) and quantum yield (Φ222nm) of HPs photolysis were measured. Kinetic model simulating results are in fair agreement with the experimental results. Through HPLC-MS analysis and DFT calculation, the impact of halogen ions on the degradation kinetics of HPS by UV222 and UV222/H2O2 was found, the possible reaction pathways and mechanisms were proposed. Compared with UV254/H2O2 for removing p-CP, UV222/H2O2 was much more energy efficient.

Temperature dependence of narrow-band UVB photoluminescence of silica–(Gd,Pr)PO4 transparent glass-ceramic phosphors

The effect of temperature on photoluminescence (PL) due to the 6P j → 8S7/2 (j = 5/2, 7/2) transitions of Gd3+ ions was examined between 200 and 500 K for a sol–gel-derived silica–(Gd,Pr)PO4 transparent glass-ceramic phosphor with negligible concentration quenching under excitation into the 5d–4f transition of Pr3+ ions at 220 nm. The intensity of the narrow-band ultraviolet B (UVB) PL at ∼313 nm associated with the 6P7/2 → 8S7/2 transition slightly increased between 200 and 300 K, but was decreased to ∼86% and ∼62% of that at 300 K when temperature was raised to 400 and 500 K, respectively. The observed magnitude of the thermal quenching of the UVB PL intensity was agreed well with that recorded in a prototype narrow-band UVB lamp consisting of another silica–(Gd,Pr)PO4 transparent glass-ceramic window and a KrCl excimer lamp as a light source at 222 nm. The silica–(Gd,Pr)PO4 transparent glass-ceramics was more resistant to the thermal quenching of the narrow-band UVB PL than a conventional powder phosphor, probably because of the encapsulation of (Gd,Pr)PO4 nanocrystals with low quenching centre concentrations in inert silica glass matrix.

Indoor Air Quality Implications of Germicidal 222 nm Light.

One strategy for mitigating the indoor transmission of airborne pathogens, including the SARS-CoV-2 virus, is irradiation by germicidal UV light (GUV). A particularly promising approach is 222 nm light from KrCl excimer lamps (GUV222); this inactivates airborne pathogens and is thought to be relatively safe for human skin and eye exposure. However, the impact of GUV222 on the composition of indoor air has received little experimental study. Here, we conduct laboratory experiments in a 150 L Teflon chamber to examine the formation of secondary species by GUV222. We show that GUV222 generates ozone (O3) and hydroxyl radicals (OH), both of which can react with volatile organic compounds to form oxidized volatile organic compounds and secondary organic aerosol particles. Results are consistent with a box model based on the known photochemistry. We use this model to simulate GUV222 irradiation under more realistic indoor air scenarios and demonstrate that under some conditions, GUV222 irradiation can lead to levels of O3, OH, and secondary organic products that are substantially elevated relative to normal indoor conditions. The results suggest that GUV222 should be used at low intensities and in concert with ventilation, decreasing levels of airborne pathogens while mitigating the formation of air pollutants.

Dose-Response Behavior of Pathogens and Surrogate Microorganisms across the Ultraviolet-C Spectrum: Inactivation Efficiencies, Action Spectra, and Mechanisms.

The dose-response behavior of pathogens and inactivation mechanisms by UV-LEDs and excimer lamps remains unclear. This study used low-pressure (LP) UV lamps, UV-LEDs with different peak wavelengths, and a 222 nm krypton chlorine (KrCl) excimer lamp to inactivate six microorganisms and to investigate their UV sensitivities and electrical energy efficiencies. The 265 nm UV-LED had the highest inactivation rates (0.47-0.61 cm2/mJ) for all tested bacteria. The bacterial sensitivity strongly fitted the absorption curve of nucleic acids at wavelengths of 200-300 nm; however, indirect damage induced by reactive oxygen species (ROS) was the leading cause of bacterial inactivation under 222 nm UV irradiation. In addition, the guanine and cytosine (GC) content and cell wall constituents of bacteria affect inactivation efficiency. The inactivation rate constant of Phi6 (0.13 ± 0.002 cm2/mJ) at 222 nm due to lipid envelope damage was significantly higher than other UVC (0.006-0.035 cm2/mJ). To achieve 2log reduction, the LP UV lamp had the best electrical energy efficiency (required less energy, average 0.02 kWh/m3) followed by 222 nm KrCl excimer lamp (0.14 kWh/m3) and 285 nm UV-LED (0.49 kWh/m3).

Different biological effects of exposure to far-UVC (222nm) and near-UVC (254nm) irradiation.

Ultraviolet C (UVC) light has long been used as a sterilizing agent, primarily through devices that emit at 254nm. Depending on the dose and duration of exposure, UV 254nm can cause erythema and photokeratitis and potentially cause skin cancer since it directly modifies nitrogenated nucleic acid bases. Filtered KrCl excimer lamps (emitting mainly at 222nm) have emerged as safer germicidal tools and have even been proposed as devices to sterilize surgical wounds. All the studies that showed the safety of 222nm analyzed cell number and viability, erythema generation, epidermal thickening, the formation of genetic lesions such as cyclobutane pyrimidine dimers (CPDs) and pyrimidine-(6-4)-pyrimidone photoproducts (6-4PPs) and cancer-inducing potential. Although nucleic acids can absorb and be modified by both UV 254nm and UV 222nm equally, compared to UV 254nm, UV 222nm is more intensely absorbed by proteins (especially aromatic side chains), causing photooxidation and cross-linking. Here, in addition to analyzing DNA lesion formation, for the first time, we evaluated changes in the proteome and cellular pathways, reactive oxygen species formation, and metalloproteinase (MMP) levels and activity in full-thickness in vitro reconstructed human skin (RHS) exposed to UV 222nm. We also performed the longest (40days) in vivo study of UV 222nm exposure in the HRS/J mouse model at the occupational threshold limit value (TLV) for indirect exposure (25mJ/cm2) and evaluated overall skin morphology, cellular pathological alterations, CPD and 6-4PP formation and MMP-9 activity. Our study showed that processes related to reactive oxygen species and inflammatory responses were more altered by UV 254nm than by UV 222nm. Our chronic in vivo exposure assay using the TLV confirmed that UV 222nm causes minor damage to the skin. However, alterations in pathways related to skin regeneration raise concerns about direct exposure to UV 222nm.

Photobiochemical mechanisms of biomolecules relevant to germicidal ultraviolet irradiation at 222 and 254 nm

To inactivate viruses and microorganisms, ultraviolet light in the short wavelength region is a promising candidate for mitigating the infection of disease. Germicidal mercury lamps emitting at 254 nm and KrCl excimer lamps emitting at 222 nm have sterilisation properties. In this work, wavelength dependence of the photobiochemical mechanisms was investigated with 222- and 254-nm irradiation to analyze the underlying damage mechanisms of DNA/RNA and proteins, using Escherichia coli, a protease, an oligopeptide, amino acids, plasmid DNA and nucleosides. The photorepair of damaged DNA and the “dark” reversion of the hydrates of uracil phosphoramidite coupling blocks were also investigated.

Inactivation of Pectobacterium carotovorum subsp. Carotovorum and Dickeya chrysanthemi on the surface of fresh produce using a 222 nm krypton–chlorine excimer lamp and 280 nm UVC light-emitting diodes

Pectobacterium carotovorum subsp. carotovorum and Dickeya chrysanthemi have been reported to cause soft-rot diseases to fresh produces. The aim of this research was to investigate the inactivation efficacy of a 222 nm KrCl excimer lamp and 280 nm UVC-LED against P. carotovorum subsp. carotovorum and D. chrysanthemi on fresh produces. When samples were subjected to UVC treatment by a excimer lamp or UVC-LED at 450 mJ/cm2, it was observed that soft-rot bacteria on the surface of iceberg lettuce, strawberry, and tomato were reduced by a maximum of 5, 3, and 5 log units, respectively. The surface properties of fresh products, such as hydrophobicity, roughness, and topographic image, were analyzed under the hypothesis that the characteristics of the sample surface affected the inactivation efficacy of the excimer lamp and UVC-LED. It was determined that there was an inverse correlation between the surface roughness and inactivation efficacy of UVC treatment. The texture properties of samples were not significantly different (P > 0.05) from those of untreated samples. The results of this research substantiate that the excimer lamp and UVC-LED can be applied to decontamination processes for inactivating soft-rot bacteria, thereby prolonging the shelf life of fresh produce and reducing economic losses.

Optimizing the spontaneous-emission of far-UVC phosphors

Far-UVC light can enable virus-deactivation while remaining harmless to human tissues. This triggered great efforts to create far-UVC light sources with sufficient emission power and efficiency. However, current sources, such as mercury lamps, KrCl excimer lamps, and LEDs, are made from hazardous chemicals or are limited by low efficiency. Consequently, an alternative approach for reaching the far-UVC is now receiving renewed interest: using phosphors for converting higher frequencies to the desired range of far-UVC. However, this concept is limited by the phosphor's conversion efficiency. In this paper, we propose to utilize principles of nanophotonics to create far-UVC sources. Specifically, we design a phosphor-dielectric multilayer that increases the efficiency of far-UVC light conversion and controls the intrinsic emission properties, including the angular spectrum and emission rate, by shaping the local density of photonic states. To exemplify our approach, we design an aperiodic multilayer nanostructure made of the phosphor material YPO4:Pr3+, showing an increase in light extraction by a factor of 3 compared to naïve bulk structures. Our approach can be applied to any phosphor material and any emitter geometry, opening avenues for engineering nanophotonic light sources in the far-UVC and other spectral regimes.

Effect of ultraviolet C emitted from KrCl excimer lamp with or without bandpass filter to mouse epidermis

It has been reported that 222-nm ultraviolet C (UVC) exerts a germicidal effect on bacteria and viruses as well as UV radiation emitted from a conventional germicidal lamp but is less toxic to the mammalian cells than that from a germicidal lamp. An excimer lamp filled with krypton chloride (KrCl) gas principally emits 222-nm UVC. However, the lamp also emits a wide band of wavelengths other than 222 nm, especially UVC at a longer wavelength than 222 nm and ultraviolet B, which cause DNA damage. There are some reports on the critical role of bandpass filters in reducing the harmful effect of UVC emitted from a KrCl excimer lamp in a human skin model and human subjects. However, the effectiveness of a bandpass filter has not been demonstrated in animal experiments. In the present study, mice were irradiated with UVC emitted from a KrCl excimer lamp with or without a bandpass filter. UVC emitted from an unfiltered KrCl lamp at doses of 50, 150 and 300 mJ/cm2 induced cyclobutyl pyrimidine dimer (CPD)-positive cells, whereas UVC emitted from a filtered lamp did not significantly increase CPD-positive cells in the epidermis. The present study suggested that the bandpass filter serves a critical role in reducing the harmful effect of emission outside of 222 nm to mouse keratinocytes.

Photochemical degradation of thiocyanate by sulfate radical-based advanced oxidation process using UVС KrCl-excilamp

The degradation of thiocyanates (SCN−) by UV-C-activated persulfate (PS) in the presence of ferric ion (Fe3+) was investigated. As a source of monochromatic far-UV-C irradiation (222 nm), mercury-free KrCl excimer lamp was used. Results showed that compared with direct photolysis, UVC/ PS and PS/ Fe3+, the combined UVC/ PS/ Fe3+ treatment had the highest initial reaction rate ω0 and removal efficiency. 99.99% conversion of thiocyanates (100 mg/L of initial concentration) was achieved in 40 min. The addition of Fe3+ in the UVC/ PS treatment was found to reduce energy consumption (calculated as amount of oxidized thiocyanates per consumed electrical energy) by 4.5 times, while only a 30% difference between direct photolysis and UVC/ PS was observed. The high efficiency of the UVC/ PS/ Fe3+ process revealed a synergistic effect (synergy index ƒ = 1.98). The effect of the initial SCN−, PS, and Fe3+ molar ratios and UV-C exposure time on SCN− removal in UVC/ PS/ Fe3+ was further investigated. It was found that at molar ratios [S2O82–]:[SCN−] = 3:1 and [S2O82–]:[Fe3+] = 1:0.1, effective decomposition of SCN− in a wide initial concentration range (from 50 to 500 mg/L or 0.86–8.6 mM) can be achieved. The strong role of •OH and SO4•− in the removal of SCN− was confirmed by the addition of radical scavengers. It was demonstrated that the presence of Cu2+ in simulated gold mine wastewater effluents neutralizes the inhibitory effects that S2O32– and NH4+ have on the degradation process.

The impact of far-UVC radiation (200-230 nm) on pathogens, cells, skin, and eyes - a collection and analysis of a hundred years of data.

Background: The ongoing coronavirus pandemic requires new disinfection approaches, especially for airborne viruses. The 254 nm emission of low-pressure vacuum lamps is known for its antimicrobial effect, but unfortunately, this radiation is also harmful to human cells. Some researchers published reports that short-wavelength ultraviolet light in the spectral region of 200–230 nm (far-UVC) should inactivate pathogens without harming human cells, which might be very helpful in many applications.Methods: A literature search on the impact of far-UVC radiation on pathogens, cells, skin and eyes was performed and median log-reduction doses for different pathogens and wavelengths were calculated. Observed damage to cells, skin and eyes was collected and presented in standardized form.Results: More than 100 papers on far-UVC disinfection, published within the last 100 years, were found. Far-UVC radiation, especially the 222 nm emission of KrCl excimer lamps, exhibits strong antimicrobial properties. The average necessary log-reduction doses are 1.3 times higher than with 254 nm irradiation. A dose of 100 mJ/cm2 reduces all pathogens by several orders of magnitude without harming human cells, if optical filters block emissions above 230 nm.Conclusion: The approach is very promising, especially for temporary applications, but the data is still sparse. Investigations with high far-UVC doses over a longer period of time have not yet been carried out, and there is no positive study on the impact of this radiation on human eyes. Additionally, far-UVC sources are unavailable in larger quantities. Therefore, this is not a short-term solution for the current pandemic, but may be suitable for future technological approaches for decontamination in rooms in the presence of people or for antisepsis.

Exposure of Human Skin Models to KrCl Excimer Lamps: The Impact of Optical Filtering†.

Far‐UVC radiation is a promising technology that is potentially both effective at killing airborne microbes such as coronaviruses and influenza, and being minimally hazardous to the skin and eyes. Our previous studies on health risks from far‐UVC have employed a krypton‐chloride (KrCl) excimer lamp, emitting principally at 222 nm, supplemented with an optical filter to remove longer wavelength emissions inherent to these lamps. This study explores KrCl lamp health hazards by comparing filtered and unfiltered KrCl lamps using effective spectral irradiance calculations and experimental skin exposures. Analysis of effective irradiances showed a notable increase in allowable exposure when using a filter. Induction of DNA dimers (CPD and 6‐4PP) was measured in human skin models exposed to a range of radiant exposures up to 500 mJ cm−2. Compared to sham‐exposed tissues, the unfiltered KrCl lamps induced a statistically significant increase in the yield of both DNA lesions at all the radiant exposures studied. Conversely, filtered KrCl lamps do not induce increased levels of dimers at the current daily TLV exposure limit for 222 nm (23 mJ cm−2). This work supports the use of filters for far‐UVC KrCl excimer lamps when used to limit disease transmission in occupied locations.

Synergy of MS2 disinfection by sequential exposure to tailored UV wavelengths

The advantages of polychromatic ultraviolet (UV) light for viral disinfection can be optimized for disinfection using emerging tailored wavelength sources including KrCl excimer lamps and light emitting diodes (LEDs). Disinfection of the common viral surrogate MS2 bacteriophage was measured after exposure to these emerging sources and conventional low pressure (LP) mercury UV lamps in individual or sequential exposures. The first dose response for any virus (MS2) exposed to a KrCl excimer lamp is reported, showing the high efficiency of fluence-based disinfection because of increased viral susceptibility at the low wavelengths emitted by the excilamp. Sequential exposure dose responses indicated synergy from sequential exposures of LP and excimer lamps, which were competitive on an electrical basis at worst-and best-case scenarios of wall plug efficiency with current medium pressure (MP) disinfection. Best-case scenarios for electrical efficiency also showed all sequential exposures to be competitive with MP UV disinfection. Predictive models for sequential exposure dose responses were assessed to support the current feasibility of incorporating sequential UV exposures to optimize tailored wavelength viral disinfection.

Photodegradation of an Herbicide (2-methyl-4-chlorophenoxyacetic acid) in the Presence of “TiO<sub>2</sub>, SnO<sub>2</sub>, SnO<sub>2</sub>/TiO<sub>2</sub> Nanoparticles – Polypropylene Fibrous Carrier” Systems

Using electronic spectroscopy and fluorescence techniques, the degradation of 2-methyl-4-chlorophenoxyacetic acid has been researched in water under the excitation with UV radiation produced by a KrCl excimer lamp in the presence of “TiO2, SnO2, SnO2/TiO2Nanoparticles – Polypropylene Fibrous Carrier” Systems. It has been determined that MCPA phototransformation is most efficient when using the “TiO2/SnO2heteronanoparticles – carrier” system with the concentration of 25/6 mg/g. The results indicate that systems with applied semiconductor particles do not exhibit sorption properties towards МСРА molecules. Therefore, the change in the spectral characteristics of a МСРА water solution after time-exposure and exposure to radiation is only associated with the phototransformations of non-adsorbed МСРА molecules and with the emergence of their photodegradation products.

Impacts of natural organic matter on perchlorate removal by an advanced reduction process

Perchlorate can be destroyed by Advanced Reduction Processes (ARPs) that combine chemical reductants (e.g., sulfite) with activating methods (e.g., UV light) in order to produce highly reactive reducing free radicals that are capable of rapid and effective perchlorate reduction. However, natural organic matter (NOM) exists widely in the environment and has the potential to influence perchlorate reduction by ARPs that use UV light as the activating method. Batch experiments were conducted to obtain data on the impacts of NOM and wavelength of light on destruction of perchlorate by the ARPs that use sulfite activated by UV light produced by low-pressure mercury lamps (UV-L) or by KrCl excimer lamps (UV-KrCl). The results indicate that NOM strongly inhibits perchlorate removal by both ARP, because it competes with sulfite for UV light. Even though the absorbance of sulfite is much higher at 222 nm than that at 254 nm, the results indicate that a smaller amount of perchlorate was removed with the UV-KrCl lamp (222 nm) than with the UV-L lamp (254 nm). The results of this study will help to develop the proper way to apply the ARPs as practical water treatment processes.

Effects of natural organic matter and nitrate on the behavior of nitrosodimethylamine during ultraviolet irradiation and chloramination

Nitrosodimethylamine (NDMA), a potent carcinogen, is found in natural and engineered water systems. Ultraviolet (UV) treatment is potentially a useful tool for controlling NDMA at water purification plants. However, a recent study has reported that UV/advanced oxidation process (AOP) treatment may provide a source of NDMA precursors. Therefore, we investigated the effect of UV treatment on the potential for NDMA formation. Synthetic water samples containing NDMA together with Suwannee River Natural Organic Matter (SRNOM) and/or nitrate were exposed to a low-pressure (LP) UV lamp, a medium-pressure (MP) UV lamp, or a KrCl excimer lamp to determine the spectral impacts. NDMA formation potential was significantly decreased in nitrate solution by LP or MP UV exposure. Nitrate exposed to UV was assumed to have produced the OH radical, which degraded NDMA precursors. The NDMA concentration increased in solutions exposed to UV, even for those without chloramination, which contributed a certain portion of the total NDMA formation. Exposure to MP UV affected the formation of NDMA more significantly than exposure to LP UV due to the overlap of wavelengths in the MP UV emission and the absorption of nitrate.

Study of the influence of the sulfide and ultraviolet treatment of the n-i-GaAs surface on the parameters of ohmic contacts

The possibility of improving the parameters of AuGe/Ni- and Ge/Cu-based ohmic contacts to n-i-GaAs by modifying the preliminarily oxidized GaAs surface in a sulfide-containing solution, as well as via the effect of ultraviolet radiation generated with a KrCl excimer lamp on a chalcogenated surface, is studied. It is shown that preliminary oxidation of the n-i-GaAs surface with subsequent chalcogenation makes it possible to decrease the density of the surface states, to increase the reproducibility of the passivation of the surface, and to decrease the reduced contact resistance of the AuGe/Ni ohmic contacts by a factor of 1.5. The treatment of the chalcogenated surface of n-i-GaAs with an ultraviolet radiation with wavelength λ = 222 nm and emission power density W = 12 mW cm−2 performed in vacuum before the deposition of metal layers of the Ge/Cu ohmic contacts makes it possible to decrease the reduced contact resistance by 25–50% andimprove the morphological characteristics of the surface of the contact area.

COMBINED APPLICATION OF UV RADIATION AND CHLORINE: IMPLICATIONS WITH RESPECT TO DBP FORMATION AND DESTRUCTION IN RECREATIONAL WATER APPLICATIONS

COMBINED APPLICATION OF UV RADIATION AND CHLORINE: IMPLICATIONS WITH RESPECT TO DBP FORMATION AND DESTRUCTION IN RECREATIONAL WATER APPLICATIONSThe photolysis of four model volatile disinfection byproducts (DBPs) (NCl3, CNCHCl2, CNCl and CH3NCl2) and free chlorine was investigated with several different collimated UV sources, including: low-pressure Hg; a KrCl excimer lamp; and a XeBr excimer lamp. Photochemically-induced changes to residual chlorine and DBPs were monitored by membrane introduction mass spectrometry. The results indicate...Author(s)Jing LiErnest R. BlatchleySourceProceedings of the Water Environment FederationSubjectSession 4: Disinfection By-ProductsDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2007ISSN1938-6478SICI1938-6478(20070101)2007:1L.128;1-DOI10.2175/193864707787932117Volume / Issue2007 / 1Content sourceDisinfection and Reuse SymposiumFirst / last page(s)128 - 133Copyright2007Word count129