40 CFR 141.65 - Maximum residual disinfectant levels.

Code of Federal Regulations, 2011 CFR

2011-07-01

... MRDL (mg/L) Chlorine 4.0 (as Cl2). Chloramines 4.0 (as Cl2). Chlorine dioxide 0.8 (as ClO2). (b... chlorine dioxide as a disinfectant or oxidant must comply with the chlorine dioxide MRDL beginning January 1, 2002. Subpart H systems serving fewer than 10,000 persons and using chlorine dioxide as a...

40 CFR 141.535 - What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection?

Code of Federal Regulations, 2013 CFR

2013-07-01

..., ozone, or chlorine dioxide for primary disinfection? 141.535 Section 141.535 Protection of Environment... § 141.535 What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection? If your system uses chloramines, ozone, or chlorine dioxide for primary disinfection, you must also...

40 CFR 141.535 - What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection?

Code of Federal Regulations, 2011 CFR

2011-07-01

..., ozone, or chlorine dioxide for primary disinfection? 141.535 Section 141.535 Protection of Environment... § 141.535 What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection? If your system uses chloramines, ozone, or chlorine dioxide for primary disinfection, you must also...

40 CFR 141.535 - What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection?

Code of Federal Regulations, 2012 CFR

2012-07-01

..., ozone, or chlorine dioxide for primary disinfection? 141.535 Section 141.535 Protection of Environment... § 141.535 What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection? If your system uses chloramines, ozone, or chlorine dioxide for primary disinfection, you must also...

40 CFR 141.535 - What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection?

Code of Federal Regulations, 2014 CFR

2014-07-01

..., ozone, or chlorine dioxide for primary disinfection? 141.535 Section 141.535 Protection of Environment... § 141.535 What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection? If your system uses chloramines, ozone, or chlorine dioxide for primary disinfection, you must also...

Chlorine dioxide reactions with indoor materials during building disinfection: surface uptake.

PubMed

Hubbard, Heidi; Poppendieck, Dustin; Corsi, Richard L

2009-03-01

Chlorine dioxide received attention as a building disinfectant in the wake of Bacillus anthracis contamination of several large buildings in the fall of 2001. It is increasingly used for the disinfection of homes and other indoor environments afflicted by mold. However, little is known regarding the interaction of chlorine dioxide and indoor materials, particularly as related to the removal of chlorine dioxide from air. Such removal may be undesirable with respect to the subsequent formation of localized zones of depleted disinfectant concentrations and potential reductions in disinfection effectiveness in a building. The focus of this paper is on chlorine dioxide removal from air to each of 24 different indoor materials. Experiments were completed with materials housed in flow-through 48-L stainless steel chambers under standard conditions of 700 ppm chlorine dioxide inlet concentration, 75% relative humidity, 24 degrees C, and 0.5 h(-1) air changes. Chlorine dioxide concentration profiles, deposition velocities, and reaction probabilities are described in this paper. Deposition velocities and reaction probabilities varied over approximately 2 orders of magnitude across all materials. For most materials, deposition velocity decreased significantly over a 16-h disinfection period; that is, materials became smaller sinks for chlorine dioxide with time. Four materials (office partition, ceiling tile, medium density fiberboard, and gypsum wallboard) accounted for the most short- and long-term consumption of chlorine dioxide. Deposition velocity was observed to be a strong function of chlorine dioxide inlet concentration, suggesting the potential importance of chemical reactions on or within test materials.

40 CFR 141.132 - Monitoring requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... discretion. (2) Chlorite. Community and nontransient noncommunity water systems using chlorine dioxide, for... samples. (ii) Reduced monitoring. Monitoring may not be reduced. (2) Chlorine dioxide—(i) Routine... three chlorine dioxide distribution system samples. If chlorine dioxide or chloramines are used to...

40 CFR 141.544 - What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection?

Code of Federal Regulations, 2013 CFR

2013-07-01

..., ozone, or chlorine dioxide for primary disinfection? 141.544 Section 141.544 Protection of Environment... Benchmark § 141.544 What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection? If your system uses chloramines, ozone or chlorine dioxide for primary disinfection your system must...

40 CFR 141.544 - What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection?

Code of Federal Regulations, 2014 CFR

2014-07-01

..., ozone, or chlorine dioxide for primary disinfection? 141.544 Section 141.544 Protection of Environment... Benchmark § 141.544 What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection? If your system uses chloramines, ozone or chlorine dioxide for primary disinfection your system must...

40 CFR 141.544 - What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection?

Code of Federal Regulations, 2012 CFR

2012-07-01

..., ozone, or chlorine dioxide for primary disinfection? 141.544 Section 141.544 Protection of Environment... Benchmark § 141.544 What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection? If your system uses chloramines, ozone or chlorine dioxide for primary disinfection your system must...

40 CFR 141.544 - What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection?

Code of Federal Regulations, 2011 CFR

2011-07-01

..., ozone, or chlorine dioxide for primary disinfection? 141.544 Section 141.544 Protection of Environment... Benchmark § 141.544 What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection? If your system uses chloramines, ozone or chlorine dioxide for primary disinfection your system must...

Effects of ozone, chlorine dioxide, chlorine, and monochloramine on Cryptosporidium parvum oocyst viability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Korich, D.G.; Mead, J.R.; Madore, M.S.

1990-05-01

Purified Cryptosporidium parvum oocysts were exposed to ozone, chlorine dioxide, chlorine, and monochloramine. Excystation and mouse infectivity were comparatively evaluated to assess oocyst viability. Ozone and chlorine dioxide more effectively inactivated oocysts than chlorine and monochloramine did. Greater than 90% inactivation as measured by infectivity was achieved by treating oocysts with 1 ppm of ozone (1 mg/liter) for 5 min. Exposure to 1.3 ppm of chlorine dioxide yielded 90% inactivation after 1 h, while 80 ppm of chlorine and 80 ppm of monochloramine required approximately 90 min for 90% inactivation. The data indicate that C. parvum oocysts are 30 timesmore » more resistant to ozone and 14 times more resistant to chlorine dioxide than Giardia cysts exposed to these disinfectants under the same conditions. With the possible exception of ozone, the use of disinfectants alone should not be expected to inactivate C. parvum oocysts in drinking water.« less

21 CFR 173.300 - Chlorine dioxide.

Code of Federal Regulations, 2012 CFR

2012-04-01

... chlorate with hydrogen peroxide in the presence of sulfuric acid. (iii) Treating an aqueous solution of sodium chlorite by electrolysis. (2) The generator effluent contains at least 90 percent (by weight) of...

21 CFR 173.300 - Chlorine dioxide.

Code of Federal Regulations, 2013 CFR

2013-04-01

... chlorate with hydrogen peroxide in the presence of sulfuric acid. (iii) Treating an aqueous solution of sodium chlorite by electrolysis. (2) The generator effluent contains at least 90 percent (by weight) of...

Study on encapsulation of chlorine dioxide in gelatin microsphere for reducing release rate

PubMed Central

Ci, Ying; Wang, Lin; Guo, Yanchuan; Sun, Ruixue; Wang, Xijie; Li, Jinyou

2015-01-01

Objective: This study aims to explore the effects of encapsulation of chlorine dioxide in a hydrophilic biodegradable polymer gelatin to reduce its release rate. Methods: An emulsification-coacervation method was adopted. The characterizations of chlorine dioxide-gelatin microspheres were described. Using UV-vis spectrophotometer the λmax of chlorine dioxide was observed at 358 nm. The particle size and distribution of chlorine oxide-gelatin microspheres was measured by a dynamic light scattering (DLS) method, the diameter was (1400~1900) nm. The entrapment of chlorine dioxide-gelatin microspheres was confirmed by IR. The surface morphology, size, and shape of chlorine dioxide-gelatin microspheres were analyzed using Scanning electron microscope (SEM). Results: It showed that the encapsulated microspheres size was around 2000 nm with uniform distribution. The percentage entrapment of chlorine dioxide in the encapsulated samples was about 80~85%. A slow release study of chlorine dioxide from the encapsulated biopolymer (gelatin) in air was also carried out, which showed continuous release up to ten days. Conclusions: It can be concluded that it is possible to make a slow release formulation of ClO2 by entrapped in a hydrophilic biodegradable polymer gelatin. ClO2-gelatin microspheres can stable release low concentration ClO2 gas over an extended period. PMID:26550151

Chlorine dioxide as a post-disinfectant for Dutch drinking water.

PubMed

Wondergem, E; van Dijk-Looijaard, A M

1991-02-01

Chlorine dioxide has some important advantages over chlorine with respect to water quality (no formation of trihalomethanes, no impairment of taste and no odor) and stability when used for oxidation/disinfection of drinking water. In this paper, results are presented of experiments into the consumption and reaction kinetics of chlorine dioxide in a number of (drinking) waters in The Netherlands. It was found that chlorine dioxide consumption is related to the dissolved oxygen content (DOC) of the water and the reaction time. Water samples from a plant that applied ozonation and activated carbon filtration had a very low chlorine dioxide consumption. Other water quality parameters, including pH and CO3(2-), did not have any influence on consumption. The temporary advised Dutch guidelines of 0.2 mg l-1 (dosage) is sufficient for activated carbon treated water. For other Dutch drinking waters, however, none of the 0.2 mg l-1 chlorine dioxide remained after a reaction time of 10 min, as was also found for the water of Dutch pumping stations where chlorine dioxide is at present used for disinfection.

Exposure to chlorine dioxide gas for 4 hours renders Syphacia ova nonviable.

PubMed

Czarra, Jane A; Adams, Joleen K; Carter, Christopher L; Hill, William A; Coan, Patricia N

2014-07-01

The purpose of our study was to evaluate the efficacy of chlorine dioxide gas for environmental decontamination of Syphacia spp. ova. We collected Syphacia ova by perianal cellophane tape impression of pinworm-infected mice. Tapes with attached ova were exposed to chlorine dioxide gas for 1, 2, 3, or 4 h. After gas exposure, ova were incubated in hatching medium for 6 h to promote hatching. For controls, tapes with attached ova were maintained at room temperature for 1, 2, 3, and 4 h without exposure to chlorine dioxide gas and similarly incubated in hatch medium for 6 h. Ova viability after incubation was assessed by microscopic examination. Exposure to chlorine dioxide gas for 4 h rendered 100% of Syphacia spp. ova nonviable. Conversely, only 17% of ova on the 4-h control slide were nonviable. Other times of exposure to chlorine dioxide gas resulted in variable effectiveness. These data suggest that exposure to chlorine dioxide gas for at least 4 h is effective for surface decontamination of Syphacia spp. ova.

Reducing the chlorine dioxide demand in final disinfection of drinking water treatment plants using activated carbon.

PubMed

Sorlini, Sabrina; Biasibetti, Michela; Collivignarelli, Maria Cristina; Crotti, Barbara Marianna

2015-01-01

Chlorine dioxide is one of the most widely employed chemicals in the disinfection process of a drinking water treatment plant (DWTP). The aim of this work was to evaluate the influence of the adsorption process with granular activated carbon (GAC) on the chlorine dioxide consumption in final oxidation/disinfection. A first series of tests was performed at the laboratory scale employing water samples collected at the outlet of the DWTP sand filter of Cremona (Italy). The adsorption process in batch conditions with seven different types of GAC was studied. A second series of tests was performed on water samples collected at the outlet of four GAC columns installed at the outlet of the DWTP sand filter. The results showed that the best chlorine dioxide demand (ClO2-D) reduction yields are equal to 60-80% and are achieved in the first 30 min after ClO2 addition, during the first 16 days of the column operation using a mineral, coal-based, mesoporous GAC. Therefore, this carbon removes organic compounds that are more rapidly reactive with ClO2. Moreover, a good correlation was found between the ClO2-D and UV absorbance at wavelength 254 nm using mineral carbons; therefore, the use of a mineral mesoporous GAC is an effective solution to control the high ClO2-D in the disinfection stage of a DWTP.

46 CFR Table 2 to Part 153 - Cargoes Not Regulated Under Subchapters D or O of This Chapter When Carried in Bulk on Non...

Code of Federal Regulations, 2011 CFR

2011-10-01

...) (with 52% Chlorine) III 2-Chloro-4-ethylamino-6-isopropylamino-5-triazine solution # Choline chloride... Ethylenediaminetetraacetic acid, tetrasodium salt solution Titanium dioxide slurry III 1,1,1-Trichloroethane C 1,1,2...

Application of Highly Purified Electrolyzed Chlorine Dioxide for Tilapia Fillet Disinfection

PubMed Central

Yu, Chen-Hsing; Huang, Tzou-Chi; Chung, Chao-Chin; Huang, Hao-Hsun

2014-01-01

This research aimed to develop an electrolysis method to generate high-concentration chlorine dioxide (ClO2) for tilapia fillet disinfection. The designed generator produced up to 3500 ppm of ClO2 at up to 99% purity. Tilapia fillets were soaked in a 400 ppm ClO2 solution for 5, 10, and 25 min. Results show that total plate counts of tilapia, respectively, decreased by 5.72 to 3.23, 2.10, and 1.09 log CFU/g. In addition, a 200 ppm ClO2 solution eliminated coliform bacteria and Escherichia coli in 5 min with shaking treatment. Furthermore, ClO2 and trihalomethanes (THMs) residuals on tilapia fillets were analyzed by GC/MS and were nondetectable (GC-MS detection limit was 0.12 ppb). The results conform to Taiwan's environmental protection regulations and act governing food sanitation. PMID:24696651

IDENTIFICATION OF NEW DRINKING WATER DISINFECTION BY-PRODUCTS FROM OZONE, CHLORINE DIOXIDE, CHLORAMINE, AND CHLORINE

EPA Science Inventory

Due to concern over the potential adverse health effects of trihalomethanes (THMs) and other chlorinated by-products in chlorinated drinking water, alternative disinfection methods are being explored. Ozone, chlorine dioxide, and chloramine are currently popular alternatives to ...

CHLORINE DIOXIDE CHEMISTRY, REACTIONS, AND DISINFECTION BY-PRODUCTS

EPA Science Inventory

This chapter contains two main sections-the first section describes the chemistry and reactions of chlorine dioxide, and the second describes the disinfection by-products (DBPs) of chlorine dioxide and their control. A short section on Research Needs completes this chapter. The...

Raman spectra and cross sections of ammonia, chlorine, hydrogen sulfide, phosgene, and sulfur dioxide toxic gases in the fingerprint region 400 1400 cm 1

DTIC Science & Technology

2015-11-24

ammonia , chlorine, hydrogen sulfide, phosgene, and sulfur dioxide toxic gases in the fingerprint region 400... ammonia (NH3), chlorine (Cl2), hydrogen sulfide (H2S), phosgene (COCl2), and sulfur dioxide (SO2) toxic gases have been measured in the fingerprint...sections of ammonia (NH3), chlorine (Cl2), hydrogen sulfide (H2S), phosgene (CCl2O), and sulfur dioxide (SO2) toxic gases in the fingerprint

Raman Spectra and Cross Sections of Ammonia, Chlorine, Hydrogen Sulfide, Phosgene, and Sulfur Dioxide Toxic Gases in the Fingerprint Region 400-1400 cm-1

DTIC Science & Technology

2015-12-14

ammonia , chlorine, hydrogen sulfide, phosgene, and sulfur dioxide toxic gases in the fingerprint region 400... ammonia (NH3), chlorine (Cl2), hydrogen sulfide (H2S), phosgene (COCl2), and sulfur dioxide (SO2) toxic gases have been measured in the fingerprint...sections of ammonia (NH3), chlorine (Cl2), hydrogen sulfide (H2S), phosgene (CCl2O), and sulfur dioxide (SO2) toxic gases in the fingerprint region

DRINKING WATER DISINFECTION BY-PRODUCTS: WHAT IS KNOWN

EPA Science Inventory

Chlorine, ozone, chlorine dioxide, and chloramine are currently the major disinfectants being used to disinfect drinking water. Although the alternative disinfectants (ozone, chlorine dioxide, and chloramine) are increasing in popularity in the United States, chlorine is still us...

Chlorine Dioxide Induced Multiple Chemical Sensitivity: MMPI Validity Problems.

ERIC Educational Resources Information Center

Tentoni, Stuart C.

This paper discusses Minnesota Multiphasic Personality Inventory (MMPI) data obtained from individuals exposed to chlorine dioxide in the workplace who developed Multiple Chemical Sensitivity Syndrome. The paper explores current research on chlorine dioxide exposed persons who were misdiagnosed on the basis of MMPI interpretations. Difficulties…

The Health Effects of Chlorine Dioxide as a Disinfectant in Potable Water: A Literature Survey

ERIC Educational Resources Information Center

Calabrese, Edward J.; And Others

1978-01-01

The use of chlorine dioxide as a disinfectant in water is being considered by the EPA. This article presents a summary of the known published reports concerning health effects of chlorine dioxide on animal and human populations. (Author/MA)

IDENTIFICATION OF CHLORINE DIOXIDE AND CHLORAMINE DRINKING WATER DISINFECTION BY-PRODUCTS

EPA Science Inventory

Due to concern over the potential adverse health effects of trihalomethanes (THMs) and other chlorinated by-products in chlorinated drinking water, alternative disinfection methods are being explored. Chlorine dioxide and chloramine are two popular alternative disinfectants, with...

40 CFR 141.130 - General requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... this subpart establish criteria under which transient NCWSs that use chlorine dioxide as a disinfectant or oxidant must modify their practices to meet the MRDL for chlorine dioxide in § 141.65. (3) EPA has... systems serving 10,000 or more persons and using chlorine dioxide as a disinfectant or oxidant must comply...

Application of Chlorine Dioxide to Lessen Bacterial Contamination during Broiler Defeathering

USDA-ARS?s Scientific Manuscript database

Due to escape of contaminated gut contents, the number of Campylobacter spp. recovered from broiler carcasses increases during feather removal. Chlorine dioxide (ClO2) is approved for use as an antimicrobial treatment during poultry processing. A chlorine dioxide generator was placed in a commerci...

IDENTIFICATION OF CHLORINE DIOXIDE DRINKING WATER DISINFECTION BY-PRODUCTS FORMED AT HIGH BROMIDE LEVELS

EPA Science Inventory

Due to concern over the potential adverse health effects of trihalomethanes (THMs), haloacetic acids, and other chlorinated by-products in chlorinated drinking water, alternative disinfection methods are being explored. Chlorine dioxide is a popular alternative, with over 500 dri...

49 CFR 173.3 - Packaging and exceptions.

Code of Federal Regulations, 2011 CFR

2011-10-01

...-unit tank car tanks. (1) A DOT 3A480 or DOT 3AA480 cylinder containing chlorine or sulphur dioxide that... containing chlorine or sulphur dioxide that has developed a leak in the valve or fusible plug may be... equipment; and (iii) Knowledge of the properties of chlorine and sulphur dioxide. (4) Packagings repaired...

40 CFR 141.133 - Compliance requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... to lower the level of chlorine dioxide below the MRDL and must notify the public pursuant to the.... Failure to take samples in the distribution system the day following an exceedance of the chlorine dioxide... corrective action to lower the level of chlorine dioxide below the MRDL at the point of sampling and will...

Plant physiological response of strawberry fruit to chlorine dioxide gas treatment during postharvest storage

USDA-ARS?s Scientific Manuscript database

Chlorine dioxide, a strong oxidizing and sanitizing agent, is used as a postharvest sanitizer for fruits and vegetables and generally applied on a packing line using a chlorine dioxide generator. The objective of this research was to study the physiological responses of strawberries to ClO2 when app...

Measurement of Chlorine Dioxide in Water by DPD Colorimetric Method

NASA Astrophysics Data System (ADS)

Song, Min; Yan, Panping; Yao, Jun

2018-01-01

In order to solve the problems of chlorine dioxide in water by DPD colorimetric method, this paper discusses the effects of the formulation, temperature, color development time and amount of color reagent on the measurement process, improving the on-line instrument for domestic and drinking water in chlorine dioxide measurement precision and accuracy.

IDENTIFICATION OF DRINKING WATER DISINFECTION BY-PRODUCTS FROM OZONE, CHLORINE DIOXIDE, CHLORAMINE, AND CHLORINE

EPA Science Inventory

Many drinking water treatment plants are currently using alternative disinfectants to treat drinking water, with ozone, chlorine dioxide, and chloramine being the most popular. However, compared to chlorine, which has been much more widely studied, there is little information abo...

Efficacy of chlorine dioxide mouthwash against halitosis

NASA Astrophysics Data System (ADS)

Bestari, M. D.; Sunarto, H.; Kemal, Y.

2017-08-01

To ascertain the effectiveness of using chlorine dioxide mouthwash in addressing halitosis. Forty people were divided equally into the test group (required to gargle with mouthwash containing chlorine dioxide) and the control group (required to gargle with aquadest). The volatile sulfur compound (VSC) and organoleptic scores were measured before gargling and 30 min, 2 h, 4 h, and 6 h after. The Wilcoxon test analysis showed a significant difference (p<0.05) in the mean value of VSC scores between the test group and the control group in four testing periods after gargling. Chlorine dioxide mouthwash is effective in addressing halitosis.

Formation of assimilable organic carbon during oxidation of natural waters with ozone, chlorine dioxide, chlorine, permanganate, and ferrate.

PubMed

Ramseier, Maaike K; Peter, Andreas; Traber, Jacqueline; von Gunten, Urs

2011-02-01

Five oxidants, ozone, chlorine dioxide, chlorine, permanganate, and ferrate were studied with regard to the formation of assimilable organic carbon (AOC) and oxalate in absence and presence of cyanobacteria in lake water matrices. Ozone and ferrate formed significant amounts of AOC, i.e. more than 100 μg/L AOC were formed with 4.6 mg/L ozone and ferrate in water with 3.8 mg/L dissolved organic carbon. In the same water samples chlorine dioxide, chlorine, and permanganate produced no or only limited AOC. When cyanobacterial cells (Aphanizomenon gracile) were added to the water, an AOC increase was detected with ozone, permanganate, and ferrate, probably due to cell lysis. This was confirmed by the increase of extracellular geosmin, a substance found in the selected cyanobacterial cells. AOC formation by chlorine and chlorine dioxide was not affected by the presence of the cells. The formation of oxalate upon oxidation was found to be a linear function of the oxidant consumption for all five oxidants. The following molar yields were measured in three different water matrices based on oxidant consumed: 2.4-4.4% for ozone, 1.0-2.8% for chlorine dioxide and chlorine, 1.1-1.2% for ferrate, and 11-16% for permanganate. Furthermore, oxalate was formed in similar concentrations as trihalomethanes during chlorination (yield ∼ 1% based on chlorine consumed). Oxalate formation kinetics and stoichiometry did not correspond to the AOC formation. Therefore, oxalate cannot be used as a surrogate for AOC formation during oxidative water treatment. Copyright © 2010 Elsevier Ltd. All rights reserved.

Distribution, identification, and quantification of residues after treatment of ready-to-eat salami with 36Cl-labeled or nonlabeled chlorine dioxide gas

USDA-ARS?s Scientific Manuscript database

Chlorine dioxide gas actively eliminates a variety of food-borne pathogens and rot organisms, including Listeria monocytogenes on food and food preparation surfaces. However the disposition and fate of chlorine dioxide gas on ready-to-eat meat products has not been previously described. When ready-t...

Direct effect of chlorine dioxide, zinc chloride and chlorhexidine solution on the gaseous volatile sulfur compounds.

PubMed

Kim, Ju-Sik; Park, Ji-Woon; Kim, Dae-Jung; Kim, Young-Ku; Lee, Jeong-Yun

2014-11-01

This study focused on the ability of aqueous anti-volatile-sulfur-compound (VSC) solutions to eliminate gaseous VSCs by direct contact in a sealed space to describe possible mode of action of anti-VSC agents. Twenty milliliters of each experimental solution, 0.16% sodium chlorite, 0.25% zinc chloride, 0.1% chlorhexidine and distilled water, was injected into a Teflon bag containing mixed VSCs, hydrogen sulfide, methyl mercaptan and dimethyl sulfide and mixed vigorously for 30 s. The VSC concentration was measured by gas chromatography before, immediately after, 30 min and 60 min after mixing. The sodium chlorite solution reduced the VSC concentration remarkably. After mixing, nearly all VSCs were eliminated immediately and no VSCs were detected at 30 and 60 min post-mixing. However, in the other solutions, the VSC concentration decreased by ∼30% immediately after mixing and there was no further decrease. The results suggest that sodium chlorite solution has the effect of eliminating gaseous VSCs directly. This must be because it can release chlorine dioxide gas which can react directly with gaseous VSCs. In the case of other solutions that have been proved to be effective to reduce halitosis clinically, it can be proposed that their anti-VSC effect is less likely due to the direct chemical elimination of gaseous VSCs in the mouth.

Raman Spectra and Cross Sections of Ammonia, Chlorine, Hydrogen Sulfide, Phosgene, and Sulfur Dioxide Toxic Gases in the Fingerprint Region 400-1400 cm-1

DTIC Science & Technology

2016-02-11

AIP ADVANCES 6, 025310 (2016) Raman spectra and cross sections of ammonia , chlorine, hydrogen sulfide, phosgene, and sulfur dioxide toxic gases in...Received 10 December 2015; accepted 3 February 2016; published online 11 February 2016) Raman spectra of ammonia (NH3), chlorine (Cl2), hydrogen...and cross sections of ammonia (NH3), chlorine (Cl2), hydrogen sulfide (H2S), phosgene (CCl2O), and sulfur dioxide (SO2) toxic gases in the fingerprint

42 CFR Appendix - Tables to Subpart L of Part 84

Code of Federal Regulations, 2010 CFR

2010-10-01

... respiratory protection against more than one gas of a type, as for use in chlorine and sulfur dioxide, the... Ammonia Equilibrated NH3 1000 32 4 50 50 Chlorine As received Cl2 500 64 3 5 35 Chlorine Equilibrated Cl2... Sulfur dioxide As received SO2 500 64 3 5 30 Sulfur dioxide Equilibrated SO2 500 32 4 5 30 1 Minimum life...

Investigation Of Ballast Water Treatment’s Effect On Corrosion

DTIC Science & Technology

2013-03-01

Lysogorski, et al | Public March 2013 N O T I C E This document is disseminated under the sponsorship of the Department of Homeland...Controlled laboratory tests were conducted using simulated chlorination, deoxygenation and chlorine dioxide disinfection . Materials were exposed to three...Great Lakes water simulated chlorination, deoxygenation, and chlorine dioxide disinfection . All testing was conducted at NRLKW. Natural, unfiltered

An evaluation of the use of chlorine dioxide (Tristel One-Shot) in an automated washer/disinfector (Medivator) fitted with a chlorine dioxide generator for decontamination of flexible endoscopes.

PubMed

Coates, D

2001-05-01

Microbiological tests were carried out to evaluate a new chlorine dioxide sterilant: Tristel OneShot. Preliminary in vitro suspension tests showed that solutions containing around 140 ppm chlorine dioxide achieved a reduction factor exceeding 10(6) of Staphylococcus aureus in 1min and of Bacillus subtilis spores in 2.5 min in the presence of 3g/L bovine albumin. Subsequent tests evaluated the effectiveness of Tristel One-Shot in a Medivator washer/disinfector fitted with a Tristel Generator for processing flexible endoscopes. Each test run involved three stages. In the first, the instrument and air-water channels of a gastroscope were inoculated with a suspension of Pseudomonas aeruginosa (10(8)cfu/ml) in 10% sodium glutamate and serum (0, 5 or 10%) and then drained, partially dried, and saline flushed through for total viable counts (TVCs). In the second stage, the channels were re-inoculated with test organisms; detergent was flushed through the channels which were then brushed; and saline was flushed through for TVCs. In the third stage, the channels were re-inoculated; detergent was flushed through the channels which were then brushed; the endoscope was processed in the Medivator; and saline was flushed through for TVCs. Carrying out all three stages enabled determination of (1) the contribution played by manual cleaning of channels prior to processing in the Medivator, and (2) the combined effect of manual cleaning followed by processing. Two series of test runs were done. In the first, the Tristel Generator was set to generate 230ppm chlorine dioxide, and in the second 150ppm. In the first, cleaning followed by processing in the Medivator consistently achieved a >/= 10(6)-fold reduction of test organisms, and in the second a >/= 10(5)-fold reduction. Pre-cleaning of channels was very important-when done the initial concentration of serum in the inoculum (0-10%) had no affect on the results obtained after processing. Copyright 2001 The Hospital infection Society.

Degradation of sulfamethoxazole using ozone and chlorine dioxide - Compound-specific stable isotope analysis, transformation product analysis and mechanistic aspects.

PubMed

Willach, Sarah; Lutze, Holger V; Eckey, Kevin; Löppenberg, Katja; Lüling, Michelle; Terhalle, Jens; Wolbert, Jens-Benjamin; Jochmann, Maik A; Karst, Uwe; Schmidt, Torsten C

2017-10-01

The sulfonamide antibiotic sulfamethoxazole (SMX) is a widely detected micropollutant in surface and groundwaters. Oxidative treatment with e.g. ozone or chlorine dioxide is regularly applied for disinfection purposes at the same time exhibiting a high potential for removal of micropollutants. Especially for nitrogen containing compounds such as SMX, the related reaction mechanisms are largely unknown. In this study, we systematically investigated reaction stoichiometry, product formation and reaction mechanisms in reactions of SMX with ozone and chlorine dioxide. To this end, the neutral and anionic SMX species, which may occur at typical pH-values of water treatment were studied. Two moles of chlorine dioxide and approximately three moles of ozone were consumed per mole SMX degraded. Oxidation of SMX with ozone and chlorine dioxide leads in both cases to six major transformation products (TPs) as revealed by high-resolution mass spectrometry (HRMS). Tentatively formulated TP structures from other studies could partly be confirmed by compound-specific stable isotope analysis (CSIA). However, for one TP, a hydroxylated SMX, it was not possible by HRMS alone to identify whether hydroxylation occurred at the aromatic ring, as suggested in literature before, or at the anilinic nitrogen. By means of CSIA and an analytical standard it was possible to identify sulfamethoxazole hydroxylamine unequivocally as one of the TPs of the reaction of SMX with ozone as well as with chlorine dioxide. H-abstraction and electron transfer at the anilinic nitrogen are suggested as likely initial reactions of ozone and chlorine dioxide, respectively, leading to its formation. Oxidation of anionic SMX with ozone did not show any significant isotopic fractionation whereas the other reactions studied resulted in a significant carbon isotope fractionation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chlorine Dioxide Inactivation of Cryptosporidium parvum Oocysts and Bacterial Spore Indicators

PubMed Central

Chauret, Christian P.; Radziminski, Chris Z.; Lepuil, Michael; Creason, Robin; Andrews, Robert C.

2001-01-01

Cryptosporidium parvum, which is resistant to chlorine concentrations typically used in water treatment, is recognized as a significant waterborne pathogen. Recent studies have demonstrated that chlorine dioxide is a more efficient disinfectant than free chlorine against Cryptosporidium oocysts. It is not known, however, if oocysts from different suppliers are equally sensitive to chlorine dioxide. This study used both a most-probable-number–cell culture infectivity assay and in vitro excystation to evaluate chlorine dioxide inactivation kinetics in laboratory water at pH 8 and 21°C. The two viability methods produced significantly different results (P < 0.05). Products of disinfectant concentration and contact time (Ct values) of 1,000 mg · min/liter were needed to inactivate approximately 0.5 log10 and 2.0 log10 units (99% inactivation) of C. parvum as measured by in vitro excystation and cell infectivity, respectively, suggesting that excystation is not an adequate viability assay. Purified oocysts originating from three different suppliers were evaluated and showed marked differences with respect to their resistance to inactivation when using chlorine dioxide. Ct values of 75, 550, and 1,000 mg · min/liter were required to achieve approximately 2.0 log10 units of inactivation with oocysts from different sources. Finally, the study compared the relationship between easily measured indicators, including Bacillus subtilis (aerobic) spores and Clostridium sporogenes (anaerobic) spores, and C. parvum oocysts. The bacterial spores were found to be more sensitive to chlorine dioxide than C. parvum oocysts and therefore could not be used as direct indicators of C. parvum inactivation for this disinfectant. In conclusion, it is suggested that future studies address issues such as oocyst purification protocols and the genetic diversity of C. parvum, since these factors might affect oocyst disinfection sensitivity. PMID:11425712

40 CFR 141.712 - Unfiltered system Cryptosporidium treatment requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... inactivation. (c) Inactivation treatment technology requirements. Unfiltered systems must use chlorine dioxide... section. (1) Systems that use chlorine dioxide or ozone and fail to achieve the Cryptosporidium...

40 CFR 141.712 - Unfiltered system Cryptosporidium treatment requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... inactivation. (c) Inactivation treatment technology requirements. Unfiltered systems must use chlorine dioxide... section. (1) Systems that use chlorine dioxide or ozone and fail to achieve the Cryptosporidium...

Effect of sanitizer washing on quality and shelf-life of fresh coriander during refrigerated storage

USDA-ARS?s Scientific Manuscript database

Fresh coriander leaves are highly perishable in nature and their sensory quality and nutritional value decreases without proper processing or preservation. In the present study, three aqueous solutions of sodium hypochlorite (SH, 100mg/L), chlorine dioxide (CD, 10 mg/L), and sodium butyl p-hydroxyb...

21 CFR 186.1750 - Sodium chlorite.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium chlorite. 186.1750 Section 186.1750 Food... of Specific Substances Affirmed as GRAS § 186.1750 Sodium chlorite. (a) Sodium chlorite (NaCLO2, CAS... passing chlorine dioxide into a solution of sodium hydroxide and hydrogen peroxide. (b) the ingredient is...

21 CFR 186.1750 - Sodium chlorite.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium chlorite. 186.1750 Section 186.1750 Food... of Specific Substances Affirmed as GRAS § 186.1750 Sodium chlorite. (a) Sodium chlorite (NaCLO2, CAS... passing chlorine dioxide into a solution of sodium hydroxide and hydrogen peroxide. (b) the ingredient is...

21 CFR 186.1750 - Sodium chlorite.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium chlorite. 186.1750 Section 186.1750 Food... of Specific Substances Affirmed as GRAS § 186.1750 Sodium chlorite. (a) Sodium chlorite (NaCLO2, CAS... passing chlorine dioxide into a solution of sodium hydroxide and hydrogen peroxide. (b) the ingredient is...

40 CFR 142.60 - Variances from the maximum contaminant level for total trihalomethanes.

Code of Federal Regulations, 2011 CFR

2011-07-01

... disinfectant or oxidant. (2) Use of chlorine dioxide as an alternate or supplemental disinfectant or oxidant... to reduce TTHM formation and, where necessary, substituting for the use of chlorine as a pre-oxidant chloramines, chlorine dioxide or potassium permanganate. (5) Use of powdered activated carbon for THM...

Disinfection of football protective equipment using chlorine dioxide produced by the ICA TriNova system

PubMed Central

Newsome, Anthony L; DuBois, John D; Tenney, Joel D

2009-01-01

Backround Community-associated methicillin-resistant Staphylococcus aureus outbreaks have occurred in individuals engaged in athletic activities such as wrestling and football. Potential disease reduction interventions include the reduction or elimination of bacteria on common use items such as equipment. Chlorine dioxide has a long history of use as a disinfectant. The purpose of this investigation was to evaluate the ability of novel portable chlorine dioxide generation devices to eliminate bacteria contamination of helmets and pads used by individuals engaged in football. Methods In field studies, the number of bacteria associated with heavily used football helmets and shoulder pads was determined before and after overnight treatment with chlorine dioxide gas. Bacteria were recovered using cotton swabs and plated onto trypticase soy agar plates. In laboratory studies, Staphylococcus aureus was applied directly to pads. The penetration of bacteria into the pads was determined by inoculating agar plates with portions of the pads taken from the different layers of padding. The ability to eliminate bacteria on the pad surface and underlying foam layers after treatment with chlorine dioxide was also determined. Results Rates of recovery of bacteria after treatment clearly demonstrated that chlorine dioxide significantly (p < 0.001) reduce and eliminated bacteria found on the surface of pads. For example, the soft surface of shoulder pads from a university averaged 2.7 × 103 recoverable bacteria colonies before chlorine dioxide treatment and 1.3 × 102 recoverable colonies after treatment. In addition, the gas was capable of penetrating the mesh surface layer and killing bacteria in the underlying foam pad layers. Here, 7 × 103 to 4.5 × 103 laboratory applied S. aureus colonies were recovered from underlying layers before treatment and 0 colonies were present after treatment. Both naturally occurring bacteria and S. aureus were susceptible to the treatment process. Conclusion Results of this study have shown that chlorine dioxide can easily and safely be used to eliminate bacteria contamination of protective pads used by football players. This could serve to reduce exposure to potential pathogens such as the methicillin-resistant Staphylococcus aureus among this group of individuals. PMID:19737415

Comparative evaluation of human pulp tissue dissolution by different concentrations of chlorine dioxide, calcium hypochlorite and sodium hypochlorite: An in vitro study

PubMed Central

Taneja, Sonali; Mishra, Neha; Malik, Shubhra

2014-01-01

Introduction: Irrigation plays an indispensable role in removal of tissue remnants and debris from the complicated root canal system. This study compared the human pulp tissue dissolution by different concentrations of chlorine dioxide, calcium hypochlorite and sodium hypochlorite. Materials and Methods: Pulp tissue was standardized to a weight of 9 mg for each sample. In all,60 samples obtained were divided into 6 groups according to the irrigating solution used- 2.5% sodium hypochlorite (NaOCl), 5.25% NaOCl, 5% calcium hypochlorite (Ca(OCl)2), 10% Ca(OCl)2, 5%chlorine dioxide (ClO2) and 13% ClO2. Pulp tissue was placed in each test tube carrying irrigants of measured volume (5ml) according to their specified subgroup time interval: 30 minutes (Subgroup A) and 60 minutes (Subgroup B). The solution from each sample test tube was filtered and was left for drying overnight. The residual weight was calculated by filtration method. Results: Mean tissue dissolution increases with increase in time period. Results showed 5.25% NaOCl to be most effective at both time intervals followed by 2.5% NaOCl at 60 minutes, 10%Ca(OCl)2 and 13% ClO2 at 60 minutes. Least amount of tissue dissolving ability was demonstrated by 5% Ca(OCl)2 and 5% ClO2 at 30 minutes. Distilled water showed no pulp tissue dissolution. Conclusion: Withinthe limitations of the study, NaOCl most efficiently dissolved the pulp tissue at both concentrations and at both time intervals. Mean tissue dissolution by Ca(OCl)2 and ClO2 gradually increased with time and with their increase in concentration. PMID:25506141

Inactivation of human and simian rotaviruses by chlorine dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Yu-Shiaw; Vaughn, J.M.

1990-05-01

The inactivation of single-particle stocks of human (type 2, Wa) and simian (SA-11) rotaviruses by chlorine dioxide was investigated. Experiments were conducted at 4{degree}C in a standard phosphate-carbonate buffer. Both virus types were rapidly inactivated, within 20 s under alkaline conditions, when chlorine dioxide concentrations ranging from 0.05 to 0.2 mg/liter were used. Similar reductions of 10{sup 5}-fold in infectivity required additional exposure time of 120 s at 0.2 mg/liter for Wa and at 0.5 mg/liter for SA-11, respectively, at pH 6.0. The inactivation of both virus types was moderate a neutral pH, and the sensitivities to chlorine dioxide weremore » similar. The observed enhancement of virucidal efficiency with increasing pH was contrary to earlier findings with chlorine- and ozone-treated rotavirus particles, where efficiencies decreased with increasing alkalinity. Comparison of 99.9% virus inactivation times revealed ozone to be the most effective virucidal agent among these three disinfectants.« less

A comparison of the virucidal properties of chlorine, chlorine dioxide, bromine chloride and iodine.

PubMed Central

Taylor, G. R.; Butler, M.

1982-01-01

Chlorine dioxide, bromine chloride and iodine were compared with chlorine as virucidal agents. Under optimal conditions all disinfectants were effective at low concentrations, but each disinfectant responded differently to acidity and alkalinity. Disinfection by chlorine was impaired by the presence of ammonia, but the other disinfectants retained much of their potency. Disinfection of poliovirus by iodine resulted in structural changes in the virions as seen by electron micrroscopy, but the other disinfectants were able to inactivate poliovirus without causing any apparent structural changes. Images Plate 1 PMID:6290566

Managing calcium oxalate scale in the bleach plant

Treesearch

Alan Rudie; Peter Hart

2005-01-01

To comply with the U.S. Environmental Protection Agency's "Cluster Rule," most U.S. mills have switched from the use of chlorine to chlorine dioxide as the oxidant in the first stage of bleaching. This process change has a downside. it increases the formation of mineral scale in bleach plants. Typically, calcium oxalate forms in the chlorine dioxide...

Stability and effectiveness of chlorine disinfectants in water distribution systems.

PubMed

Olivieri, V P; Snead, M C; Krusé, C W; Kawata, K

1986-11-01

A test system for water distribution was used to evaluate the stability and effectiveness of three residual disinfectants--free chlorine, combined chlorine, and chlorine dioxide--when challenged with a sewage contaminant. The test distribution system consisted of the street main and internal plumbing for two barracks at Fort George G. Meade, MD. To the existing pipe network, 152 m (500 ft) of 13-mm (0.5 in.) copper pipe were added for sampling, and 60 m (200 ft) of 2.54-cm (1.0 in.) plastic pipe were added for circulation. The levels of residual disinfectants tested were 0.2 mg/L and 1.0 mg/L as available chlorine. In the absence of a disinfectant residual, microorganisms in the sewage contaminant were consistently recovered at high levels. The presence of any disinfectant residual reduced the microorganism level and frequency of occurrence at the consumer's tap. Free chlorine was the most effective residual disinfectant and may serve as a marker or flag in the distribution network. Free chlorine and chlorine dioxide were the least stable in the pipe network. The loss of disinfectant in the pipe network followed first-order kinetics. The half-life determined in static tests for free chlorine, chlorine dioxide, and combined chlorine was 140, 93, and 1680 min.

Stability and effectiveness of chlorine disinfectants in water distribution systems.

PubMed Central

Olivieri, V P; Snead, M C; Krusé, C W; Kawata, K

1986-01-01

A test system for water distribution was used to evaluate the stability and effectiveness of three residual disinfectants--free chlorine, combined chlorine, and chlorine dioxide--when challenged with a sewage contaminant. The test distribution system consisted of the street main and internal plumbing for two barracks at Fort George G. Meade, MD. To the existing pipe network, 152 m (500 ft) of 13-mm (0.5 in.) copper pipe were added for sampling, and 60 m (200 ft) of 2.54-cm (1.0 in.) plastic pipe were added for circulation. The levels of residual disinfectants tested were 0.2 mg/L and 1.0 mg/L as available chlorine. In the absence of a disinfectant residual, microorganisms in the sewage contaminant were consistently recovered at high levels. The presence of any disinfectant residual reduced the microorganism level and frequency of occurrence at the consumer's tap. Free chlorine was the most effective residual disinfectant and may serve as a marker or flag in the distribution network. Free chlorine and chlorine dioxide were the least stable in the pipe network. The loss of disinfectant in the pipe network followed first-order kinetics. The half-life determined in static tests for free chlorine, chlorine dioxide, and combined chlorine was 140, 93, and 1680 min. PMID:3028767

Chlorine, Chloramine, Chlorine Dioxide, and Ozone Susceptibility of Mycobacterium avium

PubMed Central

Taylor, Robert H.; Falkinham, Joseph O.; Norton, Cheryl D.; LeChevallier, Mark W.

2000-01-01

Environmental and patient isolates of Mycobacterium avium were resistant to chlorine, monochloramine, chlorine dioxide, and ozone. For chlorine, the product of the disinfectant concentration (in parts per million) and the time (in minutes) to 99.9% inactivation for five M. avium strains ranged from 51 to 204. Chlorine susceptibility of cells was the same in washed cultures containing aggregates and in reduced aggregate fractions lacking aggregates. Cells of the more slowly growing strains were more resistant to chlorine than were cells of the more rapidly growing strains. Water-grown cells were 10-fold more resistant than medium-grown cells. Disinfectant resistance may be one factor promoting the persistence of M. avium in drinking water. PMID:10742264

Efficacy of chlorine, acidic electrolyzed water and aqueous chlorine dioxide solutions to decontaminate Escherichia coli O157:H7 from lettuce leaves.

PubMed

Keskinen, Lindsey A; Burke, Angela; Annous, Bassam A

2009-06-30

This study compared the efficacy of chlorine (20-200 ppm), acidic electrolyzed water (50 ppm chlorine, pH 2.6), acidified sodium chlorite (20-200 ppm chlorite ion concentration, Sanova), and aqueous chlorine dioxide (20-200 ppm chlorite ion concentration, TriNova) washes in reducing populations of Escherichia coli O157:H7 on artificially inoculated lettuce. Fresh-cut leaves of Romaine or Iceberg lettuce were inoculated by immersion in water containing E. coli O157:H7 (8 log CFU/ml) for 5 min and dried in a salad spinner. Leaves (25 g) were then washed for 2 min, immediately or following 24 h of storage at 4 degrees C. The washing treatments containing chlorite ion concentrations of 100 and 200 ppm were the most effective against E. coli O157:H7 populations on Iceberg lettuce, with log reductions as high as 1.25 log CFU/g and 1.05 log CFU/g for TriNova and Sanova wash treatments, respectively. All other wash treatments resulted in population reductions of less than 1 log CFU/g. Chlorine (200 ppm), TriNova, Sanova, and acidic electrolyzed water were all equally effective against E. coli O157:H7 on Romaine, with log reductions of approximately 1 log CFU/g. The 20 ppm chlorine wash was as effective as the deionized water wash in reducing populations of E. coli O157:H7 on Romaine and Iceberg lettuce. Scanning electron microscopy indicated that E. coli O157:H7 that was incorporated into biofilms or located in damage lettuce tissue remained on the lettuce leaf, while individual cells on undamaged leaf surfaces were more likely to be washed away.

[Inactivation of the chlorine-resistant bacteria isolated from the drinking water distribution system].

PubMed

Chen, Yu-Qiao; Duan, Xiao-Di; Lu, Pin-Pin; Wang, Qian; Zhang, Xiao-Jian; Chen, Chao

2012-01-01

Inactivation experiments of seven strains of chlorine-resistant bacteria, isolated from a drinking water distribution system, were conducted with four kinds of disinfectants. All the bacteria showed high resistance to chlorine, especially for Mycobacterium mucogenicum. The CT value of 99.9% inactivation for M. mucogenicum, Sphingomonas sanguinis and Methylobacterium were 120 mg x (L x min)(-1), 7 mg x (L x min)(-1) and 4 mg x (L x min)(-1), respectively. The results of inactivation experiments showed that chlorine dioxide and potassium monopersulfate could inactive 5 lg of M. mucogenicum within 30 min, which showed significantly higher efficiency than free chlorine and monochloramine. Free chlorine was less effective because the disinfectant decayed very quickly. Chloramination needed higher concentration to meet the disinfection requirements. The verified dosage of disinfectants, which could effectively inactivate 99.9% of the highly chlorine-resistant M. mucogenicum within 1 h, were 3.0 mg/L monochloramine, 1.0 mg/L chlorine dioxide (as Cl2), and 1.0 mg/L potassium monopersulfate (as Cl2). It was suggested that the water treatment plants increase the concentration of monochloramine or apply chlorine dioxide intermittently to control the disinfectant-resistant bacteria.

Chlorine dioxide-induced and Congo red-inhibited Marangoni effect on the chlorite-trithionate reaction front

NASA Astrophysics Data System (ADS)

Liu, Yang; Ren, Xingfeng; Pan, Changwei; Zheng, Ting; Yuan, Ling; Zheng, Juhua; Gao, Qingyu

2017-10-01

Hydrodynamic flows can exert multiple effects on an exothermal autocatalytic reaction, such as buoyancy and the Marangoni convection, which can change the structure and velocity of chemical waves. Here we report that in the chlorite-trithionate reaction, the production and consumption of chlorine dioxide can induce and inhibit Marangoni flow, respectively, leading to different chemo-hydrodynamic patterns. The horizontal propagation of a reaction-diffusion-convection front was investigated with the upper surface open to the air. The Marangoni convection, induced by gaseous chlorine dioxide on the surface, produced from chlorite disproportionation after the proton autocatalysis, has the same effect as the heat convection. When the Marangoni effect is removed by the reaction of chlorine dioxide with the Congo red (CR) indicator, an oscillatory propagation of the front tip is observed under suitable conditions. Replacing CR with bromophenol blue (BPB) distinctly enhanced the floating, resulting in multiple vortexes, owing to the coexistence between BPB and chlorine dioxide. Using the incompressible Navier-Stokes equations coupled with reaction-diffusion and heat conduction equations, we numerically obtain various experimental scenarios of front instability for the exothermic autocatalytic reaction coupled with buoyancy-driven convection and Marangoni convection.

A Bee Guide to Complying with the Safe Drinking Water Act

DTIC Science & Technology

1991-08-01

disinfectants commonly used in water treatment. These disinfectants include chlorine, chloramine , chlorine dioxide, and ozone. Existing toxicological...to water systems that add a disinfectant (oxidant, such as chlorine, chlorine dioxide, chloramines or ozone) to any part of the treatment process. 6...AL-TR-1 991-0075 AD-A242 509 ^tLECTE II AR M A BEE GUIDE TO COMPLYING WITH THE S SAFE DRINKING WATER ACT T R Q John G. Garland III, Major, USAF, BSCN

Chlorine dioxide

Integrated Risk Information System (IRIS)

Chlorine dioxide ; CASRN 10049 - 04 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogeni

MULTISPECTRAL IDENTIFICATION OF CHLORINE DIOXIDE DISINFECTION BYPRODUCTS IN DRINKING WATER

EPA Science Inventory

This paper discusses the identification of organic disinfection byproducts (DBPs) at a pilot plant in Evansville, IN, which uses chlorine dioxide as a primary disinfectant. Unconventional multispectral identification techniques (gas chromatography combined with high- and low reso...

MULTISPECTRAL IDENTIFICATION OF CHLORINE DIOXIDE BYPRODUCTS IN DRINKING WATER

EPA Science Inventory

This paper discusses the identification of organic disinfectant byproducts (DNPS) at a pilot plant in Evansville, IN, that uses chlorine dioxide as a primary disinfectant. nconventional multispectral identification techniques (gas chromatography combined with high- and low-resolu...

PHOTOCHEMICAL REACTIONS AMONG FORMALDEHYDE, CHLORINE, AND NITROGEN DIOXIDE IN AIR

EPA Science Inventory

Photochemical reactions among chlorine, nitrogen dioxide, and formaldehyde were studied, using parts-per-million concentrations in 1 atm of air. The reactant mixtures were irradiated by ultraviolet fluorescent lamps and simultaneously analyzed by the Fourier transform infrared te...

MULTISPECTRAL IDENTIFICATION OF CHLORINE DIOXIDE DISINFECTION BY-PRODUCTS IN DRINKING WATER

EPA Science Inventory

This paper discusses the identification of organic disinfection by-products (DBPs) at a pilot plant in Evansville, Indiana, that uses chlorine dioxide as a primary disinfectant. nconventional multispectral identification techniques (gas chromatography combined with high and low r...

Chlorine dioxide water disinfection: a prospective epidemiology study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michael, G.E.; Miday, R.K.; Bercz, J.P.

An epidemiologic study of 198 persons exposed for 3 months to drinking water disinfected with chlorine dioxide was conducted in a rural village. A control population of 118 nonexposed persons was also studied. Pre-exposure hematologic and serum chemical parameters were compared with test results after 115 days of exposure. Chlorite ion levels in the water averaged approximately 5 ppM during the study period. Statistical analysis (ANOVA) of the data failed to identify any significant exposure-related effects. This study suggests that future evaluations of chlorine dioxide disinfection should be directed toward populations with potentially increased sensitivity to hemolytic agents.

Concentration-dependence of the explosion characteristics of chlorine dioxide gas.

PubMed

Jin, Ri-ya; Hu, Shuang-qi; Zhang, Yin-ghao; Bo, Tao

2009-07-30

The explosion characteristics of chlorine dioxide gas have been studied for the first time in a cylindrical exploder with a shell capacity of 20 L. The experimental results have indicated that the lower concentration limit for the explosive decomposition of chlorine dioxide gas is 9.5% ([ClO(2)]/[air]), whereas there is no corresponding upper concentration limit. Under the experimental conditions, and within the explosion limits, the pressure of explosion increases with increasing concentration of chlorine dioxide gas; the maximum pressure of explosion relative to the initial pressure was measured as 0.024 MPa at 10% ClO(2) and 0.641 MPa at 90% ClO(2). The induction time (the time from the moment of sparking to explosion) has also been found to depend on the concentration of chlorine dioxide gas; thus, at 10% ClO(2) the induction time was 2195 ms, but at 90% ClO(2) the induction time was just 8 ms. The explosion reaction mechanism of ClO(2) is of a degenerate chain-branching type involving the formation of a stable intermediate (Cl(2)O(3)), from which the chain-branching occurs. Chain initiation takes place at the point of ignition and termination takes place at the inner walls of the exploder.

Sequential disinfection of E. coli O157:H7 on shredded lettuce leaves by aqueous chlorine dioxide, ozonated water, and thyme essential oil

NASA Astrophysics Data System (ADS)

Singh, Nepal; Singh, Rakesh K.; Bhunia, Arun K.; Stroshine, Richard L.; Simon, James E.

2001-03-01

There have been numerous studies on effectiveness of different sanitizers for microbial inactivation. However, results obtained from different studies indicate that microorganism cannot be easily removed from fresh cut vegetables because of puncture and cut surfaces with varying surface topographies. In this study, three step disinfection approach was evaluated for inactivation of E. coli O157:H7 on shredded lettuce leaves. Sequential application of thyme oil, ozonated water, and aqueous chlorine dioxide was evaluated in which thyme oil was applied first followed by ozonated water and aqueous chlorine dioxide. Shredded lettuce leaves inoculated with cocktail culture of E. coli O157:H7 (C7927, EDL 933 and 204 P), were washed with ozonated water (15 mg/l for 10min), aqueous chlorine dioxide (10 mg/l,for 10min) and thyme oil suspension (0.1%, v/v for 5min). Washing of lettuce leaves with ozonated water, chlorine dioxide and thyme oil suspension resulted in 0.44, 1.20, and 1.46 log reduction (log10 cfu/g), respectively. However, the sequential treatment achieved approximately 3.13 log reductions (log10 cfu/g). These results demonstrate the efficacy of sequential treatments in decontaminating shredded lettuce leaves containing E. coli O157:H7.

An in vitro evaluation of the antibacterial efficacy of chlorine dioxide on E. faecalis in bovine incisors.

PubMed

Eddy, Russell S; Joyce, Anthony P; Roberts, Steven; Buxton, Thomas B; Liewehr, Frederick

2005-09-01

This study investigated the ability of chlorine dioxide to eliminate Enterococcus faecalis from dentinal tubules of bovine incisors. Thirty-seven extracted bovine incisor roots were sectioned into seventy-four 5 mm disks. Standardized lumens were filled with either sterile Brain Heart Infusion Broth (contamination controls, n = 10) or BHI containing E. faecalis (1.0 x 10 cfu/ml). Disks were incubated in 5% CO2 at 37 degrees C for 72 h. To simulate endodontic instrumentation the lumens were again enlarged. Sixty disks were randomly divided into four experimental groups and filled with one of the following irrigants: 10% Clidox-S (chlorine dioxide), 13.8% BioClenz (chlorine dioxide), 5.25% Clorox, or saline. The disks were incubated for 30 min and were then frozen, pulverized, serially diluted in phosphate buffered saline, and plated on BHI plates in triplicate. Total colony forming units were counted macroscopically. Statistical analysis of the data was performed with a Kruskal-Wallis one-way ANOVA on ranks (p < 0.05, n = 60). Bacterial counts, expressed in log10 cfu/disk were as follows (">" denotes significant differences): Saline > Clidox-S = BioClenz > Clorox. All negative controls were sterile. Chlorine dioxide and NaOCL were both effective in eliminating E. faecalis from the dentinal disks within 30 min.

Comparison of commercial analytical techniques for measuring chlorine dioxide in urban desalinated drinking water.

PubMed

Ammar, T A; Abid, K Y; El-Bindary, A A; El-Sonbati, A Z

2015-12-01

Most drinking water industries are closely examining options to maintain a certain level of disinfectant residual through the entire distribution system. Chlorine dioxide is one of the promising disinfectants that is usually used as a secondary disinfectant, whereas the selection of the proper monitoring analytical technique to ensure disinfection and regulatory compliance has been debated within the industry. This research endeavored to objectively compare the performance of commercially available analytical techniques used for chlorine dioxide measurements (namely, chronoamperometry, DPD (N,N-diethyl-p-phenylenediamine), Lissamine Green B (LGB WET) and amperometric titration), to determine the superior technique. The commonly available commercial analytical techniques were evaluated over a wide range of chlorine dioxide concentrations. In reference to pre-defined criteria, the superior analytical technique was determined. To discern the effectiveness of such superior technique, various factors, such as sample temperature, high ionic strength, and other interferences that might influence the performance were examined. Among the four techniques, chronoamperometry technique indicates a significant level of accuracy and precision. Furthermore, the various influencing factors studied did not diminish the technique's performance where it was fairly adequate in all matrices. This study is a step towards proper disinfection monitoring and it confidently assists engineers with chlorine dioxide disinfection system planning and management.

Efficacy of chlorine dioxide against Listeria monocytogenes in brine chilling solutions.

PubMed

Valderrama, W B; Mills, E W; Cutter, C N

2009-11-01

Chilled brine solutions are used by the food industry to rapidly cool ready-to-eat meat products after cooking and before packaging. Chlorine dioxide (ClO(2)) was investigated as an antimicrobial additive to eliminate Listeria monocytogenes. Several experiments were performed using brine solutions made of sodium chloride (NaCl) and calcium chloride (CaCl(2)) inoculated with L. monocytogenes and/or treated with 3 ppm of ClO(2). First, 10 and 20% CaCl(2) and NaCl solutions (pH 7.0) were inoculated with a five-strain cocktail of L. monocytogenes to obtain approximately 7 log CFU/ml and incubated 8 h at 0 degrees C. The results demonstrated that L. monocytogenes survived in 10% CaCl(2), 10 and 20% NaCl, and pure water. L. monocytogenes levels were reduced approximately 1.2 log CFU/ml in 20% CaCl(2). Second, inoculated ( approximately 7 log CFU/ml) brine solutions (10 and 20% NaCl and 10% CaCl(2)) treated with 3 ppm of ClO(2) resulted in a approximately 4-log reduction of the pathogen within 90 s. The same was not observed in a solution of 20% CaCl(2); further investigation demonstrated that high levels of divalent cations interfere with the disinfectant. Spent brine solutions from hot dog and ham chilling were treated with ClO(2) at concentrations of 3 or 30 ppm. At these concentrations, ClO(2) did not reduce L. monocytogenes. Removal of divalent cations and organic material in brine solutions prior to disinfection with ClO(2) should be investigated to improve the efficacy of the compound against L. monocytogenes. The information from this study may be useful to processing establishments and researchers who are investigating antimicrobials in chilling brine solutions.

[Inactivation of Mycobacteria mucogenicum in drinking water: chlorine resistance and mechanism analysis].

PubMed

Zheng, Qi; Chen, Chao; Zhang, Xiao-Jian; Lu, Pin-Pin; Liu, Yuan-Yuan; Chen, Yu-Qiao

2013-02-01

In recent years, chlorine-resistant bacteria were detected in drinking water distribution systems which threatened the drinking water safety. Our group detected one strain named Mycobacteria mucogenicum from the drinking water distribution system of a city in south China. This paper studied chlorine resistance and mechanism of Mycobacteria mucogenicum. Inactivation experiments of one strain Mycobacteria mucogenicum were conducted with free chlorine, monochloramind and chlorine dioxide. The CT values of 99.9% inactivation by free chlorine, monochloramine and chlorine dioxide were detected as (76.25 +/- 47.55)mg.min.L-1, (1396 +/-382)mg.min.L-1, (13.5 +/- 4.9) mg.min L-1. Using transmission electronmicroscopy (TEM) observed the inactivation process of Mycobacteria mucogenicum. The bacteria surface hydrophobic of Mycobacteria mucogenicum was 37.2%. Mycobacteria mucogenicum has a higher hydrophobicity than other bacteria which prevented the diffusion of chlorine into cells. Mycobacteria mucogenicum is more resistant to chorine than other bacteria.

Field Experience with Chlorine Dioxide Fumigation of a Hospital: Timeline and Lessons Learned

EPA Science Inventory

Chlorine dioxide (Cl02) fumigation technology was developed and successfully used to remediate four large buildings contaminated with anthrax spores from 2001 through 2004. As a first application of the technology, those remediations were complex, costly and time consuming. There...

Kinetics of membrane damage to high (HNA) and low (LNA) nucleic acid bacterial clusters in drinking water by ozone, chlorine, chlorine dioxide, monochloramine, ferrate(VI), and permanganate.

PubMed

Ramseier, Maaike K; von Gunten, Urs; Freihofer, Pietro; Hammes, Frederik

2011-01-01

Drinking water was treated with ozone, chlorine, chlorine dioxide, monochloramine, ferrate(VI), and permanganate to investigate the kinetics of membrane damage of native drinking water bacterial cells. Membrane damage was measured by flow cytometry using a combination of SYBR Green I and propidium iodide (SGI+PI) staining as indicator for cells with permeabilized membranes and SGI alone to measure total cell concentration. SGI+PI staining revealed that the cells were permeabilized upon relatively low oxidant exposures of all tested oxidants without a detectable lag phase. However, only ozonation resulted in a decrease of the total cell concentrations for the investigated reaction times. Rate constants for the membrane damage reaction varied over seven orders of magnitude in the following order: ozone > chlorine > chlorine dioxide ≈ ferrate > permanganate > chloramine. The rate constants were compared to literature data and were in general smaller than previously measured rate constants. This confirmed that membrane integrity is a conservative and therefore safe parameter for disinfection control. Interestingly, the cell membranes of high nucleic acid (HNA) content bacteria were damaged much faster than those of low nucleic acid (LNA) content bacteria during treatment with chlorine dioxide and permanganate. However, only small differences were observed during treatment with chlorine and chloramine, and no difference was observed for ferrate treatment. Based on the different reactivity of these oxidants it was suggested that HNA and LNA bacterial cell membranes have a different chemical constitution. Copyright © 2010 Elsevier Ltd. All rights reserved.

42 CFR 84.207 - Bench tests; gas and vapor tests; minimum requirements; general.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 64 3 50 50 Ammonia Equilibrated NH3 1000 32 4 50 50 Chlorine As received Cl2 500 64 3 5 35 Chlorine... 4 5 50 Sulfur dioxide As received SO2 500 64 3 5 30 Sulfur dioxide Equilibrated SO2 500 32 4 5 30 1... respiratory protection against more than one type of gas or vapor, as for use in ammonia and in chlorine, the...

42 CFR 84.207 - Bench tests; gas and vapor tests; minimum requirements; general.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 64 3 50 50 Ammonia Equilibrated NH3 1000 32 4 50 50 Chlorine As received Cl2 500 64 3 5 35 Chlorine... 4 5 50 Sulfur dioxide As received SO2 500 64 3 5 30 Sulfur dioxide Equilibrated SO2 500 32 4 5 30 1... respiratory protection against more than one type of gas or vapor, as for use in ammonia and in chlorine, the...

Water disinfection agents and disinfection by-products

NASA Astrophysics Data System (ADS)

Ilavský, J.; Barloková, D.; Kapusta, O.; Kunštek, M.

2017-10-01

The aim of this work is to describe factors of water quality change in the distribution network and legislative requirements in Slovakia for disinfectants and disinfection byproducts (DBPs). In the experimental part, the time dependence of the application of the chlorine dioxide and sodium hypochlorite on the formation of some by-products of disinfection for drinking water from WTP Hriňová is studied. We monitored trihalomethanes, free chlorine, chlorine dioxide and chlorites.

Disinfection aboard cruise liners and naval units: formation of disinfection by-products using chlorine dioxide in different qualities of drinking water.

PubMed

Ufermann, Petra; Petersen, Hauke; Exner, Martin

2011-12-01

The world-wide deployment of cruise liners and naval units has caused an increased need for the disinfection of drinking water. The main cause for this is the unknown quality of drinking water in foreign harbours--besides the formation of bio-films due to the climatically disadvantageous conditions in the operational area. Water conduits on board are currently disinfected with calcium hypochlorite in case of microbiological contamination. Chemical and physical analyses after disinfection with calcium hypochlorite have shown that organic by-products consisting of trihalomethanes develop in considerable amounts during disinfection. Furthermore, the method is susceptible to handling errors and thus often leads to insufficient disinfection results. Hitherto, the use of other disinfection methods allowed by government regulations, especially chlorine dioxide, is not widely spread. Unlike disinfection with calcium hypochlorite, chlorine dioxide does not lead to the formation of trihalomethanes. Typical disinfection by-products (DBP) are the anions chlorite and chlorate, which are formed in oxidative processes. The formation conditions of these anions have not yet been elucidated. For this reason, the probability of the generation of inorganic by-products after disinfection with chlorine dioxide has been determined, and their occurrence in drinking water on board has been examined with respect to a possible correlation between water quality and the formation of chlorate and chlorite. Therefore, a chromatographic method was developed and validated in order to determine the periodical development of chlorate and chlorite from chorine dioxide in purified water at different pH-values as well as in actual drinking water samples from water conduits on board. The formation of the by-products chlorite and chlorate after disinfection with chlorine dioxide is influenced neither by pH-value nor by chemical properties of the disinfected water. Considering the examined conditions, chlorine dioxide is suitable for usage on board due to its simple handling and the low potential of producing by-products. Copyright © 2011 Elsevier GmbH. All rights reserved.

Mass Transfer Study of Chlorine Dioxide Gas Through Polymeric Packaging Materials

USDA-ARS?s Scientific Manuscript database

A continuous system for measuring the mass transfer of gaseous chlorine dioxide (ClO2), a strong oxidizing agent and used in food and pharmaceutical packaging, through 10 different types of polymeric packaging material was developed utilizing electrochemical sensor as a detector. Permeability, diff...

Chlorination of UO 2, PuO 2 and rare earth oxides using ZrCl 4 in LiCl-KCl eutectic melt

NASA Astrophysics Data System (ADS)

Sakamura, Yoshiharu; Inoue, Tadashi; Iwai, Takashi; Moriyama, Hirotake

2005-04-01

A new chlorination method using ZrCl 4 in a molten salt bath has been investigated for the pyrometallurgical reprocessing of nuclear fuels. ZrCl 4 has a high reactivity with oxygen but is not corrosive to refractory metals such as steel. Rare earth oxides (La 2O 3, CeO 2, Nd 2O 3 and Y 2O 3) and actinide oxides (UO 2 and PuO 2) were allowed to react with ZrCl 4 in a LiCl-KCl eutectic salt at 773 K to give a metal chloride solution and a precipitate of ZrO 2. An addition of zirconium metal as a reductant was effective in chlorinating the dioxides. When the oxides were in powder form, the reaction was observed to progress rapidly. Cyclic voltammetry provided a convenient way of establishing when the reaction was completed. It was demonstrated that the ZrCl 4 chlorination method, free from corrosive gas, was very simple and useful.

Development of chlorine dioxide releasing film and its application in decontaminating fresh produce

USDA-ARS?s Scientific Manuscript database

A feasibility study was conducted to develop chlorine dioxide releasing packaging films for decontaminating fresh produce. Sodium chlorite and citric acid powder were incorporated into polylactic acid (PLA) polymer. Films made with different amount of PLA (100 & 300 mg), percentage of reactant (5-60...

Effect of chlorine dioxide gas on physical, thermal, mechanical, and barrier properties of p[olymeric packaging materials

USDA-ARS?s Scientific Manuscript database

In the first part of our study we determined permeability, diffusion, and solubility coefficients of gaseous chlorine dioxide (ClO2) through the following packaging material: biaxial-oriented polypropylene (BOPP); polyethylene terephthalate (PET); poly lactic acid (PLA); multilayer structure of ethy...

40 CFR 141.544 - What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection?

Code of Federal Regulations, 2010 CFR

2010-07-01

..., ozone, or chlorine dioxide for primary disinfection? 141.544 Section 141.544 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration and Disinfection-Systems Serving Fewer Than 10,000 People Disinfection...

40 CFR 141.535 - What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection?

Code of Federal Regulations, 2010 CFR

2010-07-01

..., ozone, or chlorine dioxide for primary disinfection? 141.535 Section 141.535 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration and Disinfection-Systems Serving Fewer Than 10,000 People Disinfection Profile...

Application of chlorine dioxide to lessen bacterial contamination during broiler defeathering

USDA-ARS?s Scientific Manuscript database

Due to escape of contaminated gut contents, the number of Campylobacter spp. recovered from broiler carcasses increases during feather removal. Chlorine dioxide (ClO2) is approved for use as an antimicrobial treatment during poultry processing. A study was designed to test if application of 50 ppm...

Inactivation of human norovirus using chemical sanitizers.

PubMed

Kingsley, David H; Vincent, Emily M; Meade, Gloria K; Watson, Clytrice L; Fan, Xuetong

2014-02-03

The porcine gastric mucin binding magnetic bead (PGM-MB) assay was used to evaluate the ability of chlorine, chlorine dioxide, peroxyacetic acid, hydrogen peroxide, and trisodium phosphate to inactivate human norovirus within 10% stool filtrate. One-minute free chlorine treatments at concentrations of 33 and 189 ppm reduced virus binding in the PGM-MB assay by 1.48 and 4.14 log₁₀, respectively, suggesting that chlorine is an efficient sanitizer for inactivation of human norovirus (HuNoV). Five minute treatments with 5% trisodium phosphate (pH~12) reduced HuNoV binding by 1.6 log₁₀, suggesting that TSP, or some other high pH buffer, could be used to treat food and food contact surfaces to reduce HuNoV. One minute treatments with 350 ppm chlorine dioxide dissolved in water did not reduce PGM-MB binding, suggesting that the sanitizer may not be suitable for HuNoV inactivation in liquid form. However a 60-min treatment with 350 ppm chlorine dioxide did reduce human norovirus by 2.8 log₁₀, indicating that chlorine dioxide had some, albeit limited, activity against HuNoV. Results also suggest that peroxyacetic acid has limited effectiveness against human norovirus, since 1-min treatments with up to 195 ppm reduced human norovirus binding by <1 log₁₀. Hydrogen peroxide (4%) treatment of up to 60 min resulted in minimal binding reduction (~0.1 log₁₀) suggesting that H₂O₂ is not a good liquid sanitizer for HuNoV. Overall this study suggests that HuNoV is remarkably resistant to several commonly used disinfectants and advocates for the use of chlorine (sodium hypochlorite) as a HuNoV disinfectant wherever possible. Copyright © 2013. Published by Elsevier B.V.

Evaluation of Combined Disinfection Methods for Reducing Escherichia coli O157:H7 Population on Fresh-Cut Vegetables

PubMed Central

Petri, Eva; Rodríguez, Mariola; García, Silvia

2015-01-01

Most current disinfection strategies for fresh-cut industry are focused on the use of different chemical agents; however, very little has been reported on the effectiveness of the hurdle technology. The effect of combined decontamination methods based on the use of different sanitizers (peroxyacetic acid and chlorine dioxide) and the application of pressure (vacuum/positive pressure) on the inactivation of the foodborne pathogen E. coli O157:H7 on fresh-cut lettuce (Lactuca sativa) and carrots (Daucus carota) was studied. Fresh produce, inoculated with E. coli O157:H7, was immersed (4 °C, 2 min) in tap water (W), chlorine water (CW), chlorine dioxide (ClO2: 2 mg/L) and peroxyacetic acid (PAA: 100 mg/L) in combination with: (a) vacuum (V: 10 mbar) or (b) positive pressure application (P: 3 bar). The product quality and antimicrobial effects of the treatment on bacterial counts were determined both in process washing water and on fresh-cut produce. Evidence obtained in this study, suggests that the use of combined methods (P/V + sanitizers) results in a reduction on the microorganism population on produce similar to that found at atmospheric pressure. Moreover, the application of physical methods led to a significant detrimental effect on the visual quality of lettuce regardless of the solution used. Concerning the process water, PAA proved to be an effective alternative to chlorine for the avoidance of cross-contamination. PMID:26213954

Evaluation of Combined Disinfection Methods for Reducing Escherichia coli O157:H7 Population on Fresh-Cut Vegetables.

PubMed

Petri, Eva; Rodríguez, Mariola; García, Silvia

2015-07-23

Most current disinfection strategies for fresh-cut industry are focused on the use of different chemical agents; however, very little has been reported on the effectiveness of the hurdle technology. The effect of combined decontamination methods based on the use of different sanitizers (peroxyacetic acid and chlorine dioxide) and the application of pressure (vacuum/positive pressure) on the inactivation of the foodborne pathogen E. coli O157:H7 on fresh-cut lettuce (Lactuca sativa) and carrots (Daucus carota) was studied. Fresh produce, inoculated with E. coli O157:H7, was immersed (4 °C, 2 min) in tap water (W), chlorine water (CW), chlorine dioxide (ClO2: 2 mg/L) and peroxyacetic acid (PAA: 100 mg/L) in combination with: (a) vacuum (V: 10 mbar) or (b) positive pressure application (P: 3 bar). The product quality and antimicrobial effects of the treatment on bacterial counts were determined both in process washing water and on fresh-cut produce. Evidence obtained in this study, suggests that the use of combined methods (P/V + sanitizers) results in a reduction on the microorganism population on produce similar to that found at atmospheric pressure. Moreover, the application of physical methods led to a significant detrimental effect on the visual quality of lettuce regardless of the solution used. Concerning the process water, PAA proved to be an effective alternative to chlorine for the avoidance of cross-contamination.

21 CFR 137.200 - Whole wheat flour.

Code of Federal Regulations, 2011 CFR

2011-04-01

... not more than 45 parts per million) or chlorine dioxide, or chlorine, or a mixture of nitrosyl chloride and chlorine, may be added in a quantity not more than sufficient for bleaching and artificial...

The Chlorination Quandary

ERIC Educational Resources Information Center

Josephson, Julian

1978-01-01

Current use of chlorination technology to disinfect water supplies can cause the production of undesirable products, among them chloroform and chlorobenzene. Alternatives to this methodology include the use of ozone, chlorine dioxide, and bromine chloride in place of chlorine. Presently, the methods are feasible in developed countries only. (MA)

Sequential UV- and chlorine-based disinfection to mitigate Escherichia coli in drinking water biofilms.

PubMed

Murphy, H M; Payne, S J; Gagnon, G A

2008-04-01

This study was designed to examine the potential downstream benefits of sequential disinfection to control the persistence of Escherichia coli under conditions relevant to drinking water distribution systems. Eight annular reactors (four polycarbonate and four cast iron) were setup in parallel to address various factors that could influence biofilm growth in distribution systems. Eight reactors were treated with chlorine, chlorine dioxide and monochloramine alone or in combination with UV to examine the effects on Escherichia coli growth and persistence in both the effluent and biofilm. In general, UV-treated systems in combination with chlorine or chlorine dioxide and monochloramine achieved greater log reductions in both effluent and biofilm than systems treated with chlorine-based disinfectants alone. However, during UV-low chlorine disinfection, E. coli was found to persist at low levels, suggesting that the UV treatment had instigated an adaptive mutation. During UV-chlorine-dioxide treatment, the E. coli that was initially below the detection limit reappeared during a low level of disinfection (0.2 mg/L) in the cast iron systems. Chloramine was shown to be effective in disinfecting suspended E. coli in the effluent but was unable to reduce biofilm counts to below the detection limit. Issues such as repair mechanism of E. coli and nitrification could help explain some of these aberrations. Improved understanding of the ability of chlorine-based disinfectant in combination with UV to provide sufficient disinfection will ultimately effect in improved management and safety of drinking water.

The effect of chlorine dioxide and chitosan/essential oil coatings on the safety and quality of fresh blueberries

USDA-ARS?s Scientific Manuscript database

Blueberries are high-value fruit with strong antioxidant capacity and other health-promoting benefits. Controlled release chlorine dioxide (ClO2) or chitosan coating plus different essential oils were applied to fresh blueberries to preserve their quality and safety during postharvest storage. In vi...

Controlling Mold on Library Materials with Chlorine Dioxide: An Eight-Year Case Study.

ERIC Educational Resources Information Center

Weaver-Meyers, Pat L.; Kowaleski, Barbara; Stolt, Wilbur A.

1998-01-01

Discusses problems associated with mold growth at the University of Oklahoma libraries and describes the results of using chlorine dioxide in aqueous and gaseous forms. Highlights include toxicity compared to other preservation treatments; environmental controls; and explanations of a preference for the use of a self-activating gas packet.…

Introducing Students to a Synthetic and Spectroscopic Study of the Free Radical Chlorine Dioxide

ERIC Educational Resources Information Center

Sutton, Sarah C.; Cleland, Walter E.; Hammer, Nathan I.

2017-01-01

This advanced undergraduate chemistry laboratory exercise takes advantage of the unique spectroscopic properties of the free radical chlorine dioxide to allow for a direct comparison of its symmetric stretch in both the ground and excited states. It incorporates several subject areas covered in an undergraduate chemistry degree (synthesis,…

HIGH-RATE DISINFECTION OF COMBINED SEWER OVERFLOW USING CHLORINE DIOXIDE

EPA Science Inventory

This presentation is a state-of-the-art review of chlorine dioxide (ClO2) used for high-rate disinfection of combined sewer overflow (CSO). The review includes bench-, pilot-, and fullscale studies on the use of ClO2 as a disinfecting agent for a variety of wastewaters. Specific ...

The effectiveness of closed-circulation gaseous chlorine dioxide or ozone treatment against bacterial pathogens on produce food control

USDA-ARS?s Scientific Manuscript database

The objective of this study was to compare the effectiveness of gaseous chlorine dioxide (ClO2) and ozone (O3) treatment against Shiga toxin-producing Escherichia coli (STEC), Salmonella enterica serovars, and Listeria monocytogenes on baby-cut carrots, lowbush blueberries, and beefsteak tomatoes us...

Inactivation of Salmonella on Eggshells by Chlorine Dioxide Gas

PubMed Central

Yum, Bora; Yoon, Sung-Sik; Song, Kyoung-Ju; Kim, Jong-Rak

2016-01-01

Microbiological contamination of eggs should be prevented in the poultry industry, as poultry is one of the major reservoirs of human Salmonella. ClO2 gas has been reported to be an effective disinfectant in various industry fields, particularly the food industry. The aims of this study were to evaluate the antimicrobial effect of chlorine dioxide gas on two strains of Salmonella inoculated onto eggshells under various experimental conditions including concentrations, contact time, humidity, and percentage organic matter. As a result, it was shown that chlorine dioxide gas under wet conditions was more effective in inactivating Salmonella Enteritidis and Salmonella Gallinarum compared to that under dry conditions independently of the presence of organic matter (yeast extract). Under wet conditions, a greater than 4 log reduction in bacterial populations was achieved after 30 min of exposure to ClO2 each at 20 ppm, 40 ppm, and 80 ppm against S. Enteritidis; 40 ppm and 80 ppm against S. Gallinarum. These results suggest that chlorine dioxide gas is an effective agent for controlling Salmonella, the most prevalent contaminant in the egg industry. PMID:27499670

Cellular Response of the Amoeba Acanthamoeba castellanii to Chlorine, Chlorine Dioxide, and Monochloramine Treatments ▿

PubMed Central

Mogoa, Emerancienne; Bodet, Charles; Morel, Franck; Rodier, Marie-Hélène; Legube, Bernard; Héchard, Yann

2011-01-01

Acanthamoeba castellanii is a free-living amoebae commonly found in water systems. Free-living amoebae might be pathogenic but are also known to bear phagocytosis-resistant bacteria, protecting these bacteria from water treatments. The mode of action of these treatments is poorly understood, particularly on amoebae. It is important to examine the action of these treatments on amoebae in order to improve them. The cellular response to chlorine, chlorine dioxide, and monochloramine was tested on A. castellanii trophozoites. Doses of disinfectants leading to up to a 3-log reduction were compared by flow cytometry and electron microscopy. Chlorine treatment led to size reduction, permeabilization, and retraction of pseudopods. In addition, treatment with chlorine dioxide led to a vacuolization of the cytoplasm. Monochloramine had a dose-dependent effect. At the highest doses monochloramine treatment resulted in almost no changes in cell size and permeability, as shown by flow cytometry, but the cell surface became smooth and dense, as seen by electron microscopy. We show that these disinfectants globally induced size reduction, membrane permeabilization, and morphological modifications but that they have a different mode of action on A. castellanii. PMID:21602398

Sodium hypochlorite-, chlorine dioxide- and peracetic acid-induced genotoxicity detected by the Comet assay and Saccharomyces cerevisiae D7 tests.

PubMed

Buschini, Annamaria; Carboni, Pamela; Furlini, Mariangela; Poli, Paola; Rossi, Carlo

2004-03-01

Mutagenicity of drinking water is due not only to industrial, agricultural and urban pollution but also to chlorine disinfection by-products. Furthermore, residual disinfection is used to provide a partial safeguard against low level contamination and bacterial re-growth within the distribution system. The aims of this study were to further evaluate the genotoxic potential of the world wide used disinfectants sodium hypochlorite and chlorine dioxide in human leukocytes by the Comet assay and in Saccharomyces cerevisiae strain D7 (mitotic gene conversion, point mutation and mitochondrial DNA mutability, with and without endogenous metabolic activation) and to compare their effects with those of peracetic acid, proposed as an alternative disinfectant. All three disinfectants are weakly genotoxic in human leukocytes (lowest effective dose 0.2 p.p.m. for chlorine dioxide, 0.5 p.p.m. for sodium hypochlorite and peracetic acid). The results in S.cerevisiae show a genotoxic response on the end-points considered with an effect only at doses higher (5- to 10-fold) than the concentration normally used for water disinfection; sodium hypochlorite and peracetic acid are able to induce genotoxic effects without endogenous metabolic activation (in stationary phase cells) whereas chlorine dioxide is effective in growing cells. The Comet assay was more sensitive than the yeast tests, with effective doses in the range normally used for water disinfection processes. The biological effectiveness of the three disinfectants on S.cerevisiae proved to be strictly dependent on cell-specific physiological/biochemical conditions. All the compounds appear to act on the DNA and peracetic acid shows effectiveness similar to sodium hypochlorite and chlorine dioxide.

Enhanced Amendment Delivery to Low Permeability Zones for Chlorinated Solvent Source Area Bioremediation

DTIC Science & Technology

2014-09-01

suspend manganese dioxide particles produced from oxidation of permanganate in aqueous phase (Crimi and Ko, 2009). Xanthan gum is a biopolymer that...shear-thinning fluids for improving treatment of low-k zones. This study established that combinations of xanthan gum and potassium permanganate ...flow cell experiments using xanthan gum solution to deliver permanganate , Chokejaroenrat et al. (2013, 2014) presented a set of data supporting that

Evaluation of disinfectants and antiseptics to eliminate bacteria from the surface of turkey eggs and hatch gnotobiotic poults.

PubMed

Sylte, M J; Chandra, L C; Looft, T

2017-07-01

Bird eggs are in contact with intestinal microbiota at or after oviposition, but are protected from bacterial translocation by a glycoprotein cuticle layer, the shell, and internal membranes. In a preliminary study, turkey eggs were hatched in a germ-free environment. Firmicutes 16S rRNA gene was detected in the cecal microbiota of hatched poults, suggesting that poults may acquire spore-formers by exposure to shell contents during hatching. Generating gnotobiotic poults for research requires elimination of bacteria from the egg's surface without damaging the developing embryo. The ability of different disinfectants and antiseptics to eliminate eggshell bacteria without harming the developing embryo was tested. Different classes of disinfectants and antiseptics (halogens, biguanidines, and oxidants) were selected to target spores and vegetative bacteria likely present on the egg's surface. Eggs were treated by fully immersing in heated antiseptic (betadine or chlorhexidine) or disinfectant (alkaline bleach, acidified bleach, chlorine dioxide, Oxysept-333, or Virkon S) solutions for up to 15 minutes. Shells were aseptically harvested for aerobic and anaerobic culturing of bacteria. Toxicity to the developing embryo was assessed by gross evaluation of developmental changes in treated eggs incubated up to 27 d of embryonation. Halogen disinfectants acidified bleach and chlorine dioxide, and oxidants Oxysept-333 and Virkon-S eliminated viable bacteria from eggshells. However, addition of oxidants, alone or in combination with other treatments, produced significant (P < 0.05) embryotoxicity. The combination treatment of acidified bleach, chlorine dioxide, and betadine produced minimal embryotoxicity and eliminated viable bacteria from whole turkey eggs, and produced hatched poults in a gnotobiotic isolator. As a control, eggs were treated with PBS, incubated, and hatched under germ-replete conditions. After hatching, poults were euthanized and treated poults had no detectable bacterial growth or 16S rRNA gene qPCR amplification, demonstrating that acidified sodium hypochlorite, chlorine dioxide, and betadine safely hatched gnotobiotic poults. Generation of germ-free poults is an important tool and will be used to evaluate the host-pathogen interaction by foodborne pathogens such as Campylobacter spp. Published by Oxford University Press on behalf of Poultry Science Association 2017.

Kinetics and mechanism of styrene epoxidation by chlorite: role of chlorine dioxide.

PubMed

Leigh, Jessica K; Rajput, Jonathan; Richardson, David E

2014-07-07

An investigation of the kinetics and mechanism for epoxidation of styrene and para-substituted styrenes by chlorite at 25 °C in the pH range of 5-6 is described. The proposed mechanism in water and water/acetonitrile includes seven oxidation states of chlorine (-I, 0, I, II, III, IV, and V) to account for the observed kinetics and product distributions. The model provides an unusually detailed quantitative mechanism for the complex reactions that occur in mixtures of chlorine species and organic substrates, particularly when the strong oxidant chlorite is employed. Kinetic control of the reaction is achieved by the addition of chlorine dioxide to the reaction mixture, thereby eliminating a substantial induction period observed when chlorite is used alone. The epoxidation agent is identified as chlorine dioxide, which is continually formed by the reaction of chlorite with hypochlorous acid that results from ClO produced by the epoxidation reaction. The overall stoichiometry is the result of two competing chain reactions in which the reactive intermediate ClO reacts with either chlorine dioxide or chlorite ion to produce hypochlorous acid and chlorate or chloride, respectively. At high chlorite ion concentrations, HOCl is rapidly eliminated by reaction with chlorite, minimizing side reactions between HOCl and Cl2 with the starting material. Epoxide selectivity (>90% under optimal conditions) is accurately predicted by the kinetic model. The model rate constant for direct reaction of styrene with ClO2(aq) to produce epoxide is (1.16 ± 0.07) × 10(-2) M(-1) s(-1) for 60:40 water/acetonitrile with 0.20 M acetate buffer. Rate constants for para substituted styrenes (R = -SO3(-), -OMe, -Me, -Cl, -H, and -NO2) with ClO2 were determined. The results support the radical addition/elimination mechanism originally proposed by Kolar and Lindgren to account for the formation of styrene oxide in the reaction of styrene with chlorine dioxide.

Formation of trichloromethane in chlorinated water and fresh-cut produce and as a result of reacting with citric acid

USDA-ARS?s Scientific Manuscript database

Chlorine (sodium hypochlorite) is commonly used by the fresh produce industry to sanitize wash water, fresh and fresh-cut fruits and vegetables. However, possible formation of harmful chlorine by-products is a concern. The objectives of this study were to compare chlorine and chlorine dioxide in t...

Effect of hot acid hydrolysis and hot chlorine dioxide stage on bleaching effluent biodegradability.

PubMed

Gomes, C M; Colodette, J L; Delantonio, N R N; Mounteer, A H; Silva, C M

2007-01-01

The hot acid hydrolysis followed by chlorine dioxide (A/D*) and hot chlorine dioxide (D*) technologies have proven very useful for bleaching of eucalyptus kraft pulp. Although the characteristics and biodegradability of effluents from conventional chlorine dioxide bleaching are well known, such information is not yet available for effluents derived from hot acid hydrolysis and hot chorine dioxide bleaching. This study discusses the characteristics and biodegradability of such effluents. Combined whole effluents from the complete sequences DEpD, D*EpD, A/D*EpD and ADEpD, and from the pre-bleaching sequences DEp, D*Ep, A/D*Ep and ADEp were characterized by quantifying their colour, AOX and organic load (BOD, COD, TOC). These effluents were also evaluated for their treatability by simulation of an activated sludge system. It was concluded that treatment in the laboratory sequencing batch reactor was efficient for removal of COD, BOD and TOC of all effluents. However, colour increased after biological treatment, with the greatest increase found for the effluent produced using the AD technology. Biological treatment was less efficient at removing AOX of effluents from the sequences with D*, A/D* and AD as the first stages, when compared to the reference D stage; there was evidence of the lower treatability of these organochlorine compounds from these sequences.

40 CFR 63.445 - Standards for the bleaching system.

Code of Federal Regulations, 2010 CFR

2010-07-01

... process using secondary or non-wood fibers, that use chlorine dioxide. (b) The equipment at each bleaching... system. (a) Each bleaching system that does not use any chlorine or chlorinated compounds for bleaching... systems shall meet all the provisions of this section: (1) Bleaching systems that use chlorine; (2...

40 CFR 63.445 - Standards for the bleaching system.

Code of Federal Regulations, 2011 CFR

2011-07-01

... process using secondary or non-wood fibers, that use chlorine dioxide. (b) The equipment at each bleaching... system. (a) Each bleaching system that does not use any chlorine or chlorinated compounds for bleaching... systems shall meet all the provisions of this section: (1) Bleaching systems that use chlorine; (2...

Survival of Salmonella Typhimurium on soybean sprouts after treatment with gaseous chlorine dioxide and biocontrol Pseudomonas bacteria

USDA-ARS?s Scientific Manuscript database

Control of Salmonella Typhimurium on sprouts and minimally processed produce is crucial for food and consumer safety. The aim of this research was to assess natural microflora populations on soybean and evaluate the effects of gaseous chlorine dioxide (ClO2) and biocontrol Pseudomonas on the surviva...

Survival of Salmonella enterica on soybean sprouts following treatments with gaseous chlorine dioxide and biocontrol Pseudomonas bacteria

USDA-ARS?s Scientific Manuscript database

Control of Salmonella enterica on sprouts and minimally processed, ready-to-eat fruits and vegetables is important for food and consumer safety. The aim of this research was to assess the effects of gaseous chlorine dioxide(ClO2)and biocontrol microorganisms (Pseudomonas chlororaphis and P. fluoresc...

A quantitative study on the absorption of gaseous chlorine dioxide onto lettuce leaf

USDA-ARS?s Scientific Manuscript database

Chlorine dioxide (ClO2) is an effective surface disinfectant and it is gaining interest in the food and pharmaceutical industries, due to its bacteriocide effects. One of the most promising applications of gaseous ClO2 is to be included in the headspace of food packaging systems for vapor-phase deco...

A BAYESIAN METHOD OF ESTIMATING KINETIC PARAMETERS FOR THE INACTIVATION OF CRYPTOSPORIDIUM PARVUM OOCYSTS WITH CHLORINE DIOXIDE AND OZONE

EPA Science Inventory

The main objective of this paper is to use Bayesian methods to estimate the kinetic parameters for the inactivation kinetics of Cryptosporidium parvum oocysts with chlorine dioxide or ozone which are characterized by the delayed Chick-Watson model, i.e., a lag phase or shoulder f...

Novel pod for chlorine dioxide generation and delivery to control aerobic bacteria on the inner surface of floor drains

USDA-ARS?s Scientific Manuscript database

Floor drains in poultry processing and further processing plants are a harborage site for bacteria both free swimming and in biofilms. This population can include Listeria monocytogenes which has been shown to have potential for airborne spreading from mishandled open drains. Chlorine dioxide (ClO...

Chloroxyanion residue on seeds and sprouts after chlorine dioxide sanitation of alfalfa seed

USDA-ARS?s Scientific Manuscript database

The effects of a 6-h chlorine dioxide sanitation of alfalfa seed (0, 50, 100, and 200 mg/kg seed) on total coliform bacteria, seed germination, and on the presence of chlorate and perchlorate residues in seed rinse, seed soak, and in alfalfa sprouts was determined. Chlorate residues in 20000 ppm cal...

Groups at potentially high risk from chlorine dioxide treated water.

PubMed

Moore, G S; Calabrese, E J; Ho, S C

1980-09-01

Chlorite, a by-product of chlorine dioxide disinfection of water, is a strong oxidant compound that produces markedly exaggerated effects in vitro on red cells of G6PD deficient humans when compared to normal human cells. Levels of methemoglobin are significantly greater and GSH levels significantly lower in the G6PD deficient cells than in normal cells after chlorite exposure. Persons with G6PD deficiency may be 3 to 4 times more likely to develop hemolytic anemia from chlorite exposure as persons with normal activity levels when GSH levels are used as a measure of susceptibility. The proposed use of chlorine dioxide as an alternate disinfectant for drinking water supplies should consider this potential high risk group.

Temperature Dependence of Gas Properties in Polynomial Form

DTIC Science & Technology

1981-01-01

Carbonyl Sulfide Chlorine Chlorine (Monatomic) Chlorine Dioxide Chlorine Fluoride Chlorine Monoxide Chlorine Oxide Chlorine Trifluoride ...dis- cussed in Section 5 and the following eqn: 100-1500K~ Cp(T)= 515.3754 + 0.426933T -2.91036E-04T 2 -+ 6.836113E-08Ti CHLORINE TRIFLUORIDE C1F 3...3 Trimeric Boron Tribromide BBr3 250.538 33.186 A-3 Boron Trichloride BC1 3 117.170 70.959 A-4 Boron Trifluoride BF3 67.806 122.619 A-4 Bromine Br2

Rx for H20

ERIC Educational Resources Information Center

Yapijakis, Costas

1978-01-01

Drinking water disinfectants are discussed. Disinfectants are chlorine, chlorine dioxide, ozone, potassium permanganate, iodine, bromine, hydrogen peroxide; silver, acids and bases, ultraviolet radiation. (MR)

IDENTIFICATION OF NEW DISINFECTION BY-PRODUCTS IN DRINKING WATER

EPA Science Inventory

Due to concern over the potential adverse health effects of trihalomethanes (THMs) and other chlorinated by-products in chlorinated drinking water, alternative disinfectants are being explored. Ozone, chlorine dioxide, and chloramine are popular alternatives, as they produce low...

Chlorine dioxide against bacteria and yeasts from the alcoholic fermentation

PubMed Central

Meneghin, Silvana Perissatto; Reis, Fabricia Cristina; de Almeida, Paulo Garcia; Ceccato-Antonini, Sandra Regina

2008-01-01

The ethanol production in Brazil is carried out by fed-batch or continuous process with cell recycle, in such way that bacterial contaminants are also recycled and may be troublesome due to the substrate competition. Addition of sulphuric acid when inoculum cells are washed can control the bacterial growth or alternatively biocides are used. This work aimed to verify the effect of chlorine dioxide, a well-known biocide for bacterial decontamination of water and equipments, against contaminant bacteria (Bacillus subtilis, Lactobacillus plantarum, Lactobacillus fermentum and Leuconostoc mesenteroides) from alcoholic fermentation, through the method of minimum inhibitory concentration (MIC), as well as its effect on the industrial yeast inoculum. Lower MIC was found for B. subtilis (10 ppm) and Leuconostoc mesenteroides (50 ppm) than for Lactobacillus fermentum (75 ppm) and Lactobacillus plantarum (125 ppm). Additionally, these concentrations of chlorine dioxide had similar effects on bacteria as 3 ppm of Kamoran® (recommended dosage for fermentation tanks), exception for B. subtilis, which could not be controlled at this Kamoran® dosage. The growth of industrial yeasts was affected when the concentration of chlorine dioxide was higher than 50 ppm, but the effect was slightly dependent on the type of yeast strain. Smooth yeast colonies (dispersed cells) seemed to be more sensitive than wrinkled yeast colonies (clustered cells/pseudohyphal growth), both isolated from an alcohol-producing unit during the 2006/2007 sugar cane harvest. The main advantage in the usage of chlorine dioxide that it can replace antibiotics, avoiding the selection of resistant populations of microorganisms. PMID:24031227

Low-Temperature Decontamination with Hydrogen Peroxide or Chlorine Dioxide for Space Applications

PubMed Central

Macken, S.; Giri, K.; Walker, J. T.; Bennett, A. M.

2012-01-01

The currently used microbial decontamination method for spacecraft and components uses dry-heat microbial reduction at temperatures of >110°C for extended periods to prevent the contamination of extraplanetary destinations. This process is effective and reproducible, but it is also long and costly and precludes the use of heat-labile materials. The need for an alternative to dry-heat microbial reduction has been identified by space agencies. Investigations assessing the biological efficacy of two gaseous decontamination technologies, vapor hydrogen peroxide (Steris) and chlorine dioxide (ClorDiSys), were undertaken in a 20-m3 exposure chamber. Five spore-forming Bacillus spp. were exposed on stainless steel coupons to vaporized hydrogen peroxide and chlorine dioxide gas. Exposure for 20 min to vapor hydrogen peroxide resulted in 6- and 5-log reductions in the recovery of Bacillus atrophaeus and Geobacillus stearothermophilus, respectively. However, in comparison, chlorine dioxide required an exposure period of 60 min to reduce both B. atrophaeus and G. stearothermophilus by 5 logs. Of the three other Bacillus spp. tested, Bacillus thuringiensis proved the most resistant to hydrogen peroxide and chlorine dioxide with D values of 175.4 s and 6.6 h, respectively. Both low-temperature decontamination technologies proved effective at reducing the Bacillus spp. tested within the exposure ranges by over 5 logs, with the exception of B. thuringiensis, which was more resistant to both technologies. These results indicate that a review of the indicator organism choice and loading could provide a more appropriate and realistic challenge for the sterilization procedures used in the space industry. PMID:22492450

Bactericidal Efficacy of Sanitizers Produced by Commercial Water Treatment Generators

DTIC Science & Technology

2009-04-01

means to produce an effective sanitizing solution in the field without re-supply. They would also eliminate the logistical problems and hazards entailed...mobile kitchens to maintain sanitation without re- supply. It would also eliminate the logistical problems and hazards entailed with the purchase and... hazardous and too corrosive for sanitation. Chlorine dioxide at 100 ppm was more effective than AEW and also achieved greater than a 7 log reduction of

Chloroxyanion residue quantification in cantaloupes treated with chlorine dioxide gas

USDA-ARS?s Scientific Manuscript database

Previous studies show that treatment of cantaloupes with chlorine dioxide (ClO2) gas at 5 mg/L for 10 minutes, results in a significant reduction (p<0.05) in initial microflora, an increase in shelf life without any alteration in color, and a 4.6 and 4.3 log reduction of E. coli O157:H7 and L. monoc...

Chlorine Dioxide for Reduction of Postharvest Pathogen Inoculum during Handling of Tree Fruits

PubMed Central

Roberts, Rodney G.; Reymond, Stephen T.

1994-01-01

Alternatives to hypochlorous acid and fungicides are needed for treatment of fruit and fruit-handling facilities. Chlorine dioxide was evaluated and found effective against common postharvest decay fungi and against filamentous fungi occurring on fruit packinghouse surfaces. In vitro tests with conidial or sporangiospore suspensions of Botrytis cinerea, Penicillium expansum, Mucor piriformis, and Cryptosporiopsis perennans demonstrated >99% spore mortality within 1 min when the fungi were exposed to aqueous chlorine dioxide at 3 or 5 μg · ml-1. Longer exposure times were necessary to achieve similar spore mortalities with 1 μg · ml-1. Of the fungi tested, B. cinerea and P. expansum were the least sensitive to ClO2. In comparison with the number recovered from untreated control areas, the number of filamentous fungi recovered was significantly lower in swipe tests from hard surfaces such as belts and pads in a commercial apple and pear packinghouse after treatment of surfaces with a 14.0- to 18.0-μg · ml-1 ClO2 foam formulation. Chlorine dioxide has desirable properties as a sanitizing agent for postharvest decay management when residues of postharvest fungicides are not desired or allowed. PMID:16349354

BROMIDE-OXIDANT INTERACTIONS AND THM (TRIHALOMETHANE) FORMATION: A LITERATURE REVIEW

EPA Science Inventory

The review focuses on the interactions, not only of bromide and chlorine, but also of bromide and two common oxidation alternatives to chlorine--chlorine dioxide and monochloramine. The data evaluations include discussions of reaction products, potentials for trihalomethane (THM)...

Dissection of the mechanism of manganese porphyrin-catalyzed chlorine dioxide generation.

PubMed

Umile, Thomas P; Wang, Dong; Groves, John T

2011-10-17

Chlorine dioxide, an industrially important biocide and bleach, is produced rapidly and efficiently from chlorite ion in the presence of water-soluble, manganese porphyrins and porphyrazines at neutral pH under mild conditions. The electron-deficient manganese(III) tetra-(N,N-dimethyl)imidazolium porphyrin (MnTDMImP), tetra-(N,N-dimethyl)benzimidazolium (MnTDMBImP) porphyrin, and manganese(III) tetra-N-methyl-2,3-pyridinoporphyrazine (MnTM23PyPz) were found to be the most efficient catalysts for this process. The more typical manganese tetra-4-N-methylpyridiumporphyrin (Mn-4-TMPyP) was much less effective. Rates for the best catalysts were in the range of 0.24-32 TO/s with MnTM23PyPz being the fastest. The kinetics of reactions of the various ClO(x) species (e.g., chlorite ion, hypochlorous acid, and chlorine dioxide) with authentic oxomanganese(IV) and dioxomanganese(V)MnTDMImP intermediates were studied by stopped-flow spectroscopy. Rate-limiting oxidation of the manganese(III) catalyst by chlorite ion via oxygen atom transfer is proposed to afford a trans-dioxomanganese(V) intermediate. Both trans-dioxomanganese(V)TDMImP and oxoaqua-manganese(IV)TDMImP oxidize chlorite ion by 1-electron, generating the product chlorine dioxide with bimolecular rate constants of 6.30 × 10(3) M(-1) s(-1) and 3.13 × 10(3) M(-1) s(-1), respectively, at pH 6.8. Chlorine dioxide was able to oxidize manganese(III)TDMImP to oxomanganese(IV) at a similar rate, establishing a redox steady-state equilibrium under turnover conditions. Hypochlorous acid (HOCl) produced during turnover was found to rapidly and reversibly react with manganese(III)TDMImP to give dioxoMn(V)TDMImP and chloride ion. The measured equilibrium constant for this reaction (K(eq) = 2.2 at pH 5.1) afforded a value for the oxoMn(V)/Mn(III) redox couple under catalytic conditions (E' = 1.35 V vs NHE). In subsequent processes, chlorine dioxide reacts with both oxomanganese(V) and oxomanganese(IV)TDMImP to afford chlorate ion. Kinetic simulations of the proposed mechanism using experimentally measured rate constants were in agreement with observed chlorine dioxide growth and decay curves, measured chlorate yields, and the oxoMn(IV)/Mn(III) redox potential (1.03 V vs NHE). This acid-free catalysis could form the basis for a new process to make ClO(2).

INACTIVATION OF BACILLUS GLOBIGII BY CHLORINATION: A HIERARCHICAL BAYESIAN MODEL

EPA Science Inventory

Recent events where spores of Bacillus anthracis have been used as a bioterrorist weapon have prompted interest in determining the resistance of this organism to commonly used disinfectants, such as chlorine, chlorine dioxide and ozone. This work was undertaken to study ...

LABORATORY STUDY ON THE OXIDATION OF ARSENIC III TO ARSENIC V

EPA Science Inventory

A one-year laboratory study was performed to determine the ability of seven oxidants to oxidize As(III) to As(V). These included chlorine, permanganate, ozone, chlorine dioxide, monochloramine, a solid-phase oxidizing media, and 254 nm ultraviolet light. Chlorine and permanganate...

Bacillus subtilis vegetative isolate surviving chlorine dioxide exposure: an elusive mechanism of resistance.

PubMed

Martin, D J H; Wesgate, R L; Denyer, S P; McDonnell, G; Maillard, J-Y

2015-12-01

Oxidizing agents such as chlorine dioxide are widely used microbicides, including for disinfection of medical equipment. We isolated a Bacillus subtilis isolate from a washer-disinfector whose vegetative form demonstrated unique resistance to chlorine dioxide (0·03%) and hydrogen peroxide (7·5%). The aim of this study was to understand the mechanisms of resistance expressed by this isolate. A range of resistance mechanisms were investigated in the B. subtilis isolate and a reference B. subtilis strain (ATCC 6051) to include bacterial cell aggregation, the presence of profuse exopolysaccharide (EPS), and the expression of detoxification enzymes. The basis of resistance of the isolate to high concentrations of oxidizing agents was not linked to the presence of endospores. Although, the presence of EPS, aggregation and expression of detoxification enzymes may play a role in bacterial survival to low concentrations of chlorine dioxide, it is unlikely that the mechanisms helped tested to survive the bactericidal effect of higher oxidizer concentrations. Overall, the mechanisms conferring resistance to chlorine dioxide and hydrogen peroxide remains elusive. Based on recent advances in the mode of action of oxidizing agents and notably hydrogen peroxide, we postulate that additional efficient intracellular mechanisms may be involved to explain significant resistance to in-use concentrations of commonly used high-level disinfectants. The isolation of a highly resistant vegetative Gram-positive bacterium to a highly reactive oxidizing agent is worrying. Understanding the mechanisms conferring such resistance is essential to effectively control such bacterial isolates. Here, we postulate that there are still mechanisms of bacterial resistance that have not been fully characterized. © 2015 The Authors published by John Wiley & Sons Ltd on behalf of Society for Applied Microbiology.

Chemical Loss of Ozone in the Arctic Polar Vortex in the Winter of 1991-1992

NASA Technical Reports Server (NTRS)

Salawitch, R. J.; Wofsy, S. C.; Gottlieb, E. W.; Lait, L. R.; Newman, P. A.; Schoeberl, M. R.; Strahan, S. E.; Loewenstein, M.; Podolske, J. R.; Chan, K. R.;

The effect of pre-oxidation on NDMA formation and the influence of pH.

PubMed

Selbes, Meric; Kim, Daekyun; Karanfil, Tanju

2014-12-01

N-nitrosodimethylamine (NDMA), a probable human carcinogen, is a disinfection by-product that has been detected in chloraminated drinking water systems. Pre-oxidation of the NDMA precursors prior to chloramination can be a viable approach for water utilities to control the NDMA levels. This study examined the effects of (i) commonly used oxidants (i.e., chlorine, chlorine dioxide and ozone) in water treatment, (ii) oxidant concentration and contact time (CT), and (iii) pre-oxidation pH on the formation of NDMA from subsequent chloramination. Fifteen model precursors with NDMA molar yields ranging from approximately 0.1%-90% were examined. Pre-chlorination reduced NDMA formation from most precursors by 10%-50% except quaternary amine polymers (i.e., PolyDADMAC, PolyACRYL, PolyAMINE). Pre-oxidation with chlorine dioxide and ozone achieved the same or higher deactivation of NDMA precursors (e.g., ranitidine) while increasing NDMA formation for some other precursors (e.g., daminozid). The increases with chlorine dioxide exposure were attributed to the release of oxidation products with dimethylamine (DMA) moiety, which may form more NDMA upon chloramination than the unoxidizied parent compound. On the other hand, chlorine dioxide was effective, if a precursors NDMA yield were higher than DMA. The ozone-triggered increases could be related to direct NDMA formation from DMA which are released by ozonation of amines with DMA moiety, amides or hydrazines. However, hydroxyl radicals formed from the decomposition of ozone would be also involved in decomposition of formed NDMA, reducing the overall NDMA levels at longer contact times. pH conditions influenced significantly the effectiveness of deactivation of precursors depending on the type of precursor and oxidant used. Copyright © 2014 Elsevier Ltd. All rights reserved.

Studies on Sporulation Optimization and Chracterization of Bacillus subtilis Spore Quality

DTIC Science & Technology

2011-12-01

in the other two media. Finally, heat and bleach resistance were recommended in place of acid res istance as indicators of spore hardiness. 1S...sporicidal chemicals (e .g., hypochlorite, hydrogen peroxide/per-acetic, and chlorine dioxide gas ), are strongly recommended as spore quality...effected by exposure to one or more sporicidal chemicals (e.g., hypochlorite, hydrogen peroxide/pre-acetic, chlorine dioxide gas ), are strongly recommended

49 CFR 178.337-8 - Openings, inlets, and outlets.

Code of Federal Regulations, 2011 CFR

2011-10-01

... used to transport chlorine. The requirements for inlets and outlets on chlorine cargo tanks are in... dioxide, helium, krypton, neon, nitrogen, and xenon, or mixtures thereof. (6) In addition to the internal... equalization of pressure. (b) Inlets and discharge outlets on chlorine tanks. The inlet and discharge outlets...

49 CFR 178.337-8 - Openings, inlets, and outlets.

Code of Federal Regulations, 2010 CFR

2010-10-01

... used to transport chlorine. The requirements for inlets and outlets on chlorine cargo tanks are in... dioxide, helium, krypton, neon, nitrogen, and xenon, or mixtures thereof. (6) In addition to the internal... equalization of pressure. (b) Inlets and discharge outlets on chlorine tanks. The inlet and discharge outlets...

TRIBROMOPYRROLE, BROMINATED ACIDS, AND OTHER DISINFECTION BYPRODUCTS PRODUCED BY DISINFECTION OF DRINKING WATER RICH IN BROMIDE

EPA Science Inventory

Using gas chromatography/mass spectrometry (GC/MS), we investigated the formation of disinfection byproducts (DBPs) from high bromide waters (2 mg/L) treated with chlorine or chlorine dioxide used in combination with chlorine and chloramines. This study represents the first comp...

Compendium of Dental Residents’ Research Projects and Literature Reviews for 1989

DTIC Science & Technology

1990-05-01

K. Krause, Major, USAF, DC The effectiveness of three immersion disinfectants: Chlorine dioxide, 2% glutaraldehyde, and 5.25% sodium hypochlorite was...5.25% sodium hypochlorite disinfectants also met the same standards of effectiveness at 10 and 5 minutes, respectively. 89 26 05 THE CLINICAL EFFECT...Solutions Time Temp Culture Culture Culture Sporicidin (Control) 10 min 240C 20 0 0 Sodium Hypochlorite 1 min 370C 20 0 0 Alcide Expore 2 min 370C 20 1

Brewer spectrophotometer measurements in the Canadian Arctic

NASA Technical Reports Server (NTRS)

Kerr, J. B.; Evans, W. F. J.

1988-01-01

In the winters of 1987 and 1988 measurements were conducted with the Brewer Spectrophotometer at Alert (82.5 N) and Resolute (74.5 N). The measurements were conducted as part of our Canadian Program to search for an Arctic Ozone Hole (CANOZE). Ozone measurements were conducted in the months of December, January and February using the moon as a light source. The total ozone measurements will be compared with ozonesonde profiles, from ECC sondes, flown once per week from Alert and Resolute. A modified Brewer Spectrophotometer was used in a special study to search for chlorine dioxide at Alert in March 1987. Ground based observations at Saskatoon in February and at Alert in March 1987 failed to detect any measureable chlorine dioxide. Interference from another absorbing gas, which we speculate may be nitrous acid, prevented the measurements at the low levels of chlorine dioxide detected in the Southern Hemisphere by Solomon et al.

Wastewater Disinfectants: Many Called--Few Chosen

ERIC Educational Resources Information Center

Smith, James W.

1978-01-01

Gives a comparative study of disinfectants used to rid wastewater of pathogens. Concentrates on the effects of chlorine and ozone, with some mention of ultra-violet irradiation, bromine chloride, and chlorine dioxide. (MA)

Process for continuous production of metallic uranium and uranium alloys

DOEpatents

Hayden, H.W. Jr.; Horton, J.A.; Elliott, G.R.B.

1995-06-06

A method is described for forming metallic uranium, or a uranium alloy, from uranium oxide in a manner which substantially eliminates the formation of uranium-containing wastes. A source of uranium dioxide is first provided, for example, by reducing uranium trioxide (UO{sub 3}), or any other substantially stable uranium oxide, to form the uranium dioxide (UO{sub 2}). This uranium dioxide is then chlorinated to form uranium tetrachloride (UCl{sub 4}), and the uranium tetrachloride is then reduced to metallic uranium by reacting the uranium chloride with a metal which will form the chloride of the metal. This last step may be carried out in the presence of another metal capable of forming one or more alloys with metallic uranium to thereby lower the melting point of the reduced uranium product. The metal chloride formed during the uranium tetrachloride reduction step may then be reduced in an electrolysis cell to recover and recycle the metal back to the uranium tetrachloride reduction operation and the chlorine gas back to the uranium dioxide chlorination operation. 4 figs.

Process for continuous production of metallic uranium and uranium alloys

DOEpatents

Hayden, Jr., Howard W.; Horton, James A.; Elliott, Guy R. B.

1995-01-01

A method is described for forming metallic uranium, or a uranium alloy, from uranium oxide in a manner which substantially eliminates the formation of uranium-containing wastes. A source of uranium dioxide is first provided, for example, by reducing uranium trioxide (UO.sub.3), or any other substantially stable uranium oxide, to form the uranium dioxide (UO.sub.2). This uranium dioxide is then chlorinated to form uranium tetrachloride (UCl.sub.4), and the uranium tetrachloride is then reduced to metallic uranium by reacting the uranium chloride with a metal which will form the chloride of the metal. This last step may be carried out in the presence of another metal capable of forming one or more alloys with metallic uranium to thereby lower the melting point of the reduced uranium product. The metal chloride formed during the uranium tetrachloride reduction step may then be reduced in an electrolysis cell to recover and recycle the metal back to the uranium tetrachloride reduction operation and the chlorine gas back to the uranium dioxide chlorination operation.

General Theories of Chemical Disinfection and Sterilization of Sludge--Part 3.

ERIC Educational Resources Information Center

Wang, Mu Hao; And Others

1978-01-01

A general discussion of sewage sterilization methods, including techniques using pH, Chlorine, Chlorine Dioxide, Ozone, Iodine and Bromine, metal ions, and cationic surface active agents is presented. (MDR)

Removal of diclofenac by conventional drinking water treatment processes and granular activated carbon filtration.

PubMed

Rigobello, Eliane Sloboda; Dantas, Angela Di Bernardo; Di Bernardo, Luiz; Vieira, Eny Maria

2013-06-01

This study was carried out to evaluate the efficiency of conventional drinking water treatment processes with and without pre-oxidation with chlorine and chlorine dioxide and the use of granular activated carbon (GAC) filtration for the removal of diclofenac (DCF). Water treatment was performed using the Jar test with filters on a lab scale, employing nonchlorinated artesian well water prepared with aquatic humic substances to yield 20HU true color, kaolin turbidity of 70 NTU and 1mgL(-1) DCF. For the quantification of DCF in water samples, solid phase extraction and HPLC-DAD methods were developed and validated. There was no removal of DCF in coagulation with aluminum sulfate (3.47mgAlL(-1) and pH=6.5), flocculation, sedimentation and sand filtration. In the treatment with pre-oxidation and disinfection, DCF was partially removed, but the concentration of dissolved organic carbon (DOC) was unchanged and byproducts of DCF were observed. Chlorine dioxide was more effective than chorine in oxidizing DCF. In conclusion, the identification of DCF and DOC in finished water indicated the incomplete elimination of DCF through conventional treatments. Nevertheless, conventional drinking water treatment followed by GAC filtration was effective in removing DCF (⩾99.7%). In the oxidation with chlorine, three byproducts were tentatively identified, corresponding to a hydroxylation, aromatic substitution of one hydrogen by chlorine and a decarboxylation/hydroxylation. Oxidation with chlorine dioxide resulted in only one byproduct (hydroxylation). Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of aqueous chlorine dioxide treatment on nutritional components and shelf-life of mulberry fruit (Morus alba L.).

PubMed

Chen, Zhao; Zhu, Chuanhe; Han, Ziqiang

2011-06-01

Effects of aqueous chlorine dioxide (ClO(2)) treatment on nutritional components and shelf-life of mulberry fruit (Morus alba L.) were investigated. Mulberry fruit were immersed into 20, 60, and 80 mg/l ClO(2) solutions for 5, 10, and 15 min, respectively. Mulberries were then rinsed with potable tap water for 1 min and stored at -1°C for 14 d. ClO(2) treatment was effective in retention of flavonoid, ascorbic acid, reducing sugar, and titratable acid. ClO(2) concentration and treatment time were significant factors affecting ClO(2) treatment. The shelf-life of the samples treated by 60 mg/l ClO(2) for 15 min was extended to 14 d compared to 8 d for the control. No ClO(2), ClO(2)(-), or ClO(3)(-) residues were detected in samples treated by 60 mg/l ClO(2) for 15 min. These results indicated that ClO(2) treatment was a promising approach to preserve mulberry fruit with no significant risks of chemical residues. Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

The State of the Art. Bridge Protective Systems and Devices.

DTIC Science & Technology

1978-10-01

Chlorine io more commonly found In the marine envirorment while carbon dioxide and sulfur oxide are common Industrial con- taninants. The rate of all of...sulfur, and carbon dioxide which form acid films; and the composition of the metal. Proper maintenance can do little as far as controlling the...installations. 50PP I 8 4 ol - - - -~ ~ a-.’ PON -- Chemical corrosion resul’ from the direct attack on stool by acids or diluted acids. Chlorine, carbon

Use of 0.1% chlorine dioxide to inhibit the formation of morning volatile sulphur compounds (VSC).

PubMed

Peruzzo, Daiane Cristina; Jandiroba, Priscila Fontoura Castelo Branco; Nogueira Filho, Getulio da Rocha

2007-01-01

The aim of this study was to evaluate the VSC-inhibiting effect of a commercially available mouthrinse (0.1% chlorine dioxide) when compared to its placebo. A 2-step double blind, crossover, randomised study was conducted with 14 dental students with healthy periodontium, who refrained from any mechanical plaque and tongue coating control during two 4-day experimental periods. The subjects were instructed to rinse 3 times daily with the assigned product during each period. A 7-day washout interval was established. VSCs levels were measured by a sulphide monitor at the beginning (baseline) and at the end of each experimental period. Statistical analyses were performed using Wilcoxon's and Mann-Whitney's non-parametric tests. At baseline, intragroup analysis revealed that VSCs levels did not differ between groups (p > 0.05); at day 5, the use of the chlorine dioxide mouthrinse did not change the baseline VSCs scores in the control group (p > 0.05), while a 2-fold increase was observed with the use of the placebo mouthrinse (p < 0.05). Intergroup analysis showed a significant difference between the VSCs levels of the test and control groups (40.2 +/- 30.72 and 82.3 +/- 75.63 ppb, p < 0.001) at day 5. Within the limits of this study, the findings suggest that a mouthrinse containing chlorine dioxide can maintain VSCs at lower levels in the morning breath.

40 CFR 141.134 - Reporting and recordkeeping requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... monitoring for chlorine dioxide under the requirements of § 141.132(c). (i) The dates, result, and locations... * * * (1) System monitoring for chlorine or chloramines under the requirements of § 141.132(c) (i) The...

Evaluation of gaseous chlorine dioxide for the inactivation of Tulane virus on blueberries.

PubMed

Kingsley, David H; Pérez-Pérez, Rafael E; Niemira, Brendan A; Fan, Xuetong

2018-05-20

To determine the effectiveness of gaseous chlorine dioxide (gClO 2 ) against a human norovirus surrogate on produce, gClO 2 was generated and applied to Tulane virus-coated blueberries in a 240 ml-treatment chamber. gClO 2 was produced by an acidifying sodium chlorite solution. Initial assessments indicated that blueberries treated with gClO 2 generated from ≤1 mg acidified sodium chlorite in the small chamber appeared unaffected while gClO 2 generated from ≥10 mg of acidified sodium chlorite solution altered the appearance and quality of the blueberries. Treatments of inoculated blueberries with gClO 2 generated from 0.1 mg sodium chlorite reduced the virus populations by >1 log after exposure for 30 to 330 min. For the 1 mg sodium chlorite treatments, the virus populations were reduced by >2.2 log after 15 min exposure and to non-detectable levels (>3.3 logs reductions) after 180 min exposure. Measured concentrations of gClO 2 peaked in the treatment chamber at 0.9 μg/l after 10 min for 0.1 mg treatments and 600 μg/l after around 20 min for 1 mg treatment. Overall results indicate that gClO 2 could be a feasible waterless intervention for blueberries and other produce. Published by Elsevier B.V.

Comparing the efficacy of hyper-pure chlorine-dioxide with other oral antiseptics on oral pathogen microorganisms and biofilm in vitro.

PubMed

Herczegh, Anna; Gyurkovics, Milán; Agababyan, Hayk; Ghidán, Agoston; Lohinai, Zsolt

2013-09-01

This study examines the antibacterial properties of sodium hypochlorite (NaOCl), chlorhexidine gluconate (CHX), Listerine®, and high purity chlorine dioxide (Solumium, ClO2) on selected common oral pathogen microorganisms and on dental biofilm in vitro. Antimicrobial activity of oral antiseptics was compared to the gold standard phenol. We investigated Streptococcus mutans, Lactobacillus acidophilus, Enterococcus faecalis, Veillonella alcalescens, Eikenella corrodens, Actinobacillus actinomycetemcomitans and Candida albicans as some important representatives of the oral pathogens. Furthermore, we collected dental plaque from the upper first molars of healthy young students. Massive biofilm was formed in vitro and its reduction was measured after treating it with mouthrinses: CHX, Listerine® or hyper pure ClO2. Their biofilm disrupting effect was measured after dissolving the crystal violet stain from biofilm by photometer. The results have showed that hyper pure ClO2 solution is more effective than other currently used disinfectants in case of aerobic bacteria and Candida yeast. In case of anaerobes its efficiency is similar to CHX solution. The biofilm dissolving effect of hyper pure ClO2 is significantly stronger compared to CHX and Listerine® after 5 min treatment. In conclusion, hyper pure ClO2 has a potent disinfectant efficacy on oral pathogenic microorganisms and a powerful biofilm dissolving effect compared to the current antiseptics, therefore high purity ClO2 may be a new promising preventive and therapeutic adjuvant in home oral care and in dental or oral surgery practice.

ALTERNATIVE DISINFECTANTS FOR DRINKING WATER TREATMENT

EPA Science Inventory

During a one-year study at Jefferson Parish, Louisiana the chemical, microbiological, and mutagenic effects of using the major drinking water disinfectants (chlorine, chlorine dioxide, chloramine, ozone) were evaluated. ests were performed on samples collected from various treatm...

ALTERNATIVE OXIDANTS

EPA Science Inventory

This chapter reports on the efforts of the USEPA to study chloramines, chlorine dioxide and ozone as alternative oxidants/disinfectants to chlorine for the control of disinfection by-rpdocuts (DBPs) in drinking water. It examines the control of DBPs like trihalomethanes and haloa...

ALTERNATIVE DISINFECTION FOR DRINKING WATER TREATMENT

EPA Science Inventory

During a one-yr study at Jefferson Parish, La., the chemical, microbiological, and mutagenic effects os using the major drinkgin water disinfectants (chlorine, chlorine dioxide, chloramine, ozone) were evaluated. Tests were performed on samples collected from various treatment s...

Formation and Occurrence of Disinfection By-Products

EPA Science Inventory

Disinfection by-products (DBPs) are formed when disinfectants such as chlorine, ozone, chlorine dioxide, or chloramines react with naturally occurring organic matter, anthropogenic contaminants, bromide, and iodide during the production of drinking water. There is concern about D...

Decontamination of Bacillus spores adhered to iron and cement-mortar drinking water infrastructure in a model system using disinfectants.

PubMed

Szabo, Jeffrey G; Meiners, Greg; Heckman, Lee; Rice, Eugene W; Hall, John

2017-02-01

Decontamination of Bacillus spores adhered to common drinking water infrastructure surfaces was evaluated using a variety of disinfectants. Corroded iron and cement-mortar lined iron represented the infrastructure surfaces, and were conditioned in a 23 m long, 15 cm diameter (75 ft long, 6 in diameter) pilot-scale drinking water distribution pipe system. Decontamination was evaluated using increased water velocity (flushing) alone at 0.5 m s -1 (1.7 ft s -1 ), as well as free chlorine (5 and 25 mg L -1 ), monochloramine (25 mg L -1 ), chlorine dioxide (5 and 25 mg L -1 ), ozone (2.0 mg L -1 ), peracetic acid 25 mg L -1 ) and acidified nitrite (0.1 mol L -1 at pH 2 and 3), all followed by flushing at 0.3 m s -1 (1 ft s -1 ). Flushing alone reduced the adhered spores by 0.5 and 2.0 log 10 from iron and cement-mortar, respectively. Log 10 reduction on corroded iron pipe wall coupons ranged from 1.0 to 2.9 at respective chlorine dioxide concentrations of 5 and 25 mg L -1 , although spores were undetectable on the iron surface during disinfection at 25 mg L -1 . Acidified nitrite (pH 2, 0.1 mol L -1 ) yielded no detectable spores on the iron surface during the flushing phase after disinfection. Chlorine dioxide was the best performing disinfectant with >3.0 log 10 removal from cement-mortar at 5 and 25 mg L -1 . The data show that free chlorine, monochloramine, ozone and chlorine dioxide followed by flushing can reduce adhered spores by > 3.0 log 10 on cement-mortar. Published by Elsevier Ltd.

The formation and control of emerging disinfection by-products of health concern.

PubMed

Krasner, Stuart W

2009-10-13

When drinking water treatment plants disinfect water, a wide range of disinfection by-products (DBPs) of health and regulatory concern are formed. Recent studies have identified emerging DBPs (e.g. iodinated trihalomethanes (THMs) and acids, haloacetonitriles, halonitromethanes (HNMs), haloacetaldehydes, nitrosamines) that may be more toxic than some of the regulated ones (e.g. chlorine- and bromine-containing THMs and haloacetic acids). Some of these emerging DBPs are associated with impaired drinking water supplies (e.g. impacted by treated wastewater, algae, iodide). In some cases, alternative primary or secondary disinfectants to chlorine (e.g. chloramines, chlorine dioxide, ozone, ultraviolet) that minimize the formation of some of the regulated DBPs may increase the formation of some of the emerging by-products. However, optimization of the various treatment processes and disinfection scenarios can allow plants to control to varying degrees the formation of regulated and emerging DBPs. For example, pre-disinfection with chlorine, chlorine dioxide or ozone can destroy precursors for N-nitrosodimethylamine, which is a chloramine by-product, whereas pre-oxidation with chlorine or ozone can oxidize iodide to iodate and minimize iodinated DBP formation during post-chloramination. Although pre-ozonation may increase the formation of trihaloacetaldehydes or selected HNMs during post-chlorination or chloramination, biofiltration may reduce the formation potential of these by-products.

HIGH-RATE DISINFECTION TECHNIQUES FOR COMBIND SEWER OVERFLOW

EPA Science Inventory

This paper presents high-rate disinfection technologies for combined sewer overflow (CSO). The high-rate disinfection technologies of interest are: chlorination/dechlorination, ultraviolet light irradiation (UV), chlorine dioxide (ClO2 ), ozone (O3), peracetic acid (CH3COOOH )...

Effect of disinfection of drinking water with ozone or chlorine dioxide on survival of Cryptosporidium parvum oocysts.

PubMed Central

Peeters, J E; Mazás, E A; Masschelein, W J; Villacorta Martiez de Maturana, I; Debacker, E

1989-01-01

Demineralized water was seeded with controlled numbers of oocysts of Cryptosporidium parvum purified from fresh calf feces and subjected to different treatments with ozone or chlorine dioxide. The disinfectants were neutralized by sodium thiosulfate, and neonatal mice were inoculated intragastrically and sacrificed 7 days later for enumeration of oocyst production. Preliminary trials indicated that a minimum infection level of 1,000 oocysts (0.1-ml inoculum) per mouse was necessary to induce 100% infection. Treatment of water containing 10(4) oocysts per ml with 1.11 mg of ozone per liter (concentration at time zero [C0]) for 6 min totally eliminated the infectivity of the oocysts for neonatal mice. A level of 2.27 mg of ozone per liter (C0) was necessary to inactivate water containing 5 x 10(5) oocysts per ml within 8 min. Also, 0.4 mg of chlorine dioxide per liter (C0) significantly reduced infectivity within 15 min of contact, although some oocysts remained viable. PMID:2764564

Improvement of the air quality in student health centers with chlorine dioxide.

PubMed

Hsu, Ching-Shan; Huang, Da-Ji; Lu, Ming-Chun

2010-04-01

This study aims to monitor bioaerosol levels of a local campus of a student health center in Taiwan and then to perform disinfection by applying chlorine dioxide. First, air samples were taken and evaluated in the six areas of the center. The average background bioaerosol levels were 714 +/- 1706 CFU/m(3) for bacterium and 802 +/- 633 CFU/m(3) for fungi. Then, chlorine dioxide was applied through three different procedures: single, multiple and regular disinfections. The results indicated that both multiple and regular disinfections can achieve efficiency levels higher than 59.0%. The regression analysis on bioaerosol levels showed that the number of people present correlating to the number of persons entering the room per door-opening, had a correlation of p < 0.05. Utilizing this analysis result, an empirical model was developed to predict indoor bioaerosol concentrations. It can be inferred that for indoor human activity of health centers, regular disinfection is a very effective process.

In Situ Detection of Chlorine Dioxide (C1O2) in the Radiolysis of Perchlorates and Implications for the Stability of Organics on Mars

NASA Astrophysics Data System (ADS)

Góbi, Sándor; Bergantini, Alexandre; Kaiser, Ralf I.

2016-12-01

Magnesium perchlorate hexahydrate (Mg(ClO4)2 · 6H2O) samples were exposed to energetic electrons to investigate the products of the decomposition of perchlorates in the Martian soil and to infer their role in the degradation of organics on Mars. The samples were monitored online and in situ via infrared spectroscopy as well as electron impact (EI-QMS) and reflectron time-of-flight mass spectrometry coupled with single photon ionization (PI-ReTOF-MS). Our study reveals that besides chlorates ({{{ClO}}3}-) and molecular oxygen (O2), the chlorine dioxide radical (ClO2) was observed online and in situ for the first time as a radiolysis product of solid perchlorates. Chlorine dioxide, which is used on Earth as a strong oxidizing agent in water disinfection and bleaching, represents a proficient oxidizer—potentially more powerful than molecular oxygen—to explain the lack of abundant organics in the Martian soil.

[Analysis of UV-visible absorption spectrum on the decolorization of industrial wastewater by disinfection].

PubMed

Huang, Xin; Wang, Long-Yong; Gao, Nai-Yun; Li, Wei-Guo

2012-10-01

The UV-Visible absorption spectrum of industrial wastewater was explored to introduce a substituting method determining the color of water, and to compare the decolorization efficacy of different disinfectants. The results show that the visible absorption spectrum(350-600 nm), instead of ultraviolet absorption spectrum, should be applied to characterize the color of wastewater. There is a good correlation between the features of visible absorption spectrum and the true color of wastewater. Both ozone and chlorine dioxide has a better decolorization performance than chlorine. However, the color of chlorine dioxide itself has a negative effect on decolorization. The changes in the features of visible absorption spectrum effectively reflect the variations in the color of wastewater after disinfection.

40 CFR 141.54 - Maximum residual disinfectant level goals for disinfectants.

Code of Federal Regulations, 2011 CFR

2011-07-01

... for disinfectants. MRDLGs for disinfectants are as follows: Disinfectant residual MRDLG(mg/L) Chlorine 4 (as Cl 2). Chloramines 4 (as Cl 2). Chlorine dioxide 0.8 (as ClO2) [63 FR 69465, Dec. 16, 1998] ...

40 CFR 141.54 - Maximum residual disinfectant level goals for disinfectants.

Code of Federal Regulations, 2010 CFR

2010-07-01

... for disinfectants. MRDLGs for disinfectants are as follows: Disinfectant residual MRDLG(mg/L) Chlorine 4 (as Cl 2). Chloramines 4 (as Cl 2). Chlorine dioxide 0.8 (as ClO2) [63 FR 69465, Dec. 16, 1998] ...

Decontamination of Bacillus spores adhered to iron and ...

EPA Pesticide Factsheets

Journal Article This study examines the effectiveness of decontaminating Bacillus globigii spores attached to corroded iron and cement-mortar coupons with free chlorine at two pH levels, monochloramine, chlorine dioxide, ozone, peracetic acid (PAA) and acidified nitrite, followed by flushing.

HALOACETONITRILES VS. REGULATED HALOACETIC ACIDS: ARE NITROGEN CONTAINING DBPS MORE TOXIC?

EPA Science Inventory

Haloacetonitriles (HANs) are toxic nitrogenous drinking water disinfection by-products (N-DBPs) and are observed with chlorine, chloramine, or chlorine dioxide disinfection. Using microplate-based Chinese hamster ovary (CHO) cell assays for chronic cytotoxicity and acute genotoxi...

Efficacy of adding detergents to sanitizer solutions for inactivation of Escherichia coli O157:H7 on Romaine lettuce.

PubMed

Keskinen, Lindsey A; Annous, Bassam A

2011-06-30

Numerous Escherichia coli O157:H7 outbreaks have been linked to consumption of fresh lettuce. The development of effective and easily implemented wash treatment could reduce such incidents. The purpose of this study was to evaluate the addition of food-grade detergents to sanitizer solutions for inactivation of E. coli O157:H7 on Romaine lettuce. Freshly-cut leaves of Romaine lettuce were dip-inoculated to achieve a final cell concentration of 7.8±0.2 log CFU/g, air-dried for 2h, and stored overnight at 4 °C. Leaves were then washed for 2 min in an experimental short chain fatty acid formulation (SCFA) or in one of the following solutions with or without 0.2% dodecylbenzenesulfonic acid or 0.2% sodium 2-ethyl hexyl sulfate: 1) deionized water; 2) 100 ppm chlorine dioxide; 3) 100 ppm chlorine; and 4) 200 ppm chlorine. Following wash treatment, samples were blended in neutralizing buffer (1:3) and surface plated on the selective media CT-SMAC. The efficacy of wash treatments, with or without the detergents, in inactivating E. coli O157:H7 cells on lettuce leaves were not significantly different. The most effective wash solution was SCFA, which was capable of reducing E. coli O157:H7 populations by more than 5 log CFU/g. The rest of the wash treatments resulted in a population reduction of less than 1 log CFU/g. The effectiveness of SCFA surpasses that of other sanitizer treatments tested in this study and requires further research to optimize treatments to preserve lettuce quality. Conventional detergents did not enhance the efficacy of any of the wash treatments tested during this study. Published by Elsevier B.V.

Software User’s Manual for the RAILCAR4.1 Toxic Industrial Chemical Source Characterization Program

DTIC Science & Technology

2015-04-01

average cloud area during formation as half of the final cloud area of  Dc2/4.    Since the equations for these parameters can be quite  complex , the...hydrogen chloride  propane (LPG)  chlorine  hydrogen  cyanide  sulfur dioxide  chlorine dioxide  hydrogen fluoride  sulfuric acid  cyanogen chloride

Ballast Water Treatment, U.S. Great Lakes Bulk Carrier Engineering and Cost Study. Volume 2: Analysis of On-Board Treatment Methods, Alternative Ballast Water Management Practices, and Implementation Costs

DTIC Science & Technology

2013-11-01

flushing filter, disinfection with injected chlorine dioxide (chlorine dioxide is generated onboard from two component chemicals, sulfuric acid...Management System 400 80 250-8000 (10000) Sulfuric Acid and Purate for ClO2 generation Yes 0.005-0.028 8-18 Decreased sediment, potential corrosion...feed chemicals, Purate and sulfuric acid. 5. Operational and Maintenance Cost: Estimated operating and maintenance cost is $80/1000 m3 of ballast

High-Rate Disinfection Techniques for Combined Sewer Overflow (Proceedings Paper)

EPA Science Inventory

This paper presents high-rate disinfection technologies for combined sewer overflow (CSO). The high-rate disinfection technologies of interest are: chlorination/dechlorination, ultraviolet light irradiation (UV), chlorine dioxide (ClO2 ), ozone (O3), peracetic acid (CH3COOOH ), a...

A METHOD OF PREPARING URANIUM DIOXIDE

DOEpatents

Scott, F.A.; Mudge, L.K.

1963-12-17

A process of purifying raw, in particular plutonium- and fission- products-containing, uranium dioxide is described. The uranium dioxide is dissolved in a molten chloride mixture containing potassium chloride plus sodium, lithium, magnesium, or lead chloride under anhydrous conditions; an electric current and a chlorinating gas are passed through the mixture whereby pure uranium dioxide is deposited on and at the same time partially redissolved from the cathode. (AEC)

N-nitrosodimethylamine (NDMA) formation potential of amine-based water treatment polymers: Effects of in situ chloramination, breakpoint chlorination, and pre-oxidation.

PubMed

Park, Sang Hyuck; Padhye, Lokesh P; Wang, Pei; Cho, Min; Kim, Jae-Hong; Huang, Ching-Hua

2015-01-23

Recent studies show that cationic amine-based water treatment polymers may be important precursors that contribute to formation of the probable human carcinogen N-nitrosodimethylamine (NDMA) during water treatment and disinfection. To better understand how water treatment parameters affect NDMA formation from the polymers, the effects of in situ chloramination, breakpoint chlorination, and pre-oxidation on the NDMA formation from the polymers were investigated. NDMA formation potential (NDMA-FP) as well as dimethylamine (DMA) residual concentration were measured from poly(epichlorohydrin dimethylamine) (polyamine) and poly(diallyldimethylammonium chloride) (polyDADMAC) solutions upon reactions with oxidants including free chlorine, chlorine dioxide, ozone, and monochloramine under different treatment conditions. The results supported that dichloramine (NHCl2) formation was the critical factor affecting NDMA formation from the polymers during in situ chloramination. The highest NDMA formation from the polymers occurred near the breakpoint of chlorination. Polymer chain breakdown and transformation of the released DMA and other intermediates were important factors affecting NDMA formation from the polymers in pre-oxidation followed by post-chloramination. Pre-oxidation generally reduced NDMA-FP of the polymers; however, the treatments involving pre-ozonation increased polyDADMAC's NDMA-FP and DMA release. The strategies for reducing NDMA formation from the polymers may include the avoidance of the conditions favorable to NHCl2 formation and the avoidance of polymer exposure to strong oxidants such as ozone. Copyright © 2014 Elsevier B.V. All rights reserved.

SAGE III L2 Lunar Event Species Profiles (Binary)

Atmospheric Science Data Center

2017-10-27

... Search and Order:  Earthdata Search   FTP Access:  Data Pool Parameters:  Chlorine Dioxide Nitrogen Dioxide ... Data Additional Info:  Data Format: Big Endian/IEEE Binary; Avg Size in MB: 0.017 SCAR-B Block:  ...

Non-monotonic resonance in a spatially forced Lengyel-Epstein model

DOE PAGES

Haim, Lev; Hagberg, Aric; Meron, Ehud

2015-06-02

Here, we study resonant spatially periodic solutions of the Lengyel-Epstein model modified to describe the chlorine dioxide-iodine-malonic acid reaction under spatially periodic illumination. Using multiple-scale analysis and numerical simulations, we obtain the stability ranges of 2:1 resonant solutions, i.e., solutions with wavenumbers that are exactly half of the forcing wavenumber. We show that the width of resonant wavenumber response is a non-monotonic function of the forcing strength, and diminishes to zero at sufficiently strong forcing. Furthermore, we show that strong forcing may result in a π/2 phase shift of the resonant solutions, and argue that the nonequilibrium Ising-Bloch front bifurcationmore » can be reversed. Finally, we attribute these behaviors to an inherent property of forcing by periodic illumination, namely, the increase of the mean spatial illumination as the forcing amplitude is increased.« less

Electrochemical formation of hydroxide for enhancing carbon dioxide and acid gas uptake by a solution

DOEpatents

Rau, Gregory Hudson [Castro Valley, CA

2012-05-15

A system is described for forming metal hydroxide from a metal carbonate utilizing a water electrolysis cell having an acid-producing anode and a hydroxyl-producing cathode immersed in a water solution of sufficient ionic content to allow an electric current to pass between the hydroxyl-producing cathode and the acid-producing anode. A metal carbonate, in particular water-insoluble calcium carbonate or magnesium carbonate, is placed in close proximity to the acid-producing anode. A direct current electrical voltage is provided across the acid-producing anode and the hydroxyl-producing cathode sufficient to generate acid at the acid-producing anode and hydroxyl ions at the hydroxyl-producing cathode. The acid dissolves at least part of the metal carbonate into metal and carbonate ions allowing the metal ions to travel toward the hydroxyl-producing cathode and to combine with the hydroxyl ions to form the metal hydroxide. The carbonate ions travel toward the acid-producing anode and form carbonic acid and/or water and carbon dioxide. Among other uses, the metal hydroxide formed can be employed to absorb acid gases such as carbon dioxide from a gas mixture. The invention can also generate hydrogen and oxidative gases such as oxygen or chlorine.

MEMBRANE EXTRACTION GC/MS FOR THE ANALYSIS OF DISINFECTION BY-PRODUCTS

EPA Science Inventory

For many years, public water supplies in the U.S.have been treated with a variety of chemicals aimed at reducing or eliminating infectious diseases. Chlorine is the most common disinfectant used to combat waterborne microbial diseases; however, the use of ozone, chlorine dioxid...

TURBULENT FLAME REACTOR STUDIES OF CHLORINATED HYDROCARBON DESTRUCTION EFFICIENCY

EPA Science Inventory

Four mixtures of C₁ and C₂ chlorinated hydrocarbons, diluted in heptane, were burned in a Turbulent Flame Reactor (TFR) under high and low oxygen conditions. Emissions of undestroyed feed, stable organic by-products, carbon monoxide, carbon dioxide and oxyg...

Effects of the Safe Drinking Water Act Amendments of 1986 on Army Fixed Installation Water Treatment Plants

DTIC Science & Technology

1992-06-01

Parathion degradation product Chloramines Bromacil (4>-Nitrophenol) Chlorate Cyanazine Prometon Chlorine Cryomazine 2,4,5- T Chlorine Dioxide DCPA (and...value is the residual disinfectant concentration. T is the disinfectant contact time. Explanations of how C and T are calculated are included in Appendix...each chlorine residual disinfectant concentration sampling point. c) Disinfectant Contact Time. The disinfectant contact time ( T ) must be determined

21 CFR 176.300 - Slimicides.

Code of Federal Regulations, 2011 CFR

2011-04-01

...-dimethylhydantoin (where the dihalo (halogen) may be bromine and/or chlorine) that may contain no more than 20... chlorine). At a maximum level of 1.0 kilogram (kg) per 1,000 kg of dry weight fiber. 4...-Tetraazatricyclo[6.2.1.13,6] dodecane 3,3,4,4-Tetrachlorotetrahydrothiophene-1,1-dioxide Tetrakis(hydroxymethyl...

EVALUATION OF CHEMICALS USED FOR DRINKING WATER DISINFECTION FOR PRODUCTION OF CHROMOSOMAL DAMAGE AND SPERM-HEAD ABNORMALITIES IN MICE

EPA Science Inventory

Chemical oxidants are commonly added during water treatment for disinfection purposes. These chemicals have not been tested previously for their ability to induce genetic damage in vivo. Chlorine (hypochlorite and hypochlorous acid), monochloramine, chlorine dioxide, sodium chlor...

THE ROLE OF GC/MS AND LC/MS IN THE DISCOVERY OF DRINKING WATER DISINFECTION BY-PRODUCTS

EPA Science Inventory

Gas chromatography/mass spectrometry (GC/MS) has played a pivotal role in the discovery of disinfection by-products (DBPs) in drinking water. DBPs are formed when disinfectants, such as chlorine, ozone, chlorine dioxide, or chloramine, react with natural organic matter in the ...

OCCURRENCE, GENOTOXICITY, AND CARCINOGENICITY OF EMERGING DISINFECTION BY-PRODUCTS IN DRINKING WATER: A REVIEW AND ROADMAP FOR RESEARCH

EPA Science Inventory

Disinfection by-products (DBPs) are formed when disinfectants (chlorine, ozone, chlorine dioxide, or chloramines) react with naturally occurring organic matter, anthropogenic contaminants, bromide, and iodide during the production of drinking water. Here we review 30 years of re...

Electrochemical incineration of wastes

NASA Technical Reports Server (NTRS)

Kaba, L.; Hitchens, G. D.; Bockris, J. O'M.

1989-01-01

A low temperature electrolysis process has been developed for the treatment of solid waste material and urine. Experiments are described in which organic materials are oxidized directly at the surface of an electrode. Also, hypochlorite is generated electrochemically from chloride component of urine. Hypochlorite can act as a strong oxidizing agent in solution. The oxidation takes place at 30-60 C and the gaseous products from the anodic reaction are carbon dioxide, nitrogen, oxygen. Hydrogen is formed at the cathode. Carbon monoxide, and nitrogen oxides and methane were not detected in the off gases. Chlorine was evolved at the anode in relatively low amounts.

Products identified at an alternative disinfection pilot plant.

PubMed Central

Lykins, B W; Koffskey, W

1986-01-01

Many drinking water utilities have recently changed or are seriously considering changing their disinfection practice from chlorine to some alternative treatment process. However, most of these utilities are changing their disinfectants without evaluating chemical impacts. Therefore, a research cooperative agreement was developed with Jefferson Parish, LA, to evaluate four parallel streams treated with four different disinfectants (chlorine, monochloramine, chlorine dioxide, and ozone.) These streams, along with a fifth parallel stream, which was not treated with a disinfectant (control), were passed through both sand and granular activated carbon (GAC). Ozonation reduced the total organic carbon (TOC) and total organic halide (TOX) concentration by 0.3 mg/L and 10 micrograms/L, respectively. The average concentration of TOC for the other disinfectants was comparable to that associated with the nondisinfected stream (3.3 mg/L). The average instantaneous TOX concentration for chlorine dioxide, chloramine, and chlorine disinfection after 30 min contact time increased by 60, 92, and 238 micrograms/L, respectively, from a nondisinfected concentration of 25 micrograms/L. The volatile organics most affected by disinfection (chlorination) were the trihalomethanes. No significant change in concentration was noted after disinfection for the other volatile organics evaluated, such as 1,2-dichlorethane, dichloromethane, trichloroethylene, 1,1,2-trichloroethane, and carbon tetrachloride. Ozonation produced an average concentration reduction of 11 to 84% for most of the nonvolatiles evaluated. Conversely, a concentration increase of 43 to 100% was noted, after chlorination, for some of the nonvolatile organics. PMID:3816717

Products identified at an alternative disinfection pilot plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lykins, B.W. Jr.; Koffskey, W.

1986-11-01

Many drinking water utilities have recently changed or are seriously considering changing their disinfection practice from chlorine to some alternative treatment process. However, most of these utilities are changing their disinfectants without evaluating chemical impacts. Therefore, a research cooperative agreement was developed with Jefferson Parish, LA, to evaluate four parallel streams treated with four different disinfectants (chlorine, monochloramine, chlorine dioxide, and ozone.) These streams, along with a fifth parallel stream, which was not treated with a disinfectant (control), were passed through both sand and granular activated carbon (GAC). Ozonation reduced the total organic carbon (TOC) and total organic halide (TOX)more » concentration by 0.3 mg/L and 10 micrograms/L, respectively. The average concentration of TOC for the other disinfectants was comparable to that associated with the nondisinfected stream (3.3 mg/L). The average instantaneous TOX concentration for chlorine dioxide, chloramine, and chlorine disinfection after 30 min contact time increased by 60, 92, and 238 micrograms/L, respectively, from a nondisinfected concentration of 25 micrograms/L. The volatile organics most affected by disinfection (chlorination) were the trihalomethanes. No significant change in concentration was noted after disinfection for the other volatile organics evaluated, such as 1,2-dichlorethane, dichloromethane, trichloroethylene, 1,1,2-trichloroethane, and carbon tetrachloride. Ozonation produced an average concentration reduction of 11 to 84% for most of the nonvolatiles evaluated. Conversely, a concentration increase of 43 to 100% was noted, after chlorination, for some of the nonvolatile organics.« less

Mutagenic activity associated with by-products of drinking water disinfection by chlorine, chlorine dioxide, ozone and UV-irradiation.

PubMed Central

Zoeteman, B C; Hrubec, J; de Greef, E; Kool, H J

1982-01-01

A retrospective epidemiological study in The Netherlands showed a statistical association between chlorination by-products in drinking water and cancer of the esophagus and stomach for males. A pilot-plant study with alternative disinfectants was carried out with stored water of the Rivers Rhine and Meuse. It was demonstrated that the increase of direct acting mutagens after treatment with chlorine dioxide is similar to the effect of chlorination. Ozonation of Rhine water reduced the mutagenic activity for Salmonella typhimurium TA 98 both with and without metabolic activation. UV alone hardly affects the mutagenicity of the stored river water for S. typh. TA 98. In all studies, practically no mutagenic activity for S. typh. TA 100 was found. Although remarkable changes in the concentration of individual organic compounds are reported, the identity of the mutagens detected is yet unclear. Compounds of possible interest due to their removal by ozonation are 1,3,3-trimethyloxindole, dicyclopentadiene and several alkylquinolines. Compounds which might be responsible for the increased mutagenicity after chlorination are two brominated acetonitriles and tri(2-chlorethyl) phosphate. Furthermore, the concentration procedure with adsorption on XAD resin and the subsequent elution step may have affected the results. It is proposed to focus further research more on the less volatile by-products of disinfection than on the trihalomethanes. PMID:7151762

Cross-Resistance of UV- or Chlorine Dioxide-Resistant Echovirus 11 to Other Disinfectants

PubMed Central

Zhong, Qingxia; Carratalà, Anna; Ossola, Rachele; Bachmann, Virginie; Kohn, Tamar

2017-01-01

The emergence of waterborne viruses with resistance to disinfection has been demonstrated in the laboratory and in the environment. Yet, the implications of such resistance for virus control remain obscure. In this study we investigate if viruses with resistance to a given disinfection method exhibit cross-resistance to other disinfectants. Chlorine dioxide (ClO2)- or UV-resistant populations of echovirus 11 were exposed to five inactivating treatments (free chlorine, ClO2, UV radiation, sunlight, and heat), and the extent of cross-resistance was determined. The ClO2-resistant population exhibited cross-resistance to free chlorine, but to none of the other inactivating treatments tested. We furthermore demonstrated that ClO2 and free chlorine act by a similar mechanism, in that they mainly inhibit the binding of echovirus 11 to its host cell. As such, viruses with host binding mechanisms that can withstand ClO2 treatment were also better able to withstand oxidation by free chlorine. Conversely, the UV-resistant population was not significantly cross-resistant to any other disinfection treatment. Overall, our results indicate that viruses with resistance to multiple disinfectants exist, but that they can be controlled by inactivating methods that operate by a distinctly different mechanism. We therefore suggest to utilize two disinfection barriers that act by different mechanisms in order to control disinfection-resistant viruses. PMID:29046672

THE ROLE OF GC-MS AND LC-MS IN THE DISCOVERY OF DRINKING WATER DISINFECTION BY-PRODUCTS

EPA Science Inventory

Gas chromatography-mass spectrometry (GC-MS) has played a pivotal role in the discovery of disinfection by-products (DBPs) in drinking water. DBPs are formed when disinfectants, such as chlorine, ozone, chlorine dioxide or chloramine, react with natural organic matter in the wate...

Benefits of carbon dioxide as pH reducer in chlorinated indoor swimming pools.

PubMed

Gomà, Anton; Guisasola, Albert; Tayà, Carlota; Baeza, Juan A; Baeza, Mireia; Bartrolí, Albert; Lafuente, Javier; Bartrolí, Jordi

2010-06-01

Carbon dioxide is seldom used as pH reducer in swimming pools. Nevertheless it offers two interesting advantages. First, its use instead of the usual hydrochloric acid avoids the characteristic and serious accident of mixing the disinfectant with that strong acid, which forms a dangerous chlorine gas cloud and, second, it allows the facility to become slightly a depository of that greenhouse gas. This work introduces the experience of using CO(2) as pH reducer in real working swimming pools, showing three more advantages: lower chlorine consumption, lower presence of oxidants in the air above the swimming pool and a diminished formation of trihalomethanes in the swimming pool water. Experiments lasted 4years and they were run in three swimming pools in the Barcelona area, where the conventional system based upon HCl and a system based upon CO(2) were consecutively exchanged.

Ground and Surface Water for Drinking: A Laboratory Study on Genotoxicity Using Plant Tests

PubMed Central

Feretti, Donatella; Ceretti, Elisabetta; Gustavino, Bianca; Zerbini, llaria; Zani, Claudia; Monarca, Silvano; Rizzoni, Marco

2012-01-01

Surface waters are increasingly utilized for drinking water because groundwater sources are often polluted. Several monitoring studies have detected the presence of mutagenicity in drinking water, especially from surface sources due to the reaction of natural organic matter with disinfectant. The study aimed to investigate the genotoxic potential of the products of reaction between humic substances, which are naturally present in surface water, and three disinfectants: chlorine dioxide, sodium hypochlorite and peracetic acid. Commercial humic acids dissolved in distilled water at different total organic carbon (TOC) concentrations were studied in order to simulate natural conditions of both ground water (TOC=2.5 mg/L) and surface water (TOC=7.5 mg/L). These solutions were treated with the biocides at a 1:1 molar ratio of C:disinfectant and tested for genotoxicity using the anaphase chromosomal aberration and micronucleus tests in Allium cepa, and the Vicia faba and Tradescantia micronucleus tests. The tests were carried out after different times and with different modes of exposure, and at 1:1 and 1:10 dilutions of disinfected and undisinfected humic acid solutions. A genotoxic effect was found for sodium hypochlorite in all plant tests, at both TOCs considered, while chlorine dioxide gave positive results only with the A.cepa tests. Some positive effects were also detected for PAA (A.cepa and Tradescantia). No relevant differences were found in samples with different TOC values. The significant increase in all genotoxicity end-points induced by all tested disinfectants indicates that a genotoxic potential is exerted even in the presence of organic substances at similar concentrations to those frequently present in drinking water. PMID:25170443

Controlled clinical evaluations of chlorine dioxide, chlorite and chlorate in man.

PubMed Central

Lubbers, J R; Chauan, S; Bianchine, J R

1982-01-01

To assess the relative safety of chronically administered chlorine water disinfectants in man, a controlled study was undertaken. The clinical evaluation was conducted in the three phases common to investigational drug studies. Phase I, a rising dose tolerance investigation, examined the acute effects of progressively increasing single doses of chlorine disinfectants to normal healthy adult male volunteers. Phase II considered the impact on normal subjects of daily ingestion of the disinfectants at a concentration of 5 mg/l. for twelve consecutive weeks. Persons with a low level of glucose-6-phosphate dehydrogenase may be expected to be especially susceptible to oxidative stress; therefore, in Phase III, chlorite at a concentration of 5 mg/l. was administered daily for twelve consecutive weeks to a small group of potentially at-risk glucose-6-phosphate dehydrogenase-deficient subjects. Physiological impact was assessed by evaluation of a battery of qualitative and quantitative tests. The three phases of this controlled double-blind clinical evaluation of chlorine dioxide and its potential metabolites in human male volunteer subjects were completed uneventfully. There were no obvious undesirable clinical sequellae noted by any of the participating subjects or by the observing medical team. In several cases, statistically significant trends in certain biochemical or physiological parameters were associated with treatment; however, none of these trends was judged to have physiological consequence. One cannot rule out the possibility that, over a longer treatment period, these trends might indeed achieve proportions of clinical importance. However, by the absence of detrimental physiological responses within the limits of the study, the relative safety of oral ingestion of chlorine dioxide and its metabolites, chlorite and chlorate, was demonstrated. PMID:6961033

Breathing spiral waves in the chlorine dioxide-iodine-malonic acid reaction-diffusion system.

PubMed

Berenstein, Igal; Muñuzuri, Alberto P; Yang, Lingfa; Dolnik, Milos; Zhabotinsky, Anatol M; Epstein, Irving R

2008-08-01

Breathing spiral waves are observed in the oscillatory chlorine dioxide-iodine-malonic acid reaction-diffusion system. The breathing develops within established patterns of multiple spiral waves after the concentration of polyvinyl alcohol in the feeding chamber of a continuously fed, unstirred reactor is increased. The breathing period is determined by the period of bulk oscillations in the feeding chamber. Similar behavior is obtained in the Lengyel-Epstein model of this system, where small amplitude parametric forcing of spiral waves near the spiral wave frequency leads to the formation of breathing spiral waves in which the period of breathing is equal to the period of forcing.

Examination of Treatment Methods for Cyanide Wastes.

DTIC Science & Technology

1979-05-15

industry,is alkaline chlorination. This process oxidizes cyanide to cyanate followed by complete decomposition yielding carbon dioxide and nitrogen or...decomposition yielding carbon dioxide and nitrogen, or ammonium salts depending on final treatment methods. The major oxidizing agents that have been...2H20 (X represents a cation.) 29 NADC-78198-60 This liberates carbon dioxide and nitrogen gas as end products. Possible acid hydrolysis has been

Using digital flow cytometry to assess the degradation of three cyanobacteria species after oxidation processes.

PubMed

Wert, Eric C; Dong, Mei Mei; Rosario-Ortiz, Fernando L

2013-07-01

Depending on drinking water treatment conditions, oxidation processes may result in the degradation of cyanobacteria cells causing the release of toxic metabolites (microcystin), odorous metabolites (MIB, geosmin), or disinfection byproduct precursors. In this study, a digital flow cytometer (FlowCAM(®)) in combination with chlorophyll-a analysis was used to evaluate the ability of ozone, chlorine, chlorine dioxide, and chloramine to damage or lyse cyanobacteria cells added to Colorado River water. Microcystis aeruginosa (MA), Oscillatoria sp. (OSC) and Lyngbya sp. (LYN) were selected for the study due to their occurrence in surface water supplies, metabolite production, and morphology. Results showed that cell damage was observed without complete lysis or fragmentation of the cell membrane under many of the conditions tested. During ozone and chlorine experiments, the unicellular MA was more susceptible to oxidation than the filamentous OSC and LYN. Rate constants were developed based on the loss of chlorophyll-a and oxidant exposure, which showed the oxidants degraded MA, OSC, and LYN according to the order of ozone > chlorine ~ chlorine dioxide > chloramine. Digital and binary images taken by the digital flow cytometer provided qualitative insight regarding cell damage. When applying this information, drinking water utilities can better understand the risk of cell damage or lysis during oxidation processes. Copyright © 2013 Elsevier Ltd. All rights reserved.

Shelf-Life of Chlorine Solutions Recommended in Ebola Virus Disease Response.

PubMed

Iqbal, Qais; Lubeck-Schricker, Maya; Wells, Emma; Wolfe, Marlene K; Lantagne, Daniele

2016-01-01

In Ebola Virus Disease (EVD) outbreaks, it is widely recommended to wash living things (handwashing) with 0.05% (500 mg/L) chlorine solution and non-living things (surfaces, personal protective equipment, dead bodies) with 0.5% (5,000 mg/L) chlorine solution. Chlorine solutions used in EVD response are primarily made from powdered calcium hypochlorite (HTH), granular sodium dichloroisocyanurate (NaDCC), and liquid sodium hypochlorite (NaOCl), and have a pH range of 5-11. Chlorine solutions degrade following a reaction highly dependent on, and unusually sensitive to, pH, temperature, and concentration. We determined the shelf-life of 0.05% and 0.5% chlorine solutions used in EVD response, including HTH, NaDCC, stabilized NaOCl, generated NaOCl, and neutralized NaOCl solutions. Solutions were stored for 30 days at 25, 30, and 35°C, and tested daily for chlorine concentration and pH. Maximum shelf-life was defined as days until initial concentration fell to <90% of initial concentration in ideal laboratory conditions. At 25-35°C, neutralized-NaOCl solutions (pH = 7) had a maximum shelf-life of a few hours, NaDCC solutions (pH = 6) 2 days, generated NaOCl solutions (pH = 9) 6 days, and HTH and stabilized NaOCl solutions (pH 9-11) >30 days. Models were developed for solutions with maximum shelf-lives between 1-30 days. Extrapolating to 40°C, the maximum predicted shelf-life for 0.05% and 0.5% NaDCC solutions were 0.38 and 0.82 hours, respectively; predicted shelf-life for 0.05% and 0.5% generated NaOCl solutions were >30 and 5.4 days, respectively. Each chlorine solution type offers advantages and disadvantages to responders, as: NaDCC is an easy-to-import high-concentration effervescent powder; HTH is similar, but forms a precipitate that may clog pipes; and, NaOCl solutions can be made locally, but are difficult to transport. We recommend responders chose the most appropriate source chlorine compound for their use, and ensure solutions are stored at appropriate temperatures and used or replaced before expiring.

Chlorine stabilizer T-128 enhances efficacy of chlorine against cross-contamination by E. coli O157:H7 and Salmonella in fresh-cut lettuce processing.

PubMed

Nou, Xiangwu; Luo, Yaguang; Hollar, LaVonda; Yang, Yang; Feng, Hao; Millner, Patricia; Shelton, Daniel

2011-04-01

During fresh-cut produce processing, organic materials released from cut tissues can rapidly react with free chlorine in the wash solution, leading to the potential survival of foodborne bacterial pathogens, and cross-contamination when the free chlorine is depleted. A reported chlorine stabilizer, T-128, has been developed to address this problem. In this study, we evaluated the ability of T-128 to stabilize free chlorine in wash solutions in the presence of high organic loads generated by the addition of lettuce extract or soil. Under conditions used in this study, T-128 significantly (P<0.001) decreased the rate of free chlorine depletion at the presence of soil. T-128 also slightly decreased the rate of free chlorine depletion caused by the addition of lettuce extract in wash solution. Application of T-128 significantly reduced the survival of bacterial pathogens in wash solutions with high organic loads and significantly reduced the potential of cross-contamination, when contaminated and uncontaminated produce were washed together. However, T-128 did not enhance the efficacy of chlorinated wash solutions for microbial reduction on contaminated iceberg lettuce. Evaluation of several produce quality parameters, including overall visual appearance, package headspace O2 and CO2 composition, and lettuce electrolyte leakage, during 15 d of storage indicated that iceberg lettuce quality and shelf life were not negatively impacted by washing fresh-cut lettuce in chlorine solutions containing 0.1% T-128.   Reported chlorine stabilizer is shown to enhance chlorine efficacy against potential bacterial cross-contamination in the presence of high organic loads without compromising product quality and shelf life.

Bioaugmentation for Groundwater Remediation

DTIC Science & Technology

2010-02-01

in biofouling control. Citric acid is optimal as it serves as an acid and a metal chelating agent • Daily application of chlorine dioxide or other...26 6.6.4.1 Chlorinated Ethenes and Ethene ............................................. 26 6.6.4.2 Volatile Fatty Acids ...47 8.3.2 Passive Bioaugmentation and Passive Biostimulation Comparison ......... 48 8.3.2.1 Site Description

DEMONSTRATION OF A LIQUID CARBON DIOXIDE PROCESS FOR CLEANING METAL PARTS

EPA Science Inventory

The report gives results of a demonstration of liquid carbon dioxide (LCO2) as an alternative to chlorinated solvents for cleaning metal parts. It describes the LCO2 process, the parts tested, the contaminants removed, and results from preliminary laboratory testing and on-site d...

PROCESSES FOR SEPARATING AND RECOVERING CONSTITUENTS OF NEUTRON IRRADIATED URANIUM

DOEpatents

Connick, R.E.; Gofman, J.W.; Pimentel, G.C.

1959-11-10

Processes are described for preparing plutonium, particularly processes of separating plutonium from uranium and fission products in neutron-irradiated uraniumcontaining matter. Specifically, plutonium solutions containing uranium, fission products and other impurities are contacted with reducing agents such as sulfur dioxide, uranous ion, hydroxyl ammonium chloride, hydrogen peroxide, and ferrous ion whereby the plutoninm is reduced to its fluoride-insoluble state. The reduced plutonium is then carried out of solution by precipitating niobic oxide therein. Uranium and certain fission products remain behind in the solution. Certain other fission products precipitate along with the plutonium. Subsequently, the plutonium and fission product precipitates are redissolved, and the solution is oxidized with oxidizing agents such as chlorine, peroxydisulfate ion in the presence of silver ion, permanganate ion, dichromate ion, ceric ion, and a bromate ion, whereby plutonium is oxidized to the fluoride-soluble state. The oxidized solution is once again treated with niobic oxide, thus precipitating the contamirant fission products along with the niobic oxide while the oxidized plutonium remains in solution. Plutonium is then recovered from the decontaminated solution.

Inactivation of Escherichia coli O157:H7 in biofilm on food-contact surfaces by sequential treatments of aqueous chlorine dioxide and drying.

PubMed

Bang, Jihyun; Hong, Ayoung; Kim, Hoikyung; Beuchat, Larry R; Rhee, Min Suk; Kim, Younghoon; Ryu, Jee-Hoon

2014-11-17

We investigated the efficacy of sequential treatments of aqueous chlorine and chlorine dioxide and drying in killing Escherichia coli O157:H7 in biofilms formed on stainless steel, glass, plastic, and wooden surfaces. Cells attached to and formed a biofilm on wooden surfaces at significantly (P ≤ 0.05) higher levels compared with other surface types. The lethal activities of sodium hypochlorite (NaOCl) and aqueous chlorine dioxide (ClO₂) against E. coli O157:H7 in a biofilm on various food-contact surfaces were compared. Chlorine dioxide generally showed greater lethal activity than NaOCl against E. coli O157:H7 in a biofilm on the same type of surface. The resistance of E. coli O157:H7 to both sanitizers increased in the order of wood>plastic>glass>stainless steel. The synergistic lethal effects of sequential ClO₂ and drying treatments on E. coli O157:H7 in a biofilm on wooden surfaces were evaluated. When wooden surfaces harboring E. coli O157:H7 biofilm were treated with ClO₂ (200 μg/ml, 10 min), rinsed with water, and subsequently dried at 43% relative humidity and 22 °C, the number of E. coli O157:H7 on the surface decreased by an additional 6.4 CFU/coupon within 6 h of drying. However, when the wooden surface was treated with water or NaOCl and dried under the same conditions, the pathogen decreased by only 0.4 or 1.0 log CFU/coupon, respectively, after 12 h of drying. This indicates that ClO₂ treatment of food-contact surfaces results in residual lethality to E. coli O157:H7 during the drying process. These observations will be useful when selecting an appropriate type of food-contact surfaces, determining a proper sanitizer for decontamination, and designing an effective sanitization program to eliminate E. coli O157:H7 on food-contact surfaces in food processing, distribution, and preparation environments. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of sanitation, freezing and frozen storage on enteric viruses in berries and herbs.

PubMed

Butot, S; Putallaz, T; Sánchez, G

2008-08-15

Norovirus (NV) and hepatitis A virus (HAV) are foodborne enteric viruses associated with outbreaks of disease following consumption of fresh or frozen produce. Model experiments were performed to determine the effectiveness of certain commercial processes for the removal of enteric viruses that might be present in berries and herbs. The survival and persistence of HAV, NV, rotavirus (RV) and feline calicivirus (FCV), a surrogate for NV, in frozen produce over time were determined. Survival and inactivation of HAV, RV and FCV were assessed by viral culture and quantitative reverse transcription-PCR (RT-PCR), whereas NV persistence was determined by quantitative RT-PCR only. Freezing did not significantly reduce the viability of any of the viruses except the infectivity of FCV in strawberries. Frozen storage for 3 months had limited effects on HAV and RV survival in all tested food products, whereas in frozen raspberries and strawberries FCV infectivity showed the highest decay rate due to acid pH. To simulate postharvesting conditions, fresh berries and herbs were rinsed with tap, warm or chlorinated water or with a chlorine dioxide (ClO(2)) solution. Available chlorine at a concentration of 200 ppm and ClO(2) at 10 ppm reduced measurable enteric viruses in raspberry and parsley samples by less than 2 log(10) units.

The effect of pH and chloride concentration on the stability and antimicrobial activity of chlorine-based sanitizers.

PubMed

Waters, Brian W; Hung, Yen-Con

2014-04-01

Chlorinated water and electrolyzed oxidizing (EO) water solutions were made to compare the free chlorine stability and microbicidal efficacy of chlorine-containing solutions with different properties. Reduction of Escherichia coli O157:H7 was greatest in fresh samples (approximately 9.0 log CFU/mL reduction). Chlorine loss in "aged" samples (samples left in open bottles) was greatest (approximately 40 mg/L free chlorine loss in 24 h) in low pH (approximately 2.5) and high chloride (Cl(-) ) concentrations (greater than 150 mg/L). Reduction of E. coli O157:H7 was also negatively impacted (<1.0 log CFU/mL reduction) in aged samples with a low pH and high Cl(-) . Higher pH values (approximately 6.0) did not appear to have a significant effect on free chlorine loss or numbers of surviving microbial cells when fresh and aged samples were compared. This study found chloride levels in the chlorinated and EO water solutions had a reduced effect on both free chlorine stability and its microbicidal efficacy in the low pH solutions. Greater concentrations of chloride in pH 2.5 samples resulted in decreased free chlorine stability and lower microbicidal efficacy. © 2014 Institute of Food Technologists®

A comparison of six different ballast water treatment systems based on UV radiation, electrochlorination and chlorine dioxide.

PubMed

Stehouwer, Peter Paul; Buma, Anita; Peperzak, Louis

2015-01-01

The spread of aquatic invasive species through ballast water is a major ecological and economical threat. Because of this, the International Maritime Organization (IMO) set limits to the concentrations of organisms allowed in ballast water. To meet these limits, ballast water treatment systems (BWTSs) were developed. The main techniques used for ballast water treatment are ultraviolet (UV) radiation and electrochlorination (EC). In this study, phytoplankton regrowth after treatment was followed for six BWTSs. Natural plankton communities were treated and incubated for 20 days. Growth, photosystem II efficiency and species composition were followed. The three UV systems all showed similar patterns of decrease in phytoplankton concentrations followed by regrowth. The two EC and the chlorine dioxide systems showed comparable results. However, UV- and chlorine-based treatment systems showed significantly different responses. Overall, all BWTSs reduced phytoplankton concentrations to below the IMO limits, which represents a reduced risk of aquatic invasions through ballast water.

Effect of 5% Chlorine Dioxide Irrigant on Micro Push Out Bond Strength of Resin Sealer to Radicular Dentin: An In Vitro Study

PubMed Central

Devarasanahalli, Swapna V; Aswathanarayana, Ranjini M; Rashmi, K; Gowda, Yashwanth; Nadig, Roopa R

2017-01-01

Introduction Chlorine dioxide (ClO2) has been recently investigated as a possible root canal irrigant due to its broad spectrum of antimicrobial action, tissue dissolution and smear layer removal properties. Literature is scarce on the effect of chlorine dioxide irrigation on the resin sealer dentin bond strength. Aim To compare 5% chlorine dioxide (ClO2) with or without Ethylene Diamine Tetra Acetic acid (EDTA) with 3% Sodium hypochlorite (NaOCl) and EDTA combination as endodontic irrigants on the adhesion of AH Plus sealer to radicular dentin using micro- Push out Bond Strength (µPBS) test. Materials and Methods Forty freshly extracted central incisors were decoronated and randomly divided into four groups based on the different irrigation regimes followed during irrigation: Group I - 3% NaOCl + 17% EDTA, Group II - 5% ClO2 + 17% EDTA, Group III - 5% ClO2 and Group IV – Saline, and canal enlarged till Protaper F3. All the samples were obturated with F3 gutta-percha cones using AH Plus sealer and sectioned perpendicular to long axis to obtain 1mm thick slices from the middle and coronal portions for µPBS measurement in universal testing machine followed by assessment of failure pattern under stereomicroscope. Data was analysed using One-way analysis of variance (ANOVA), Bonferroni and t-test. Results Bond strength values were in the following order: Group I>Group II>Group III>Group IV, with no statistically significant difference amongst experimental groups on intergroup comparison, except with saline. The µPBS values were more in coronal third than middle third in all specimens, with no statistical significant difference. Mode of failure showed mixed patterns in all experimental groups except saline. Conclusion In the present study, the bond strength values of ClO2 were comparable with conventional NaOCl and EDTA combination and hence, ClO2 can be considered as an effective alternative endodontic irrigant. PMID:28658907

Mixing of gaseous reactants in chemical generation of atomic iodine for COIL: two-dimensional study

NASA Astrophysics Data System (ADS)

Jirasek, Vit; Spalek, Otomar; Kodymova, Jarmila; Censky, Miroslav

2003-11-01

Two-dimensional CFD model was applied for the study of mixing and reaction between gaseous chlorine dioxide and nitrogen monoxide diluted with nitrogen during atomic iodine generation. The influence of molecular diffusion on the production of atomic chlorine as a precursor of atomic iodine was predominantly studied. The results were compared with one-dimensional modeling of the system.

Monitoring of Legionella pneumophila viability after chlorine dioxide treatment using flow cytometry.

PubMed

Mustapha, Pascale; Epalle, Thibaut; Allegra, Séverine; Girardot, Françoise; Garraud, Olivier; Riffard, Serge

2015-04-01

The viability of three Legionella pneumophila strains was monitored after chlorine dioxide (ClO2) treatment using a flow cytometric assay. Suspensions of L. pneumophila cells were submitted to increasing concentrations of ClO2. Culturable cells were still detected when using 4 mg/L, but could no longer be detected after exposure to 6 mg/L of ClO2, although viable but not culturable (VBNC) cells were found after exposure to 4-5 mg/L of ClO2. When testing whether these VBNC were infective, two of the strains were resuscitated after co-culture with Acanthamoeba polyphaga, but neither of them could infect macrophage-like cells. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

A novel microfluidic mixer-based approach for determining inactivation kinetics of Escherichia coli O157:H7 in chlorine solutions.

PubMed

Zhang, Boce; Luo, Yaguang; Zhou, Bin; Wang, Qin; Millner, Patricia D

2015-08-01

Determination of the minimum free chlorine concentration needed to prevent pathogen survival/cross-contamination during produce washing is essential for the development of science-based food safety regulations and practices. Although the trend of chlorine concentration-contact time on pathogen inactivation is generally understood, specific information on chlorine and the kinetics of pathogen inactivation at less than 1.00 s is urgently needed by the produce processing industry. However, conventional approaches to obtain this critical data have been unable to adequately measure very rapid responses. This paper reports our development, fabrication, and test of a novel microfluidic device, and its application to obtain the necessary data on pathogen inactivation by free chlorine in produce wash solution in times as short as 0.10 s. A novel microfluidic mixer with the capability to accurately determine the reaction time and control the chlorine concentration was designed with three inlets for bacterial, chlorine and dechlorinating solutions, and one outlet for effluent collection. The master mold was fabricated on a silicon wafer with microchannels via photopolymerization. Polydimethylsiloxane replicas with patterned microchannels were prototyped via soft lithography. The replicas were further assembled into the micromixer on glass via O2 plasma treatment, and the inlets were connected to a syringe pump for solution delivery. To determine the kinetics of free chlorine on pathogen inactivation, chlorine solutions of varying concentrations were first pumped into the micromixer, together with the addition of bacterial suspension of Escherichia coli O157:H7 through a separate inlet. This was followed by injection of dechlorinating solution to stop the chlorine-pathogen reaction. The effluent was collected and the surviving bacteria cells were enumerated using a modified 'Most Probable Number' method. Free chlorine concentration was determined using a standard colorimetric method. The contact time was experimentally set by adjusting the solution flow rate, and was estimated by computational fluid dynamics modeling. Results showed that 1) pathogen inactivation was significantly affected by free chlorine concentration (P < 0.0001) and subsecond reaction time (P < 0.0001) and their interactions (P < 0.0001); and 2) the current industry practice of using 1.0 mg/L free chlorine will require more than 1.00 s total contact to achieve a 5-log10 reduction in an E. coli O157:H7 population, whereas a 10.0 mg/L free chlorine solution will achieve 5-log10 reduction in as little as 0.25 s. Information obtained from this study will provide critical insight on kinetics of bacterial inactivation for a broad range of sanitizers and produce wash operational conditions, thus facilitating the development and implementation of science-based food safety regulations and practices for improving food safety. Published by Elsevier Ltd.

33 CFR 160.204 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

....7: (i) Ammonia, anhydrous; (ii) Chlorine; (iii) Ethane; (iv) Ethylene oxide; (v) Methane (LNG); (vi) Methyl bromide; (vii) Sulfur dioxide; and (viii) Vinyl chloride. Charterer means the person or...

Artificial leaf device for solar fuel production.

PubMed

Amao, Yutaka; Shuto, Naho; Furuno, Kana; Obata, Asami; Fuchino, Yoshiko; Uemura, Keiko; Kajino, Tsutomu; Sekito, Takeshi; Iwai, Satoshi; Miyamoto, Yasushi; Matsuda, Masatoshi

2012-01-01

Solar fuels, such as hydrogen gas produced from water and methanol produced from carbon dioxide reduction by artificial photosynthesis, have received considerable attention. In natural leaves the photosynthetic proteins are well-organized in the thylakoid membrane. To develop an artificial leaf device for solar low-carbon fuel production from CO2, a chlorophyll derivative chlorin-e6 (Chl-e6; photosensitizer), 1-carboxylundecanoyl-1'-methyl-4,4'-bipyrizinium bromide, iodide (CH3V(CH2)9COOH; the electron carrier) and formate dehydrogenase (FDH) (the catalyst) immobilised onto a silica-gel-based thin layer chromatography plate (the Chl-V-FDH device) was investigated. From luminescence spectroscopy measurements, the photoexcited triplet state of Chl-e6 was quenched by the CH3V(CH2)9COOH moiety on the device, indicating the photoinduced electron transfer from the photoexcited triplet state of Chl-e6 to the CH3V(CH2)9COOH moiety. When the CO2-saturated sample solution containing NADPH (the electron donor) was flowed onto the Chl-V-FDH device under visible light irradiation, the formic acid concentration increased with increasing irradiation time.

Accuracy, Precision, Ease-Of-Use, and Cost of Methods to Test Ebola-Relevant Chlorine Solutions

PubMed Central

Wells, Emma; Wolfe, Marlene K.; Murray, Anna; Lantagne, Daniele

2016-01-01

To prevent transmission in Ebola Virus Disease (EVD) outbreaks, it is recommended to disinfect living things (hands and people) with 0.05% chlorine solution and non-living things (surfaces, personal protective equipment, dead bodies) with 0.5% chlorine solution. In the current West African EVD outbreak, these solutions (manufactured from calcium hypochlorite (HTH), sodium dichloroisocyanurate (NaDCC), and sodium hypochlorite (NaOCl)) have been widely used in both Ebola Treatment Unit and community settings. To ensure solution quality, testing is necessary, however test method appropriateness for these Ebola-relevant concentrations has not previously been evaluated. We identified fourteen commercially-available methods to test Ebola-relevant chlorine solution concentrations, including two titration methods, four DPD dilution methods, and six test strips. We assessed these methods by: 1) determining accuracy and precision by measuring in quintuplicate five different 0.05% and 0.5% chlorine solutions manufactured from NaDCC, HTH, and NaOCl; 2) conducting volunteer testing to assess ease-of-use; and, 3) determining costs. Accuracy was greatest in titration methods (reference-12.4% error compared to reference method), then DPD dilution methods (2.4–19% error), then test strips (5.2–48% error); precision followed this same trend. Two methods had an accuracy of <10% error across all five chlorine solutions with good precision: Hach digital titration for 0.05% and 0.5% solutions (recommended for contexts with trained personnel and financial resources), and Serim test strips for 0.05% solutions (recommended for contexts where rapid, inexpensive, and low-training burden testing is needed). Measurement error from test methods not including pH adjustment varied significantly across the five chlorine solutions, which had pH values 5–11. Volunteers found test strip easiest and titration hardest; costs per 100 tests were $14–37 for test strips and $33–609 for titration. Given the ease-of-use and cost benefits of test strips, we recommend further development of test strips robust to pH variation and appropriate for Ebola-relevant chlorine solution concentrations. PMID:27243817

Toxicity of chlorine to zebrafish embryos

PubMed Central

Kent, Michael L.; Buchner, Cari; Barton, Carrie; Tanguay, Robert L.

2014-01-01

Surface disinfection of fertilized fish eggs is widely used in aquaculture to reduce extraovum pathogens that may be released from brood fish during spawning, and this is routinely used in zebrafish (Danio rerio) research laboratories. Most laboratories use approximately 25 – 50 ppm unbuffered chlorine solution for 5 – 10 min. Treatment of embryos with chlorine has significant germicidal effects for many Gram-negative bacteria, viruses, and trophozoite stages of protozoa, it has reduced efficacy against cyst or spore stages of protozoa and certain Mycobacterium spp. Therefore, we evaluated the toxicity of unbufferred and buffered chlorine solution to embryos exposed at 6 or 24 hours post-fertilization (hpf) to determine if higher concentrations can be used for treating zebrafish embryos. Most of our experiments entailed using an outbred line (5D), with both mortality and malformations as endpoints. We found that 6 hpf embryos consistently were more resistant than 24 hpf embryos to the toxic effects of chlorine. Chlorine is more toxic and germicidal at lower pHs, and chlorine causes elevated pH. Consistent with this, we found that unbufferred chlorine solutions (pH ca 8–9) were less toxic at corresponding concentrations than solutions buffered to pH 7. Based on our findings here, we recommend treating 6 hpf embryos for 10 min and 24 hpf for 5 min with unbuffered chlorine solution at 100 ppm. One trial indicated that AB fish, a popular outbred line, are more susceptible to toxicity than 5Ds. This suggests that variability between zebrafish lines occurs, and researchers should evaluate each line or strain under their particular laboratory conditions for selection of the optimum chlorine treatment procedure. PMID:24429474

Comparative study on the efficiency of peracetic acid and chlorine dioxide at low doses in the disinfection of urban wastewaters.

PubMed

De Luca, Giovanna; Sacchetti, Rossella; Zanetti, Franca; Leoni, Erica

2008-01-01

A comparison was made between the efficiency of low doses of peracetic acid (PAA: 1.5 mg/l) and chlorine dioxide (ClO(2): 1.5 and 2.0 mg/l) in the disinfection of secondary effluents of a wastewater treatment plant. Peracetic acid was seen to be more active than chlorine dioxide and less influenced by the organic content of the waste. Both PAA and ClO(2) (2.0 mg/l) lead to a higher reduction in total and faecal coliforms and E. coli than in phages (somatic coliphages and F-specific RNA bacteriophages) and enterococci. Detection of faecal coliforms and E. coli should therefore be accompanied by a search for these more resistant microorganisms when assessing the conformity of wastewater for irrigation use, or for discharge into surface waters. Coliphages are also considered suitable indicators of the presence of enteric viruses. Although the application of low doses of both disinfectants offers advantages in terms of costs and produces not significant quantities of byproducts, it is not sufficient to obtain wastewater suitable for irrigation according to the Italian norms (E. coli < 10/100 ml in 80 % of samples and <100/100 ml in the remaining samples). Around 65 % of the samples, however, presented concentrations of E. coli lower than the limit of 5,000/100 ml established by Italian norms for discharge into surface waters.

Sensitivity of free-living amoeba trophozoites and cysts to water disinfectants.

PubMed

Dupuy, Mathieu; Berne, Florence; Herbelin, Pascaline; Binet, Marie; Berthelot, Nelsie; Rodier, Marie-Hélène; Soreau, Sylvie; Héchard, Yann

2014-03-01

Free-living amoebae are naturally present in water. These protozoa could be pathogenic and could also shelter pathogenic bacteria. Thus, they are described as a potential hazard for health. Also, free-living amoebae have been described to be resistant to biocides, especially under their cyst resistant form. There are several studies on amoeba treatments but none of them compare sensitivity of trophozoites and cysts from different genus to various water disinfectants. In our study, we tested chlorine, monochloramine and chlorine dioxide on both cysts and trophozoites from three strains, belonging to the three main genera of free-living amoebae. The results show that, comparing cysts to trophozoites inactivation, only the Acanthamoeba cysts were highly more resistant to treatment than trophozoites. Comparison of the disinfectant efficiency led to conclude that chlorine dioxide was the most efficient treatment in our conditions and was particularly efficient against cysts. In conclusion, our results would help to adapt water treatments in order to target free-living amoebae in water networks. Copyright © 2013 Elsevier GmbH. All rights reserved.

Improvement of indoor air quality in pet shop using gaseous chlorine dioxide.

PubMed

Lu, Ming-Chun; Huang, Da-Ji; Hsu, Ching-Shan; Liang, Chih-Kuo; Chen, Geng-Min

2018-06-01

Many studies have shown that pet shops have a high concentration of bioaerosols. Thus, effective disinfection protocols are essential to protect the pet shop staff and visitors to the store. The present study examines the effectiveness of gaseous chlorine dioxide (ClO 2 ) fogging in minimizing the residual bacteria and fungi levels in a typical pet shop in Taiwan consisting of a commodity area, a lodging area, and a grooming area. This investigation uses three disinfection modes (DMs) according to different disinfection periods, namely once every hour (1DM), once every 2 h (2DM), and once every 3 h (3DM). The bacteria and fungi concentrations are measured before and after disinfection treatment, and the effectiveness of each disinfection mode is evaluated using standard statistical techniques. To assess the effect of the environmental factors on the disinfection efficiency, measurements are taken of temperature, relative humidity, airflow velocity, the carbon dioxide concentration, the PM 1 , PM 2.5 , PM 7 , PM 10 , and TSP level at each sampling locations. The results reveal that the effectiveness of the three disinfection modes depends on both the environmental parameters and the use of the three areas (e.g., commodity, lodging, or grooming). Hence, the choice of disinfection method should be adjusted accordingly. For all three disinfection modes, a faster air velocity is beneficial in spreading the disinfectant throughout the indoor space and improving the disinfection performance. Overall, the results presented in this study confirm that gaseous chlorine dioxide disinfection improves the air quality in the pet shop interior, and thus beneficial in safeguarding the health of the pet shop staff and visitors.

The Henry's constant of monochloramine.

PubMed

Garcia, Miguel A; Anderson, Michael A

2018-02-01

Monochloramine is a secondary disinfectant used in drinking water and is also formed in chlorinated wastewater. While known to hydrolyze over time and react with dissolved organic matter, its partitioning between the aqueous and gas phase has not been extensively studied. Preliminary experiments demonstrated that monochloramine concentrations in solutions open to the atmosphere or actively aerated decreased more rapidly than in sealed solutions, indicating significant losses to the atmosphere. For example, a monochloramine solution open to the atmosphere yielded a loss rate constant of 0.08 d -1 , a value twice that for sealed samples without headspace (0.04 d -1 ) where loss occurs exclusively as a result of hydrolysis. A solution aerated at 10 mL s -1 had a loss rate constant nearly 10× greater than that for hydrolysis alone (0.35 d -1 ). To better understand partitioning of monochloramine to the gas phase and potential for volatilization, the dimensionless Henry's law constants of monochloramine (K H ) were determined using an equilibrium headspace technique at five different temperatures (11, 16, 21, 27, and 32 °C). The resulting values ranged from 8 × 10 -3 to 4 × 10 -2 , indicating a semi-volatile compound, and were found to be consistent with quantitative structure activity relationship predictions. At 20 °C, monochloramine exhibits a dimensionless Henry's constant of about 1.7 × 10 -2 which is 35 times greater than ammonia but comparable to the Henry's constant of inorganic semi-volatile compounds such sulfur dioxide. The Henry's constant values for monochloramine suggests that volatilization could be a relevant loss process in open systems such as rivers receiving chlorinated wastewater effluent, swimming pools and cooling towers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrochemical incineration of wastes

NASA Technical Reports Server (NTRS)

Bhardwaj, R. C.; Sharma, D. K.; Bockris, J. OM.

1990-01-01

The novel technology of waste removal in space vehicles by electrochemical methods is presented to convert wastes into chemicals that can be eventually recycled. The important consideration for waste oxidation is to select a right kind of electrode (anode) material that should be stable under anodic conditions and also a poor electrocatalyst for oxygen and chlorine evolution. On the basis of long term electrolysis experiments on seven different electrodes and on the basis of total organic carbon reduced, two best electrodes were identified. The effect of redox ions on the electrolyte was studied. Though most of the experiments were done in mixtures of urine and waste, the experiments with redox couples involved 2.5 M sulfuric acid in order to avoid the precipitation of redox ions by urea. Two methods for long term electrolysis of waste were investigated: (1) the oxidation on Pt and lead dioxide electrodes using the galvanostatic methods; and (2) potentiostatic method on other electrodes. The advantage of the first method is the faster rate of oxidation. The chlorine evolution in the second method is ten times less then in the first. The accomplished research has shown that urine/feces mixtures can be oxidized to carbon dioxide and water, but current densities are low and must be improved. The perovskite and Ti4O7 coated with RuO2 are the best electrode materials found. Recent experiment with the redox agent improves the current density, however, sulphuric acid is required to keep the redox agent in solution to enhance oxidation effectively. It is desirable to reduce the use of acid and/or find substitutes.

Mutagenic activity of disinfection by-products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cognet, L.; Courtois, Y.; Mallevialle, J.

1986-11-01

Data on raw water quality, disinfection treatment practices, and the resulting mutagenic properties of the treated water were compiled from pilot- and full-scale treatment experiments to evaluate that parameter which might produce variability in the results of a mutagenic study. Analysis of the data and comparison of treatment practices indicated that the measured mutagenic activity is strongly related to the characteristics of the organic matter in the raw water, the methodology used to sample and detect mutagens, the scale of the study both in terms of treatment flow and period of study, and the point at which and the conditionsmore » under which oxidants are added during treatment. Conclusions regarding disinfection systems in full-scale water treatment plants include the following: When raw water is pretreated and high concentrations of organics are present in the raw water, both ozonation and chlorination increased mutagenic activity. However, no significant difference in mutagenicity was found between the two oxidants. Both in the case of a nitrified groundwater and a clarified surface water, the mutagenic activity of the water after ozonation was related to its mutagenic activity before ozonation. With ozonation, mutagenic activity decreased after granular activated carbon (GAC) filtration. Thus, when GAC filtration follows ozone disinfection, early addition of oxidants may not be deleterious to the finished water quality. When chlorine or chlorine dioxide is added after GAC filtration, chlorine dioxide was found to produce a less mutagenic water than chlorine. Although these conclusions suggest means of controlling mutagenic activity during treatment, it must be stressed that the measurement of mutagenicity is a presumptive index of contamination level.« less

Strategies for Controlling and Removing Trace Organic Compounds Found in Potable Water Supplies at Fixed Army Installations

DTIC Science & Technology

1985-08-01

have been practiced at Army and municipal water treatment plants. Oxidation/ Disinfection - T -HM Control Although THMs are the only halogenated organics...Table 9 USEPA-Identlf led Methods to Achieve Compliance With 0.1 mg/L, MCL for THMs * Using chloramines as an alternative or supplemental disinfectant ...chlorine Is applied for final disinfection . A residual disinfection coin be added to the distribution systems using chloramines or chlorine dioxide

Chlorine Dioxide Disinfection in the Use of Individual Water Purification Devices

DTIC Science & Technology

2006-03-01

CTs ranging from 1.7-17.6 mg-min/L necessary for 2-log Giardia muris cyst inactivation (reference 23). The SWTR provides the following CT values...reference 3). A comparison of CTs required for a 2-log inactivation for E. Coli bacteria, Poliovirus 1, and Giardia cysts showed Giardia cysts were 2-5...Cryptosporidium oocysts are the most resistant, being 8-16 times more resistant than Giardia cysts (reference 5). Chlorine dioxide’s general disinfection

INTERACTION OF AQUEOUS SOLUTIONS OF CHLORINE WITH MALIC ACID, TARTARIC ACID, AND VARIOUS FRUIT JUICES, A SOURCE OF MUTAGENS

EPA Science Inventory

The interactions of aqueous solutions of chlorine with some fruit acids (citric acid, DL-malic acid, and L-tartaric acid) at different pH values were studied. iethyl ether extraction followed by GC/MS analysis indicated that a number of mutagens (certain chlorinated propanones an...

Calcium Hypochlorite Solutions: Evaluation of Surface Tension and Effect of Different Storage Conditions and Time Periods over pH and Available Chlorine Content.

PubMed

Leonardo, Natália Gomes e Silva; Carlotto, Israel Bangel; Luisi, Simone Bonato; Kopper, Patrícia Maria Poli; Grecca, Fabiana Soares; Montagner, Francisco

2016-04-01

The aim of this study was to evaluate the pH and the available chlorine content from sodium hypochlorite (NaOCl) and calcium hypochlorite (Ca[OCl]2) solutions stored in different conditions and time periods and the surface tension of Ca(OCl)2 solutions in comparison with NaOCl. Solutions at 0.5%, 1%, 2.5%, and 5.25% concentrations were prepared. The pH level and the available chlorine content of freshly prepared solutions and solutions stored for 30, 60, and 90 days at 25°C, 4°C, or 37°C were evaluated in a digital pH meter and by titration, respectively. Surface tension was tested using a Du Nouy tensiometer (Sigma 702, Force Tensiometer; Attension, Espoo, Finland). Descriptive and inferential statistical analyses were performed. A precipitate formed by 2.5% and 5.25% Ca(OCl)2 solutions was observed. Ca(OCl)2 showed a higher concentration of available chlorine than NaOCl. Both 2.5% and 5.25% NaOCl and Ca(OCl)2 had a decrease in the available chlorine content when compared with freshly prepared solutions; 0.5% and 1% NaOCl tend to have a lower pH compared with 0.5% and 1% Ca(OCl)2. NaOCl, 5.25%, showed higher pH compared with 5.25% Ca(OCl)2. NaOCl and Ca(OCl)2 in 0.5% and 1% concentrations tend to show a reduced pH level, whereas 2.5% and 5.25% solutions showed an increase in pH. The heat contributed to the instability of the solutions. NaOCl showed lower surface tension values than Ca(OCl)2. Ca(OCl)2 solutions are extremely alkaline and tend to have more available chlorine content than NaOCl but have a higher surface tension than NaOCl. Regarding the available chlorine content, these solutions tend to be stable to 30 days of storage when kept at 4°C or at 25°C. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

21 CFR 173.300 - Chlorine dioxide.

Code of Federal Regulations, 2010 CFR

2010-04-01

... sodium chlorite by electrolysis. (2) The generator effluent contains at least 90 percent (by weight) of... Health Association, 800 I St. NW., Washington, DC 20001-3750. You may inspect a copy at the Center for...

Inactivation of Bacillus anthracis Spores in Soil Matrices with ...

EPA Pesticide Factsheets

Report This report documents the results of a laboratory study designed to better understand the effectiveness of chlorine dioxide (ClO2) gas to decontaminate soil materials contaminated with Bacillus anthracis spores.

Potential biodefense model applications for portable chlorine dioxide gas production.

PubMed

Stubblefield, Jeannie M; Newsome, Anthony L

2015-01-01

Development of decontamination methods and strategies to address potential infectious disease outbreaks and bioterrorism events are pertinent to this nation's biodefense strategies and general biosecurity. Chlorine dioxide (ClO2) gas has a history of use as a decontamination agent in response to an act of bioterrorism. However, the more widespread use of ClO2 gas to meet current and unforeseen decontamination needs has been hampered because the gas is too unstable for shipment and must be prepared at the application site. Newer technology allows for easy, onsite gas generation without the need for dedicated equipment, electricity, water, or personnel with advanced training. In a laboratory model system, 2 unique applications (personal protective equipment [PPE] and animal skin) were investigated in the context of potential development of decontamination protocols. Such protocols could serve to reduce human exposure to bacteria in a decontamination response effort. Chlorine dioxide gas was capable of reducing (2-7 logs of vegetative and spore-forming bacteria), and in some instances eliminating, culturable bacteria from difficult to clean areas on PPE facepieces. The gas was effective in eliminating naturally occurring bacteria on animal skin and also on skin inoculated with Bacillus spores. The culturable bacteria, including Bacillus spores, were eliminated in a time- and dose-dependent manner. Results of these studies suggested portable, easily used ClO2 gas generation systems have excellent potential for protocol development to contribute to biodefense strategies and decontamination responses to infectious disease outbreaks or other biothreat events.

Plants as air-pollution indicators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meeuse, B.J.D.

This paper deals with the use of plants as biological indicators of air pollution. The author acquaints the reader with some sensitive methods of air pollution monitoring which are based on the use of plants. Some of the pollutants considered are sulfur dioxide, ozone, fluorides, chlorine, ethylene, and carbon dioxide. Some of the indicator plants discussed are alfalfa, buckwheat, clovers, gladiolus, june grass, petunia, nettle, rye grass, spinach, tobacco, and tulips.

Determination of chlorine in silicate rocks

USGS Publications Warehouse

Peck, L.C.

1959-01-01

In a rapid accurate method for the determination of chlorine in silicate rocks, the rock powder is sintered with a sodium carbonate flux containing zinc oxide and magnesium carbonate. The sinter cake is leached with water, the resulting solution is filtered, and the filtrate is acidified with nitric acid. Chlorine is determined by titrating this solution with mercuric nitrate solution using sodium nitroprusside as the indicator. The titration is made in the dark with a beam of light shining through the solution. The end point of the titration is found by visually comparing the intensity of this beam of light with that of a similar beam of light in a reference solution.

Household Water Treatment Uptake during a Public Health Response to a Large Typhoid Fever Outbreak in Harare, Zimbabwe

PubMed Central

Imanishi, Maho; Kweza, Patience F.; Slayton, Rachel B.; Urayai, Tanaka; Ziro, Odrie; Mushayi, Wellington; Francis-Chizororo, Monica; Kuonza, Lazarus R.; Ayers, Tracy; Freeman, Molly M.; Govore, Emmaculate; Duri, Clemence; Chonzi, Prosper; Mtapuri-Zinyowera, Sekesai; Manangazira, Portia; Kilmarx, Peter H.; Mintz, Eric; Lantagne, Daniele

2014-01-01

Locally manufactured sodium hypochlorite (chlorine) solution has been sold in Zimbabwe since 2010. During October 1, 2011–April 30, 2012, 4,181 suspected and 52 confirmed cases of typhoid fever were identified in Harare. In response to this outbreak, chlorine tablets were distributed. To evaluate household water treatment uptake, we conducted a survey and water quality testing in 458 randomly selected households in two suburbs most affected by the outbreak. Although 75% of households were aware of chlorine solution and 85% received chlorine tablets, only 18% had reportedly treated stored water and had the recommended protective level of free chlorine residuals. Water treatment was more common among households that reported water treatment before the outbreak, and those that received free tablets during the outbreak (P < 0.01), but was not associated with chlorine solution awareness or use before the outbreak (P > 0.05). Outbreak response did not build on pre-existing prevention programs. PMID:24664784

Antimicrobial Cellulose: Preparation and Application of 5-Methyl-5-Aminomethylhydantoin

DTIC Science & Technology

2006-08-01

they release active chlorine to microbes relatively more rapidly and kill the pathogens in the shortest time. Amide N-Cl bonds being relatively more...for 5~35 min. A 1% Clorox solution was used for chlorination without pH adjustment. bCoating solution: 5 % AH in distilled water. cCoating solution...0.37% 0.75 % 0.94 % 0.80 % 0.80 % aThe cloth samples were cured at 1450C for 35 min and then chlorinated with 1% Clorox 12 without pH adjustment

Chlorination and chloramination of aminophenols in aqueous solution: oxidant demand and by-product formation.

PubMed

Mehrez, O Abou; Dossier-Berne, F; Legube, B

2015-01-01

Chlorination and monochloramination of aminophenols (AP) were carried out in aqueous solution at 25°C and at pH 8.5. Oxidant demand and disinfection by-product formation were determined in excess of oxidant. Experiments have shown that chlorine consumption of AP was 40-60% higher than monochloramine consumption. Compared with monochloramination, chlorination of AP formed more chloroform and haloacetic acids (HAA). Dichloroacetic acid was the major species of HAA. Chloroform and HAA represented, respectively, only 1-8% and 14-15% of adsorbable organic halides (AOX) by monochloramination but up to 29% and 39% of AOX by chlorination.

Antarctic stratospheric chemistry of chlorine nitrate, hydrogen chloride, and ice - Release of active chlorine

NASA Technical Reports Server (NTRS)

Molina, Mario J.; Tso, Tai-Ly; Molina, Luisa T.; Wang, Frank C.-Y.

1987-01-01

The reaction rate between atmospheric hydrogen chloride (HCl) and chlorine nitrate (ClONO2) is greatly enhanced in the presence of ice particles; HCl dissolves readily into ice, and the collisional reaction probability for ClONO2 on the surface of ice with HCl in the mole fraction range from about 0.003 to 0.010 is in the range from about 0.05 to 0.1 for temperatures near 200 K. Chlorine is released into the gas phase on a time scale of at most a few milliseconds, whereas nitric acid (HNO3), the other product, remains in the condensed phase. This reaction could play an important role in explaining the observed depletion of ozone over Antarctica; it releases photolytically active chlorine from its most abundant reservoir species, and it promotes the formation of HNO3 and thus removes nitrogen dioxide from the gas phase. Hence it establishes the necessary conditions for the efficient catalytic destruction of ozone by halogenated free radicals.

Effects of free and combined chlorine and exposure duration on rainbow trout, channel catfish, and emerald shiners

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brooks, A.S.; Bartos, J.M.

1984-11-01

Laboratory bioassays to determine the acute toxicity of monochloramine, dichloramine, hypochlorous acid, and hypochlorite ion to emerald shiners Notropis atherinoides, channel catfish Ictalurus punctatus, and rainbow trout Salmo gairdneri were conducted. Four exposure regimes typical of chlorination schedules at operating steam electric power plants were used. Fish were exposed for single 15-minute, 30-minute, 120-minute, and 4 x 30-minute periods. Based on median lethal concentrations (LC50s), the nominal solution of hypochlorous acid was the most toxic, followed closely by the solution dominated by dichloramine; nominal monochloramine and hypochlorite ion solutions had a third to a quarter the toxicity of the othermore » two. On the average, emerald shiners were 1.8 times more sensitive than channel catfish and 3.3 times more sensitive than rainbow trout to the four forms of chlorine. The fish were most tolerant of chlorine during short-duration exposures and least tolerant during the continuous 120-minute exposures. The differences in toxicity noted among the chlorine forms suggest that, when chlorination regimes and regulations are established, careful attention should be paid not only to total residual chlorine but to both the chlorine forms and fish species present and the duration of exposure. 24 references, 1 figure, 1 table.« less

Determination of chlorine in atmosphere by kinetic spectrophotometry.

PubMed

Meng, Jian-Xin; Wang, Xiao-Bo; Ruan, Ge-Lan; Li, Guo-Qiang; Deng, Zhao-Xia

2005-03-01

A kinetic method for determination of chlorine in air was described in the present work. The method based on fading of methyl orange (MO) containing solution in air absorption process. A determination limit of 2.64 microg L(-1) was found. With the present method, chlorine concentration could be determined in several minutes with convenient manipulation. As concentration variation of methyl orange in the absorption solution did not affect the experimental results, fabrication and preservation of the stock absorption is also convenient. The present method is promising in monitoring chlorine concentration in atmosphere.

Determination of chlorine in atmosphere by kinetic spectrophotometry

NASA Astrophysics Data System (ADS)

Meng, Jian-Xin; Wang, Xiao-Bo; Ruan, Ge-Lan; Li, Guo-Qiang; Deng, Zhao-Xia

2005-03-01

A kinetic method for determination of chlorine in air was described in the present work. The method based on fading of methyl orange (MO) containing solution in air absorption process. A determination limit of 2.64 μg L -1 was found. With the present method, chlorine concentration could be determined in several minutes with convenient manipulation. As concentration variation of methyl orange in the absorption solution did not affect the experimental results, fabrication and preservation of the stock absorption is also convenient. The present method is promising in monitoring chlorine concentration in atmosphere.

In Situ Bioremediation of Energetic Compounds In Groundwater

DTIC Science & Technology

2012-03-01

Figure 1.2; Fournier et al., 2002; Bhushan et al., 2003). The Cytochrome P450 isozyme CYP177A1, XplA (XplA) has been identified as the key enzyme system...e.g., chlorine dioxide, sodium hypochlorite, and hydrogen peroxide), acid treatment, enzyme addition, liquid carbon dioxide, intermittent pumping...P450 system XplA/B. Proceedings of the National Academy of Science 104:16822-16827. Kaplan, D. L., and A. M. Kaplan. 1992. Thermophilic

33 CFR 127.005 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Chlorine T Dimethylamine F+T Ethane F Ethyl chloride F+T Ethylene F Ethylene oxide F+T Methyl-acetylene and propadiene (mixtures) F Methyl bromide F+T Methyl chloride F+T Propane F Propylene F Sulphur dioxide T Vinyl...

33 CFR 127.005 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Chlorine T Dimethylamine F+T Ethane F Ethyl chloride F+T Ethylene F Ethylene oxide F+T Methyl-acetylene and propadiene (mixtures) F Methyl bromide F+T Methyl chloride F+T Propane F Propylene F Sulphur dioxide T Vinyl...

General RMP Guidance - Appendix F: Supplemental Risk Management Program Guidance for Wastewater Treatment Plants

EPA Pesticide Factsheets

Additional information for wastewater treatment plants (WWTPs), including publicly owned treatment works (POTWs) and other industrial treatment systems; about compliance for chlorine, ammonia (anhydrous and aqueous), sulfur dioxide, and digester gas.

Effects of Chlorine Promoted Oxidation on Arsenic Release from Sulfide Minerals

NASA Astrophysics Data System (ADS)

West, N.; Schreiber, M.; Gotkowitz, M.

2007-12-01

High arsenic concentrations (>100 ppb) have been measured in wells completed in the Ordovician St. Peter sandstone aquifer of eastern Wisconsin. The primary source of arsenic is As-bearing sulfide minerals within the aquifer. Periodic disinfection of wells by chlorination may facilitate arsenic release to groundwater by increasing the rate of sulfide mineral oxidation. During typical well disinfection procedures, aquifer solids exposed along uncased portions of wells remain in direct contact with chlorine disinfection solutions for up to twenty-four hours. Due to the redox sensitivity of arsenic mobility in groundwater, it is important to evaluate the effect of repeatedly adding oxidizers to an arsenic impacted aquifer system. This study focuses on abiotic processes that mobilize arsenic from the solid phase during controlled exposure to chlorinated solutions. Two St. Peter samples with As concentrations of 21 and 674 ppm were selected for the experiments. Before reaction, the aquifer mineralogy is characterized using scanning electron microscopy (SEM) and electron microprobe analysis (EMPA). The samples are then reacted with solutions of 60 mg/L free chlorine, 1200 mg/L free chlorine, or nanopure water (control) at pH 7.0 and pH 8.5. These parameters represent typical solution chemistries present within the wells after disinfection. Solutions are sampled periodically during the experiments and analyzed for As, Fe, other trace metals such as Co, Mo, Cr, and Ni, and sulfate. Analysis of the post-reaction solids using SEM, EMPA, laser ablation ICP-MS and Raman techniques are used to document the changes in mineralogy due to chlorination and to document which solid phases contain As.

Prevalence of Chronic Respiratory Disease in a Pulp Mill and a Paper Mill in the United States1

PubMed Central

Ferris, B. G.; Burgess, W. A.; Worcester, J.

1967-01-01

A sample of 147 men drawn from the workers in a pulp mill was compared with one of 124 men from a paper mill. The former included those exposed to chlorine and to sulphur dioxide. No significant differences were found in respiratory symptoms or in simple tests of ventilatory function in the two samples, but men working in chlorine had a somewhat poorer respiratory function and more shortness of breath than those working in sulphur dioxide. The working population of both mills together had a lower prevalence of respiratory disease than that of the male population of Berlin, N.H., previously studied, suggesting that working populations may not be representative of the general population. Further, a low prevalence of disease in a working population exposed to pollutants may not indicate their `safety' in general populations. PMID:6017136

Reaction of Cl- ions in electrolyte solution induced electrical discharge plasma in the presence of argon fine bubbles

NASA Astrophysics Data System (ADS)

Hayashi, Yui; Takada, Noriharu; Wahyudiono, Kanda, Hideki; Goto, Motonobu

2017-05-01

Active chlorine species such as chlorine molecules and hypochlorous acid have been known as high performance sanitizers. They would act more reactive on chemical and biological substances when an electrical discharge was introduced in water containing an electrolyte substance. Here, the reaction of chloride (Cl-) ions were examined by introducing of a pulsed discharge plasma in sodium chloride (NaCl) solution as an electrolyte solution at room temperature. The results show that a large electrical current generated by the pulsed discharge plasma affected the reaction of Cl- ions to result available chlorine. The reaction pathway for available chlorine production was assumed similar with the reaction pathway as electrolysis. A pulsed discharge plasma in NaCl solution in the presence of argon (Ar) fine bubbles exhibited intense emissions and high electron density compared to when no Ar fine bubbles were introduced. At these conditions, the dissociation reaction rate of water increased drastically leads to the formation of 0 atoms. As a result, the reaction of Cl- ions and the available chlorine generation were also increased.

Use of xylanase in the TCF bleaching of eucalyptus kraft pulp

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roncero, B.; Vidal, T.; Torres, A.L.

1996-10-01

Environmental pressures are forcing the pulp and paper industry to develop new technologies that reduce or eliminate the presence of various contaminants in bleaching plant effluents. Oxygen delignification techniques, replacement of elemental chlorine with chlorine dioxide, ozone, hydrogen peroxide and new agents as well as the use of xylanase enzymes for biobleaching, reduce o eliminate the production of chlorinated organic substances. This paper compares the sequence XOZP with OZP in the bleaching of Eucalyptus globulus kraft pulps. It has been studied the influence of enzymatic treatment on the consumption of bleaching agents: ozone and hydrogen peroxide. Chemical, physical, optical andmore » refining properties of pulps, as well as COD and colour of effluent are also studied. The xylanase treatment is positive and it is possible to manufacture fully bleached pulps at high brightness and viscosity without using chlorine compounds at a low ozone and hydrogen peroxide consumption.« less

Rapid and selective determination of free chlorine in aqueous solution using electrophilic addition to styrene by gas chromatography/mass spectrometry.

PubMed

Wakigawa, Kengo; Gohda, Akinaga; Fukushima, Sunao; Mori, Takeshi; Niidome, Takuro; Katayama, Yoshiki

2013-01-15

We developed a rapid and selective method for determination of free chlorine in aqueous solution by gas chromatography/mass spectrometry for the first time. Free chlorine was converted to styrene chlorohydrin using electrophilic addition to styrene in sodium acetate buffer solution (pH 5). The chlorine derivative obtained was extracted with chloroform, and then analyzed by GC/MS. The calibration curve showed good linearity from 0.2-100 μg/mL (as available chlorine). The detection limit was 0.1 μg/mL, and the intra- and interday accuracy were measured at concentrations of 10, 50, and 75 μg/mL to be -1.3 to 6.9% (intraday) and 3.8-8.0% (interday) as % Bias. The precision was between 1.4 and 4.5% as % RSD. These results indicate that this method is a superior technique for the identification of free chlorine. This method was successfully applied to quantification in commercial samples and in samples of a criminal case. Copyright © 2012 Elsevier B.V. All rights reserved.

The Portable Chemical Sterilizer (PCS), D-FENS, and D-FEND ALL: novel chlorine dioxide decontamination technologies for the military.

PubMed

Doona, Christopher J; Feeherry, Florence E; Setlow, Peter; Malkin, Alexander J; Leighton, Terrence J

2014-06-29

There is a stated Army need for a field-portable, non-steam sterilizer technology that can be used by Forward Surgical Teams, Dental Companies, Veterinary Service Support Detachments, Combat Support Hospitals, and Area Medical Laboratories to sterilize surgical instruments and to sterilize pathological specimens prior to disposal in operating rooms, emergency treatment areas, and intensive care units. The following ensemble of novel, 'clean and green' chlorine dioxide technologies are versatile and flexible to adapt to meet a number of critical military needs for decontamination(6,15). Specifically, the Portable Chemical Sterilizer (PCS) was invented to meet urgent battlefield needs and close critical capability gaps for energy-independence, lightweight portability, rapid mobility, and rugged durability in high intensity forward deployments(3). As a revolutionary technological breakthrough in surgical sterilization technology, the PCS is a Modern Field Autoclave that relies on on-site, point-of-use, at-will generation of chlorine dioxide instead of steam. Two (2) PCS units sterilize 4 surgical trays in 1 hr, which is the equivalent throughput of one large steam autoclave (nicknamed "Bertha" in deployments because of its cumbersome size, bulky dimensions, and weight). However, the PCS operates using 100% less electricity (0 vs. 9 kW) and 98% less water (10 vs. 640 oz.), significantly reduces weight by 95% (20 vs. 450 lbs, a 4-man lift) and cube by 96% (2.1 vs. 60.2 ft(3)), and virtually eliminates the difficult challenges in forward deployments of repairs and maintaining reliable operation, lifting and transporting, and electrical power required for steam autoclaves.

Algal toxicity of the alternative disinfectants performic acid (PFA), peracetic acid (PAA), chlorine dioxide (ClO2) and their by-products hydrogen peroxide (H2O2) and chlorite (ClO2-).

PubMed

Chhetri, Ravi Kumar; Baun, Anders; Andersen, Henrik Rasmus

2017-05-01

Environmental effect evaluation of disinfection of combined sewer overflow events with alternative chemical disinfectants requires that the environmental toxicity of the disinfectants and the main by-products of their use are known. Many disinfectants degrade quickly in water which should be included in the evaluation of both their toxicity as determined in standardized tests and their possible negative effect in the water environment. Here we evaluated according to the standardized ISO 8692 test the toxicity towards the green microalgae, Pseudokirchneriella subcapitata, of three disinfectants: performic acid (PFA), peracetic acid (PAA) and chlorine dioxide (ClO 2 ) as well as two by-products of their use: hydrogen peroxide (H 2 O 2 ) and chlorite. All of the five chemicals investigated showed clear toxicity to the algae with well-defined dose response curves. The EC 50 values ranged from 0.16 to 2.9mg/L based on nominal concentrations leading to the labeling of the chemicals as either toxic or very toxic. The five investigated chemicals decreased in toxicity in the order chlorine dioxide, performic acid, peracetic acid, chlorite and hydrogen peroxide. The stability of the chemicals increased in the same order as the toxicity decrease. This indicates that even though ClO 2 has the highest environmental hazard potential, it may still be suitable as an alternative disinfectant due to its rapid degradation in water. Copyright © 2016 Elsevier GmbH. All rights reserved.

A review of the contrasting behavior of two magmatic volatiles: Chlorine and carbon dioxide

USGS Publications Warehouse

Lowenstern, J. B.

2000-01-01

Chlorine (Cl) and carbon dioxide (CO2) are common magmatic volatiles with contrasting behaviors. CO2 solubility increases with pressure whereas Cl solubility shows relatively little pressure or temperature effect. CO2 speciation changes with silicate melt composition, dissolving as carbonate in basaltic magmas and molecular CO2 in more silicic compositions. In H2O-bearing systems, the strongly non-ideal behavior of alkali chlorides causes unmixing of the volatile phase to form a H2O-rich vapor and a hydrosaline phase with important implications for the maximum concentration of Cl in magmas. Addition of CO2 to magma hastens immiscibility at crustal pressures (<500 MPa), inducing the formation of CO2-rich vapors and Cl-rich hydrosaline melts. (C) 2000 Elsevier Science B.V. All rights reserved.Chlorine (Cl) and carbon dioxide (CO2) are common magmatic volatiles with contrasting behaviors. CO2 solubility increases with pressure whereas Cl solubility shows relatively little pressure or temperature effect. CO2 speciation changes with silicate melt composition, dissolving as carbonate in basaltic magmas and molecular CO2 in more silicic compositions. In H2O-bearing systems, the strongly non-ideal behavior of alkali chlorides causes unmixing of the volatile phase to form a H2O-rich vapor and a hydrosaline phase with important implications for the maximum concentration of Cl in magmas. Addition of CO2 to magma hastens immiscibility at crustal pressures (<500 MPa), inducing the formation of CO2-rich vapors and Cl-rich hydrosaline melts.

Bromine, chlorine and sulfur emission into the free troposphere from a Rift volcano

NASA Astrophysics Data System (ADS)

Bobrowski, N.; Giuffrida, G. B.; Tedeso, D.; Yalire, M. M.; Galle, B.

2007-12-01

In June 2007 spectroscopic measurements were carried out at the crater rim of the Niyragongo volcano located 15 km north of the city Goma, North Kivu region (DRC). Niyragongo volcano belongs to the Virunga volcanic chain and it is associated with the Western branch of the Great Rift Valley. The volcanism at Niyragongo is caused by the rifting of the Earth's crust where two parts of the African plates are breaking apart. Niyragongo is a 3470 m high stratovolcano, which a large summit crater usually containing a lava lake inside and it is considered one of the most active volcanoes in Africa. Satellite measurements show an extremely large sulphur dioxide plume since May 2002, and it is considered one of the biggest sulphur dioxide sources on Earth. The ground - based remote sensing technique - MAX-DOAS (Multi Axis Differential Optical Absorption Spectroscopy) using scattered sunlight has been applied during a one week field trip on top of the crater rim of Niyragongo volcano to measure nitrogen oxide, halogen oxides and sulphur dioxide. The used Mini-MAX-DOAS is a lightweight, compact, robust instrument and has very low power consumption which allows to be deployed over several days with some small lead batteries. The measurements provide valuable information of the chemical composition as well its variability within the volcanic plume of the lava lake and allowed also studying chemical transformation processes of the halogens inside the plume. Bromine-sulphur and chlorine-sulphur ratios were investigated and a minimal bromine and chlorine emission flux estimation will be presented.

Characterization of supersonic radiation diffusion waves

DOE PAGES

Moore, Alastair S.; Guymer, Thomas M.; Morton, John; ...

2015-02-27

Supersonic and diffusive radiation flow is an important test problem for the radiative transfer models used in radiation-hydrodynamics computer codes owing to solutions being accessible via analytic and numeric methods. We present experimental results with which we compare these solutions by studying supersonic and diffusive flow in the laboratory. Here, we present results of higher-accuracy experiments than previously possible studying radiation flow through up to 7 high-temperature mean free paths of low-density, chlorine-doped polystyrene foam and silicon dioxide aerogel contained by an Au tube. Measurements of the heat front position and absolute measurements of the x-ray emission arrival at themore » end of the tube are used to test numerical and analytical models. We find excellent absolute agreement with simulations provided that the opacity and the equation of state are adjusted within expected uncertainties; analytical models provide a good phenomenological match to measurements but are not in quantitative agreement due to their limited scope.« less

Characterization of supersonic radiation diffusion waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, Alastair S.; Guymer, Thomas M.; Morton, John

Supersonic and diffusive radiation flow is an important test problem for the radiative transfer models used in radiation-hydrodynamics computer codes owing to solutions being accessible via analytic and numeric methods. We present experimental results with which we compare these solutions by studying supersonic and diffusive flow in the laboratory. Here, we present results of higher-accuracy experiments than previously possible studying radiation flow through up to 7 high-temperature mean free paths of low-density, chlorine-doped polystyrene foam and silicon dioxide aerogel contained by an Au tube. Measurements of the heat front position and absolute measurements of the x-ray emission arrival at themore » end of the tube are used to test numerical and analytical models. We find excellent absolute agreement with simulations provided that the opacity and the equation of state are adjusted within expected uncertainties; analytical models provide a good phenomenological match to measurements but are not in quantitative agreement due to their limited scope.« less

40 CFR 141.711 - Filtered system additional Cryptosporidium treatment requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... either one or a combination of the following: bag filters, bank filtration, cartridge filters, chlorine dioxide, membranes, ozone, or UV, as described in §§ 141.716 through 141.720. (c) Failure by a system in...

40 CFR 141.711 - Filtered system additional Cryptosporidium treatment requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... either one or a combination of the following: bag filters, bank filtration, cartridge filters, chlorine dioxide, membranes, ozone, or UV, as described in §§ 141.716 through 141.720. (c) Failure by a system in...

CRYPTOSPORIDIUM INACTIVATION AND REMOVAL RESEARCH

EPA Science Inventory

Bench- and pilot-scale tests were performed to assess the ability of conventional treatment, ozonation and chlorine dioxide to remove and inactivate Cryptosporidium oocysts. The impacts of coagulant type, coagulant dose, raw water quality, filter loading rates and filter media w...

Appendix F: Supplemental Risk Management Program Guidance for Wastewater Treatment Plants

EPA Pesticide Factsheets

Detail for wastewater treatment plants (WWTPs), including publicly owned treatment works (POTWs) and other industrial treatment systems, on complying with part 68 with respect to chlorine, ammonia (anhydrous and aqueous), sulfur dioxide, and digester gas.

Ultrafast measurements of chlorine dioxide photochemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ludowise, P.D.

Time-resolved mass spectrometry and time-resolved photoelectron spectroscopy are used to study the ultrafast photodissociation dynamics of chlorine dioxide, an important constituent in stratospheric ozone depletion. Chapter 1 introduces these pump/probe techniques, in which a femtosecond pump pulse excites a molecule to a dissociative state. At a later time, a second femtosecond probe pulse ionizes the molecule. The resulting mass and photoelectron spectra are acquired as a function of the delay between the pump and probe pulses, which follows the evolution of the molecule on the excited state. A comparison to other techniques used to study reaction dynamics is discussed. Chaptermore » 2 includes a detailed description of the design and construction of the experimental apparatus, which consists of a femtosecond laser system, a molecular beam time-of-flight spectrometer, and a data acquisition system. The time-of-flight spectrometer is specifically designed to have a short flight distance to maximize the photoelectron collection efficiency without degrading the resolution, which is limited by the bandwidth of the femtosecond laser system. Typical performance of the apparatus is demonstrated in a study of the time-resolved photoelectron spectroscopy of nitric oxide. The results of the time-resolved mass spectrometry experiments of chlorine dioxide are presented in Chapter 3. Upon excitation to the A {sup 2}A{sub 2} state near 3.2 eV, the molecule dissociates through an indirect two-step mechanism. The direct dissociation channel has been predicted to be open, but is not observed. A quantum beat is observed in the OClO{sup +} species, which is described as a vibrational coherence of the optically prepared A {sup 2}A{sub 2} state. Chapter 4 presents the results of the time-resolved photoelectron experiments of chlorine dioxide. At short delay time, the quantum beat of the OClO{sup +} species is observed in the X {sup 1}A{sub 1} state of the ion. At infinite delay, the signal is dominated by the ClO{sup +} ion, observed in a variety of electronic states. The photoelectron data is shown to support the indirect two-step dissociation mechanism derived from the mass results. Conclusions of the mass and photoelectron results are discussed in context of the stratospheric ozone depletion problem.« less

Water disinfection: A relationship between ozone and aldehyde production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gilli, G.; Scursatone, E.; Palin, L.

In the water potabilization plant of Turin city (Italy), the oxidation process is carried out with ozone. Due to its well-known insufficient performance, it is necessary to add alternative oxidants (hypochlorite ion and chlorine dioxide). In this paper, the authors discuss the formation of linear carbonyl groups during surface water treatment in Turni. The results obtained in the field confirm the synthesis of some aliphatic carbonyl compounds of low molecular weight. This phenomenon happens preeminently during the ozone disinfection process and, secondarily, during the other disinfection processes. Experimental results show that, in this last event, chlorine reacts with organic substances,more » and in a second moment, after organics consumption, if chlorine is still in a sufficient concentration, oxidizing them.« less

Combined Excitatory and Inhibitory Coupling in a 1-D Array of Belousov-Zhabotinsky Droplets

DTIC Science & Technology

2014-01-01

with numerical chemical models of the BZ reaction in which components that participate in the excitatory (bromine dioxide and bromous acid) and...verify the transport through the fluorinated oil of chlorine dioxide and several weak acids, including malonic acid. 1. Introduction Recent studies1...finite element model (COMSOLs) of the reaction - diffusion equation in 1-D, 2-D and 3-D, where each drop is modeled as a point, disk or sphere

Chemical fate and changes in mutagenic activity of antibiotics nitrofurazone and furazolidone during aqueous chlorination.

PubMed

Nakamura, Hitomi; Kawakami, Tsuyoshi; Niino, Tatsuhiro; Takahashi, Yasuo; Onodera, Sukeo

2008-12-01

Reactions of nitrofuran antibiotics (nitrofurazone (NFZ) and frazolidone (FZD)) with hypochlorite in aqueous solution were investigated under the conditions that simulate wastewater disinfection. The chlorination byproducts were determined by high performance liquid chromatography. At the levels of 5 microM, NFZ reacted rapidly with free chlorine in neutral pH (7.0), while the FZD-hypochlorite reaction was reasonably slow under the same pH. Nevertheless, the strong mutagenic parents disappeared completely after the hypochlorite reactions, and the chlorination byproducts were observed to exert a weak mutagenic effect on Salmonella typhimurium TA100 without S9-mix. The extent of the reactions depended on the chlorine dose, solution pH and compound structures.

Reaction kinetics and transformation of carbadox and structurally related compounds with aqueous chlorine.

PubMed

Shah, Amisha D; Kim, Jae-Hong; Huang, Ching-Hua

2006-12-01

The potential release of carbadox (CDX), a commonly used antibacterial agent in swine husbandry, into water systems is of a concern due to its carcinogenic and genotoxic effects. Until this study, the reactivity of carbadox (possessing quinoxaline N,N'-dioxide and hydrazone moieties) toward aqueous chlorine has yetto be investigated in depth. Chemical reactivity, reaction kinetics, and transformation pathways of carbadox and structurally related compounds with free chlorine under typical water treatment conditions were determined. This study found that only CDX and desoxycarbadox (DCDX), a main metabolite of CDX with no ring N-oxide groups, react rapidly with free chlorine while other structurally related compounds including olaquindox, quindoxin, quinoxaline N-oxide, quinoxaline, and quinoline N-oxide do not. The reaction kinetics of CDX and DCDX with chlorine are highly pH dependent (e.g., the apparent second-order rate constant, kapp, for CDX ranges from 51.8 to 3.15 x 10(4) M(-1)s(-1) at pH 4-11). The high reactivity of CDX and DCDX to chlorine involves deprotonation of their hydrazone N-H moieties where initial chlorine attack results in a reactive intermediate that is further attacked by nucleophiles in the matrix to yield non-chlorinated, hydroxylated, and larger molecular weight byproducts. All of the CDX's byproducts retain their biologically active N-oxide groups, suggesting that they may remain as active antibacterial agents.

Development of a Chlorine Dosing Strategy for Fresh Produce Washing Process to Maintain Microbial Food Safety and Minimize Residual Chlorine.

PubMed

Chen, Xi; Hung, Yen-Con

2018-06-01

The residual free chlorine level in fresh produce wash solution is closely correlated to the chemical and microbial safety of produce. Excess amount of free chlorine can quickly react with organic matters to form hazardous disinfection by-products (DBPs) above EPA-permitted levels, whereas deficiency of residual chlorine in produce wash solution may result in incompletely removing pathogens on produce. The purpose of this study was to develop a chlorine dosing strategy to optimize the chlorine dosage during produce washing process without impacting the microbial safety of fresh produce. Prediction equations were developed to estimate free chlorine needed to reach targeted residual chlorine at various sanitizer pH and organic loads, and then validated using fresh-cut iceberg lettuce and whole strawberries in an automated produce washer. Validation results showed that equations successfully predicted the initial chlorine concentration needed to achieve residual chlorine at 10, 30, 60, and 90 mg/L for both lettuce and strawberry washing processes, with the root mean squared error at 4.45 mg/L. The Escherichia coli O157:H7 reductions only slightly increased on iceberg lettuce and strawberries with residual chlorine increasing from 10 to 90 mg/L, indicating that lowering residual chlorine to 10 mg/L would not compromise the antimicrobial efficacy of chlorine-based sanitizer. Based on the prediction equations and E. coli O157:H7 reduction results, a chlorine dosing strategy was developed to help the produce industry to maintain microbial inactivation efficacy without adding excess amount of free chlorine. The chlorine dosing strategy can be used for fresh produce washing process to enhance the microbial food safety and minimize the DBPs formation potential. © 2018 Institute of Food Technologists®.

PROCESS OF DISSOLVING FUEL ELEMENTS OF NUCLEAR REACTORS

DOEpatents

Wall, E.M.V.; Bauer, D.T.; Hahn, H.T.

1963-09-01

A process is described for dissolving stainless-steelor zirconium-clad uranium dioxide fuel elements by immersing the elements in molten lead chloride, adding copper, cuprous chloride, or cupric chloride as a catalyst and passing chlorine through the salt mixture. (AEC)

Biofilm formation and sporulation by Bacillus cereus on a stainless steel surface and subsequent resistance of vegetative cells and spores to chlorine, chlorine dioxide, and a peroxyacetic acid-based sanitizer.

PubMed

Ryu, Jee-Hoon; Beuchat, Larry R

2005-12-01

Biofilm formation by Bacillus cereus 038-2 on stainless steel coupons, sporulation in the biofilm as affected by nutrient availability, temperature, and relative humidity, and the resistance of vegetative cells and spores in biofilm to sanitizers were investigated. Total counts in biofilm formed on coupons immersed in tryptic soy broth (TSB) at 12 and 22 degrees C consisted of 99.94% of vegetative cells and 0.06% of spores. Coupons on which biofilm had formed were immersed in TSB or exposed to air with 100, 97, 93, or 85% relative humidity. Biofilm on coupons immersed in TSB at 12 degrees C for an additional 6 days or 22 degrees C for an additional 4 days contained 0.30 and 0.02% of spores, respectively, whereas biofilm exposed to air with 100 or 97% relative humidity at 22 degrees C for 4 days contained 10 and 2.5% of spores, respectively. Sporulation did not occur in biofilm exposed to 93 or 85% relative humidity at 22 degrees C. Treatment of biofilm on coupons that had been immersed in TSB at 22 degrees C with chlorine (50 microg/ml), chlorine dioxide (50 microg/ml), and a peroxyacetic acid-based sanitizer (Tsunami 200, 40 microg/ml) for 5 min reduced total cell counts (vegetative cells plus spores) by 4.7, 3.0, and 3.8 log CFU per coupon, respectively; total cell counts in biofilm exposed to air with 100% relative humidity were reduced by 1.5, 2.4, and 1.1 log CFU per coupon, respectively, reflecting the presence of lower numbers of vegetative cells. Spores that survived treatment with chlorine dioxide had reduced resistance to heat. It is concluded that exposure of biofilm formed by B. cereus exposed to air at high relative humidity (> or =97%) promotes the production of spores. Spores and, to a lesser extent, vegetative cells embedded in biofilm are protected against inactivation by sanitizers. Results provide new insights to developing strategies to achieve more effective sanitation programs to minimize risks associated with B. cereus in biofilm formed on food contact surfaces and on foods.

Effects of UV 254 irradiation on residual chlorine and DBPs in chlorination of model organic-N precursors in swimming pools.

PubMed

Weng, ShihChi; Li, Jing; Blatchley, Ernest R

2012-05-15

Ultraviolet (UV) irradiation is commonly applied as a secondary disinfection process in chlorinated pools. UV-based systems have been reported to yield improvements in swimming pool water and air chemistry, but to date these observations have been largely anecdotal. The objectives of this investigation were to evaluate the effects of UV irradiation on chlorination of important organic-N precursors in swimming pools. Creatinine, L-arginine, L-histidine, glycine, and urea, which comprise the majority of the organic-N in human sweat and urine, were selected as precursors for use in conducting batch experiments to examine the time-course behavior of several DBPs and residual chlorine, with and without UV(254) irradiation. In addition, water samples from two natatoria were subjected to monochromatic UV irradiation at wavelengths of 222 nm and 254 nm to evaluate changes of liquid-phase chemistry. UV(254) irradiation promoted formation and/or decay of several chlorinated N-DBPs and also increased the rate of free chlorine consumption. UV exposure resulted in loss of inorganic chloramines (e.g., NCl(3)) from solution. Dichloromethylamine (CH(3)NCl(2)) formation from creatinine was promoted by UV exposure, when free chlorine was present in solution; however, when free chlorine was depleted, CH(3)NCl(2) photodecay was observed. Dichloroacetonitrile (CNCHCl(2)) formation (from L-histidine and L-arginine) was promoted by UV(254) irradiation, as long as free chlorine was present in solution. Likewise, UV exposure was observed to amplify cyanogen chloride (CNCl) formation from chlorination of L-histidine, L-arginine, and glycine, up to the point of free chlorine depletion. The results from experiments involving UV irradiation of chlorinated swimming pool water were qualitatively consistent with the results of model experiments involving UV/chlorination of precursors in terms of the behavior of residual chlorine and DBPs measured in this study. The results indicate that UV(254) irradiation promotes several reactions that are involved in the formation and/or destruction of chlorinated N-DBPs in pool settings. Enhancement of DBP formation was consistent with a mechanism whereby a rate-limiting step in DBP formation was promoted by UV exposure. Promotion of these reactions also resulted in increases of free chlorine consumption rates. Copyright © 2012 Elsevier Ltd. All rights reserved.

Antifouling strategies and corrosion control in cooling circuits.

PubMed

Cristiani, P; Perboni, G

2014-06-01

Biofouling and corrosion phenomena dramatically reduce the functionality of industrial cooling circuits, especially in marine environments. This study underlines the effectiveness of a low level chlorination treatment of seawater to prevent biological fouling and biocorrosion. Reported examples emphasize the reaction of chlorine with bromide, ammonia and organic compounds in seawater and the effectiveness of a treatment performed in such a way to guarantee a residual concentration lower than 3μM at the outlet of the condensers. In a brief review of antifouling strategies, alternatives to chlorination and the monitoring approach able to optimize the treatments are also reported. An integrated, on-line system based on electrochemical probes (Biox system and a linear polarization resistance probe) demonstrated to be sufficient to monitor in real time: corrosion, biofilm growth and chemical treatments based on chlorine or alternative oxidant products (chlorine dioxide, etc.). A careful electrochemical monitoring and the optimized treatments help the plant operators of industrial cooling circuits prevent the decay of the equipment performance, allowing at the same time the control of the halogenated by-products formation. Copyright © 2014 Elsevier B.V. All rights reserved.

49 CFR 173.313 - UN Portable Tank Table for Liquefied Compressed Gases.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Normal 0.51 7.0 7.0 7.0 1012 Butylene 8.0 Allowed Normal 0.53 7.0 7.0 7.0 1017 Chlorine 19.0 Not § 178... tanks— Not Allowed § 178.276(e)(3) 0.78 1041 Ethylene oxide and carbon dioxide mixture with more than 9...(a) Allowed Normal See § 173.32(f) 1079 Sulphur dioxide 11.6 Not Allowed § 178.276(e)(3) 1.23 10.3 8...

49 CFR 173.313 - UN Portable Tank Table for Liquefied Compressed Gases.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Normal 0.51 7.0 7.0 7.0 1012 Butylene 8.0 Allowed Normal 0.53 7.0 7.0 7.0 1017 Chlorine 19.0 Not § 178... tanks— Not Allowed § 178.276(e)(3) 0.78 1041 Ethylene oxide and carbon dioxide mixture with more than 9...(a) Allowed Normal See § 173.32(f) 1079 Sulphur dioxide 11.6 Not Allowed § 178.276(e)(3) 1.23 10.3 8...

Degradation of clofibric acid in UV/chlorine disinfection process: kinetics, reactive species contribution and pathways

PubMed Central

Tang, Yuqing; Shi, Xueting; Liu, Yongze; Zhang, Liqiu

2018-01-01

As a potential endocrine disruptor, clofibric acid (CA) was investigated in this study for its degradation kinetics and pathways in UV/chlorine process. The results showed that CA in both UV photolysis and UV/chlorine processes could be degraded via pseudo-first-order kinetics, while it almost could not be degraded in the dark chlorination process. The observed rate constant (kobs) in UV photolysis was 0.0078 min−1, and increased to 0.0107 min−1 combining with 0.1 mM chlorine. The kobs increased to 0.0447 min−1 with further increasing the chlorine dosage from 0.1 to 1.0 mM, and reached a plateau at higher dosage (greater than 1.0 mM). The higher kobs was obtained at acid solution rather than basic solution. Moreover, the calculated contributions of radical species to kobs indicated that the HO• contributed significantly to CA degradation in acidic conditions, while the reactive chlorine species and UV direct photolysis dominated in neutral and basic solution. The degradation of CA was slightly inhibited in the presence of HCO3− (1 ∼ 50 mM), barely affected by the presence of Cl− (1 ∼ 200 mM) and greatly suppressed by humic acid (0 ∼ 5 mg l−1). Thirteen main degradation intermediates and three degradation pathways of CA were identified during UV/chlorine process. PMID:29515853

Degradation of clofibric acid in UV/chlorine disinfection process: kinetics, reactive species contribution and pathways.

PubMed

Tang, Yuqing; Shi, Xueting; Liu, Yongze; Feng, Li; Zhang, Liqiu

2018-02-01

As a potential endocrine disruptor, clofibric acid (CA) was investigated in this study for its degradation kinetics and pathways in UV/chlorine process. The results showed that CA in both UV photolysis and UV/chlorine processes could be degraded via pseudo-first-order kinetics, while it almost could not be degraded in the dark chlorination process. The observed rate constant ( k obs ) in UV photolysis was 0.0078 min -1, and increased to 0.0107 min -1 combining with 0.1 mM chlorine. The k obs increased to 0.0447 min -1 with further increasing the chlorine dosage from 0.1 to 1.0 mM, and reached a plateau at higher dosage (greater than 1.0 mM). The higher k obs was obtained at acid solution rather than basic solution. Moreover, the calculated contributions of radical species to k obs indicated that the HO• contributed significantly to CA degradation in acidic conditions, while the reactive chlorine species and UV direct photolysis dominated in neutral and basic solution. The degradation of CA was slightly inhibited in the presence of [Formula: see text] (1 ∼ 50 mM), barely affected by the presence of Cl - (1 ∼ 200 mM) and greatly suppressed by humic acid (0 ∼ 5 mg l -1 ). Thirteen main degradation intermediates and three degradation pathways of CA were identified during UV/chlorine process.

77 FR 33290 - National Organic Program (NOP); Sunset Review (2012)

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-06

... the SUPPLEMENTARY INFORMATION. FOR FURTHER INFORMATION CONTACT: Melissa R. Bailey, Ph.D., Director, Standards Division, Telephone: (202) 720-3252; Fax: (202) 205-7808. SUPPLEMENTARY INFORMATION: I. Background... sprout production according to EPA label directions. (i) Calcium hypochlorite. (ii) Chlorine dioxide...

Alternative sanitization methods for minimally processed lettuce in comparison to sodium hypochlorite

PubMed Central

Bachelli, Mara Lígia Biazotto; Amaral, Rívia Darla Álvares; Benedetti, Benedito Carlos

2013-01-01

Lettuce is a leafy vegetable widely used in industry for minimally processed products, in which the step of sanitization is the crucial moment for ensuring a safe food for consumption. Chlorinated compounds, mainly sodium hypochlorite, are the most used in Brazil, but the formation of trihalomethanes from this sanitizer is a drawback. Then, the search for alternative methods to sodium hypochlorite has been emerging as a matter of great interest. The suitability of chlorine dioxide (60 mg L−1/10 min), peracetic acid (100 mg L−1/15 min) and ozonated water (1.2 mg L−1 /1 min) as alternative sanitizers to sodium hypochlorite (150 mg L−1 free chlorine/15 min) were evaluated. Minimally processed lettuce washed with tap water for 1 min was used as a control. Microbiological analyses were performed in triplicate, before and after sanitization, and at 3, 6, 9 and 12 days of storage at 2 ± 1 °C with the product packaged on LDPE bags of 60 μm. It was evaluated total coliforms, Escherichia coli, Salmonella spp., psicrotrophic and mesophilic bacteria, yeasts and molds. All samples of minimally processed lettuce showed absence of E. coli and Salmonella spp. The treatments of chlorine dioxide, peracetic acid and ozonated water promoted reduction of 2.5, 1.1 and 0.7 log cycle, respectively, on count of microbial load of minimally processed product and can be used as substitutes for sodium hypochlorite. These alternative compounds promoted a shelf-life of six days to minimally processed lettuce, while the shelf-life with sodium hypochlorite was 12 days. PMID:24516433

Alternative sanitization methods for minimally processed lettuce in comparison to sodium hypochlorite.

PubMed

Bachelli, Mara Lígia Biazotto; Amaral, Rívia Darla Álvares; Benedetti, Benedito Carlos

2013-01-01

Lettuce is a leafy vegetable widely used in industry for minimally processed products, in which the step of sanitization is the crucial moment for ensuring a safe food for consumption. Chlorinated compounds, mainly sodium hypochlorite, are the most used in Brazil, but the formation of trihalomethanes from this sanitizer is a drawback. Then, the search for alternative methods to sodium hypochlorite has been emerging as a matter of great interest. The suitability of chlorine dioxide (60 mg L(-1)/10 min), peracetic acid (100 mg L(-1)/15 min) and ozonated water (1.2 mg L(-1)/1 min) as alternative sanitizers to sodium hypochlorite (150 mg L(-1) free chlorine/15 min) were evaluated. Minimally processed lettuce washed with tap water for 1 min was used as a control. Microbiological analyses were performed in triplicate, before and after sanitization, and at 3, 6, 9 and 12 days of storage at 2 ± 1 °C with the product packaged on LDPE bags of 60 μm. It was evaluated total coliforms, Escherichia coli, Salmonella spp., psicrotrophic and mesophilic bacteria, yeasts and molds. All samples of minimally processed lettuce showed absence of E. coli and Salmonella spp. The treatments of chlorine dioxide, peracetic acid and ozonated water promoted reduction of 2.5, 1.1 and 0.7 log cycle, respectively, on count of microbial load of minimally processed product and can be used as substitutes for sodium hypochlorite. These alternative compounds promoted a shelf-life of six days to minimally processed lettuce, while the shelf-life with sodium hypochlorite was 12 days.

Control of Legionella Contamination and Risk of Corrosion in Hospital Water Networks following Various Disinfection Procedures

PubMed Central

Ferranti, Greta; Mansi, Antonella; Marcelloni, Anna M.; Proietto, Anna R.; Saini, Navneet; Borella, Paola; Bargellini, Annalisa

2016-01-01

Physical and chemical disinfection methods have been proposed with the aim of controlling Legionella water contamination. To date, the most effective procedures for reducing bacterial contamination have not yet been defined. The aim of this study was to assess the long-term effectiveness of various disinfection procedures in order to reduce both culturable and nonculturable (NC) legionellae in different hospital water networks treated with heat, chlorine dioxide, monochloramine, and hydrogen peroxide. The temperature levels and biocide concentrations that proved to give reliable results were analyzed. In order to study the possible effects on the water pipes, we verified the extent of corrosion on experimental coupons after applying each method for 6 months. The percentage of positive points was at its lowest after treatment with monochloramine, followed by chlorine dioxide, hydrogen peroxide, and hyperthermia. Different selections of Legionella spp. were observed, as networks treated with chlorine-based disinfectants were contaminated mainly by Legionella pneumophila serogroup 1, hyperthermia was associated with serogroups 2 to 14, and hydrogen peroxide treatment was associated mainly with non-pneumophila species. NC cells were detected only in heat-treated waters, and also when the temperature was approximately 60°C. The corrosion rates of the coupons were within a satisfactory limit for water networks, but the morphologies differed. We confirm here that chemical disinfection controls Legionella colonization more effectively than hyperthermia does. Monochloramine was the most effective treatment, while hydrogen peroxide may be a promising alternative to chlorine-based disinfectants due to its ability to select for other, less virulent or nonpathogenic species. PMID:26969696

Genotoxicity and cytotoxicity assessment in lake drinking water produced in a treatment plant.

PubMed

Buschini, Annamaria; Carboni, Pamela; Frigerio, Silvia; Furlini, Mariangela; Marabini, Laura; Monarca, Silvano; Poli, Paola; Radice, Sonia; Rossi, Carlo

2004-09-01

Chemical analyses and short-term mutagenicity bioassays have revealed the presence of genotoxic disinfection by-products in drinking water. In this study, the influence of the different steps of surface water treatment on drinking water mutagen content was evaluated. Four different samples were collected at a full-scale treatment plant: raw lake water (A), water after pre-disinfection with chlorine dioxide and coagulation (B), water after pre-disinfection, coagulation and granular activated carbon filtration (C) and tap water after post-disinfection with chlorine dioxide just before its distribution (D). Water samples, concentrated by solid phase adsorption on silica C18 columns, were tested in human leukocytes and HepG2 hepatoma cells using the comet assay and in HepG2 cells in the micronuclei test. A significant increase in DNA migration was observed in both cell types after 1 h treatment with filtered and tap water, and, to a lesser extent, chlorine dioxide pre-disinfected water. Similar findings were observed for the induction of "ghost" cells. Overloading of the carbon filter, with a consequent peak release, might explain the high genotoxicity found in water samples C and D. Cell toxicity and DNA damage increases were also detected in metabolically competent HepG2 cells treated with a lower concentration of tap water extract for a longer exposure time (24 h). None of the water extracts significantly increased micronuclei frequencies. Our monitoring approach appears to be able to detect contamination related to the different treatment stages before drinking water consumption and the results suggest the importance of improving the technologies for drinking water treatment to prevent human exposure to potential genotoxic compounds.

Conventional oxidation treatments for the removal of arsenic with chlorine dioxide, hypochlorite, potassium permanganate and monochloramine.

PubMed

Sorlini, Sabrina; Gialdini, Francesca

2010-11-01

Arsenic is widespread in soils, water and air. In natural water the main forms are arsenite (As(III)) and arsenate (As(V)). The consumption of water containing high concentration of arsenic produces serious effects on human health, like skin and lung cancer. In Italy, Legislative Decree 2001/31 reduced the limit of arsenic from 50 to 10 μg/L, in agreement with the European Directive 98/83/EC. As consequence, many drinking water treatment plant companies needed to upgrade the existing plants where arsenic was previously removed or to build up new plants for arsenic removal when this contaminant was not previously a critical parameter. Arsenic removal from water may occur through the precipitation with iron or aluminum salts, adsorption on iron hydroxide or granular activated alumina (AA), reverse osmosis and ion exchange (IE). Some of the above techniques, especially precipitation, adsorption with AA and IE, can reach good arsenic removal yields only if arsenic is oxidized. The aim of the present work is to investigate the efficiency of the oxidation of As(III) by means of four conventional oxidants (chlorine dioxide, sodium hypochlorite, potassium permanganate and monochloramine) with different test conditions: different type of water (demineralised and real water), different pH values (5.7-6-7 and 8) and different doses of chemicals. The arsenic oxidation yields were excellent with potassium permanganate, very good with hypochlorite and low with monochloramine. These results were observed both on demineralised and real water for all the tested reagents with the exception of chlorine dioxide that showed a better arsenic oxidation on real groundwater than demineralised water. Copyright © 2010 Elsevier Ltd. All rights reserved.

The Portable Chemical Sterilizer (PCS), D-FENS, and D-FEND ALL: Novel Chlorine Dioxide Decontamination Technologies for the Military

PubMed Central

Doona, Christopher J.; Feeherry, Florence E.; Setlow, Peter; Malkin, Alexander J.; Leighton, Terrence J.

2014-01-01

There is a stated Army need for a field-portable, non-steam sterilizer technology that can be used by Forward Surgical Teams, Dental Companies, Veterinary Service Support Detachments, Combat Support Hospitals, and Area Medical Laboratories to sterilize surgical instruments and to sterilize pathological specimens prior to disposal in operating rooms, emergency treatment areas, and intensive care units. The following ensemble of novel, ‘clean and green’ chlorine dioxide technologies are versatile and flexible to adapt to meet a number of critical military needs for decontamination6,15. Specifically, the Portable Chemical Sterilizer (PCS) was invented to meet urgent battlefield needs and close critical capability gaps for energy-independence, lightweight portability, rapid mobility, and rugged durability in high intensity forward deployments3. As a revolutionary technological breakthrough in surgical sterilization technology, the PCS is a Modern Field Autoclave that relies on on-site, point-of-use, at-will generation of chlorine dioxide instead of steam. Two (2) PCS units sterilize 4 surgical trays in 1 hr, which is the equivalent throughput of one large steam autoclave (nicknamed “Bertha” in deployments because of its cumbersome size, bulky dimensions, and weight). However, the PCS operates using 100% less electricity (0 vs. 9 kW) and 98% less water (10 vs. 640 oz.), significantly reduces weight by 95% (20 vs. 450 lbs, a 4-man lift) and cube by 96% (2.1 vs. 60.2 ft3), and virtually eliminates the difficult challenges in forward deployments of repairs and maintaining reliable operation, lifting and transporting, and electrical power required for steam autoclaves. PMID:24998679

In-situ generation of chlorine dioxide for surface decontamination of produce

USDA-ARS?s Scientific Manuscript database

Fruits and vegetables, particularly fresh-cut products, are frequently contaminated with bacterial pathogens and implicated in foodborne illnesses. The objective of this study was to develop a unique in-situ sequential surface decontamination method for produce using sodium chlorite and acid. The ...

The effects of multiple antimicrobial interventions on processing, lipid, textural, instrumental color and sensory characteristics when used in a ground beef patty production system.

PubMed

Jimenez-Villarreal, J R; Pohlman, F W; Johnson, Z B; Brown, A H

2003-11-01

The impact of multiple antimicrobial interventions on ground beef processing, lipid, textural, instrumental color and sensory characteristics were evaluated. Beef trimmings were treated with 0.5% cetylpyridinium chloride followed by 10% trisodium phosphate (CT), 200-ppm chlorine dioxide followed by 0.5% cetylpyridinium chloride (CLC), 200-ppm chlorine dioxide followed by 10% trisodium phosphate (CLT), or 2% lactic acid followed by 0.5% cetylpyridinium chloride (LC) and compared to an untreated control (C). Sensory panelists found LC and CT treatments similar (P>0.05) in grinding ability to C. By day 2 of display, CT, CLT and LC patties were redder (a(∗); P<0.05) than C. Sensory panelists found CT patties redder (P<0.05) than C by day 2 of display. Sensory panelists found CT and CLT juicier than C. Therefore, the use of these multiple antimicrobial intervention agents on beef trimmings may improve sensory characteristics and shelf-life of ground beef patties.

The efficacy of chlorine dioxide in controlling Salmonella contamination and its effect on product quality of chicken broiler carcasses.

PubMed

Thiessen, G P; Usborne, W R; Orr, H L

1984-04-01

A large spin-type chiller in an Ontario poultry processing plant was adapted so that the chill water could be treated with various levels of chlorine dioxide ( ClO2 ), increasing the concentration of ClO2 from 0 to 1.39 mg/liter resulting in reducing the bacteria count to the point where salmonellae could not be isolated from the chill water or the chilled broiler carcasses. In addition, coliform, psychrotroph , and aerobic plate counts were all greatly reduced (less than 1 log cycle) in chill water but were only slightly reduced (less than .5 log cycle) in macerated chicken broiler breast skin. Shelf-life was lengthened for broiler carcasses treated with 1.33 and 1.39 mg/liter ClO2 as compared to control carcasses. Sensory panelists reported no off flavors for any ClO2 concentration but rated broiler skin as being slightly lighter in color compared to control carcasses at all concentrations of ClO2 treatment.

Contaminated environments in the subsurface and bioremediation: organic contaminants.

PubMed

Holliger, C; Gaspard, S; Glod, G; Heijman, C; Schumacher, W; Schwarzenbach, R P; Vazquez, F

1997-07-01

Due to leakages, spills, improper disposal and accidents during transport, organic compounds have become subsurface contaminants that threaten important drinking water resources. One strategy to remediate such polluted subsurface environments is to make use of the degradative capacity of bacteria. It is often sufficient to supply the subsurface with nutrients such as nitrogen and phosphorus, and aerobic treatments are still dominating. However, anaerobic processes have advantages such as low biomass production and good electron acceptor availability, and they are sometimes the only possible solution. This review will focus on three important groups of environmental organic contaminants: hydrocarbons, chlorinated and nitroaromatic compounds. Whereas hydrocarbons are oxidized and completely mineralized under anaerobic conditions in the presence of electron acceptors such as nitrate, iron, sulfate and carbon dioxide, chlorinated and nitroaromatic compounds are reductively transformed. For the aerobic often persistent polychlorinated compounds, reductive dechlorination leads to harmless products or to compounds that are aerobically degradable. The nitroaromatic compounds are first reductively transformed to the corresponding amines and can subsequently be bound to the humic fraction in an aerobic process. Such new findings and developments give hope that in the near future contaminated aquifers can efficiently be remediated, a prerequisite for a sustainable use of the precious-subsurface drinking water resources.

Highly selective transformation of ammonia nitrogen to N2 based on a novel solar-driven photoelectrocatalytic-chlorine radical reactions system.

PubMed

Ji, Youzhi; Bai, Jing; Li, Jinhua; Luo, Tao; Qiao, Li; Zeng, Qingyi; Zhou, Baoxue

2017-11-15

A highly selective method for transforming ammonia nitrogen to N 2 was proposed, based on a novel solar-driven photoelectrocatalytic-chlorine radical reactions (PEC-chlorine) system. The PEC-chlorine system was facilitated by a visible light response WO 3 nanoplate array (NPA) electrode in an ammonia solution containing chloride ions (Cl - ). Under illumination, photoholes from WO 3 promote the oxidation of Cl - to chlorine radical (Cl). This radical can selectively transform ammonia nitrogen to N 2 (79.9%) and NO 3 - (19.2%), similar to the breakpoint chlorination reaction. The ammonia nitrogen removal efficiency increased from 10.6% (PEC without Cl - ) to 99.9% with the PEC-chlorine system within 90 min operation, which can be attributed to the cyclic reactions between Cl - /Cl and the reaction intermediates (NH 2 , NHCl, etc.) that expand the degradation reactions from the surface of the electrodes to the whole solution system. Moreover, Cl is the main radical species contributing to the transformation of ammonia nitrogen to N 2 , which is confirmed by the tBuOH capture experiment. Compared to conventional breakpoint chlorination, the PEC-chlorine system is a more economical and efficient means for ammonia nitrogen degradation because of the fast removal rate, no additional chlorine cost, and its use of clean energy (since it is solar-driven). Copyright © 2017 Elsevier Ltd. All rights reserved.

CHLORINE ABSORPTION IN S(IV) SOLUTIONS

EPA Science Inventory

The report gives results of measurements of the rate of Chlorine (Cl2) absorption into aqueous sulfite/bisulfite -- S(IV) -- solutions at ambient temperature using a highly characterized stirred-cell reactor. The reactor media were 0 to 10 mM S(IV) with pHs of 3.5-8.5. Experiment...

Part I. Development of a concept inventory addressing students' beliefs and reasoning difficulties regarding the greenhouse effect, Part II. Distribution of chlorine measured by the Mars Odyssey Gamma Ray Spectrometer

NASA Astrophysics Data System (ADS)

Keller, John Michael

This work presents two research efforts, one involving planetary science education research and a second involving the surface composition of Mars. In the former, student beliefs and reasoning difficulties associated with the greenhouse effect were elicited through student interviews and written survey responses from >900 US undergraduate non-science majors. This guided the development of the Greenhouse Effect Concept Inventory (GECI), an educational research tool designed to assess pre- and post-instruction conceptual understanding of the greenhouse effect. Three versions of this multiple-choice instrument were administered to >2,500 undergraduates as part of the development and validation process. In contrast to previous research efforts regarding causes, consequences, and solutions to the enhanced greenhouse effect, the GECI focuses primarily on the physics of energy flow through Earth's atmosphere. The GECI is offered to the science education community as a research tool for assessing instructional strategies on this topic. It was confirmed that the study population subscribes to several previously identified beliefs. These include correct understandings that carbon dioxide is an important greenhouse gas and the greenhouse effect increases planetary surface temperatures. Students also commonly associate the greenhouse effect with increased penetration of sunlight into and trapping of solar energy in the atmosphere. Students intermix concepts associated with the greenhouse effect, global warming, and ozone depletion. Reinforcing the latter concept, a majority believe that the Sun radiates most of its energy as ultraviolet light. Students also describe inaccurate and incomplete trapping models, which include permanent trapping, trapping through reflection, and trapping of gases and pollution. Another reasoning difficulty involves the idea that Earth's surface radiates energy primarily during the nighttime. The second research effort describes the distribution of chlorine on Mars measured by the Mars Odyssey Gamma Ray Spectrometer (GRS). The distribution of chlorine is heterogeneous across the surface, with a concentration of high chlorine centered over the Medusa Fossae Formation. The distribution of chlorine correlates positively with hydrogen and negatively with silicon and thermal inertia. Four mechanisms (aeolian, volcanic, aqueous, and hydrothermal) are discussed as possible factors influencing the distribution of chlorine measured within the upper few tens of centimeters of the surface.

WIRELESS ELECTROCHEMICAL CLO2 MONITOR FOR DECONTAMINATION OPERATIONS - PHASE I

EPA Science Inventory

The U.S. Environmental Protection Agency has identified the need for an accurate and field-rugged instrument to monitor chlorine dioxide (ClO₂) for use in monitoring building decontamination operations.

The proposed Phase I study will evaluate the feasibil...

WIRELESS ELECTROCHEMICAL CLO2 MONITOR FOR DECONTAMINATION OPERATIONS - PHASE II

EPA Science Inventory

Recognizing the importance of ClO₂ in disinfection and decontamination operations, the U.S. Environmental Protection Agency (EPA) had identified the need for portable, accurate and field-rugged chlorine dioxide (ClO₂) monitors for use in monitoring buildi...

Laboratory research on the efficacy of chlorine dioxide fumigation for the remediation of mold-contaminated buildings--conference paper

EPA Science Inventory

The purpose of this project was to determine the efficacy ofCl02 fumigation to inactivate viable mold, mycotoxins, and allergens on building materials. Alternaria alternata, Aspergillus versicolor, Aspergillus Jumigatus, Chaetomium globosum, and Stachybotrys chartarum were indivi...

HETEROGENOUS PHOTOCATALYSIS ON AEROSOL PROCESSED NANOSTRUCTURED TITANIA PARTICLES: ROLE OF PARTICLE SIZE

EPA Science Inventory

Heterogenous photocatalysis with TiO2 has been extensively investigated as a method to oxidize organic pollutants in water and air, including phenols, chlorinated hydrocarbons, and other hydrocarbons. In addition, the use of titanium dioxide as a photocatalyst has also been demon...

Handbook for Evaluating Ecological Effects of Pollution at DARCOM installations. Volume 2, Essential Background Data. (Installation Environmental Impact Assessment)

DTIC Science & Technology

1979-12-01

Nitrates Sulfur dioxide Xylene Nitrites Oxides of nitrogen Mercaptans "Red Water" Carbon monoxide Chlorine Acids: Ketones Fluorine Hydrochloric Esters...Trichloroethylene Varnishes Methylchloroform Undercoatings Mineral spirits Liquid styrene Naphtha Adhesives Halgenated hydrocarbons Nonmethane hydrocarbons

Improving Pathogen Reduction by Chlorine Wash Prior to Cutting in Fresh-Cut Processing

USDA-ARS?s Scientific Manuscript database

Introduction: Currently, most fresh-cut processing facilities in the United States use chlorinated water or other sanitizer solutions for microbial reduction after lettuce is cut. Freshly cut lettuce releases significant amounts of organic matter that negatively impacts the effectiveness of chlorine...

The reaction of chlorobenzene with plasma of H2O, CO2 and CH4 obtained by an alternating-current plasma torch with a vortex stabilization

NASA Astrophysics Data System (ADS)

Surov, A. V.; Subbotin, D. I.; Obraztsov, N. V.; Popov, S. D.; Popov, V. E.; Litvyakova, A. I.; Pavlov, A. V.; Serba, E. O.; Spodobin, V. A.; Nakonechny, Gh V.

2018-01-01

This paper presents the three-phase ac plasma torch with a vortex stabilization of the arc, and two inputs of plasma environments: the electrode zone and the arc zone. Shielding gas (carbon dioxide) is supplied in the electrode zone and steam, methane and vapor of chlorobenzene are fed in the arc zone. By means of it the life time of electrodes is increased significantly. Chlorobenzene is selected, as it is the simplest aromatic chlorine-containing substance. The chemical process flows in two pathways: the formation of synthesis gas and the formation of soot. The gaseous chlorine-containing compound was only hydrogen chloride, yield of soot was 0.98% by weight of the raw materials, and the chlorine content was 2.08 wt% by the soot.

Effect of variation in indium concentration on the photosensitivity of chlorine doped In{sub 2}S{sub 3} thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cherian, Angel Susan; Kartha, C. Sudha; Vijayakumar, K. P.

2014-01-28

Consequence of variation in Indium concentration in chlorine doped In2S{sub 3} thin films deposited by spray pyrolysis technique was studied. Chlorine was incorporated in the spray solution, using HCl and Indium concentration was varied by adjusting In/S ratio Interestingly, the photo response of all chlorine doped samples augmented compared to pristine samples; but the highest photosensitivity value of ∼2300 was obtained only when 36ml 0.5M HCl was added to the solution of In{sub 2}S{sub 3} having In/S=2/8. It was also observed that samples with high photosensitivity possess higher band gap and variation in sub band gap absoption levels were observedmore » with increase in Indium concentration. The present study proved that concentration of Indium plays an important role in controlling the crystallinity and photosensitivity of chlorine doped samples.« less

Effectiveness of chlorine, organic acids and UV treatments in reducing Escherichia coli O157:H7 and Yersinia enterocolitica on apples.

PubMed

Escudero, M E; Velázquez, L; Favier, G; de Guzmán, A M

2003-06-01

This study assessed the effectiveness of 200 and 500 ppm of chlorine and organic acids (0.5% lactic acid and 0.5% citric acid) in wash solutions, and UV radiation for reducing Escherichia coli O157:H7 and Yersinia enterocolitica on apples contaminated by two different methods. Residual levels of these pathogens after different treatments were compared. On dip inoculated apples, Y. enterocolitica reductions of 2.66 and 2.77 logs were obtained with 200 and 500 ppm chlorine combined with 0.5% lactic acid, respectively. The E. coli O157:H7 population decreased 3.35 log with 0.5% lactic acid wash solution, and 2.72 and 2.62 logs after 500 ppm chlorine and 500 ppm chlorine plus 0.5% lactic acid treatments, respectively. Similar reductions were obtained with UV radiation. On spot inoculated apples, significant (p < 0.05) decreases of 4.67 and 4.58 logs were observed in E. coli O157:H7 and Y. enterocolitica levels, respectively, after 500 ppm chlorine plus 0.5% lactic acid treatment as compared with the control. In sectioned apples, microorganisms infiltrated in inner core region and pulp were not significantly (p < 0.05) affected by disinfection treatments. No pathogens were detected in the natural microflora on apples. Reductions such as those obtained with 500 ppm chlorine plus 0.5% lactic acid solution were very proximal to the 5-log score required by FDA for apple disinfection.

Gamma-irradiation produces active chlorine species (ACS) in physiological solutions: Secoisolariciresinol diglucoside (SDG) scavenges ACS - A novel mechanism of DNA radioprotection

PubMed Central

Mishra, Om P.; Popov, Anatoliy V.; Pietrofesa, Ralph A.; Christofidou-Solomidou, Melpo

2017-01-01

Background Secoisolariciresinol diglucoside (SDG), the main lignan in whole grain flaxseed, is a potent antioxidant and free radical scavenger with known radioprotective properties. However, the exact mechanism of SDG radioprotection is not well understood. The current study identified a novel mechanism of DNA radioprotection by SDG in physiological solutions by scavenging active chlorine species (ACS) and reducing chlorinated nucleobases. Methods The ACS scavenging activity of SDG was determined using two highly specific fluoroprobes: hypochlorite-specific 3′-(p-aminophenyl) fluorescein (APF) and hydroxyl radical-sensitive 3′-(p-hydroxyphenyl) fluorescein (HPF). Dopamine, an SDG structural analog, was used for proton 1H NMR studies to trap primary ACS radicals. Taurine N-chlorination was determined to demonstrate radiation-induced generation of hypochlorite, a secondary ACS. DNA protection was assessed by determining the extent of DNA fragmentation and plasmid DNA relaxation following exposure to ClO− and radiation. Purine base chlorination by ClO− and γ-radiation was determined by using 2-aminopurine (2-AP), a fluorescent analog of 6-aminopurine. Results: Chloride anions (Cl−) consumed >90% of hydroxyl radicals in physiological solutions produced by γ-radiation resulting in ACS formation, which was detected by 1H NMR. Importantly, SDG scavenged hypochlorite- and γ-radiation-induced ACS. In addition, SDG blunted ACS-induced fragmentation of calf thymus DNA and plasmid DNA relaxation. SDG treatment before or after ACS exposure decreased the ClO− or γ-radiation-induced chlorination of 2-AP. Exposure to γ-radiation resulted in increased taurine chlorination, indicative of ClO− generation. NMR studies revealed formation of primary ACS radicals (chlorine atoms (Cl•) and dichloro radical anions (Cl2−•)), which were trapped by SDG and its structural analog dopamine. Conclusion We demonstrate that γ-radiation induces the generation of ACS in physiological solutions. SDG treatment scavenged ACS and prevented ACS-induced DNA damage and chlorination of 2-aminopurine. This study identified a novel and unique mechanism of SDG radioprotection, through ACS scavenging, and supports the potential usefulness of SDG as a radioprotector and mitigator for radiation exposure as part of cancer therapy or accidental exposure. PMID:27261092

Gamma-irradiation produces active chlorine species (ACS) in physiological solutions: Secoisolariciresinol diglucoside (SDG) scavenges ACS - A novel mechanism of DNA radioprotection.

PubMed

Mishra, Om P; Popov, Anatoliy V; Pietrofesa, Ralph A; Christofidou-Solomidou, Melpo

2016-09-01

Secoisolariciresinol diglucoside (SDG), the main lignan in whole grain flaxseed, is a potent antioxidant and free radical scavenger with known radioprotective properties. However, the exact mechanism of SDG radioprotection is not well understood. The current study identified a novel mechanism of DNA radioprotection by SDG in physiological solutions by scavenging active chlorine species (ACS) and reducing chlorinated nucleobases. The ACS scavenging activity of SDG was determined using two highly specific fluoroprobes: hypochlorite-specific 3'-(p-aminophenyl) fluorescein (APF) and hydroxyl radical-sensitive 3'-(p-hydroxyphenyl) fluorescein (HPF). Dopamine, an SDG structural analog, was used for proton (1)H NMR studies to trap primary ACS radicals. Taurine N-chlorination was determined to demonstrate radiation-induced generation of hypochlorite, a secondary ACS. DNA protection was assessed by determining the extent of DNA fragmentation and plasmid DNA relaxation following exposure to ClO(-) and radiation. Purine base chlorination by ClO(-) and γ-radiation was determined by using 2-aminopurine (2-AP), a fluorescent analog of 6-aminopurine. Chloride anions (Cl(-)) consumed >90% of hydroxyl radicals in physiological solutions produced by γ-radiation resulting in ACS formation, which was detected by (1)H NMR. Importantly, SDG scavenged hypochlorite- and γ-radiation-induced ACS. In addition, SDG blunted ACS-induced fragmentation of calf thymus DNA and plasmid DNA relaxation. SDG treatment before or after ACS exposure decreased the ClO(-) or γ-radiation-induced chlorination of 2-AP. Exposure to γ-radiation resulted in increased taurine chlorination, indicative of ClO(-) generation. NMR studies revealed formation of primary ACS radicals (chlorine atoms (Cl) and dichloro radical anions (Cl2¯)), which were trapped by SDG and its structural analog dopamine. We demonstrate that γ-radiation induces the generation of ACS in physiological solutions. SDG treatment scavenged ACS and prevented ACS-induced DNA damage and chlorination of 2-aminopurine. This study identified a novel and unique mechanism of SDG radioprotection, through ACS scavenging, and supports the potential usefulness of SDG as a radioprotector and mitigator for radiation exposure as part of cancer therapy or accidental exposure. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Kinetics of chlorination of zirconia in mixture with petroleum coke by chlorine gas

NASA Astrophysics Data System (ADS)

Jena, P. K.; Brocchi, E. A.; Reis, M. L. Dos

1999-06-01

Studies on the kinetics of carbothermic chlorination of zirconium dioxide in gaseous chlorine were carried out with petroleum coke fines in powder form. The amounts of ZrO2 chlorinated were found to be directly proportional to the time of chlorination in the temperature range studied (973 to 1273 K). The activation energy values for chlorination of ZrO2, in mixture with petroleum coke, was found to be 18.3 kJ/mole. The influence of particle size of petroleum coke on the chlorination of ZrO2 (-38 + 25 µm) was studied, and it was found that the rate of chlorination increased up to the size range of -75 to +53 µm, and the size finer than this produced negligible increase. The amount of petroleum coke in the mixture above 17.41 pct in excess of the stoichiometry resulted in very little increase in the rate. The effect of the partial pressure of chlorine ( pCl2) on the rate of chlorination was found to obey the following relationship, derived from the Langmuir adsorption isotherm: v = {k \\cdot K \\cdot pCl_2 }/{l + K \\cdot pCl_2 } where v is the amount of ZrO2 (g/min) reacted, k is the rate constant, and K is the equilibrium constant for adsorption of two chlorine atoms (obtained from the dissociation of a molecule of Cl2 at the carbon surface) on the surface of ZrO2. By plotting 1/ v vs 1/ pCl2, a straight-line relationship with an intercept in x-axis is obtained, further supporting the preceding equation. The dissociation of the adsorbed complex, Cl … ZrO2 … Cl to ZrCl2 and O2 is suggested to be the rate-controlling step. Subsequently, the less stable ZrCl2 combines with Cl2 to form ZrCl4 and the oxygen combines with C to form CO and CO2.

Optimal design and management of chlorination in drinking water networks: a multi-objective approach using Genetic Algorithms and the Pareto optimality concept

NASA Astrophysics Data System (ADS)

Nouiri, Issam

2017-11-01

This paper presents the development of multi-objective Genetic Algorithms to optimize chlorination design and management in drinking water networks (DWN). Three objectives have been considered: the improvement of the chlorination uniformity (healthy objective), the minimization of chlorine booster stations number, and the injected chlorine mass (economic objectives). The problem has been dissociated in medium and short terms ones. The proposed methodology was tested on hypothetical and real DWN. Results proved the ability of the developed optimization tool to identify relationships between the healthy and economic objectives as Pareto fronts. The proposed approach was efficient in computing solutions ensuring better chlorination uniformity while requiring the weakest injected chlorine mass when compared to other approaches. For the real DWN studied, chlorination optimization has been crowned by great improvement of free-chlorine-dosing uniformity and by a meaningful chlorine mass reduction, in comparison with the conventional chlorination.

Quantitative structure-activity relationships (QSARs) for the transformation of organic micropollutants during oxidative water treatment.

PubMed

Lee, Yunho; von Gunten, Urs

2012-12-01

Various oxidants such as chlorine, chlorine dioxide, ferrate(VI), ozone, and hydroxyl radicals can be applied for eliminating organic micropollutant by oxidative transformation during water treatment in systems such as drinking water, wastewater, and water reuse. Over the last decades, many second-order rate constants (k) have been determined for the reaction of these oxidants with model compounds and micropollutants. Good correlations (quantitative structure-activity relationships or QSARs) are often found between the k-values for an oxidation reaction of closely related compounds (i.e. having a common organic functional group) and substituent descriptor variables such as Hammett or Taft sigma constants. In this study, we developed QSARs for the oxidation of organic and some inorganic compounds and organic micropollutants transformation during oxidative water treatment. A number of 18 QSARs were developed based on overall 412 k-values for the reaction of chlorine, chlorine dioxide, ferrate, and ozone with organic compounds containing electron-rich moieties such as phenols, anilines, olefins, and amines. On average, 303 out of 412 (74%) k-values were predicted by these QSARs within a factor of 1/3-3 compared to the measured values. For HO(·) reactions, some principles and estimation methods of k-values (e.g. the Group Contribution Method) are discussed. The developed QSARs and the Group Contribution Method could be used to predict the k-values for various emerging organic micropollutants. As a demonstration, 39 out of 45 (87%) predicted k-values were found within a factor 1/3-3 compared to the measured values for the selected emerging micropollutants. Finally, it is discussed how the uncertainty in the predicted k-values using the QSARs affects the accuracy of prediction for micropollutant elimination during oxidative water treatment. Copyright © 2012 Elsevier Ltd. All rights reserved.

Control of Legionella Contamination and Risk of Corrosion in Hospital Water Networks following Various Disinfection Procedures.

PubMed

Marchesi, Isabella; Ferranti, Greta; Mansi, Antonella; Marcelloni, Anna M; Proietto, Anna R; Saini, Navneet; Borella, Paola; Bargellini, Annalisa

2016-05-15

Physical and chemical disinfection methods have been proposed with the aim of controlling Legionella water contamination. To date, the most effective procedures for reducing bacterial contamination have not yet been defined. The aim of this study was to assess the long-term effectiveness of various disinfection procedures in order to reduce both culturable and nonculturable (NC) legionellae in different hospital water networks treated with heat, chlorine dioxide, monochloramine, and hydrogen peroxide. The temperature levels and biocide concentrations that proved to give reliable results were analyzed. In order to study the possible effects on the water pipes, we verified the extent of corrosion on experimental coupons after applying each method for 6 months. The percentage of positive points was at its lowest after treatment with monochloramine, followed by chlorine dioxide, hydrogen peroxide, and hyperthermia. Different selections of Legionella spp. were observed, as networks treated with chlorine-based disinfectants were contaminated mainly by Legionella pneumophila serogroup 1, hyperthermia was associated with serogroups 2 to 14, and hydrogen peroxide treatment was associated mainly with non-pneumophila species. NC cells were detected only in heat-treated waters, and also when the temperature was approximately 60°C. The corrosion rates of the coupons were within a satisfactory limit for water networks, but the morphologies differed. We confirm here that chemical disinfection controls Legionella colonization more effectively than hyperthermia does. Monochloramine was the most effective treatment, while hydrogen peroxide may be a promising alternative to chlorine-based disinfectants due to its ability to select for other, less virulent or nonpathogenic species. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Do 'chlorine covers' exert a sustained bactericidal effect on the bacterial hand flora?

PubMed

Koller, W; Rotter, M L; Gottardi, W

1995-11-01

Treatment of skin with chlorine generates 'chlorine covers' which, in a previous study, exerted significant sustained bactericidal effects against transient skin flora on the upper arm and forearm. In this investigation, this effect was studied on both the transient and resident flora of the hands using test models for the evaluation of hand disinfectants as agreed upon in Austria and Germany. Chlorine covers were generated by bathing hands in a solution of 2% sodium tosylchloramide for 1 min. Subsequently, this cover was destroyed on one, randomly selected, hand by bathing it in a solution of 0.5% sodium thiosulphate for 15 s. The amount of chlorine on the fingertips of chlorinated hands was 2.2 +/- 0.4 micrograms/cm2; that on subsequently dechlorinated hands was 0.2 +/- 0.1 microgram/cm2. In experiments with artificially contaminated hands (Escherichia coli), the kinetics of bacterial die-off were the same on both hands. Also, in experiments with resident flora, the kinetics of bacterial die-off did not suggest bacterial reductions that increase with the duration of contact with the chlorine cover. It was concluded that with the test models used, a significant sustained antimicrobial effect of the chlorine cover could not be demonstrated on hands.

40 CFR 142.60 - Variances from the maximum contaminant level for total trihalomethanes.

Code of Federal Regulations, 2014 CFR

2014-07-01

... disinfectant or oxidant. (2) Use of chlorine dioxide as an alternate or supplemental disinfectant or oxidant... of raw water. Use of ozone as an alternate or supplemental disinfectant or oxidant. (d) If the... PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS...

Effects of Pseudomonas chlororaphis and gaseous chlorine dioxide on the survival of Salmonella enterica on tomatoes

USDA-ARS?s Scientific Manuscript database

Produce contamination incited by Salmonella enterica serovars on tomatoes and various outbreaks of Salmonellisis have been reported periodically. Post-harvest intervention measures applied to limit produce contamination will improve food and consumer safety. The aim of this reserach was to evaluat...

7 CFR 205.603 - Synthetic substances allowed for use in organic livestock production.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Water Act. (i) Calcium hypochlorite. (ii) Chlorine dioxide. (iii) Sodium hypochlorite. (8) Electrolytes... additives. (1) DL-Methionine, DL-Methionine—hydroxy analog, and DL-Methionine—hydroxy analog calcium (CAS... following maximum levels of synthetic methionine per ton of feed: laying chickens—4 pounds; broiler chickens...

7 CFR 205.603 - Synthetic substances allowed for use in organic livestock production.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Water Act. (i) Calcium hypochlorite. (ii) Chlorine dioxide. (iii) Sodium hypochlorite. (8) Electrolytes... additives. (1) DL-Methionine, DL-Methionine—hydroxy analog, and DL-Methionine—hydroxy analog calcium (CAS... following maximum levels of synthetic methionine per ton of feed: laying chickens—4 pounds; broiler chickens...

7 CFR 205.603 - Synthetic substances allowed for use in organic livestock production.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Water Act. (i) Calcium hypochlorite. (ii) Chlorine dioxide. (iii) Sodium hypochlorite. (8) Electrolytes.... (1) DL-Methionine, DL-Methionine-hydroxy analog, and DL-Methionine-hydroxy analog calcium (CAS #'s 59... maximum levels of synthetic methionine per ton of feed: Laying and broiler chickens—2 pounds; turkeys and...

7 CFR 205.603 - Synthetic substances allowed for use in organic livestock production.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Water Act. (i) Calcium hypochlorite. (ii) Chlorine dioxide. (iii) Sodium hypochlorite. (8) Electrolytes.... (1) DL-Methionine, DL-Methionine-hydroxy analog, and DL-Methionine-hydroxy analog calcium (CAS #'s 59... maximum levels of synthetic methionine per ton of feed: Laying and broiler chickens—2 pounds; turkeys and...

Microscale Chemistry in a Plastic Petri Dish: Preparation and Chemical Properties of Chlorine Gas

NASA Astrophysics Data System (ADS)

Choi, Martin M. F.

2002-08-01

This experiment demonstrates some of the chemistry of chlorine on a microscale, about the size of a water droplet. Chlorine gas was prepared from an acidified bleach solution in a plastic petri dish. The chlorine gas generated in situ reacted with other chemical reagents in the dish by diffusion. Some of the oxidizing properties and bleaching power of chlorine gas were shown visually and could be observed within 10 minutes. These experiments provide suitable hands-on experience for students at secondary-school level.

Investigation of saponification for determination of polychlorinated biphenyls in marine sediments.

PubMed

Numata, Masahiko; Yarita, Takashi; Aoyagi, Yoshie; Yamazaki, Misako; Takatsu, Akiko

2005-02-01

The effects of saponification conditions (temperature and water content of saponifying solution) on the determination of chlorinated biphenyls (CBs) in marine sediments were investigated. Although highly chlorinated biphenyls (nona- to deca-CBs) decomposed during high-temperature saponification, the degree of degradation was reduced by adding water to the ethanolic potassium hydroxide saponifying solution. Room-temperature saponification yielded quantitative recovery of highly chlorinated biphenyl surrogates but low extraction efficiencies of lightly chlorinated biphenyls (mono- to di-CBs). The same samples were analyzed by other extraction techniques, for example, pressurized liquid extraction, and analytical results were compared. The mono- and di-CB concentrations were correlated with the extraction temperatures of various extraction techniques. In particular, the concentrations of some CB congeners (CB11, CB14) were higher with saponification. The low degree of degradation of highly chlorinated biphenyls and the high recovery of lightly chlorinated biphenyls were compatible when room-temperature and high-temperature saponification were combined. Except for the anomalies of CB11 and CB14, the combined method gave satisfactory results for analysis of PCBs.

Chlorine-36 in fossil rat urine: an archive of cosmogenic nuclide deposition during the past 40,000 years.

PubMed

Plummer, M A; Phillips, F M; Fabryka-Martin, J; Turin, H J; Wigand, P E; Sharma, P

1997-07-25

Knowledge of the production history of cosmogenic nuclides, which is needed for geological and archaeological dating, has been uncertain. Measurements of chlorine-36/chlorine (36Cl/Cl) ratios in fossil packrat middens from Nevada that are radiocarbon-dated between about 38 thousand years ago (ka) and the present showed that 36Cl/Cl ratios were higher by a factor of about 2 before approximately 11 ka. This raises the possibility that cosmogenic production rates just before the close of the Pleistocene were up to 50% higher than is suggested by carbon-14 calibration data. The discrepancy could be explained by addition of low-carbon-14 carbon dioxide to the atmosphere during that period, which would have depressed atmospheric radiocarbon activity. Alternatively, climatic effects on 36Cl deposition may have enhanced the 36Cl/Cl ratios.

Kraft pulp bleaching and delignification by dikaryons and monokaryons of trametes versicolor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Addleman, K.; Archibald, F.

1993-01-01

To reduce the levels of chlorinated lignin residues in effluents from the pulp and paper industry, interest has focused on the white rot basidiomycete fungi. The kraft process, the most common commercial delignification method, produces a dark pulp which is bleached by use of chlorine, chlorine dioxide, and caustic extraction. A dikaryon of Trametes (Coriolus) versicolor has been shown to bleach and delignify kraft pulp, offering a possible alternative to chlorine. A monokaryon strain, if comparable to the effect of the dikaryon, would be a much simpler system for study of mechanisms and genetic munipulation. The researchers compared strains ofmore » both and conclude that the following characteristics justify replacing the parent dikaryon with monokaryon 52J in future work on biobleaching and biological delignification: (1) reduced biomass and slower growth rate; (2)no dark pigment production; (3) superior biological bleaching ability; (4) a simpler system for genetic manipulation and biochemical analysis. The involvement of MnP, but not LP, in pulp bleaching, delignification is strongly suggested. 40 refs., 3 figs., 4 tabs.« less

Inactivation of Heat Adapted and Chlorine Adapted Listeria Monocytogenes ATCC 7644 on Tomatoes Using Sodium Dodecyl Sulphate, Levulinic Acid and Sodium Hypochlorite Solution.

PubMed

Ijabadeniyi, Oluwatosin Ademola; Mnyandu, Elizabeth

2017-04-13

The effectiveness of sodium dodecyl sulphate (SDS), sodium hypochlorite solution and levulinic acid in reducing the survival of heat adapted and chlorine adapted Listeria monocytogenes ATCC 7644 was evaluated. The results against heat adapted L. monocytognes revealed that sodium hypochlorite solution was the least effective, achieving log reduction of 2.75, 2.94 and 3.97 log colony forming unit (CFU)/mL for 1, 3 and 5 minutes, respectively. SDS was able to achieve 8 log reduction for both heat adapted and chlorine adapted bacteria. When used against chlorine adapted L. monocytogenes sodium hypochlorite solution achieved log reduction of 2.76, 2.93 and 3.65 log CFU/mL for 1, 3 and 5 minutes, respectively. Using levulinic acid on heat adapted bacteria achieved log reduction of 3.07, 2.78 and 4.97 log CFU/mL for 1, 3, 5 minutes, respectively. On chlorine adapted bacteria levulinic acid achieved log reduction of 2.77, 3.07 and 5.21 log CFU/mL for 1, 3 and 5 minutes, respectively. Using a mixture of 0.05% SDS and 0.5% levulinic acid on heat adapted bacteria achieved log reduction of 3.13, 3.32 and 4.79 log CFU/mL for 1, 3 and 5 minutes while on chlorine adapted bacteria it achieved 3.20, 3.33 and 5.66 log CFU/mL, respectively. Increasing contact time also increased log reduction for both test pathogens. A storage period of up to 72 hours resulted in progressive log reduction for both test pathogens. Results also revealed that there was a significant difference (P≤0.05) among contact times, storage times and sanitizers. Findings from this study can be used to select suitable sanitizers and contact times for heat and chlorine adapted L. monocytogenes in the fresh produce industry.

Title: Efficacy of chlorine dioxide gas to decontaminate fresh produce used for in-store and vendor juicing operations

USDA-ARS?s Scientific Manuscript database

Introduction: Unpasteurized juices are increasingly popular as consumers aim to find convenient, healthy options. Contamination of produce with pathogens such as Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes poses a risk. In-store treatment of small batches of mixed types of fresh...

Self-contained chlorine dioxide generation and delivery pods for controlling Listeria monocytogenes in model floor drains.

USDA-ARS?s Scientific Manuscript database

Listeria monocytogenes is a foodborne pathogen that has been associated with poultry products. This organism is ubiquitous in nature and has been found to enter poultry further processing plants on incoming raw product. Once in the plant, L. monocytogenes can become a long term persistent colonize...

49 CFR 180.405 - Qualification of cargo tanks.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., refrigerated liquid; or hydrogen chloride, refrigerated liquid shall remove the exemption number stenciled on... after July 1, 2001, or July 1, 2003, whichever is earlier. (n) Thermal activation. No later than the... compressed gas, other than carbon dioxide and chlorine, that has a water capacity of 13,247.5 L (3,500...

49 CFR 180.405 - Qualification of cargo tanks.

Code of Federal Regulations, 2014 CFR

2014-10-01

..., refrigerated liquid; or hydrogen chloride, refrigerated liquid shall remove the exemption number stenciled on... after July 1, 2001, or July 1, 2003, whichever is earlier. (n) Thermal activation. No later than the... compressed gas, other than carbon dioxide and chlorine, that has a water capacity of 13,247.5 L (3,500...

49 CFR 180.405 - Qualification of cargo tanks.

Code of Federal Regulations, 2011 CFR

2011-10-01

..., refrigerated liquid; or hydrogen chloride, refrigerated liquid shall remove the exemption number stenciled on... after July 1, 2001, or July 1, 2003, whichever is earlier. (n) Thermal activation. No later than the... compressed gas, other than carbon dioxide and chlorine, that has a water capacity of 13,247.5 L (3,500...

49 CFR 180.405 - Qualification of cargo tanks.

Code of Federal Regulations, 2013 CFR

2013-10-01

..., refrigerated liquid; or hydrogen chloride, refrigerated liquid shall remove the exemption number stenciled on... after July 1, 2001, or July 1, 2003, whichever is earlier. (n) Thermal activation. No later than the... compressed gas, other than carbon dioxide and chlorine, that has a water capacity of 13,247.5 L (3,500...

49 CFR 180.405 - Qualification of cargo tanks.

Code of Federal Regulations, 2010 CFR

2010-10-01

..., refrigerated liquid; or hydrogen chloride, refrigerated liquid shall remove the exemption number stenciled on... after July 1, 2001, or July 1, 2003, whichever is earlier. (n) Thermal activation. No later than the... compressed gas, other than carbon dioxide and chlorine, that has a water capacity of 13,247.5 L (3,500...

Decontamination Efficacy of Three Commercial Off-the-Shelf Sporicidal Agents on Medium-Sized Panels Contaminated with Surrogates of Bacillus anthracis

DTIC Science & Technology

2012-04-01

chlorine dioxide (CD) or vapor hydrogen peroxide ( VHP ). A wide-area release and contamination of building exteriors and the outdoors would likely...from the panels. Depending on the surface composition and the decontamination technology tested, viable spore recovery from the panels varied after

CFD modeling to improve safe and efficient distribution of chlorine dioxide gas for packaging fresh produce

USDA-ARS?s Scientific Manuscript database

The efficiency of the packaging system in inactivating food borne pathogens and prolonging the shelf life of fresh-cut produce is influenced by the design of the package apart from material and atmospheric conditions. Three different designs were considered to determine a specific package design ens...

Evaluation of chlorine dioxide as a supplementary pretreatment reagent for lignocellulosic biomass.

PubMed

Acharjee, Tapas C; Jiang, Zhihua; Haynes, Robert Daniel; Lee, Yoon Y

2017-11-01

Chlorine dioxide (ClO 2 ) is a bleaching reagent used in paper industry. Two different types of pretreatment methods were investigated incorporating ClO 2 as a secondary reagent: (a) alkaline followed by ClO 2 treatment; (b) dilute-sulfuric acid followed ClO 2 treatment. In these methods, ClO 2 treatment has shown little effect on delignification. Scheme-a has shown a significant improvement in enzymatic digestibility of glucan far above that treated by ammonia alone. On the contrary, dilute-acid followed by ClO 2 treatment has shown negative effect on the enzymatic hydrolysis. The main factors affecting the enzymatic hydrolysis are the changes of the chemical structure of lignin and its distribution on the biomass surface. ClO 2 treatment significantly increases the carboxylic acid content and reduces phenolic groups of lignin, affecting hydrophobicity of lignin and the H-bond induced association between the enzyme and lignin. This collectively led to reduction of unproductive binding of enzyme with lignin, consequently increasing the digestibility. Copyright © 2017 Elsevier Ltd. All rights reserved.

Etching Rate of Silicon Dioxide Using Chlorine Trifluoride Gas

NASA Astrophysics Data System (ADS)

Miura, Yutaka; Kasahara, Yu; Habuka, Hitoshi; Takechi, Naoto; Fukae, Katsuya

2009-02-01

The etching rate behavior of silicon dioxide (SiO2, fused silica) using chlorine trifluoride (ClF3) gas is studied at substrate temperatures between 573 and 1273 K at atmospheric pressure in a horizontal cold-wall reactor. The etching rate increases with the ClF3 gas concentration, and the overall reaction is recognized to be of the first order. The change of the etching rate with increasing substrate temperature is nonlinear, and the etching rate tends to approach a constant value at temperatures exceeding 1173 K. The overall rate constant is estimated by numerical calculation, taking into account the transport phenomena in the reactor, including the chemical reaction at the substrate surface. The activation energy obtained in this study is 45.8 kJ mol-1, and the rate constant is consistent with the measured etching rate behavior. A reactor system in which there is minimum etching of the fused silica chamber by ClF3 gas can be achieved using an IR lamp heating unit and a chamber cooling unit to maintain a sufficiently low temperature of the chamber wall.

Degradation of lindane and hexachlorobenzene in supercritical carbon dioxide using palladium nanoparticles stabilized in microcellular high-density polyethylene.

PubMed

Wu, Bei-Zen; Chen, GuanYu; Yak, HwaKwang; Liao, Weisheng; Chiu, KongHwa; Peng, Shie-Ming

2016-06-01

Palladium nanoparticles stabilized in microcellular high-density polyethylene prepared through supercritical foaming, supercritical impregnation, and H2 reduction are used for the hydrodechlorination of lindane and hexachlorobenzene in supercritical carbon dioxide below 100 °C. Both lindane and hexachlorobenzene can be almost 100% transformed to cyclohexane in 1 h. Reaction intermediates, such as lower chlorinated products or benzene, are not observed or exist in trace amount indicating that most of them may undergo reactions without leaving the metal surface. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of chemical sanitizer combined with modified atmosphere packaging on inhibiting Escherichia coli O157:H7 in commercial spinach.

PubMed

Lee, Sun-Young; Baek, Seung-Youb

2008-06-01

Escherichia coli O157:H7 contaminated spinach has recently caused several outbreaks of human illness in the USA and Canada. However, to date, there has been no study demonstrating an effective way to eliminate E. coli O157:H7 in spinach. Therefore, this study was conducted to investigate the effect of chemical sanitizers alone or in combination with packaging methods such as vacuum and modified atmosphere packaging (MAP) on inactivating E. coli O157:H7 in spinach during storage time. Spinach inoculated with E. coli O157:H7 was packaged in four different methods (air, vacuum, N(2) gas, and CO(2) gas packaging) following treatment with water, 100 ppm chlorine dioxide, or 100 ppm sodium hypochlorite for 5 min at room temperature and stored at 7+/-2 degrees C. Treatment with water did not significantly reduce levels of E. coli O157:H7 in spinach. However, treatment with chlorine dioxide and sodium hypochlorite significantly decreased levels of E. coli O157:H7 by 2.6 and 1.1 log(10)CFU/g, respectively. Levels of E. coli O157:H7 in samples packaged in air following treatments grew during storage time, whereas levels were maintained in samples packaged in other packaging methods (vacuum, N(2) gas, and CO(2) gas packaging). Therefore there were significant differences (about 3-4 log) of E. coli O157:H7 populations between samples packed in air and other packaging methods following treatment with chemical sanitizers after 7 days storage. These results suggest that the combination of treatment with chlorine dioxide and packaging methods such as vacuum and MAP may be useful for improving the microbial safety of spinach against E. coli O157:H7 during storage.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Centrifugal bubble O2 (1Δ) gas generator with a total pressure of 100 Torr

NASA Astrophysics Data System (ADS)

Zagidulin, M. V.; Nikolaev, V. D.; Svistun, M. I.; Khvatov, N. A.

2008-08-01

A centrifugal bubbling singlet-oxygen gas generator is developed in which chlorine with helium are injected into the rotating layer of the alkali solution of hydrogen peroxide through cylindrical nozzles directed at an angle of 30° to the bubbler surface. The concentrations of water vapour and O2 (1Δ) and the gas temperature were determined by using the multichannel recording of the emission bands of oxygen at 634, 703, 762 and 1268 nm. For the chlorine and helium flow rates of 60 and 90 mmol s-1, respectively, the specific chlorine load of 3.2 mmol cm-2, a total pressure of 100 Torr in the working region of the gas generator and the oxygen partial pressure of 36 Torr, the chlorine utilisation was 90% and the content of O2 (1Δ) was ≈60%. For the ratio of the flow rates of chlorine and the alkali solution of hydrogen peroxide equal to 1 mol L-1, the water vapour content was ≈25%. The chemical efficiency of the oxygen—iodine laser with this gas generator achieved 23% for the specific power of 12.7 W cm per 1 cm3 s-1 per pass of the solution through the gas generator.

Elucidating the Higher Stability of Vanadium (V) Cations in Mixed Acid Based Redox Flow Battery Electrolytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vijayakumar, M.; Wang, Wei; Nie, Zimin

2013-11-01

The Vanadium (V) cation structures in mixed acid based electrolyte solution were analysed by density functional theory (DFT) based computational modelling and 51V and 35Cl Nuclear Magnetic Resonance (NMR) spectroscopy. The Vanadium (V) cation exists as di-nuclear [V2O3Cl2.6H2O]2+ compound at higher vanadium concentrations (≥1.75M). In particular, at high temperatures (>295K) this di-nuclear compound undergoes ligand exchange process with nearby solvent chlorine molecule and forms chlorine bonded [V2O3Cl2.6H2O]2+ compound. This chlorine bonded [V2O3Cl2.6H2O]2+ compound might be resistant to the de-protonation reaction which is the initial step in the precipitation reaction in Vanadium based electrolyte solutions. The combined theoretical and experimental approachmore » reveals that formation of chlorine bonded [V2O3Cl2.6H2O]2+ compound might be central to the observed higher thermal stability of mixed acid based Vanadium (V) electrolyte solutions.« less

Outbreak of Legionnaires' disease on a cruise ship: lessons for international surveillance and control.

PubMed

Regan, C M; McCann, B; Syed, Q; Christie, P; Joseph, C; Colligan, J; McGaffin, A

2003-06-01

A sporadic case of Legionnaires' disease was linked to travel on a cruise ship. Investigation identified two further cases of Legionnaires' Disease and one case of non-pneumonic Legionella infection. An Incident Team confirmed the source to be the ship's water system and control measures were instituted that included pasteurisation, super chlorination and chlorine dioxide dosing. The Public Health Laboratory Service (PHLS) Communicable Disease Surveillance Centre (CDSC), through the European Surveillance Scheme for Travel Associated Legionnaires' Disease, identified three previous cases associated with the same ship's water system including one fatality. Lessons for the international surveillance and control of Legionnaires' disease on cruise ships are discussed.

Cold plasma processing of local planetary ores for oxygen and metallurgically important metals

NASA Technical Reports Server (NTRS)

Lynch, D. C.; Bullard, D.; Ortega, R.

1991-01-01

The utilization of a cold or nonequilibrium plasma in chlorination processing is discussed. Titanium dioxide (TiO2) was successfully chlorinated at temperatures between 700 and 900 C without the aid of carbon. In addition to these initial experiments, a technique was developed for determining the temperature of a specimen in a plasma. Development of that technique has required evaluating the emissivity of TiO2, ZrO2, and FeOTiO2 and analyzing the specimen temperature in a plasma as a function of both power absorbed by the plasma and the pressure of the plasma. The mass spectrometer was also calibrated with TiCl4 and CCl4 vapor.

SUBCHRONIC SODIUM CHLORATE EXPOSURE IN DRINKING WATER RESULTS IN A CONCENTRATION-DEPENDENT INCREASE IN RAT THYROID FOLLICULAR CELL HYPERPLASIA

EPA Science Inventory

Chlorine dioxide (C102) is an effective water disinfectant but sodium chlorate (NaC103) has been identified as a potentially harmful disinfection by-product. Studies were performed to describe the development of thyroid lesions in animals exposed to NaC103 in drinking water. Mal...

40 CFR Appendix I to Part 264 - Recordkeeping Instructions

Code of Federal Regulations, 2011 CFR

2011-07-01

... incinerator T11Molten salt destructor T12Pyrolysis T13Wet air oxidation T14Calcination T15Microwave discharge... T22Chemical oxidation T23Chemical precipitation T24Chemical reduction T25Chlorination T26Chlorinolysis... Furnace T87Smelting, Melting, or Refining Furnace T88Titanium Dioxide Chloride Process Oxidation Reactor...

40 CFR Appendix I to Part 264 - Recordkeeping Instructions

Code of Federal Regulations, 2012 CFR

2012-07-01

... incinerator T11Molten salt destructor T12Pyrolysis T13Wet air oxidation T14Calcination T15Microwave discharge... T22Chemical oxidation T23Chemical precipitation T24Chemical reduction T25Chlorination T26Chlorinolysis... Furnace T87Smelting, Melting, or Refining Furnace T88Titanium Dioxide Chloride Process Oxidation Reactor...

40 CFR Appendix I to Part 264 - Recordkeeping Instructions

Code of Federal Regulations, 2013 CFR

2013-07-01

... incinerator T11Molten salt destructor T12Pyrolysis T13Wet air oxidation T14Calcination T15Microwave discharge... T22Chemical oxidation T23Chemical precipitation T24Chemical reduction T25Chlorination T26Chlorinolysis... Furnace T87Smelting, Melting, or Refining Furnace T88Titanium Dioxide Chloride Process Oxidation Reactor...

40 CFR Appendix I to Part 264 - Recordkeeping Instructions

Code of Federal Regulations, 2014 CFR

2014-07-01

... incinerator T11Molten salt destructor T12Pyrolysis T13Wet air oxidation T14Calcination T15Microwave discharge... T22Chemical oxidation T23Chemical precipitation T24Chemical reduction T25Chlorination T26Chlorinolysis... Furnace T87Smelting, Melting, or Refining Furnace T88Titanium Dioxide Chloride Process Oxidation Reactor...

Hexeneuronic acid content of chemical pulp

Treesearch

Junyong Zhu; X.S. Chai

2007-01-01

This method describes a procedure to determine hexeneuronic acid groups (HexA) in chemical pulps. HexA affects the kappa number determination by reaction with permanganate, and can react with certain bleaching chemicals, e.g. chlorine dioxide and ozone, but not with some others such as oxygen and peroxide. The method is based on the highly selective hydrolysis of HexA...

Rapid Determination of Endospore Viability by Hyperspectral Reflectance Following Surface Decontamination

DTIC Science & Technology

2008-12-01

Alexandria, VA ABSTRACT Bacterial spores , or endospores, such as those of Bacillus anthracis, are an asymmetrical threat. Decontamination... Bacillus subtilis spores by hypochlorite and chlorine dioxide, J. Appl Microbiol., 95(1), 54-67. ...have the ability to distinguish viable from non-viable endospores. In the laboratory, we have exploited the oxidative alteration of the spore coat

Why does Kevlar decompose, while Nomex does not, when treated with aqueous chlorine solutions?

PubMed

Akdag, Akin; Kocer, Hasan B; Worley, S D; Broughton, R M; Webb, T R; Bray, Travis H

2007-05-24

Kevlar and Nomex are high-performance polymers which have wide varieties of applications in daily life. Recently, they have been proposed to be biocidal materials when reacted with household bleach (sodium hypochlorite solution) because they contain amide moieties which can be chlorinated to generate biocidal N-halamine functional groups. Although Nomex can be chlorinated without any significant decomposition, Kevlar decomposes under the same chlorination conditions. In this study, two mimics for each of the polymers were synthesized to simulate the carboxylate and diaminophenylene components of the materials. It was found that the p-diaminophenylene component of the Kevlar mimic is oxidized to a quinone-type structure upon treatment with hypochlorous acid, which then decomposes. However, such a mechanism for the Nomex mimic is not possible. In this paper, based upon these observations, a plausible answer will be provided to the title question.

Lethality of chlorine, chlorine dioxide, and a commercial fruit and vegetable sanitizer to vegetative cells and spores of Bacillus cereus and spores of Bacillus thuringiensis.

PubMed

Beuchat, Larry R; Pettigrew, Charles A; Tremblay, Mario E; Roselle, Brian J; Scouten, Alan J

2004-08-01

Chlorine, ClO2, and a commercial raw fruit and vegetable sanitizer were evaluated for their effectiveness in killing vegetative cells and spores of Bacillus cereus and spores of Bacillus thuringiensis. The ultimate goal was to use one or both species as a potential surrogate(s) for Bacillus anthracis in studies that focus on determining the efficacy of sanitizers in killing the pathogen on food contact surfaces and foods. Treatment with alkaline (pH 10.5 to 11.0) ClO2 (200 microg/ml) produced by electrochemical technologies reduced populations of a five-strain mixture of vegetative cells and a five-strain mixture of spores of B. cereus by more than 5.4 and more than 6.4 log CFU/ml respectively, within 5 min. This finding compares with respective reductions of 4.5 and 1.8 log CFU/ml resulting from treatment with 200 microg/ml of chlorine. Treatment with a 1.5% acidified (pH 3.0) solution of Fit powder product was less effective, causing 2.5- and 0.4-log CFU/ml reductions in the number of B. cereus cells and spores, respectively. Treatment with alkaline ClO2 (85 microg/ml), acidified (pH 3.4) ClO2 (85 microg/ml), and a mixture of ClO2 (85 microg/ml) and Fit powder product (0.5%) (pH 3.5) caused reductions in vegetative cell/spore populations of more than 5.3/5.6, 5.3/5.7, and 5.3/6.0 log CFU/ml, respectively. Treatment of B. cereus and B. thuringiensis spores in a medium (3.4 mg/ml of organic and inorganic solids) in which cells had grown and produced spores with an equal volume of alkaline (pH 12.1) ClO2 (400 microg/ml) for 30 min reduced populations by 4.6 and 5.2 log CFU/ml, respectively, indicating high lethality in the presence of materials other than spores that would potentially react with and neutralize the sporicidal activity of ClO2.

Chlorination Revisited: Does Cl- Serve as a Catalyst in the Chlorination of Phenols?

PubMed

Lau, Stephanie S; Abraham, Sonali M; Roberts, A Lynn

2016-12-20

The aqueous chlorination of (chloro)phenols is one of the best-studied reactions in the environmental literature. Previous researchers have attributed these reactions to two chlorine species: HOCl (at circum-neutral and high pH) and H 2 OCl + (at low pH). In this study, we seek to examine the roles that two largely overlooked chlorine species, Cl 2 and Cl 2 O, may play in the chlorination of (chloro)phenols. Solution pH, chloride concentration, and chlorine dose were systematically varied in order to assess the importance of different chlorine species as chlorinating agents. Our findings indicate that chlorination rates at pH < 6 increase substantially when chloride is present, attributed to the formation of Cl 2 . At pH 6.0 and a chlorine dose representative of drinking water treatment, Cl 2 O is predicted to have at best a minor impact on chlorination reactions, whereas Cl 2 may contribute more than 80% to the overall chlorination rate depending on the (chloro)phenol identity and chloride concentration. While it is not possible to preclude H 2 OCl + as a chlorinating agent, we were able to model our low-pH data by considering Cl 2 only. Even traces of chloride can generate sufficient Cl 2 to influence chlorination kinetics, highlighting the role of chloride as a catalyst in chlorination reactions.

Evaluating fluorescence spectroscopy as a tool to characterize cyanobacteria intracellular organic matter upon simulated release and oxidation in natural water.

PubMed

Korak, Julie A; Wert, Eric C; Rosario-Ortiz, Fernando L

2015-01-01

Intracellular organic matter (IOM) from cyanobacteria may be released into natural waters following cell death in aquatic ecosystems and during oxidation processes in drinking water treatment plants. Fluorescence spectroscopy was evaluated to identify the presence of IOM from three cyanobacteria species during simulated release into natural water and following oxidation processes (i.e. ozone, free chlorine, chloramine, chlorine dioxide). Peak picking and the fluorescence index (FI) were explored to determine which IOM components (e.g., pigments) provide unique and persistent fluorescence signatures with minimal interferences from the background dissolved organic matter (DOM) found in Colorado River water (CRW). When IOM was added to ultrapure water, the fluorescence signature of the three cyanobacteria species showed similarities to each other. Each IOM exhibited a strong protein-like fluorescence and fluorescence at Ex 370 nm and Em 460 nm (FDOM), where commercial fluorescence sensors monitor. All species also had strong phycobiliprotein fluorescence (i.e. phycocyanin or phycoerythrin) in the higher excitation range (500-650 nm). All three IOM isolates had FI values greater than 2. When IOM was added to CRW, phycobiliprotein fluorescence was quenched through interactions between IOM and CRW-DOM. Mixing IOM and CRW demonstrated that protein-like and FDOM intensity responses were not a simple superposition of the starting material intensities, indicating that interactions between IOM and CRW-DOM fluorescing moieties were important. Fluorescence intensity in all regions decreased with exposure to ozone, free chlorine, and chlorine dioxide, but the FI still indicated compositional differences compared to CRW-DOM. The phycobiliproteins in IOM are not promising as a surrogate for IOM release, because their fluorescence intensity is quenched by interactions with DOM and decreased during oxidation processes. Increases in both FDOM intensity and FI are viable qualitative indicators of IOM release in natural waters and following oxidation and may provide a more robust real-time indication of the presence of IOM than conventional dissolved organic carbon or UV absorbance measurements.

Toxic Hazards Research Unit

NASA Technical Reports Server (NTRS)

Macewen, J. D.; Vernot, E. H.

1971-01-01

The activities of the Toxic Hazards Research Unit (THRU) for the period of June 1970 through May 1971 reviewed. Modification of the animal exposure facilities primarily for improved human safety but also for experimental integrity and continuity are discussed. Acute toxicity experiments were conducted on hydrogen fluoride (HF), hydrogen chloride (HCl), nitrogen dioxide (NO2), and hydrogen cyanide (HCN) both singly and in combination with carbon dioxide (CO). Additional acute toxicity experiments were conducted on oxygen difluoride (OF2) and chlorine pentafluoride (ClF5). Subacute toxicity studies were conducted on methylisobutylketone and dichloromethane (methylene dichloride). The interim results of further chronic toxicity experiments on monomethylhydrazine (MMH) are also described.

Lorentz force on sodium and chlorine ions in a salt water solution flow under a transverse magnetic field

NASA Astrophysics Data System (ADS)

DeLuca, R.

2009-05-01

It is shown that, by applying elementary concepts in electromagnetism and electrochemistry to a system consisting of salt water flowing in a thin rectangular pipe at an average velocity vA under the influence of a transverse magnetic field B0, an electromotive force generator can be conceived. In fact, the Lorentz force acting on the sodium and chlorine ions in a water solution gives rise to a so-called Faraday voltage across the two metal electrodes, positioned at the sides of the pipe. The effect is carried along the following chemical reactions at the electrodes: at the cathode, water is reduced (instead of sodium ions) and hydrogen gas is generated; at the anode, chlorine gas is produced. In college physics teaching, this interdisciplinary subject can be adopted to stress analogies and differences between the Hall voltage in conductors and the Faraday voltage in electrolyte solutions.

Study of degradation intermediates formed during electrochemical oxidation of pesticide residue 2,6-dichlorobenzamide (BAM) in chloride medium at boron doped diamond (BDD) and platinum anodes.

PubMed

Madsen, Henrik Tækker; Søgaard, Erik Gydesen; Muff, Jens

2015-02-01

For electrochemical oxidation to become applicable in water treatment outside of laboratories, a number of challenges must be elucidated. One is the formation and fate of degradation intermediates of targeted organics. In this study the degradation of the pesticide residue 2,6-dichlorobenzamide, an important groundwater pollutant, was investigated in a chloride rich solution with the purpose of studying the effect of active chlorine on the degradation pathway. To study the relative importance of the anodic oxidation and active chlorine oxidation in the bulk solution, a non-active BDD and an active Pt anode were compared. Also, the effect of the active chlorine oxidation on the total amount of degradation intermediates was investigated. We found that for 2,6-dichlorobenzamide, active chlorine oxidation was determining for the initial step of the degradation, and therefore yielded a completely different set of degradation intermediates compared to an inert electrolyte. For the Pt anode, the further degradation of the intermediates was also largely dependent on active chlorine oxidation, while for the BDD anode anodic oxidation was most important. It was also found that the presence of active chlorine led to fewer degradation intermediates compared to treatment in an inert electrolyte. Copyright © 2014 Elsevier Ltd. All rights reserved.

[Efficiency of oxidant gas generator cells powered by electric or solar energy].

PubMed

Brust Carmona, H; Benitez, A; Zarco, J; Sánchez, E; Mascher, I

1998-02-01

Diseases caused by microbial contaminants in drinking water continue to be a serious problem in countries like Mexico. Chlorination, using chlorine gas or chlorine compounds, is one of the best ways to treat drinking water. However, difficulties in handling chlorine gas and the inefficiency of hypochlorite solution dosing systems--due to sociopolitical, economic, and cultural factors--have reduced the utility of these chlorination procedures, especially in far-flung and inaccessible rural communities. These problems led to the development of appropriate technologies for the disinfection of water by means of the on-site generation of mixed oxidant gases (chlorine and ozone). This system, called MOGGOD, operates through the electrolysis of a common salt solution. Simulated system evaluation using a hydraulic model allowed partial and total costs to be calculated. When powered by electrical energy from the community power grid, the system had an efficiency of 90%, and in 10 hours it was able to generate enough gases to disinfect about 200 m3 of water at a cost of approximately N$8 (US $1.30). When the electrolytic cell was run on energy supplied through a photoelectric cell, the investment costs were higher. A system fed by photovoltaic cells could be justified in isolated communities that lack electricity but have a gravity-fed water distribution system.

[Determination of Chloride Salt Solution by NIR Spectroscopy].

PubMed

Zhang, Bin; Chen, Jian-hong; Jiao, Ming-xing

2015-07-01

Determination of chloride salt solution by near infrared spectrum plays a very important role in Biomedicine. The near infrared spectrum analysis of Sodium chloride, potassium chloride, calcium chloride aqueous solution shows that the concentration change of chloride salt can affect hydrogen bond, resulting in the variation of near infrared spectrum of water. The temperature influence on NIR spectrum has been decreased by choosing reasonable wavelength range and the wavelength where the temperature effects are zero (isosbestic point). Chlorine salt prediction model was established based on partial least squares method and used for predicting the concentration of the chlorine ion. The impact on near infrared spectrum of the cation ionic radius, the number of ionic charge, the complex effect of ionic in water has also discussed in this article and the reason of every factor are analysed. Experimental results show that the temperature and concentration will affect the near-infrared spectrum of the solution, It is found that the effect of temperature plays the dominant role at low concentrations of chlorine salt; rather, the ionic dominates at high concentration. Chloride complexes are formed in aqueous solution, It has an effect on hydrogen bond of water combining with the cations in chlorine salt solution, Comparing different chloride solutions at the same concentration, the destruction effects of chloride complexes and catnions on the hydrogen bond of water increases in the sequences: CaCl2 >NaCl>KC. The modeling result shows that the determination coefficients (R2) = 99.97%, the root mean square error of cross validation (RM- SECV) = 4.51, and the residual prediction deviation (RPD) = 62.7, it meets the daily requirements of biochemical detection accuracy.

Decontamination of Drinking Water Infrastructure ...

EPA Pesticide Factsheets

Technical Brief This study examines the effectiveness of decontaminating corroded iron and cement-mortar coupons that have been contaminated with spores of Bacillus atrophaeus subsp. globigii (B. globigii), which is often used as a surrogate for pathogenic B. anthracis (anthrax) in disinfection studies. Bacillus spores are persistent on common drinking water material surfaces like corroded iron, requiring physical or chemical methods to decontaminate the infrastructure. In the United States, free chlorine and monochloramine are the primary chemical disinfectants used by the drinking water industry to inactivate microorganisms. Flushing is also a common, easily implemented practice in drinking water distribution systems, although large volumes of contaminated water needing treatment could be generated. Identifying readily available alternative disinfectant formulations for infrastructure decontamination could give water utilities options for responding to specific types of contamination events. In addition to presenting data on flushing alone, which demonstrated the persistence of spores on water infrastructure in the absence of high levels of disinfectants, data on acidified nitrite, chlorine dioxide, free chlorine, monochloramine, ozone, peracetic acid, and followed by flushing are provided.

Biochars made from agro-industrial by-products remove chlorine and lower water toxicity

NASA Astrophysics Data System (ADS)

Tzachristas, Andreas; Xirou, Maria; Manariotis, Ioannis D.; Dailianis, Stefanos; Karapanagioti, Hrissi K.

2016-04-01

Chlorination is the most common disinfection process for water and treated wastewater. For the industrial use of water in food production, chlorine can add undesired taste and odor to the final product. For this reason, dechlorination is desired for food industries that use municipal tap water. For treated wastewater discharge or reuse, chlorine can be toxic to the receiving aqueous systems and to the irrigated plants. In both the above cases, dechlorination is also required. Traditionally activated carbon has been used as the ideal material for the removal of chlorine. The main mechanisms that describe the interaction between activated carbon and HOCl or OCl- are described by the following equations (AWWA, 1990): HOCl + C* → C*O + H+ + Cl- (1), OCl- + C* → C*O + Cl- (2) Where C* and C*O represent the activated carbon surface and a surface oxide, respectively. The present study proposes the use of agro-industrial by-products for the production of biochars that will be used for dechlorination of tap-water used for food-industry production. Different raw materials such as malt spent rootlets, coffee residue, olive and grape seeds, etc. are used for the production of biochar. Various temperatures and air-to-solid ratios are tested for optimizing biochar production. Batch tests as well as a column test are employed to study the dechlorination efficiency and kinetics of the different raw and biochar materials as well as those of commercial activated carbons. As chlorine concentration increases the removal also increases linearily. After 1 and 24 hours of contact the chlorine relative removal efficiencies for the biochar made from olive seeds are 50 and 77 ± 4%, respectively. It seems that the removal kinetics are faster during the first hour; then, removal continues but with a slower rate. Most of the biochars tested (with 3 mg of solid in 20 mL of chlorine solution at initial concentration Co=1.5 mg/L) demonstrated removal efficiencies with an average of 9.4 ± 0.5 mg/g. For the two commercial activated carbons, removal efficiencies were 11.4 ± 0.2 mg/g. The column experiment also showed positive results; no breakthrough has been observed after 1L of chlorine solution has passed through a column packed with 4 g of biochar made from the pyrolysis of grape seeds. Toxicity tests were also performed with the chlorine solution before and after passing through this column. The toxicity of the solution decreased after passing through the column packed with biochar suggesting that no toxic compounds are formed during the removal of chlorine by the biochar. The overall idea of this study is the sustainable use of the solid by-products of a food industry or producer to treat water or treated wastewater in order to enhance its quality and lower its toxicity. American Water Works Association (AWWA) 1990 Water quality and treatment, a handbook of community water supplies, Fourth edition.

Enhanced Inactivation of Salmonella and Pseudomonas Biofilms on Stainless Steel by Use of T-128, a Fresh-Produce Washing Aid, in Chlorinated Wash Solutions

PubMed Central

Shen, Cangliang; Luo, Yaguang; Nou, Xiangwu; Bauchan, Gary; Zhou, Bin; Wang, Qin

2012-01-01

The effect of the washing aid T-128 (generally recognized as safe [GRAS] formulation, composed mainly of phosphoric acid and propylene glycol) on inactivation of Salmonella and Pseudomonas populations in biofilms on stainless steel was evaluated under conditions of increasing organic matter loads in chlorinated wash solutions dominated by hypochlorous acid. Biofilms were formed statically on stainless steel coupons suspended in 2% lettuce extract after inoculation with Salmonella enterica serovar Thompson or Newport or with Pseudomonas fluorescens. Coupons with biofilms were washed in chlorine solutions (0, 0.5, 1, 2, 5, 10, or 20 mg/liter at pH 6.5, 5.0 and 2.9), with or without T-128, and with increasing loads of organic matter (0, 0.25, 0.5, 0.75, or 1.0% lettuce extract). Cell populations on coupons were dispersed using intermittent, pulsed ultrasonication and vortexing and enumerated by colony counts on XLT-4 or Pseudomonas agars. Cell responses to fluorescent viability staining of biofilm treatment washing solutions were examined using confocal laser scanning microscopy. Results showed that 0.1% T-128 (without chlorine) reduced P. fluorescens biofilm populations by 2.5 log10 units but did not reduce Salmonella populations. For both Salmonella and Pseudomonas, the sanitizing effect of free chlorine (1.0 to 5.0 mg/liter) was enhanced (P < 0.05) when it was combined with T-128. Application of T-128 decreased the free chlorine depletion rate caused by increasing organic matter in wash waters and significantly (P < 0.05) augmented inactivation of bacteria in biofilms compared to treatments without T-128. Image analysis of surfaces stained with SYTO and propidium iodide corroborate the cultural assay results showing that T-128 can aid in reducing pathogen viability in biofilms and thus can aid in sanitizing stainless steel contact surfaces during processing of fresh-cut produce. PMID:22752180

Chlorine disinfection increases both intracellular and extracellular antibiotic resistance genes in a full-scale wastewater treatment plant.

PubMed

Liu, Shan-Shan; Qu, Hong-Mei; Yang, Dong; Hu, Hui; Liu, Wei-Li; Qiu, Zhi-Gang; Hou, Ai-Ming; Guo, Jianhua; Li, Jun-Wen; Shen, Zhi-Qiang; Jin, Min

2018-06-01

The emergence and spread of antibiotic resistance has posed a major threat to both human health and environmental ecosystem. Although the disinfection has been proved to be efficient to control the occurrence of pathogens, little effort is dedicated to revealing potential impacts of disinfection on transmission of antibiotic resistance genes (ARGs), particularly for free-living ARGs in final disinfected effluent of urban wastewater treatment plants (UWWTP). Here, we investigated the effects of chlorine disinfection on the occurrence and concentration of both extracellular ARGs (eARGs) and intracellular ARGs (iARGs) in a full-scale UWWTP over a year. We reported that the concentrations of both eARGs and iARGs would be increased by the disinfection with chlorine dioxide (ClO 2 ). Specifically, chlorination preferentially increased the abundances of eARGs against macrolide (ermB), tetracycline (tetA, tetB and tetC), sulfonamide (sul1, sul2 and sul3), β-lactam (ampC), aminoglycosides (aph(2')-Id), rifampicin (katG) and vancomycin (vanA) up to 3.8 folds. Similarly, the abundances of iARGs were also increased up to 7.8 folds after chlorination. In terms of correlation analyses, the abundance of Escherichia coli before chlorination showed a strong positive correlation with the total eARG concentration, while lower temperature and higher ammonium concentration were assumed to be associated with the concentration of iARGs. This study suggests the chlorine disinfection could increase the abundances of both iARGs and eARGs, thereby posing risk of the dissemination of antibiotic resistance in environments. Copyright © 2018 Elsevier Ltd. All rights reserved.

A Rapid and Inexpensive Bioassay to Evaluate the Decontamination of Organophosphates

DTIC Science & Technology

2012-01-01

weather natu- rally over time. Actual chemical degradation of the tox- in often relied on harsh chemicals such as calcium oxide and chlorine dioxide...New decontaminating compounds have been developed that are more effective or more en- vironmentally friendly, including organophosphorous acid ...quires sophisticated instrumental analytical techniques such as liquid or gas chromatography, which involves expensive equipment and trained personnel

CFD Simulation of the distribution of ClO2 in fresh produce to improve safety

USDA-ARS?s Scientific Manuscript database

The shelf life of fresh-cut produce may be prolonged with the injection of bactericide gases like chlorine dioxide (ClO2). A comparative study has been conducted by modeling the injection of three different gases, CO2, ClO2 and N2 inside a PET clamshell containers commonly use to package fresh produ...

Mechanistic aspects of ingested chlorine dioxide on thyroid function: impact of oxidants on iodide metabolism.

PubMed Central

Bercz, J P; Jones, L L; Harrington, R M; Bawa, R; Condie, L

1986-01-01

Toxicological studies dealing with recent findings of health effects of drinking water disinfectants are reviewed. Experiments with monkeys and rodents indicate that the biological activity of ingested disinfectants is expressed via their chemical interaction with the mucosal epithelia, secretory products, and nutritional contents of the alimentary tract. Evidence exists that a principal partner of this redox interaction is the iodide of nutritional origin that is ubiquitous in the gastrointestinal tract. Thus the observation that subchronic exposure to chlorine dioxide (ClO2) in drinking water decreases serum thyroxine levels in mammalian species can be best explained with changes produced in the chemical form of the bioavailable iodide. Ongoing and previously reported mechanistic studies indicate that oxidizing agents such as chlorine-based disinfectants oxidize the basal iodide content of the gastrointestinal tract. The resulting reactive iodine species readily attaches to organic matter by covalent bonding. Evidence suggests that the extent to which such iodinated organics are formed is proportional to the magnitude of the electromotive force and stoichiometry of the redox couple between iodide and the disinfectant. Because the extent of thyroid uptake of the bioavailable iodide does not decrease during ClO2 ingestion, it seems that ClO2 does not cause iodide deficiency of sufficient magnitude to account for the decrease in hormonogenesis. Absorption of one or more of iodinated molecules, e.g., nutrients, hormones, or cellular constituents of the alimentary tract having thyromimetic or thyroid inhibitory properties, is a better hypothesis for the effects seen. Images FIGURE 1. a FIGURE 1. b FIGURE 1. c PMID:3816729

Adsorption of chlorine dioxide gas on activated carbons.

PubMed

Wood, Joseph P; Ryan, Shawn P; Snyder, Emily Gibb; Serre, Shannon D; Touati, Abderrahmane; Clayton, Matthew J

2010-08-01

Research and field experience with chlorine dioxide (ClO2) gas to decontaminate structures contaminated with Bacillus anthracis spores and other microorganisms have demonstrated the effectiveness of this sterilant technology. However, because of its hazardous properties, the unreacted ClO2, gas must be contained and captured during fumigation events. Although activated carbon has been used during some decontamination events to capture the ClO2 gas, no data are available to quantify the performance of the activated carbon in terms of adsorption capacity and other sorbent property operational features. Laboratory experiments were conducted to determine and compare the ClO2 adsorption capacities of five different types of activated carbon as a function of the challenge ClO2 concentration. Tests were also conducted to investigate other sorbent properties, including screening tests to determine gaseous species desorbed from the saturated sorbent upon warming (to provide an indication of how immobile the ClO2 gas and related compounds are once captured on the sorbent). In the adsorption tests, ClO2 gas was measured continuously using a photometric-based instrument, and these measurements were verified with a noncontinuous method utilizing wet chemistry analysis. The results show that the simple activated carbons (not impregnated or containing other activated sorbent materials) were the most effective, with maximum adsorption capacities of approximately 110 mg/g. In the desorption tests, there was minimal release of ClO(2) from all sorbents tested, but desorption levels of chlorine (Cl2) gas (detected as chloride) varied, with a maximum release of nearly 15% of the mass of ClO2 adsorbed.

A comparison of disinfection by-products formation during sequential or simultaneous disinfection of surface waters with chlorine dioxide and chlor(am)ine.

PubMed

Shi, Yanwei; Ling, Wencui; Qiang, Zhimin

2013-01-01

The effect of chlorine dioxide (ClO2) oxidation on the formation of disinfection by-products (DBPs) during sequential (ClO2 pre-oxidation for 30 min) and simultaneous disinfection processes with free chlorine (FC) or monochloramine (MCA) was investigated. The formation of DBPs from synthetic humic acid (HA) water and three natural surface waters containing low bromide levels (11-27 microg/L) was comparatively examined in the FC-based (single FC, sequential ClO2-FC, and simultaneous ClO2/FC) and MCA-based (single MCA, ClO2-MCA, and ClO2/MCA) disinfection processes. The results showed that much more DBPs were formed from the synthetic HA water than from the three natural surface waters with comparative levels of dissolved organic carbon. In the FC-based processes, ClO2 oxidation could reduce trihalomethanes (THMs) by 27-35% and haloacetic acids (HAAs) by 14-22% in the three natural surface waters, but increased THMs by 19% and HAAs by 31% in the synthetic HA water after an FC contact time of 48 h. In the MCA-based processes, similar trends were observed although DBPs were produced at a much lower level. There was an insignificant difference in DBPs formation between the sequential and simultaneous processes. The presence of a high level of bromide (320 microg/L) remarkably promoted the DBPs formation in the FC-based processes. Therefore, the simultaneous disinfection process of ClO2/MCA is recommended particularly for waters with a high bromide level.

Controlled-release of Chlorine Dioxide in a Perforated Packaging System to Extend the Storage Life and Improve the Safety of Grape Tomatoes.

PubMed

Sun, Xiuxiu; Baldwin, Elizabeth; Plotto, Anne; Narciso, Jan; Ference, Christopher; Ritenour, Mark; Harrison, Ken; Gangemi, Joseph; Bai, Jinhe

2017-04-07

A controlled-release chlorine dioxide (ClO2) pouch was developed by sealing a slurry form of ClO2 into semipermeable polymer film; the release properties of the pouch were monitored in containers with or without fruit. The pouch was affixed to the inside of a perforated clamshell containing grape tomatoes, and the effect on microbial population, firmness, and weight loss was evaluated during a 14 day storage period at 20 °C. Within 3 days, the ClO2 concentration in the clamshells reached 3.5 ppm and remained constant until day 10. Thereafter, it decreased to 2 ppm by day 14. The ClO2 pouch exhibited strong antimicrobial activity, reducing Escherichia coli populations by 3.08 log CFU/g and Alternaria alternata populations by 2.85 log CFU/g after 14 days of storage. The ClO2 treatment also reduced softening and weight loss and extended the overall shelf life of the tomatoes. Our results suggest that ClO2 treatment is useful for extending the shelf life and improving the microbial safety of tomatoes during storage without impairing their quality.

The use of chlorine dioxide for the inactivation of copepod zooplankton in drinking water treatment.

PubMed

Lin, Tao; Chen, Wei; Cai, Bo

2014-01-01

The presence of zooplankton in drinking water treatment system may cause a negative effect on the aesthetic value of drinking water and may also increase the threat to human health due to they being the carriers of bacteria. Very little research has been done on the effects of copepod inactivation and the mechanisms involved in this process. In a series of bench-scale experiments we used a response surface method to assess the sensitivity of copepod to inactivation when chlorine dioxide (ClO₂) was used as a disinfectant. We also assessed the effects of the ClO₂dosage, exposure time, organic matter concentration and temperature. Results indicated that the inactivation rate improved with increasing dosage, exposure time and temperature, whereas it decreased with increasing organic matter concentration. Copepod inactivation was more sensitive to the ClO₂dose than that to the exposure time, while being maintained at the same Ct-value conditions. The activation energy at different temperatures revealed that the inactivation of copepods with ClO₂was temperature-dependent. The presence of organic matter resulted in a lower available dose as well as a shorter available exposure time, which resulted in a decrease in inactivation efficiency.

Disinfection of bore well water with chlorine dioxide/sodium hypochlorite and hydrodynamic cavitation.

PubMed

Wang, Yifei; Jia, Aiyin; Wu, Yue; Wu, Chunde; Chen, Lijun

2015-01-01

The effect of hydrodynamic cavitation (HC) on potable water disinfection of chemicals was investigated. The bore well water was introduced into HC set-up to examine the effect of HC alone and combination of HC and chemicals such as chlorine dioxide and sodium hypochlorite. The effect of inlet pressure and geometrical parameters on disinfection was studied using HC alone and the results showed that increasing inlet pressure and using more and bigger holes of orifice plates can result in a higher disinfection rates. When HC was combined with chemicals, HC can reduce the doses of the chemicals and shorten the time of disinfection. It was also found that the decrease in bacteria concentration followed a first-order kinetic model. As for the experiment of combination of HC and sodium hypochlorite for disinfection, HC not only improves the disinfection rate but also degrades natural organic matter and chloroform. Compared with only sodium hypochlorite disinfection, combined processes get higher disinfection rate and lower production of chloroform, particularly the pretreatment with HC enhances the disinfection rate by 32% and there is a simultaneous reduction in production of chloroform by 39%.

Structure of the Cyanuric Acid Hydrolase TrzD Reveals Product Exit Channel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bera, Asim K.; Aukema, Kelly G.; Elias, Mikael

Cyanuric acid hydrolases are of industrial importance because of their use in aquatic recreational facilities to remove cyanuric acid, a stabilizer for the chlorine. Degradation of excess cyanuric acid is necessary to maintain chlorine disinfection in the waters. Cyanuric acid hydrolase opens the cyanuric acid ring hydrolytically and subsequent decarboxylation produces carbon dioxide and biuret. In the present study, we report the X-ray structure of TrzD, a cyanuric acid hydrolase from Acidovorax citrulli. The crystal structure at 2.19 Å resolution shows a large displacement of the catalytic lysine (Lys163) in domain 2 away from the active site core, whereas themore » two other active site lysines from the two other domains are not able to move. The lysine displacement is proposed here to open up a channel for product release. Consistent with that, the structure also showed two molecules of the co-product, carbon dioxide, one in the active site and another trapped in the proposed exit channel. Previous data indicated that the domain 2 lysine residue plays a role in activating an adjacent serine residue carrying out nucleophilic attack, opening the cyanuric acid ring, and the mobile lysine guides products through the exit channel.« less

Plasma membrane damage to Candida albicans caused by chlorine dioxide (ClO2).

PubMed

Wei, M-K; Wu, Q-P; Huang, Q; Wu, J-L; Zhang, J-M

2008-08-01

To investigate the plasma membrane damage of chlorine dioxide (ClO(2)) to Candida albicans ATCC10231 at or below the minimal fungicidal concentration (MFC). ClO(2) at MFC or below was adopted to treat the cell suspensions of C. albicans ATCC10231. Using transmission electron microscopy, no visible physiological alteration of cell shape and plasma membrane occurred. Potassium (K(+)) leakages were significant; likewise, it showed time- and dose-dependent increases. However, adenosine triphosphate (ATP) leakages were very slight. Research shows that when 99% of the cells were inactivated, the leakage was measured at 0.04% of total ATP. Compared with the mortality-specific fluorescent dye of DiBAC(4)(3), majority of the inactivated cells were poorly stained by propidium iodide, another mortality-specific fluorescent dye which can be traced by flow cytometry. At or below MFC, ClO(2) damages the plasma membranes of C. albicans mainly by permeabilization, rather than by the disruption of their integrity. K(+) leakage and the concomitant depolarization of the cell membrane are some of the critical events. These insights into membrane damages are helpful in understanding the action mode of ClO(2).

Letter to the Editor: Appropriate selection of dose coefficients in radiological assessments: C-14 and Cl-36: response to the letter of G Smith and M Thorne (2015 J. Radiol. Prot. 35 737-40)

DOE PAGES

Harrison, John D.; Leggett, Richard Wayne

2016-01-01

This letter to the editor of Journal of Radiological Protection is in response to a letter to the editor from G. M. Smith and M. C. Thorne of Great Britain concerning the appropriate selection of dose coefficients for ingested carbon-14 and chlorine-36, two of the most important long-lived components of radioactive wastes. Smith and Thorne argue that current biokinetic models of the International Commission on Radiological Protection (ICRP) for carbon and chlorine are overly cautious models from the standpoint of radiation dose estimates for C-14 and Cl-36, and that more realistic models are needed for evaluation of the hazards ofmore » these radionuclides in nuclear wastes. We (Harrison and Leggett) point out that new biokinetic models for these and other elements (developed at ORNL) will soon appear in ICRP Publications. These new models generally are considerably more realistic than current ICRP models. Here, examples are given for C-14 inhaled as carbon dioxide or ingested in water as bicarbonate, carbonate, or carbon dioxide.« less

Inactivation of bacterial biothreat agents in water, a review.

PubMed

Rose, L J; Rice, E W

2014-12-01

Water supplies and water distribution systems have been identified as potential targets for contamination by bacterial biothreat agents. Since the 2001 Bacillus anthracis bioterrorist attacks, additional efforts have been aimed at research to characterize biothreat organisms in regards to their susceptibility to disinfectants and technologies currently in use for potable water. Here, we present a review of research relevant to disinfection of bacteria with the potential to pose a severe threat to public health and safety, and their potential surrogates. The efficacy of chlorine, monochloramine, chlorine dioxide, and ultraviolet light to inactivate each organism in suspension is described. The complexities of disinfection under varying water conditions and when the organisms are associated with biofilms in distribution systems are discussed.

Inactivation of bacterial biothreat agents in water, a review

PubMed Central

Rice, E. W.

2016-01-01

Water supplies and water distribution systems have been identified as potential targets for contamination by bacterial biothreat agents. Since the 2001 Bacillus anthracis bioterrorist attacks, additional efforts have been aimed at research to characterize biothreat organisms in regards to their susceptibility to disinfectants and technologies currently in use for potable water. Here, we present a review of research relevant to disinfection of bacteria with the potential to pose a severe threat to public health and safety, and their potential surrogates. The efficacy of chlorine, monochloramine, chlorine dioxide, and ultraviolet light to inactivate each organism in suspension is described. The complexities of disinfection under varying water conditions and when the organisms are associated with biofilms in distribution systems are discussed. PMID:25473971

A computer simulation of the afterburning processes occurring within solid rocket motor plumes in the troposphere

NASA Technical Reports Server (NTRS)

Gomberg, R. I.; Stewart, R. B.

1976-01-01

As part of a continuing study of the environmental effects of solid rocket motor (SRM) operations in the troposphere, a numerical model was used to simulate the afterburning processes occurring in solid rocket motor plumes and to predict the quantities of potentially harmful chemical species which are created. The calculations include the effects of finite-rate chemistry and turbulent mixing. It is found that the amount of NO produced is much less than the amount of HCl present in the plume, that chlorine will appear predominantly in the form of HCl although some molecular chlorine is present, and that combustion is complete as is evident from the predominance of carbon dioxide over carbon monoxide.

Removal of contaminant gases from an electrolytic urine pretreatment process. [in spacecraft life support systems

NASA Technical Reports Server (NTRS)

Colombo, G. V.; Putnam, D. F.

1977-01-01

The effluent gas stream from an electrolytic urine pretreatment process was analyzed by gas chromatography-mass spectroscopy and wet chemical methods to determine its composition. The major constituents were identified as: hydrogen, carbon dioxide, oxygen, nitrogen, water vapor, and chlorine. The trace impurities were chlorinated light hydrocarbons, and a number of other organic impurities in the low ppm range. Several methods of removing all of the undesirable gases to levels acceptable for return to a space cabin atmosphere were investigated experimentally. A subsystem concept comprised of the following sequential unit processes and operations was successfully demonstrated: (1) raw urine scrubbing, (2) silica gel sorption, (3) dilution with cabin air, and (4) catalytic oxidation.

Oxidation of spin-traps by chlorine dioxide (ClO2) radical in aqueous solutions: first ESR evidence of formation of new nitroxide radicals.

PubMed

Ozawa, T; Miura, Y; Ueda, J

1996-01-01

The reactivities of the chlorine dioxide (ClO2), which is a stable free radical towards some water-soluble spin-traps were investigated in aqueous solutions by an electron spin resonance (ESR) spectroscopy. The ClO2 radical was generated from the redox reaction of Ti3+ with potassium chlorate (KClO3) in aqueous solutions. When one of the spin-traps, 5,5-dimethyl-1-pyrroline N-oxide (DMPO), was included in the Ti3+-KClO3 reaction system, ESR spectrum due to the ClO2 radical completely disappeared and a new ESR spectrum [aN(1) = 0.72 mT, aH(2) = 0.41 mT], which is different from that of DMPO-ClO2 adduct, was observed. The ESR parameters of this new ESR signal was identical to those of 5,5-dimethylpyrrolidone-(2)-oxyl-(1) (DMPOX), suggesting the radical species giving the new ESR spectrum is assignable to DMPOX. The similar ESR spectrum consisting of a triplet [aN(1) = 0.69 mT] was observed when the derivative of DMPO, 3,3,5,5-tetramethyl-1-pyrroline N-oxide (M4PO) was included in the Ti3+-KClO3 reaction system. This radical species is attributed to the oxidation product of M4PO, 3,3,5,5-tetramethylpyrrolidone-(2)-oxyl-(1) (M4POX). When another nitrone spin-trap, alpha-(4-pyridyl-1-oxide)-N-t-butylnitrone (POBN) was used as a spin-trap, the ESR signal intensity due to the ClO2 radical decreased and a new ESR signal consisting of a triplet [aN(1) = 0.76 mT] was observed. The similar ESR spectrum was observed when N-t-butyl-alpha- nitrone (PBN) was used as a spin-trap. This ESR parameter [a(N)(1) = 0.85 mT] was identical to the oxidation product of PBN, PBNX. Thus, the new ESR signal observed from POBN may be assigned to the oxidation product of POBN, POBNX. These results suggest that the ClO2, radical does not form the stable spin adducts with nitrone spin-traps, but oxidizes these spin-traps to give the corresponding nitroxyl radicals. On the other hand, nitroso spin-traps, 5,5-dibromo-4-nitrosobenzenesulfonate (DBNBS), and 2-methyl-2-nitrosopropane (MNP) did not trap the ClO2 radical. This result indicates that an unpaired electron of the ClO2 radical is localized on oxygen atom, because nitroso spin-traps cannot form the stable spin adduct with oxygen-centered radical.

A Residual Chlorine Removal Method to Allow Drinking Water Monitoring by Biological Early Warning Systems

DTIC Science & Technology

2005-03-18

Lepomis macrochirus). have been disinfected with chloramines The threshold for a toxicity alarm by was not determined. Biomonitor users the USACEHR...residual solution. This caused an elevated chlorine from water disinfected with chlorine level (measured at 0.08 FRC) chloramines . In testing with a rapid...have been disinfected A Handbook, Volume 2, 8. Kluwer with chloramines . Academic/Plenum Publishers, New York, NY, pp 123-141. 5. Recommendations

Use of gas chromatography-mass spectrometry-olfactometry and a conventional flask test to identify off-flavor compounds generated from phenylalanine during chlorination of drinking water.

PubMed

Matsushita, Taku; Sakuma, Miki; Tazawa, Shiori; Hatase, Taiki; Shirasaki, Nobutaka; Matsui, Yoshihiko

2017-11-15

Off-flavor in drinking water can be caused by transformation products (TPs) generated from organic compounds, such as amino acids, present during chlorination. However, the contributions of many of these TPs to overall off-flavor have not been quantified, mainly because the lack of appropriate chemical standards prevents sensory evaluation by means of a conventional flask test. In the present study, we used gas chromatography-mass spectrometry-olfactometry (GC-MS-O) to identify compounds responsible for the off-flavor generated by chlorination of an aqueous solution of the amino acid phenylalanine, and we propose a sensory evaluation procedure for quantification of the contributions of the identified TPs to the overall off-flavor, regardless of the availability of chemical standards of the TPs. GC-MS-O revealed that two TPs, N-chlorophenylacetaldimine and 2-chloro-2-phenylacetaldehyde, for which chemical standards are not commercially available, were the main components responsible for the off-flavor of the chlorinated solution. By using a sensory evaluation procedure involving a combination of GC-MS-O and a conventional flask test, we quantified the contributions of TPs to the overall off-flavor of the chlorinated solution. Approximately 60% of the off-flavor was attributable to free chlorine (13%), 2-chloro-2-phenylacetaldehyde (13%), trichloramine (12%) phenylacetaldehyde (11%) phenylacetonitrile (8%), and N-chlorophenylacetaldimine (2%). Treatment with powdered activated carbon (PAC) removed the off-flavor. Experiments with chlorination of 15 N-labeled phenylalanine suggested that PAC reductively decomposed trichloramine into N 2 gas and adsorbed all of the other identified TPs. Superfine PAC (median diameter, 0.7 μm) removed the off-flavor more rapidly than normal-size PAC (median diameter, 8.0 μm). Copyright © 2017 Elsevier Ltd. All rights reserved.

Combustion of chlorinated volatile organic compounds (VOCs) using bimetallic chromium-copper supported on modified H-ZSM-5 catalyst.

PubMed

Abdullah, Ahmad Zuhairi; Bakar, Mohamad Zailani Abu; Bhatia, Subhash

2006-02-28

The paper reports on the performance of chromium or/and copper supported on H-ZSM-5(Si/Al = 240) modified with silicon tetrachloride (Cr1.5/SiCl4-Z, Cu1.5/SiCl4-Z and Cr1.0Cu0.5/SiCl4-Z) as catalysts in the combustion of chlorinated VOCs (Cl-VOCs). A reactor operated at a gas hourly space velocity (GHSV) of 32,000 h(-1), a temperature between 100 and 500 degrees C with 2500 ppm of dichloromethane (DCM), trichloromethane (TCM) and trichloroethylene (TCE) is used for activity studies. The deactivation study is conducted at a GHSV of 3800 h(-1), at 400 degrees C for up to 12 h with a feed concentration of 35,000 ppm. Treatment with silicon tetrachloride improves the chemical resistance of H-ZSM-5 against hydrogen chloride. TCM is more reactive compared to DCM but it produces more by-products due to its high chlorine content. The stabilization of TCE is attributed to resonance effects. Water vapor increases the carbon dioxide yield through its role as hydrolysis agent forming reactive carbocations and acting as hydrogen-supplying agent to suppress chlorine-transfer reactions. The deactivation of Cr1.0Cu0.5/SiCl4-Z is mainly due to the chlorination of its metal species, especially with higher Cl/H feed. Coking is limited, particularly with DCM and TCM. In accordance with the Mars-van Krevelen model, the weakening of overall metal reducibility due to chlorination leads to a loss of catalytic activity.

Semiconductor photoelectrochemistry

NASA Technical Reports Server (NTRS)

Buoncristiani, A. M.; Byvik, C. E.

1983-01-01

Semiconductor photoelectrochemical reactions are investigated. A model of the charge transport processes in the semiconductor, based on semiconductor device theory, is presented. It incorporates the nonlinear processes characterizing the diffusion and reaction of charge carriers in the semiconductor. The model is used to study conditions limiting useful energy conversion, specifically the saturation of current flow due to high light intensity. Numerical results describing charge distributions in the semiconductor and its effects on the electrolyte are obtained. Experimental results include: an estimate rate at which a semiconductor photoelectrode is capable of converting electromagnetic energy into chemical energy; the effect of cell temperature on the efficiency; a method for determining the point of zero zeta potential for macroscopic semiconductor samples; a technique using platinized titanium dioxide powders and ultraviolet radiation to produce chlorine, bromine, and iodine from solutions containing their respective ions; the photoelectrochemical properties of a class of layered compounds called transition metal thiophosphates; and a technique used to produce high conversion efficiency from laser radiation to chemical energy.

Propagation of gas jet in liquid

NASA Astrophysics Data System (ADS)

Surin, V. A.; Yevchenko, V. N.; Rubin, V. M.

1984-07-01

A comprehensive experimental study was made of discharge of a gas jet from an orifice and its evolution in a liquid medium. Nitrogen, air, helium, chlorine, carbon dioxide, hydrogen chloride, ammonia, and water vapor superheated to 200 to 250 C were discharged vertically up, vertically down, or laterally into water at 18 to 100 C as well as into aqueous solutions of KOH and NaOH, under pressures varied from hydrostatic to 41x10(5) Pa. They were discharged through sonic cylindrical, conical nozzles and supersonic leLaval, axisymmetric, flat nozzles with orifices 2 to 50 mm wide. The discharge velocity varied from 2 to 1000 m/s and the jet underexpansion ratio varied from 1 to 20. The study has yielded data on the mechanisms of gas-liquid interaction, structure and dynamics of the interaction space, and dependence of those on the discharge conditions and on the degree of gas assimilation. Experiments were performed in both continuous and pulse modes, the latter for a study of transients and back shocks.

Role of drinking water biofilms on residual chlorine decay and trihalomethane formation: An experimental and modeling study.

PubMed

Xu, Jianeng; Huang, Conghui; Shi, Xiaoyang; Dong, Shengkun; Yuan, Baoling; Nguyen, Thanh H

2018-06-13

PVC pipe loops were constructed to simulate household premise plumbing. These pipe loops were exposed to water treated by physical processes at three water treatment plants in Xiamen, China from August 2016 to June 2017. After the biofilms were allowed to develop inside the pipes, these pipes were deconstructed and exposed to organic-free chlorine solution buffered at pH 6.8 ± 0.2 for 48 h. The decay of chlorine by these biofilms was higher than by the effluent waters that were used to grow the biofilms. A chlorine consumption mass balance model elucidated the role of both the diffusion of chlorine into the biofilm and the reaction of chlorine with the biofilm matrix. Comparable concentrations of trihalomethanes were quantified from the reaction between chlorine and source water organic matters, and chlorine and the biofilm, further emphasizing the role of biofilms in the safety of disinfected drinking water. These findings imply that when chlorine is used in the drinking water distribution system, the ubiquitous presence of biofilms may cause the depletion of chlorine and the formation of non-negligible levels of toxic disinfection byproducts. Copyright © 2018 Elsevier B.V. All rights reserved.

Determination of fluorine and chlorine in geological materials by induction furnace pyrohydrolysis and standard-addition ion-selective electrode measurement.

PubMed

Rice, T D

1988-03-01

Fluorine and chlorine in geological materials are volatilized by pyrohydrolysis at about 1150 degrees in a stream of oxygen (1000 ml/min) plus steam in an induction furnace. The catalyst is a 7:2:1 mixture of silica gel, tungstic oxide and potassium dihydrogen phosphate. The sample/catalyst mixture is pyrohydrolysed in a re-usable alumina crucible (already containing four drops of 1 + 3 phosphoric acid) inserted in a silica-enclosed graphite crucible. The absorption solution is buffered at pH 6.5 and spiked with 1.6 mug of fluoride and 16 mug of chloride per g of solution, to ensure rapid and linear electrode response during subsequent standard-addition measurement. The simple plastic absorption vessel has 99.5% efficiency. The 3s limits of detection are 5-10 mug/g and 40-100 mug/g for fluorine and chlorine respectively. The procedure is unsuitable for determining chlorine in coal.

Polychlorinated biphenyls (PCB), chlorinated pesticides, and polycyclic aromatic hydrocarbons (PAHs) in environmental standard reference materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poster, D.L.; Schantz, M.M.; Parris, R.M.

1995-12-31

Standard reference materials (SRMs) are certified reference materials issued by the National Institute of Standards and Technology (NIST). Natural matrix environmental sample SRMs have been developed the Analytical Chemistry Division to assist in validating measurements for organic contaminants in the environment. Many of these are well characterized for contaminants such as polychlorinated biphenyls (PCBs), chlorinated pesticides, and polycyclic aromatic hydrocarbons (PAHs). SRM 1649, Organics in Urban Dust, is currently available with certified concentrations for 5 PAHs but because of the widespread use of this material in air pollution monitoring programs and to expand the usefulness of this material, the authorsmore » are further characterizing the material for a larger number of PAHs as well as PCBs and chlorinated pesticides. They will also soon issue a diesel particulate extract (SRM 1975) that is well characterized for PAHS, including many nitrogen substituted compounds. In addition to natural matrix materials, solutions useful for calibrating chromatographic detector response factors and retention times, and spiking sample blanks for determination of analyte recoveries, are also available. Solution SRMs currently available contain PCS congeners, chlorinated pesticides, and PAHs. New solution SRMs in preparation will contain additional chlorinated pesticides, PCB congeners (e.g., non-ortho substituted chlorobiphenyls), and perdeuterated PAHs. Recent SRM work will be presented with particular attention on the methods used for determining organic contaminant concentrations in the urban dust material and in the diesel particulate extract.« less

Chlorine-36 and chlorine concentrations within several compartments of a deciduous forest ecosystem in Meuse/Haute-Marne (France)

NASA Astrophysics Data System (ADS)

Pupier, Julie; Benedetti, Lucilla; Bourles, Didier; Leclerc, Elisabeth; Thiry, Yves

2013-04-01

Chlorine-36 is a cosmogenic nuclide mainly produced in the atmosphere by interactions between energetic particles originating from the cosmic radiations and 40Ar. Because of its long half-life (T1-2 = 3.01 105 yr) and its high mobility, chlorine-36 is a critical radionuclide concerning radioactive waste repository sites. Moreover, it has been shown that inorganic chlorine could be enriched along the trophic chain due to its high solubility and bioavailability (Ashworth and Shaw, 2006). Additionally, many studies during the last decades have established that due to chlorination process, organic chlorine may account for a large proportion of the total soil chlorine pool (more than 80 % in surface soils of temperate ecosystems. Redon et al., 2012). The aim of this study is thus to measure chlorine-36 in all the compartments of the biogeochemical cycle, to better understand its recycling in the biosphere. The study site is the experimental beech forest site of the Andra long-term monitoring and testing system (OPE*). It is located at Montiers-sur-Saulx, North-East of France and is associated to the future radioactive waste repository site of Bure. Since March 2012, rainwater above (rainfall collected from a 45 m high tower built on purpose) and below (throughfall and stemflow) the canopy, has been collected monthly, as well as soil solutions (gravitational and bound waters) at four depths (0, 10, 30, 60 cm deep). Chlorine-36 and chlorine have been measured in the rainfall samples between March and July 2012 and in water solutions collected from all compartments of the biosphere using isotope dilution mass spectrometry at the french AMS national facility ASTER located at CEREGE. The results yielded from the rainfall samples allow to study the temporal fluctuations of chlorine-36 in the atmosphere, which represents the main inflow of chlorine-36 in its biogeochemical cycle. The first results indicate a flow increase during the late spring-early summer. Santos et al., 2004 have also observed a similar pattern in southern Spain. This increase might be due to a tropopause break, a natural process which occurs in spring and in fall. This break implies an increase of the air masses exchange between the tropopause and the stratosphere and therefore could cause high chlorine-36 inflow. All together, those results allow to draw a profile of the evolution of chlorine-36 concentrations in the various pools of the biogeochemical cycle (from the upper rainfall through stemflow and throughfall to the lower soil). Both 36Cl and Cl concentrations in stemflow samples are 25-50% higher than in the rainfall and throughfall samples. In water solutions collected from the soil, chlorine-36 concentrations vary between 3 to 8 10 3 at/ml, with an increase in the concentration at 30 cm depth. To understand the chlorine-36 recycling in soil, the next step will be to isolate and measure the 36Cl concentrations in the inorganic and organic fractions of chlorine in a soil profile. * : OPE : Observatoire Pérenne de l'Environnement (SOERE), French national long-term monitoring and experimental system for research in environment, www.andra-ope.fr Ashworth, D. J. and Shaw, G. (2006). A comparison of the soil migration and plant uptake of radioactive chlorine and iodine from contaminated groundwater. Journal of environmental radioactivity, 89(1) :61-80. Redon, P.-O., Jolivet, C., Saby, N. P. a., Abdelouas, A., and Thiry, Y. (2012). Occurrence of natural organic chlorine in soils for different land uses. Biogeochemistry (In press), doi : 10.1007/s10533- 012-9771-7. Santos, F., Lopez-Gutierrez, J., Garcia-Leon, M., Schnabel, C., Synal, H., and Suter, M. (2004). Analysis of 36Cl in atmospheric samples from Seville (Spain) by AMS. Nuclear Instruments and Methods in Physics Research Section B : Beam Interactions with Materials and Atoms, 223-224 :501-506.

[Chlorine coatings on skin surfaces. II. Parameters influencing the coating strength].

PubMed

Gottardi, W; Karl, A

1991-05-01

Although active chlorine compounds have been used for more than 140 years (Semmelweis, 1848) as a skin disinfectant the phenomenon of the "chlorine covers" not earlier than 1988 has been described for the first time (Hyg. + Med. 13 (1988) 157). It deals with a chemical alteration of the uppermost skin layer which comes apparent in an oxydizing action against aqueous iodide. Its origin is chlorine covalently bound in the form of N-Cl functions to the protein matrix of the horny skin. Since the chlorine covers exhibit a persistant disinfecting activity which might be important for practice, the factors influencing their strength have been established. The most important are: the kind of the chlorine system, the concentration (oxydation capacity), pH, temperature and the volume of the used solution, the time of action, the application technique and the state of the skin. Variations of the latter can be observed at different skin areas of one and the same person as well as at the same areas of different persons, and result in differences of the cover strength up to 100%. The stability on dry skin is very good, showing a decomposition rate of approximately 1.2% per hour. However on skin surfaces moistened by sweat (e.g. hands covered by surgeons gloves) the chlorine cover is disingrated much more faster (decomposition rate: 40-50% per hour). Washing with soap as well as the action of alcohols cause virtually no decrease in the cover strength, while wetting by solutions of reducing agents (e.g. thiosulfate, cysteine, iodide) provokes a fast decomposition suitable for removing the chlorine covers.(ABSTRACT TRUNCATED AT 250 WORDS)

Method of determining pH by the alkaline absorption of carbon dioxide

DOEpatents

Hobbs, David T.

1992-01-01

A method for measuring the concentration of hydroxides in alkaline solutions in a remote location using the tendency of hydroxides to absorb carbon dioxide. The method includes the passing of carbon dioxide over the surface of an alkaline solution in a remote tank before and after measurements of the carbon dioxide solution. A comparison of the measurements yields the absorption fraction from which the hydroxide concentration can be calculated using a correlation of hydroxide or pH to absorption fraction.

A marine sink for chlorine in natural organic matter [Natural chlorination of marine organic matter

DOE PAGES

Leri, Alessandra C.; Northrup, Paul A.; Mayer, Lawrence M.; ...

2015-07-06

Chloride, Cl –, is the most abundant solute in seawater, amounting to 55% of ions by weight. Cl – is more difficult to oxidize than bromide, and marine halogenating enzymes tend to be bromoperoxidases that are incapable of forming organochlorines. Consequently, most halogenated natural products identified in the marine environment are organobromines. Known exceptions include small quantities of volatile chlorocarbons emitted by marine algae and dissolved chlorinated benzoic acids.

Method for combined removal of mercury and nitrogen oxides from off-gas streams

DOEpatents

Mendelsohn, Marshall H [Downers Grove, IL; Livengood, C David [Lockport, IL

2006-10-10

A method for removing elemental Hg and nitric oxide simultaneously from a gas stream is provided whereby the gas stream is reacted with gaseous chlorinated compound to convert the elemental mercury to soluble mercury compounds and the nitric oxide to nitrogen dioxide. The method works to remove either mercury or nitrogen oxide in the absence or presence of each other.

Establishment of a Vaporous Hydrogen Peroxide Bio-Decontamination Capability

DTIC Science & Technology

2007-02-01

of Colorado at Denver and Health Sciences Center. There he utilised mass spectrometry to investigate the biochemical pathways involved in lipid... techniques (NMR, GC). Since then she has worked in a variety of areas including: (a) computer simulation of vapour dispersion for early warning to...to inactivate biological agents such as B. anthracis and these include beta-propiolactone, chlorine dioxide, ethylene oxide, propylene oxide, ozone

40 CFR Appendix A to Subpart Q of... - NPDWR Violations and Other Situations Requiring Public Notice 1

Code of Federal Regulations, 2014 CFR

2014-07-01

....544, 141.560-141.564. 8. Filter Backwash Recycling Rule violations 2 141.76(c) 3 141.76(b), (d) 9... 16, 1999. The Surface Water Treatment Rule remains in effect for systems serving at least 10,000...-141.630 take effect under the schedule in § 141.620(c). 15. Failure to monitor for chlorine dioxide at...

Efficient dechlorination of chlorinated solvent pollutants under UV irradiation by using the synthesized TiO2 nano-sheets in aqueous phase.

PubMed

Ndong, Landry Biyoghe Bi; Ibondou, Murielle Primaelle; Miao, Zhouwei; Gu, Xiaogang; Lu, Shuguang; Qiu, Zhaofu; Sui, Qian; Mbadinga, Serge Maurice

2014-05-01

Titanium dioxide (TiO2), which is the widely used photo-catalyst, has been synthesized by simple hydrothermal solution containing tetrabutyl titanate and hydrofluoric acid. The synthesized product has been applied to photo-degradation in aqueous phase of chlorinated solvents, namely tetrachloroethene (PCE), trichloroethene (TCE) and 1,1,1-trichloroethane (TCA). The photo-degradation results revealed that the degradation of these harmful chemicals was better in UV/synthesized TiO2 system compared to UV/commercial P25 system and UV only system. The photo-catalytic efficiency of the synthesized TiO2 was 1.4, 1.8 and 3.0 folds higher compared to the commercial P25 for TCA, TCE and PCE degradation, respectively. Moreover, using nitrobenzene (NB) as a probe of hydroxyl radical (·OH), the degradation rate was better over UV/synthesized TiO2, suggesting the high concentration of ·OH generated in UV/synthesized TiO2 system. In addition, ·OH concentration was confirmed by the strong peak displayed in EPR analysis over UV/synthesized TiO2 system. The characterization result using XRD and TEM showed that the synthesized TiO2 was in anatase form and consisted of well-defined sheet-shaped structures having a rectangular outline with a thickness of 4 nm, side length of 50 nm and width of 33 nm and a surface 90.3 m(2)/g. XPS analysis revealed that ≡Ti-F bond was formed on the surface of the synthesized TiO2. The above results on both photocatalytic activity and the surface analysis demonstrated the good applicability of the synthesized TiO2 nano-sheets for the remediation of chlorinated solvent contaminated groundwater. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Catalytic processes in the atmospheres of earth and Venus

NASA Technical Reports Server (NTRS)

Demore, W. B.; Yung, Y. L.

1982-01-01

Photochemical processes in planetary atmospheres are strongly influenced by catalytic effects of minor constituents. Catalytic cycles in the atmospheres of Earth and Venus are closely related. For example, chlorine oxides (ClOx) act as catalysts in the two atmospheres. On earth, they serve to convert odd oxygen (atomic oxygen and ozone) to molecular oxygen. On Venus they have a similar effect, but in addition they accelerate the reactions of atomic and molecular oxygen with carbon monoxide. The latter process occurs by a unique combination of ClOx catalysis and sulful dioxide photosensitization. The mechanism provides an explanation for the very low extent of carbon dioxide decomposition by sunlight in the Venus atmosphere.

Atomically precise edge chlorination of nanographenes and its application in graphene nanoribbons

PubMed Central

Tan, Yuan-Zhi; Yang, Bo; Parvez, Khaled; Narita, Akimitsu; Osella, Silvio; Beljonne, David; Feng, Xinliang; Müllen, Klaus

2013-01-01

Chemical functionalization is one of the most powerful and widely used strategies to control the properties of nanomaterials, particularly in the field of graphene. However, the ill-defined structure of the present functionalized graphene inhibits atomically precise structural characterization and structure-correlated property modulation. Here we present a general edge chlorination protocol for atomically precise functionalization of nanographenes at different scales from 1.2 to 3.4 nm and its application in graphene nanoribbons. The well-defined edge chlorination is unambiguously confirmed by X-ray single-crystal analysis, which also discloses the characteristic non-planar molecular shape and detailed bond lengths of chlorinated nanographenes. Chlorinated nanographenes and graphene nanoribbons manifest enhanced solution processability associated with decreases in the optical band gap and frontier molecular orbital energy levels, exemplifying the structure-correlated property modulation by precise edge chlorination. PMID:24212200

Selective recovery of uranium from Ca-Mg uranates by chlorination

NASA Astrophysics Data System (ADS)

Pomiro, Federico J.; Gaviría, Juan P.; Quinteros, Raúl D.; Bohé, Ana E.

2017-07-01

A chlorination process is proposed for the uranium extraction and separation using Calciumsbnd Magnesium uranates such as starting reactants which were obtained by precipitation from uranyl nitrate solutions with calcium hydroxide. The study is based on thermodynamic and reaction analysis using chlorine gas as chlorination agent. The results showed that the chlorination reaction of Ca uranate is more feasible to occur than the Mg uranate. The products obtained after chlorination reactions were washed with deionized water to remove the chlorides produced and analyzed. The XRD patterns of the washed products indicated that the chlorination between 400 and 500 °C result in a single phase of calcium uranate (CaUO4) as reaction product. The formation of U3O8 and MgU3O10 was observed at temperatures between 600 °C and 700 °C for 8 hs. The optimal conditions to recover uranium were 3 l h-1 of chlorine and 10 hs of reaction at 700 °C being U3O8 the single uranium product obtained.

Electrochemistry of Interhalogen Cathodes

DTIC Science & Technology

sources. Chlorine trifluoride , with a theoretical 2120 whr/lb in combination with lithium, is also known to support substantial current densities when... chlorine trifluoride as a power source cathode material. A half-cell study was made on dilute ClF3 solutions at 5C in 1 M NaF-HF by the cyclic

IN-FLIGHT CAPTURE OF ELEMENTAL MERCURY BY A CHLORINE-IMPREGNATED ACTIVATED CARBON

EPA Science Inventory

The paper discusses the in-flight capture of elemental mercury (Hgo) by a chlorine (C1)-impregnated activated carbon. Efforts to develop sorbents for the control of Hg emissions have demonstrated that C1-impregnation of virgin activated carbons using dilute solutions of hydrogen ...

Degradation kinetics of organic chloramines and formation of disinfection by-products during chlorination of creatinine.

PubMed

Zhang, Tianyang; Xu, Bin; Wang, Anqi; Cui, Changzheng

2018-03-01

Organic chloramines can interfere with the measurement of effective combined chlorine in chlorinated water and are potential intermediate products of highly toxic disinfection by-products (DBPs). In order to know more about the degradation and transformation of organic chloramines, a typical organic chloramine precursor creatinine was selected for investigation and a corresponding individual organic chloramine chlorocreatinine was prepared in this study. The preparation condition of chlorocreatinine by chlorination was established as chlorine/creatinine = 1 M/M, reaction time = 2 h and pH = 7.0. Then the degradation kinetics of chlorocreatinine during further chlorination was studied, and a second-order rate constant of 1.16 (±0.14) M -1 s -1 was obtained at pH 7.0. Solution pH significantly influenced the degradation rate, and the elementary rate constants of chlorocreatinine with HOCl+H + , HOCl, OCl - and chlorocreatinine - with OCl - were calculated as 2.43 (±1.55) × 10 4  M -2  s -1 , 1.05 (±0.09) M -1 s -1 , 2.86 (±0.30) M -1 s -1 and 3.09 (±0.24) M -1 s -1 , respectively. Besides, it was found that chlorocreatinine could be further converted into several C-DBPs (chloroform and trichloroacetone) and N-DBPs (dichloroacetonitrile (DCAN) and trichloronitromethane (TCNM)) during chlorination. The total yield of DBPs increased obviously with increasing pH, especially for TCNM. In addition, the presence of humic acid in creatinine solution could increase the formation of DCAN obviously during chlorination. Based on the UPLC-Q-TOF-MS analysis, the conversion pathways of chlorocreatinine were proposed. Several kinds of intermediate products were also identified as organic chloramines and some of them could even exist stably during the further chlorination. Copyright © 2017 Elsevier Ltd. All rights reserved.

Assessment of residual active chlorine in sodium hypochlorite solutions after dissolution of porcine incisor pulpal tissue.

PubMed

Clarkson, R M; Smith, T K; Kidd, B A; Evans, G E; Moule, A J

2013-12-01

In previous studies, surfactant-containing Hypochlor brands of sodium hypochlorite showed better tissue solubilizing abilities than Milton; differences not explained by original active chlorine content or presence of surfactant. It was postulated that exhaustion of active chlorine content could explain differences. This study aimed to assess whether Milton's poorer performance was due to exhaustion of active chlorine. Parallel experiments assessed the influence of titration methods, and the presence of chlorates, on active chlorine measurements. Time required to dissolve one or groups of 10 samples of porcine incisor pulp samples in Milton was determined. Residual active chlorine was assessed by thermometric titration. Iodometric and thermometric titration was carried out on samples of Milton. Chlorate content was also measured. Dissolution of single and 10 pulp samples caused a mean loss of 1% and 3% respectively of active chlorine, not being proportional to tissue dissolved. Thermometric ammonium ion titration resulted in 10% lower values than iodometric titration. Chlorate accounted for much of this difference. Depletion of active chlorine is not the reason for differences in tissue dissolving capabilities of Milton. Thermometric ammonium ion titration gives more accurate measurement of active chlorine content than iodometric titration. © 2013 Australian Dental Association.

Elevated gas flux and trace metal degassing from the 2014-2015 fissure eruption at the Bárðarbunga volcanic system, Iceland

NASA Astrophysics Data System (ADS)

Gauthier, Pierre-Jean; Sigmarsson, Olgeir; Gouhier, Mathieu; Haddadi, Baptiste; Moune, Séverine

2016-03-01

The 2014 Bárðarbunga rifting event in Iceland resulted in a 6-month long eruption at Holuhraun. This eruption was characterized by high lava discharge rate and significant gas emission. The SO2 flux for the first 3 months was measured with satellite sensors and the petrologic method. High-resolution time series of the satellite data give 1200 kg/s that concurs with 1050 kg/s obtained from melt inclusion minus degassed lava sulfur contents scaled to the mass of magma produced. A high-purity gas sample, with elevated S/Cl due to limited chlorine degassing, reveals a similar degassing pattern of trace metals as observed at Kīlauea (Hawai'i) and Erta Ale (Ethiopia). This suggests a common degassing mechanism at mantle plume-related volcanoes. The trace metal fluxes, calculated from trace element to sulfur ratios in the gas sample and scaled to the sulfur dioxide flux, are 1-2 orders of magnitude stronger at Holuhraun than Kīlauea and Erta Ale. In contrast, volcanoes at convergent margins (Etna and Stromboli, Italy) have 1-2 orders of magnitude higher trace element fluxes, most likely caused by abundant chlorine degassing. This emphasizes the importance of metal degassing as chlorine species. Short-lived disequilibria between radon daughters, 210Pb-210Bi-210Po measured in the gas, suggest degassing of a continuously replenished magma batch beneath the eruption site. Earlier and deep degassing phase of carbon dioxide and polonium is inferred from low (210Po/210Pb) in the gas, consistent with magma transfer rate of 0.75 m/s.

Development and field testing of a mobile chlorine dioxide generation system for the decontamination of buildings contaminated with Bacillus anthracis.

PubMed

Wood, Joseph P; Blair Martin, G

2009-05-30

The numerous buildings that became contaminated with Bacillus anthracis (the bacterium causing the disease anthrax) in 2001, and more recent B. anthracis - related events, point to the need to have effective decontamination technologies for buildings contaminated with biological threat agents. The U.S. Government developed a portable chlorine dioxide (ClO(2)) generation system to decontaminate buildings contaminated with B. anthracis spores, and this so-called mobile decontamination trailer (MDT) prototype was tested through a series of three field trials. The first test of the MDT was conducted at Fort McClellan in Anniston, AL. during October 2004. Four test attempts occurred over two weekends; however, a number of system problems resulted in termination of the activity prior to any ClO(2) introduction into the test building. After making several design enhancements and equipment changes, the MDT was subjected to a second test. During this test, extensive leak checks were made using argon and nitrogen in lieu of chlorine gas; each subsystem was checked for functionality, and the MDT was operated for 24h. This second test demonstrated the MDT flow and control systems functioned satisfactorily, and thus it was decided to proceed to a third, more challenging field trial. In the last field test, ClO(2) was generated and routed directly to the scrubber in a 12-h continuous run. Measurement of ClO(2) levels at the generator outlet showed that the desired production rate was not achieved. Additionally, only one of the two scrubbers performed adequately with regard to maintaining ClO(2) emissions below the limit. Numerous lessons were learned in the field trials of this ClO(2) decontamination technology.

FLAME DENITRATION AND REDUCTION OF URANIUM NITRATE TO URANIUM DIOXIDE

DOEpatents

Hedley, W.H.; Roehrs, R.J.; Henderson, C.M.

1962-06-26

A process is given for converting uranyl nitrate solution to uranium dioxide. The process comprises spraying fine droplets of aqueous uranyl nitrate solution into a hightemperature hydrocarbon flame, said flame being deficient in oxygen approximately 30%, retaining the feed in the flame for a sufficient length of time to reduce the nitrate to the dioxide, and recovering uranium dioxide. (AEC)

Photocatalytic destruction of chlorinated solvents in water with solar energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pacheco, J.E.; Prairie, M.R.; Yellowhorse, L.

1993-08-01

Sandia National Laboratories and the National Renewable Energy Laboratory are developing a photocatalytic process to destroy organic contaminants in water. Tests with common water pollutants have been conducted at Sandia's Solar Thermal Facility using a near commercial scale, single-axis tracking parabolic trough system with a glass pipe reactor mounted at its focus. Experiments at this scale provide verification of laboratory studies and allow examination of design and operation issues at a real-lifescale. The catalyst, titanium dioxide (TiO[sub 2]), is a harmless material found in paint, cosmetics, and toothpaste. Experiments were conducted to determine the effects of key process parameters onmore » destruction rates of chlorinated organic compounds that are common water pollutants. This paper summarizes the engineering-scale results of these experiments and analyses.« less

NIOSH Manual of Analytical Methods (third edition). Fourth supplement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1990-08-15

The NIOSH Manual of Analytical Methods, 3rd edition, was updated for the following chemicals: allyl-glycidyl-ether, 2-aminopyridine, aspartame, bromine, chlorine, n-butylamine, n-butyl-glycidyl-ether, carbon-dioxide, carbon-monoxide, chlorinated-camphene, chloroacetaldehyde, p-chlorophenol, crotonaldehyde, 1,1-dimethylhydrazine, dinitro-o-cresol, ethyl-acetate, ethyl-formate, ethylenimine, sodium-fluoride, hydrogen-fluoride, cryolite, sodium-hexafluoroaluminate, formic-acid, hexachlorobutadiene, hydrogen-cyanide, hydrogen-sulfide, isopropyl-acetate, isopropyl-ether, isopropyl-glycidyl-ether, lead, lead-oxide, maleic-anhydride, methyl-acetate, methyl-acrylate, methyl-tert-butyl ether, methyl-cellosolve-acetate, methylcyclohexanol, 4,4'-methylenedianiline, monomethylaniline, monomethylhydrazine, nitric-oxide, p-nitroaniline, phenyl-ether, phenyl-ether-biphenyl mixture, phenyl-glycidyl-ether, phenylhydrazine, phosphine, ronnel, sulfuryl-fluoride, talc, tributyl-phosphate, 1,1,2-trichloro-1,2,2-trifluoroethane, trimellitic-anhydride, triorthocresyl-phosphate, triphenyl-phosphate, and vinyl-acetate.

Transformation of pharmaceuticals during oxidation/disinfection processes in drinking water treatment.

PubMed

Postigo, Cristina; Richardson, Susan D

2014-08-30

Pharmaceuticals are emerging contaminants of concern and are widespread in the environment. While the levels of these substances in finished drinking waters are generally considered too low for human health concern, there are now concerns about their disinfection by-products (DBPs) that can form during drinking water treatment, which in some cases have been proven to be more toxic than the parent compounds. The present manuscript reviews the transformation products of pharmaceuticals generated in water during different disinfection processes, i.e. chlorination, ozonation, chloramination, chlorine dioxide, UV, and UV/hydrogen peroxide, and the main reaction pathways taking place. Most of the findings considered for this review come from controlled laboratory studies involving reactions of pharmaceuticals with these oxidants used in drinking water treatment. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis, structural investigations on organotin(IV) chlorin-e6 complexes, their effect on sea urchin embryonic development and induced apoptosis.

PubMed

Pellerito, Claudia; D'Agati, Paolo; Fiore, Tiziana; Mansueto, Caterina; Mansueto, Valentina; Stocco, Giancarlo; Nagy, László; Pellerito, Lorenzo

2005-06-01

Four new organotin(IV) chlorin derivatives, [chlorin=chlorin-e(6)=21H,23H-porphine-2-propanoic acid, 18-carboxy-20-(carboxymethyl)-8-ethenyl-13-ethyl-2,3-di-hydro-3,7,12,17-tetramethyl-(2S-trans)-], with formula (R(2)Sn)(3)(chlorin)(2).2H(2)O (R=Me, n-Bu) and (R(3)Sn)(3)chlorin.2H(2)O (R=Me, Ph) have been synthesized. The solid state and solution phase structures have been investigated by FT-IR, (119)Sn Mössbauer, (1)H and (13)C NMR spectroscopy. In the solid state, (R(2)Sn)(3)(chlorin)(2).2H(2)O complexes contain six coordinated Sn(IV), in a skew trapezoidal environment by forming trans-R(2)SnO(4) polymeric units. As far as (R(3)Sn)(3)chlorin.2H(2)O complexes are concerned, Sn(IV) is five coordinated in a polymeric (oligomeric) trigonal bipyramidal environment and eq-R(3)SnO(2) units, in the solid state. In saturated solutions, a polymeric structure comparable to the solid phase, with carboxylate groups of the ligand behaving in monoanionic bidentate fashion bridging Sn(IV) atoms, was detected for the (Me(3)Sn)(3)chlorin.2H(2)O complex, while in more diluted ones a tetrahedral configuration for the trimethyltin(IV) moieties was observed. Cytotoxic activity of the novel organotin(IV) chlorin was investigated in order to assay the effect on sea urchin embryonic development. The results obtained demonstrated that (n-Bu(2)Sn)(3)(chlorin)(2).2H(2)O and (Ph(3)Sn)(3)chlorin.2H(2)O exerted the antimitotic effect on the early stages of sea urchin development. In addition, the cytotoxic effect exerted by (n-Bu(2)Sn)(3)(chlorin)(2).2H(2)O appeared with necrosis of the blastomeres, which were clearly destroyed. After treatment with (Ph(3)Sn)(3)chlorin.2H(2)O, a programmed cell death was triggered, as shown by light microscope observations through morphological assays. The apoptotic events in 2-cell stage embryos revealed: (i) DNA fragmentation, with the TUNEL reaction (terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling); (ii) phosphatidylserine translocation in the membrane, with Annexin-V assay and (iii) cytoplasm blebbing, with the TUNEL reaction. The results demonstrated that the novel compound (Ph(3)Sn)(3)chlorin.2H(2)O was the most toxic derivative, by exerting antimitotic effect very early and by triggering apoptosis in the 2-cell stage of sea urchin embryonic development.

Method of determining pH by the alkaline absorption of carbon dioxide

DOEpatents

Hobbs, D.T.

1992-10-06

A method is described for measuring the concentration of hydroxides in alkaline solutions in a remote location using the tendency of hydroxides to absorb carbon dioxide. The method includes the passing of carbon dioxide over the surface of an alkaline solution in a remote tank before and after measurements of the carbon dioxide solution. A comparison of the measurements yields the absorption fraction from which the hydroxide concentration can be calculated using a correlation of hydroxide or pH to absorption fraction. 2 figs.

Seeking Clearer Recommendations for Hand Hygiene in Communities Facing Ebola: A Randomized Trial Investigating the Impact of Six Handwashing Methods on Skin Irritation and Dermatitis.

PubMed

Wolfe, Marlene K; Wells, Emma; Mitro, Brittany; Desmarais, Anne Marie; Scheinman, Pamela; Lantagne, Daniele

2016-01-01

To prevent disease transmission, 0.05% chlorine solution is commonly recommended for handwashing in Ebola Treatment Units. In the 2014 West Africa outbreak this recommendation was widely extended to community settings, although many organizations recommend soap and hand sanitizer over chlorine. To evaluate skin irritation caused by frequent handwashing that may increase transmission risk in Ebola-affected communities, we conducted a randomized trial with 91 subjects who washed their hands 10 times a day for 28 days. Subjects used soap and water, sanitizer, or one of four chlorine solutions used by Ebola responders (calcium hypochlorite (HTH), sodium dichloroisocyanurate (NaDCC), and generated or pH-stabilized sodium hypochlorite (NaOCl)). Outcomes were self-reported hand feel, irritation as measured by the Hand Eczema Score Index (HECSI) (range 0-360), signs of transmission risk (e.g., cracking), and dermatitis diagnosis. All groups experienced statistically significant increases in HECSI score. Subjects using sanitizer had the smallest increases, followed by higher pH chlorine solutions (HTH and stabilized NaOCl), and soap and water. The greatest increases were among neutral pH chlorine solutions (NaDCC and generated NaOCl). Signs of irritation related to higher transmission risk were observed most frequently in subjects using soap and least frequently by those using sanitizer or HTH. Despite these irritation increases, all methods represented minor changes in HECSI score. Average HECSI score was only 9.10 at endline (range 1-33) and 4% (4/91) of subjects were diagnosed with dermatitis, one each in four groups. Each handwashing method has benefits and drawbacks: soap is widely available and inexpensive, but requires water and does not inactivate the virus; sanitizer is easy-to use and effective but expensive and unacceptable to many communities, and chlorine is easy-to-use but difficult to produce properly and distribute. Overall, we recommend Ebola responders and communities use whichever handwashing method(s) are most acceptable, available, and sustainable for community handwashing. International Standard Randomized Controlled Trial Registry ISRCTN89815514.

SCAVENGER AND PROCESS OF SCAVENGING

DOEpatents

Olson, C.M.

1960-04-26

Carrier precipitation processes are given for the separation and recovery of plutonium from aqueous acidic solutions containing plutonium and fission products. Bismuth phosphate is precipitated in the acidic solution while plutonlum is maintained in the hexavalent oxidation state. Preformed, uncalcined, granular titanium dioxide is then added to the solution and the fission product-carrying bismuth phosphate and titanium dioxide are separated from the resulting mixture. Fluosilicic acid, which dissolves any remaining titanium dioxide particles, is then added to the purified plutonium-containing solution.

Removal of the cyanotoxin anatoxin-a by drinking water treatment processes: a review.

PubMed

Vlad, Silvia; Anderson, William B; Peldszus, Sigrid; Huck, Peter M

2014-12-01

Anatoxin-a (ANTX-a) is a potent alkaloid neurotoxin, produced by several species of cyanobacteria and detected throughout the world. The presence of cyanotoxins, including ANTX-a, in drinking water sources is a potential risk to public health. This article presents a thorough examination of the cumulative body of research on the use of drinking water treatment technologies for extracellular ANTX-a removal, focusing on providing an analysis of the specific operating parameters required for effective treatment and on compiling a series of best-practice recommendations for owners and operators of systems impacted by this cyanotoxin. Of the oxidants used in drinking water treatment, chlorine-based processes (chlorine, chloramines and chlorine dioxide) have been shown to be ineffective for ANTX-a treatment, while ozone, advanced oxidation processes and permanganate can be successful. High-pressure membrane filtration (nanofiltration and reverse osmosis) is likely effective, while adsorption and biofiltration may be effective but further investigation into the implementation of these processes is necessary. Given the lack of full-scale verification, a multiple-barrier approach is recommended, employing a combination of chemical and non-chemical processes.

Protective Clothing Part 4. Industrial Environments (A Bibliography with Abstracts)

DTIC Science & Technology

1976-04-01

Synthetic rubber, Textiles, Sprays, Gas detectors, Damage control , Propellants IDENTIFIERS: Chlorine trifluoride AD-661 333...and Petroleum (107) Apr 75 Excludes flue gas and other post-combustion sulfur con- trol NTIS/PS-75/381/4GSB Coal Gasification and Liquefaction... desulfurization NTIS/PS-75/455/6GSB Sulfur Dioxide Control . Vol 1. 1964-1972 (159) May 75 NTIS/PS-75/456/4GSB Activated Carbon (221) May

An Approach to the Management of Hazardous Materials.

DTIC Science & Technology

1981-09-01

fluoride carbon disulfide carbon monoxide hydrochloric acid hydrogen sulfide acetone cyanohydrin phosgene Group XII: Poison B - Meeflaneous a) Gases...b) Liquids sulfur dioxide bromine chlorine boron trifluoride Group XIII: Poison C Group XIV: Poison D Liquid Gas tetraethyl lead fluorine Group XV...with a high and o Nitric acid leaks from a 5,000 gallon storage tank In a growing concentration of electronics industries. Over plant one night and

An Integrated Civilian Medical Response to Mass Casualty Incidents

DTIC Science & Technology

2005-05-01

Industrial Hygiene Association Journal. March-April (2003). [5] Ishizaki, K., Shinriki N., and Matsuyama H. Inactivation of bacillus spores by gaseous ozone... Bacillus subtilis spores under controlled humidity, gas concentration, and temperature at atmospheric pressure. Based on the findings of above study...34Decontamination of bacillus thuringiensis spores on selected surfaces by chlorine dioxide gas", Journal of Environmental Health 66: 16-20 6. Jeng, D. K., and

Reactive formulations for a neutralization of toxic industrial chemicals

DOEpatents

Tucker, Mark D [Albuqueruqe, NM; Betty, Rita G [Rio Rancho, NM

2006-10-24

Decontamination formulations for neutralization of toxic industrial chemicals, and methods of making and using same. The formulations are effective for neutralizing malathion, hydrogen cyanide, sodium cyanide, butyl isocyanate, carbon disulfide, phosgene gas, capsaicin in commercial pepper spray, chlorine gas, anhydrous ammonia gas; and may be effective at neutralizing hydrogen sulfide, sulfur dioxide, formaldehyde, ethylene oxide, methyl bromide, boron trichloride, fluorine, tetraethyl pyrophosphate, phosphorous trichloride, arsine, and tungsten hexafluoride.

Effects of Vaporized Decontamination Systems on Selected Building Interior Materials: Chlorine Dioxide

DTIC Science & Technology

2009-02-01

Chemical Biological Center (ECBC) to take advantage of ECBC’s extensive expertise and specialized research facilities for the decontamination of surfaces...Agency (EPA) established an Interagency Agreement with the U.S. Army Edgewood Chemical Biological Center (ECBC) to take advantage of ECBC’s extensive...Detector (Waters Corporation, Milford, MA). Conductivity suppression was carried out using an ERIS 1000HP Autosuppressor ( Alltech Corporation, Deerfield

Enantioseparation of novel chiral sulfoxides on chlorinated polysaccharide stationary phases in supercritical fluid chromatography.

PubMed

West, Caroline; Konjaria, Mari-Luiza; Shashviashvili, Natia; Lemasson, Elise; Bonnet, Pascal; Kakava, Rusudan; Volonterio, Alessandro; Chankvetadze, Bezhan

2017-05-26

Asymmetric sulfoxides is a particular case of chirality that may be found in natural as well as synthetic products. Twenty-four original molecules containing a sulfur atom as a centre of chirality were analyzed in supercritical fluid chromatography on seven polysaccharide-based chiral stationary phases (CSP) with carbon dioxide - methanol mobile phases. While all the tested CSP provided enantioseparation for a large part of the racemates, chlorinated cellulosic phases proved to be both highly retentive and highly enantioselective towards these species. Favourable structural features were determined by careful comparison of the enantioseparation of the probe molecules. Molecular modelling studies indicate that U-shaped (folded) conformations were most favorable to achieve high enantioresolution on these CSP, while linear (extended) conformations were not so clearly discriminated. For a subset of these species adopting different conformations, a broad range of mobile phase compositions, ranging from 20 to 100% methanol in carbon dioxide, were investigated. While retention decreased continuously in this range, enantioseparation varied in a non-monotonous fashion. Abrupt changes in the tendency curves of retention and selectivity were observed when methanol proportion reaches about 60%, suggesting that a change in the conformation of the analytes and/or chiral selector is occurring at this point. Copyright © 2017 Elsevier B.V. All rights reserved.

Powering microbes with electricity: direct electron transfer from electrodes to microbes.

PubMed

Lovley, Derek R

2011-02-01

The discovery of electrotrophs, microorganisms that can directly accept electrons from electrodes for the reduction of terminal electron acceptors, has spurred the investigation of a wide range of potential applications. To date, only a handful of pure cultures have been shown to be capable of electrotrophy, but this process has also been inferred in many studies with undefined consortia. Potential electron acceptors include: carbon dioxide, nitrate, metals, chlorinated compounds, organic acids, protons and oxygen. Direct electron transfer from electrodes to cells has many advantages over indirect electrical stimulation of microbial metabolism via electron shuttles or hydrogen production. Supplying electrons with electrodes for the bioremediation of chlorinated compounds, nitrate or toxic metals may be preferable to adding organic electron donors or hydrogen to the subsurface or bioreactors. The most transformative application of electrotrophy may be microbial electrosynthesis in which carbon dioxide and water are converted to multi-carbon organic compounds that are released extracellularly. Coupling photovoltaic technology with microbial electrosynthesis represents a novel photosynthesis strategy that avoids many of the drawbacks of biomass-based strategies for the production of transportation fuels and other organic chemicals. The mechanisms for direct electron transfer from electrodes to microorganisms warrant further investigation in order to optimize envisioned applications. © 2010 Society for Applied Microbiology and Blackwell Publishing Ltd.

Efficacy of electrolyzed oxidizing water in inactivating Salmonella on alfalfa seeds and sprouts.

PubMed

Kim, Chyer; Hung, Yen-Con; Brackett, Robert E; Lin, Chyi-Shen

2003-02-01

Studies have demonstrated that electrolyzed oxidizing (EO) water is effective in reducing foodborne pathogens on fresh produce. This study was undertaken to determine the efficacy of EO water and two different forms of chlorinated water (chlorine water from Cl2 and Ca(OCl)2 as sources of chlorine) in inactivating Salmonella on alfalfa seeds and sprouts. Tengram sets of alfalfa seeds inoculated with a five-strain cocktail of Salmonella (6.3 x 10(4) CFU/g) were subjected to 90 ml of deionized water (control), EO water (84 mg/liter of active chlorine), chlorine water (84 mg/liter of active chlorine), and Ca(OCl)2 solutions at 90 and 20,000 mg/liter of active chlorine for 10 min at 24 +/- 2 degrees C. The application of EO water, chlorinated water, and 90 mg/liter of Ca(OCl)2 to alfalfa seeds for 10 min reduced initial populations of Salmonella by at least 1.5 log10 CFU/g. For seed sprouting, alfalfa seeds were soaked in the different treatment solutions described above for 3 h. Ca(OCl)2 (20,000 mg/liter of active chlorine) was the most effective treatment in reducing the populations of Salmonella and non-Salmonella microflora (4.6 and 7.0 log10 CFU/g, respectively). However, the use of high concentrations of chlorine generates worker safety concerns. Also, the Ca(OCl)2 treatment significantly reduced seed germination rates (70% versus 90 to 96%). For alfalfa sprouts, higher bacterial populations were recovered from treated sprouts containing seed coats than from sprouts with seed coats removed. The effectiveness of EO water improved when soaking treatments were applied to sprouts in conjunction with sonication and seed coat removal. The combined treatment achieved 2.3- and 1.5-log10 CFU/g greater reductions than EO water alone in populations of Salmonella and non-Salmonella microflora, respectively. This combination treatment resulted in a 3.3-log10 CFU/g greater reduction in Salmonella populations than the control (deionized water) treatment.

Interactions of N,N'-dimethylaminoethanol with steel surfaces in alkaline and chlorine containing solutions

NASA Astrophysics Data System (ADS)

Welle, A.; Liao, J. D.; Kaiser, K.; Grunze, M.; Mäder, U.; Blank, N.

1997-10-01

Formulations based on dilute aqueous solutions of N,N'-dimethylethanolamine (DMEA) are used to protect reinforcement steel bars ('rebar') in concrete from corrosion. In a previous paper we discussed the usefulness of X-ray photoelectron spectroscopy (XPS) to detect DMEA adsorbed from solution and the application of secondary neutral mass spectrometry (SNMS) to study migration of DMEA through a cement matrix. In this report we present XPS data of DMEA adsorbed on steel surfaces from alkaline and chlorine containing solutions of variable concentration range and discuss models for the interaction of DMEA with the oxidized steel surface and the mechanism of corrosion inhibition of DMEA. DMEA is strongly bonded to the steel surface and displaces ionic species from the substrate/solution interface hence protecting the ironoxide surface from ionic attack.

The study on the extraction and recovery of Au from scrap of the used computer using chloride solvent

NASA Astrophysics Data System (ADS)

Oh, Su-ji; Choi, Eunju; Choi, Nagchoul; Park, Cheonyoung

2013-04-01

Recently, due to the realization of environmental problems of cyanide, it is a worldwide quest to find viable alternatives. One of the alternatives is a chloride solvent(chlorine-hypochlorite acid) with an appropriate oxidizing agent. The rate of dissolution of Au by chloride solvent is much faster than that by cyanide. Also, due to presence of chloride ions, there is no passivation of gold surfaces during chlorination. The objective of this work was to investigate the effect of Au extraction efficiency under various experimental conditions(pulp density, chlorine-hypochlorite ratio and concentration of NaCl) from scrap of the used computer by chloride solvent. In addition, the recovery experiment was conducted to examine of the precipitation efficiency of Au under various metabisulfite concentration from extracted solution. In an EDS analysis, valuable metals such as Cu, Sn, Sb, Al, Ni, Pb and Au were observed in scrap of the used computer. The result of extraction experiment showed that the highest extraction rate was obtained under 1% of pulp density with a chlorine-hypochlorite ratio of 2:1, and a concentration of NaCl at 2M. The highest Au recovery(precipitation) rate was observed the addition of sodium metabisulfite at 2M concentration. Under these conditions, chlorine-hypochlorite could effectively Au extraction from scrap of the used computer sections and the additive reagent using sodium metabisulfite could easily precipitate the Au from the chlorine-hypochlorite solution.

Photo-oxidation method using MoS2 nanocluster materials

DOEpatents

Wilcoxon, Jess P.

2001-01-01

A method of photo-oxidizing a hydrocarbon compound is provided by dispersing MoS.sub.2 nanoclusters in a solvent containing a hydrocarbon compound contaminant to form a stable solution mixture and irradiating the mixture to photo-oxide the hydrocarbon compound. Hydrocarbon compounds of interest include aromatic hydrocarbon and chlorinated hydrocarbons. MoS.sub.2 nanoclusters with an average diameter less than approximately 10 nanometers are shown to be effective in decomposing potentially toxic aromatic and chlorinated hydrocarbons, such as phenol, pentachlorophenol, chlorinated biphenols, and chloroform, into relatively non-toxic compounds. The irradiation can occur by exposing the MoS.sub.2 nanoclusters and hydrocarbon compound mixture with visible light. The MoS.sub.2 nanoclusters can be introduced to the toxic hydrocarbons as either a MoS.sub.2 solution or deposited on a support material.

Inactivation of Hepatitis A Virus (HAV) by Chlorine and Iodine in Water

DTIC Science & Technology

1986-11-01

treatment practices utilizing chemical disinfection, primarily chlorination, are generally believed to * be effective in producing microbiologically safe...OCl) in 1 liter of HDFW. Stock solution was then diluted in tesi water (halogen demand-free, 0.01M phosphate buffer, pH 4.5, 7.0 or 9.5 in initial

MANGANESE DIOXIDE METHOD FOR PREPARATION OF PROTACTINIUM

DOEpatents

Katzin, L.I.

1958-08-12

A method of obtaining U/sup 233/ is described. An aqueous solution of neutriln irradiated thoriunn is treated by forming tberein a precipitate of manganese dioxide which carries and thus separates the Pa/sup 233/ from the solution. The carrier precipitate so formed is then dissolved in an acidic solution containing a reducing agent sufficiently electronegative to reduce the tetravalent manganese to the divalent state. Further purification of the Pa/sup 233/ may be obtained by forming another manganese dioxide carrier precipitate and subsequently dissolving it. Ater a sufficient number of such cycles have brought the Pa/sup 233/ to the desired purity, the solution is aged, allowing the formation ot U/sup 233/ by radioaetive decay. A manganese dioxide precipitate is then formed in the U/sup 233/ containing solution. This precipitate carries down any remaining Pa/sup 233/ thus leaving the separated U/sup 233/solution, from whieh it may be easily recovered.

Heterogeneous chemical reaction of chlorine nitrate and water on sulfuric-acid surfaces at room temperature

NASA Technical Reports Server (NTRS)

Rossi, Michel J.; Malhotra, Ripudaman; Golden, David M.

1987-01-01

The use of H2SO4 as a catalyst for aerosol production of chlorine compounds in the chemistry of the antarctic stratosphere was investigated in laboratory trials. The experiments involved the gas surface collision rate of a molecule on a given surface during its residence time in a Knudsen cell in molecular flow conditions. Chlorine nitrate gas was made to flow through a chamber exposed to a container holding a 95.6 pct H2SO4 solution. Gas leaving the cell was scanned with a mass spectrometer. A sticking coefficient of 0.00032 was found for the chlorine nitrate, a value five times that previously reported.

Chlorine isotope fractionation between chloride (Cl-) and dichlorine (Cl2)

NASA Astrophysics Data System (ADS)

Giunta, Thomas; Labidi, Jabrane; Eggenkamp, Hans G. M.

2017-09-01

The use of chlorine stable isotopes (35Cl and 37Cl) can help to constrain natural processes that involve chlorine species with different oxidation states. Theoretical studies based on thermodynamic and quantum mechanical approaches predict large isotope fractionation during redox reactions but to date, these reactions have not been studied experimentally. Here, we explore the chlorine isotope fractionation during the oxidation of hydrated Cl- (redox state of -I) to Cl2 (redox state of 0) at 25 °C and at 0 °C. Our apparatus consists of a sealed glass reactor where liquid HCl is mixed with liquid H2O2, a strong oxidant. Following complex reaction pathways, this mixture ultimately leads to the oxidation of Cl- and to the formation of Cl2 gas. As long as it is degassing, the Cl2 gas is flushed out of solution using N2 as a vector-gas from the glass-reactor to a potassium hydroxide (KOH) solution (pH 14) where it disproportionates into soluble species: Cl- and ClO-. After each experiment, the chlorine isotopic composition was measured in the recovered KOH-trap solution, as well as in the residual HCl solution. Consistent with theoretical predictions, the produced Cl2 gas is always enriched in the heavier 37Cl as compared to the initial Cl-reservoir. The following isotope fractionation factors are obtained: At 0 °C the isotopic fractionation 1000ln α(Cl2-Cl-) is 4.51 (+1.65/-0.49)‰ At 25 °C the isotopic fractionation 1000ln α(Cl2-Cl-) is 3.94 (+0.69/-0.18)‰. From the obtained data it is suggested that the production of Cl2 gas in our experiments is best described by a closed-system distillation. Our results are in agreement with published theoretical ab-initio calculations.

The occurrence of chlorine in serpentine minerals

USGS Publications Warehouse

Miura, Y.; Rucklidge, J.; Nord, G.L.

1981-01-01

Partially serpentinized dunites containing small amounts of Chlorine (< 0.5%) from Dumont, Quebec, and Horoman, Hokkaido, Japan, and one containing less than 0.05% Chlorine from Higashi-Akaishi-Yama, Ehime, Japan have been examined using the electron probe microanalyzer and scanning transmission electron microscope with X-ray analytical capabilities. Chlorine was found together with Si, Mg, Ca and Fe in the serpentine minerals of the Dumont and Hokkaido dunites but not in the Ehime dunite. Chlorine is found associated only with the most finely crystalline facies of the serpentine (grain size less than 10 nm). The Ehime dunite contained no such fine grained serpentine, and was thus effectively chlorine-free, as are the coarser grained serpentines of the other samples. The finegrained chlorine-bearing serpentine also has a much higher concentration of Fe, and can contain smaller amounts of Ca, Ni and Mn than the coarse-grained variety as well as minute awaruite (FeNi3) grains. This fine-grained serpentine probably represents an early stage in the transformation of olivine to serpentine, with chlorine from hydrothermal solutions assisting the necessary chemical changes. The Cl increases the reaction rate by lowering the activation barrier to reaction by the introduction of reaction steps. ?? 1981 Springer-Verlag.

Addition of chlorine during water purification reduces iodine content of drinking water and contributes to iodine deficiency.

PubMed

Samson, L; Czegeny, I; Mezosi, E; Erdei, A; Bodor, M; Cseke, B; Burman, K D; Nagy, E V

2012-01-01

Drinking water is the major natural source of iodine in many European countries. In the present study, we examined possible sites of iodine loss during the usual water purification process.Water samples from 6 sites during the technological process were taken and analyzed for iodine content. Under laboratory circumstances, prepared iodine in water solution has been used as a model to test the effect of the presence of chlorine. Samples from the purification sites revealed that in the presence of chlorine there is a progressive loss of iodine from the water. In the chlorine concentrations employed in the purification process, 24-h chlorine exposure eliminated more than 50% of iodine when the initial iodine concentration was 250 μg/l or less. Iodine was completely eliminated if the starting concentration was 16 μg/l.We conclude that chlorine used during water purification may be a major contributor to iodine deficiency in European communities.

46 CFR Table 2 to Part 153 - Cargoes Not Regulated Under Subchapters D or O of This Chapter When Carried in Bulk on Non...

Code of Federal Regulations, 2012 CFR

2012-10-01

... Category 2-Amino-2-hydroxymethyl-1,3-propanediol solution III Ammonium hydrogen phosphate solution D...) D Ammonium phosphate, Urea solution, see also Urea, Ammonium phosphate solution D Ammonium..., Magnesium nitrate, Potassium chloride solution III Caramel solutions III Chlorinated paraffins (C14-C17...

[Formation mechanism and chemical safety of nonintentional chemical substances present in chlorinated drinking water and wastewater].

PubMed

Onodera, Sukeo

2010-09-01

This paper reviews the formation mechanism and chemical safety of nonintentional chemical substances (NICS) present in chlorine-treated water containing organic contaminants. Undesirable compounds, i.e., NICS, may be formed under certain conditions when chlorine reacts with organic matter. The rate and extent of chlorine consumption with organics are strongly dependent on their chemical structures, particularly whether double bonds or sulfur and nitrogen atoms occur in the molecules. Organothiophosphorus pesticides (P=S type) are easily oxidized to their phosphorus compounds (P=O type) in chlorinated water containing HOCl as little as 0.5 mg/l, resulting in an increase in cholinesterase-inhibitory activity. Chlorination of phenols in water also produces a series of highly chlorinated compounds, including chlorophenols, chloroquinones, chlorinated carboxylic acids, and polychlorinated phenoxyphenols (PCPPs). In some of these chloroquinones, 2,6-dichloroalkylsemiquinones exhibit a strong mutagenic response as do positive controls used in the Ames test. 2-phenoxyphenols in these PCPPs are particularly interesting, as they are present in the chlorine-treated phenol solution and they are also precursors (predioxins) of the highly toxic chlorinated dioxins. Polynuclear aromatic hydrocarbons (PAHs) were found to undergo chemical changes due to hypochlorite reactions to give chloro-substituted PAHs, oxygenated (quinones) and hydroxylated (phenols) compounds, but they exhibit a lower mutagenic response. In addition, field work was performed in river water and drinking water to obtain information on chemical distribution and their safety, and the results are compared with those obtained in the model chlorination experiments.

Recent advances in drinking water disinfection: successes and challenges.

PubMed

Ngwenya, Nonhlanhla; Ncube, Esper J; Parsons, James

2013-01-01

Drinking water is the most important single source of human exposure to gastroenteric diseases, mainly as a result of the ingestion of microbial contaminated water. Waterborne microbial agents that pose a health risk to humans include enteropathogenic bacteria, viruses, and protozoa. Therefore, properly assessing whether these hazardous agents enter drinking water supplies, and if they do, whether they are disinfected adequately, are undoubtedly aspects critical to protecting public health. As new pathogens emerge, monitoring for relevant indicator microorganisms (e.g., process microbial indicators, fecal indicators, and index and model organisms) is crucial to ensuring drinking water safety. Another crucially important step to maintaining public health is implementing Water Safety Plans (WSPs), as is recommended by the current WHO Guidelines for Drinking Water Quality. Good WSPs include creating health-based targets that aim to reduce microbial risks and adverse health effects to which a population is exposed through drinking water. The use of disinfectants to inactivate microbial pathogens in drinking water has played a central role in reducing the incidence of waterborne diseases and is considered to be among the most successful interventions for preserving and promoting public health. Chlorine-based disinfectants are the most commonly used disinfectants and are cheap and easy to use. Free chlorine is an effective disinfectant for bacteria and viruses; however, it is not always effective against C. parvum and G. lamblia. Another limitation of using chlorination is that it produces disinfection by-products (DBPs), which pose potential health risks of their own. Currently, most drinking water regulations aggressively address DBP problems in public water distribution systems. The DBPs of most concern include the trihalomethanes (THMs), the haloacetic acids (HAAs), bromate, and chlorite. However, in the latest edition of the WHO Guidelines for Drinking Water Quality, it is recommended that water disinfection should never be compromised by attempting to control DBPs. The reason for this is that the risks of human illness and death from pathogens in drinking water are much greater than the risks from exposure to disinfectants and disinfection by-products. Nevertheless, if DBP levels exceed regulatory limits, strategies should focus on eliminating organic impurities that foster their formation, without compromising disinfection. As alternatives to chlorine, disinfectants such as chloramines, ozone, chlorine dioxide, and UV disinfection are gaining popularity. Chlorine and each of these disinfectants have individual advantage and disadvantage in terms of cost, efficacy-stability, ease of application, and nature of disinfectant by-products (DBPs). Based on efficiency, ozone is the most efficient disinfectant for inactivating bacteria, viruses, and protozoa. In contrast, chloramines are the least efficient and are not recommended for use as primary disinfectants. Chloramines are favored for secondary water disinfection, because they react more slowly than chlorine and are more persistent in distribution systems. In addition, chloramines produce lower DBP levels than does chlorine, although microbial activity in the distribution system may produce nitrate from monochloramine, when it is used as a residual disinfectant, Achieving the required levels of water quality, particularly microbial inactivation levels, while minimizing DBP formation requires the application of proper risk and disinfection management protocols. In addition, the failure of conventional treatment processes to eliminate critical waterborne pathogens in drinking water demand that improved and/or new disinfection technologies be developed. Recent research has disclosed that nanotechnology may offer solutions in this area, through the use of nanosorbents, nanocatalysts, bioactive nanoparticles, nanostructured catalytic membranes, and nanoparticle-enhanced filtration.

Inactivation of Ichthyophonus spores using sodium hypochlorite and polyvinyl pyrrolidone iodine

USGS Publications Warehouse

Hershberger, P.K.; Pacheco, C.A.; Gregg, J.L.

2008-01-01

Chlorine and iodine solutions were effective at inactivating Ichthyophonus spores in vitro. Inactivation in sea water increased directly with halogen concentration and exposure duration, with significant differences (P < 0.05) from controls occurring at all chlorine concentrations and exposure durations tested (1.5-13.3 ppm for 1-60 min) and at most iodine concentrations and exposure durations tested (1.2 ppm for 60 min and 5.9-10.7 ppm for 1-60 min). However, 10-fold reductions in spore viability occurred only after exposure to halogen solutions at higher concentrations and/or longer durations (13 ppm total chlorine for 1-60 min, 5.9 ppm total iodine for 60 min, and 10.7 ppm total iodine for 1-60 min). Inactivation efficacy was greater when halogen solutions were prepared in fresh water, presumably because of combined effects of halogen-induced inactivation and general spore instability in fresh water. The results have practical implications for disinfection and biocontainment in research laboratories and other facilities that handle live Ichthyophonus cultures and/or infected fish.

Photocatalytic destruction of chlorinated solvents with solar energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pacheco, J.; Prairie, M.; Yellowhorse, L.

1990-01-01

Sandia National Laboratories and the Solar Energy Research Institute are developing a photocatalytic process to destroy organic contaminants in water. Tests with common water pollutants are being conducted at Sandia's Solar Thermal Test Facility using a near commercial-scale single-axis tracking parabolic trough system with glass pipe mounted at its focus. Experiments at this scale provide verification of laboratory studies and allow examination of design and operation issues at a real-life scale. The catalyst, titanium dioxide (TiO{sub 2}), is a harmless material found in paint, cosmetics and toothpaste. Experiments were conducted to determine the effect of key process parameters on destructionmore » rates of two chlorinated organic compounds which are common water pollutants: trichloroethylene and trichloroethane. In this paper, we summarize the engineering-scale results of these experiments and analyses. 21 refs., 8 figs.« less

Sulfide chemiluminescence detection

DOEpatents

Spurlin, Stanford R.; Yeung, Edward S.

1985-01-01

A method of chemiluminescently determining a sulfide which is either hydrogen sulfide or methyl mercaptan by reacting the sulfide with chlorine dioxide at low pressure and under conditions which allow a longer reaction time in emission of a single photon for every two sulfide containing species, and thereafter, chemiluminescently detecting and determining the sulfide. The invention also relates not only to the detection method, but the novel chemical reaction and a specifically designed chemiluminescence detection cell for the reaction.

European Science Notes. Volume 40, Number 9

DTIC Science & Technology

1986-09-01

15 invited speakers pre- oxygen ases s asaon dioxide and senting talks on various topics in the oxygen as well as ammonia, chlorine, hy-ara fbisnsr...tantalum oxides (H+), work involves the contributions of elec- special lasses (H+, Na+, K+), valinomy- trical engineers as well as chemists. cin (K), tetra...copy only devise circuitry but work on concep- may be obtained from me]) he derived a tual design as well . Incidentally, the theorem that gives the

Gallium(III) complexes of methyl pyropheophorbide-a as synthetic models for investigation of diastereomerically controlled axial ligation towards chlorophylls.

PubMed

Sasaki, Shin-Ichi; Mizoguchi, Tadashi; Tamiaki, Hitoshi

2006-03-01

Gallium(III) chlorins possessing a series of axial ligands were synthesized as model compounds of natural chlorophylls. A pair of diastereomers arising from the fifth axial coordination onto the asymmetric chlorin pi-macrocycle could be discriminated in a solution by both (1)H- and (13)C NMR spectroscopies.

Whole-leaf sanitizing wash improves chlorine efficacy for microbial reduction and prevents pathogen cross contamination during fresh-cut lettuce processing

USDA-ARS?s Scientific Manuscript database

Currently, nearly all fresh-cut lettuce processing facilities in the United States use chlorinated water or other sanitizer solutions for microbial reduction after lettuce is cut. It is believed that freshly cut lettuce releases significant amounts of organic matters that negatively impact the effec...

Relationship of drinking water disinfectants to plasma cholesterol and thyroid hormone levels in experimental studies.

PubMed Central

Revis, N W; McCauley, P; Bull, R; Holdsworth, G

1986-01-01

The effects of drinking water containing 2 or 15 ppm chlorine (pH 6.5 and 8.5), chlorine dioxide, and monochloramine on thyroid function and plasma cholesterol were studied because previous investigators have reported cardiovascular abnormalities in experimental animals exposed to chlorinated water. Plasma thyroxine (T4) levels, as compared to controls, were significantly decreased in pigeons fed a normal or high-cholesterol diet and drinking water containing these drinking water disinfectants at a concentration of 15 ppm (the exception was chlorine at pH 6.5) for 3 months. In most of the treatment groups, T4 levels were significantly lower following the exposure to drinking water containing the 2 ppm dose. Increases in plasma cholesterol were frequently observed in the groups with lower T4 levels. This association was most evident in pigeons fed the high-cholesterol diet and exposed to these disinfectants at a dose of 15 ppm. For example, after 3 months of exposure to deionized water or water containing 15 ppm monochloramine, plasma cholesterol was 1266 +/- 172 and 2049 +/- 212 mg/dl, respectively, a difference of 783 mg/dl. The factor(s) associated with the effect of these disinfectants on plasma T4 and cholesterol is not known. We suggest however that these effects are probably mediated by products formed when these disinfectants react with organic matter in the upper gastrointestinal tract. PMID:3456597

Antimicrobial effects of electrolytic products of sodium chloride--comparative evaluation with sodium hypochlorite solution and efficacy in handwashing.

PubMed

Hitomi, S; Baba, S; Yano, H; Morisawa, Y; Kimura, S

1998-11-01

We examined the in vitro bactericidal effects and efficacy on handwashing of water containing electrolytic products of sodium chloride (electrolytic water). The electrolytic water, whose pH and concentration of free residual chlorine were 6.7-6.9 and 20-22 ppm, respectively, showed equal reduction of both Staphylococcus aureus and Escherichia coli to dilution of commercially available sodium hypochlorite containing 60 ppm of free residual chlorine. This bactericidal effect was calculated to be due to hypochlorous acid, based on the pH and the amount of chlorine in solution. Handwashing with the electrolytic water reduced the numbers of S. aureus on hands by 1/10(2), while running water and 0.2% benzalkonium chloride with 80% ethanol gave a 1/10 and 1/10(5) reduction, respectively. We conclude that electrolytic water might be applicable for handwashing in place of running water.

Chlorine inactivation of fungal spores on cereal grains.

PubMed

Andrews, S; Pardoel, D; Harun, A; Treloar, T

1997-04-01

Although 0.4% chlorine for 2 min has been recommended for surface disinfection of food samples before direct plating for fungal enumeration, this procedure may not be adequate for highly contaminated products. The effectiveness of a range of chlorine solutions was investigated using barley samples artificially contaminated with four different concentrations of Aspergillus flavus. A. niger, A. ochraceus, Eurotium repens, Penicillium brevicompactum P. chrysogenum and Cladosporium cladosporioides. At initial contamination levels greater than 10(4)/g, 0.4% chlorine did not inactivate sufficient spores to produce less than 20% contamination. Of the test fungi, ascospores of E. repens were the most resistant to chlorine inactivation, whereas the conidia of C. cladosporioides were the most sensitive. Rinsing the samples with 70% ethanol improved the effectiveness of the recommended surface disinfection procedure. However, some ethanol appears to permeate into the grains and may inactivate sensitive internal fungi, although a minimal effect only was observed on wheat infected with Alternaria.

NDMA formation during chlorination and chloramination of aqueous diuron solutions.

PubMed

Chen, Wei-Hsiang; Young, Thomas M

2008-02-15

Formation of the potent carcinogen N-nitrosodimethylamine (NDMA) during chlorine disinfection of water containing secondary amines is now generally acknowledged. The phenylurea herbicide diuron is one of the most widely used herbicides in California, has been frequently detected in California's water sources with a transient nature of appearance, and has a structure that suggests it might be an NDMA precursor. This study sought to quantify the potential for NDMA formation from aqueous diuron solutions under varied chlorine and chloramine conditions. NDMA formation was consistently observed even in the absence of added ammonia, which has usually been the source of the nitroso-nitrogen during chloramination of other precursors. It appears that both nitrogen atoms in NDMA are donated by diuron during chlorination in the absence of added ammonia. For a given chlorine and diuron dose, NDMA formation increased in the order OCl- < NH2Cl < NHCl2, a result consistentwith previous NDMAformation studies. Significant quantities of NDMA (170 ng/L) were produced during dichloramination of diuron using a low dichloramine concentration and a diuron concentration at the upper end of typically detected concentrations in California (20 microg/L), suggesting a need for further investigation to accurately assess the human health risks posed by diuron with respect to NDMA formation potential. A reaction pathway is proposed to provide a possible explanation for NDMA formation from diuron during chlorination or chloramination. The findings in this study identify a specific potential precursor of NDMA formation, one that arises from nonpoint sources. This further highlights the difficulties associated with determining the environmental safety of chemicals and their associated byproducts.

Reactive Minerals and Dechlorinating Communities: Mechanisms Governing the Degradation of Chlorinated Ethenes during Back Diffusion from Low Permeability Zones in Aerobic and Anaerobic Environments

NASA Astrophysics Data System (ADS)

Berns, E. C.; Zeng, R.; Singh, H.; Valocchi, A. J.; Sanford, R. A.; Strathmann, T. J.; Schaefer, C. E.; Werth, C. J.

2017-12-01

Low permeability zones (LPZs) comprised of silts and clays, and contaminated with chlorinated ethenes, can act as a long term source of contaminated groundwater by diffusion into adjacent high permeability zones (HPZs). Following initial remediation efforts, chlorinated ethenes that have diffused into LPZs will back diffuse and recontaminate HPZs. Because chlorinated ethenes are known to cause cancer and damage the liver, kidneys, and central nervous system, it is important to understand how they degrade in natural systems and how to model their fate and transport. Previous work has shown that anaerobic hydrogenolysis reactions are facilitated by both dechlorinating microorganisms and reactive minerals. Abiotic dichloro-elimination reactions with reactive minerals can also degrade chlorinated ethenes to acetylene, albeit at slower rates than biotic processes. More recently, studies have explored aerobic abiotic degradation of chlorinated ethenes to formate, glycolate, and carbon dioxide. This study focuses on these biotic and abiotic reactions and their contributions to chlorinated ethene degradation under aerobic and anaerobic conditions at the LPZ/HPZ interface. A two-dimensional flow cell was constructed to model this interface using clay and sand from Pease Air Force Base. The clay was inoculated with a dechlorinating enrichment culture. Tenax adsorbent beads equilibrated with trichloroethylene (TCE) were used as a chlorinated ethene source zone at the base of the clay. TCE and its degradation products diffused from the clay into the sand, where they were removed from the flow cell by groundwater at a rate of 50 mL/day. Volatile compounds were trapped in a sample loop and removed every 48 hours for analysis by GC-FID. Organic and inorganic ions in the effluent were analyzed on the HPLC and IC. The experiment was terminated by freezing the flow cell, and chemical profiles through the flow cell material were created to show the spatial distribution of degradation products. Chemical profiles through the clay were modeled using a 1D diffusion-reaction model, and the contributions of abiotic and biotic processes to TCE degradation were determined. The model and experimental data lend insights into transformation processes that control the fate and transport of chlorinated ethenes at contaminated sites.

PRECIPITATION OF PROTACTINIUM

DOEpatents

Moore, R.L.

1958-07-15

An lmprovement in the separation of protactinium from aqueous nitric acid solutions is described. 1t covers the use of lead dioxide and tin dioxide as carrier precipitates for the protactinium. In carrying out the process, divalent lead or divalent tin is addcd to the solution and oxidized, causing formation of a carrier precipitate of lead dioxide or stannic oxide, respectively.

46 CFR Table 2 to Part 153 - Cargoes Not Regulated Under Subchapters D or O of This Chapter When Carried in Bulk on Non...

Code of Federal Regulations, 2014 CFR

2014-10-01

...) (with 52% Chlorine) III 2-Chloro-4-ethylamino-6-isopropylamino-5-triazine solution # Choline chloride...-5-triazine solution # 4-Chloro-2-methylphenoxyacetic acid, dimethylamine salt solution * Y Choline...

Effectiveness of antimicrobial food packaging materials.

PubMed

Cooksey, K

2005-10-01

Antimicrobial additives have been used successfully for many years as direct food additives. The literature provides evidence that some of these additives may be effective as indirect food additives incorporated into food packaging materials. Antimicrobial food packaging is directed toward the reduction of surface contamination of processed, prepared foods such as sliced meats and Frankfurter sausages (hot dogs). The use of such packaging materials is not meant to be a substitute for good sanitation practices, but it should enhance the safety of food as an additional hurdle for the growth of pathogenic and/or spoilage microorganisms. Studies have focused on establishing methods for coating low-density polyethylene film or barrier films with methyl cellulose as a carrier for nisin. These films have significantly reduced the presence of Listeria monocytogenes in solutions and in vacuum packaged hot dogs. Other research has focused on the use of chitosan to inhibit L. monocytogenes and chlorine dioxide sachets for the reduction of Salmonella on modified atmosphere-packaged fresh chicken breasts. Overall, antimicrobial packaging shows promise as an effective method for the inhibition of certain bacteria in foods, but barriers to their commercial implementation continue to exist.

Extraction of titanium from low-iron nitrided Malaysian ilmenite by chlorination

NASA Astrophysics Data System (ADS)

Ibrahim, Najwa; Ahmadi, Eltefat; Rahman, Shaik Abdul; Fauzi, M. N. Ahmad; Rezan, Sheikh Abdul

2017-01-01

In this paper, production of TiCl4 from low-iron nitrided ilmenite samples at relatively low temperature using chlorine gas generated from the reaction between KMnO4 and HCl has been investigated. The effects of chlorination soaking time, potassium permanganate (KMnO4) to hydrochloric acid (HCl) molar ratio and aluminium powder catalyst in chlorine gas generation on titanium extraction from nitrided Malaysian ilmenite were examined. The low-iron nitrided Malaysian ilmenite contained titanium oxycarbonitride (TiOxCyNz) after carbothermal reduction and nitridation with subsequent leaching. Chlorination process was performed at 500°C for 30 - 60 minutes. Statistical analysis of the data was done by Design of Experiment (DOE) to identify the significant variables and their interactions. The results achieved in this study showed that the highest extent of chlorination was about 98.34% at 500°C for 60 minutes. The lowest extent of chlorination was about 68.51% obtained in KMnO4 to HCl molar ratio of 2.0 and 0.35 g of aluminium powder. The chlorinated titanium oxycarbonitride powders and TiCl4 solutions were analyzed by X-ray diffraction (XRD) and inductively coupled plasma-optical emission spectroscopy (ICP-OES), respectively. The purpose of this study was to explore the relationship between the processing parameters on extracting titanium via pyrometallurgical technique.

Partition Coefficients of Organics between Water and Carbon Dioxide Revisited: Correlation with Solute Molecular Descriptors and Solvent Cohesive Properties.

PubMed

Roth, Michal

2016-12-06

High-pressure phase behavior of systems containing water, carbon dioxide and organics has been important in several environment- and energy-related fields including carbon capture and storage, CO 2 sequestration and CO 2 -assisted enhanced oil recovery. Here, partition coefficients (K-factors) of organic solutes between water and supercritical carbon dioxide have been correlated with extended linear solvation energy relationships (LSERs). In addition to the Abraham molecular descriptors of the solutes, the explanatory variables also include the logarithm of solute vapor pressure, the solubility parameters of carbon dioxide and water, and the internal pressure of water. This is the first attempt to include also the properties of water as explanatory variables in LSER correlations of K-factor data in CO 2 -water-organic systems. Increasing values of the solute hydrogen bond acidity, the solute hydrogen bond basicity, the solute dipolarity/polarizability, the internal pressure of water and the solubility parameter of water all tend to reduce the K-factor, that is, to favor the solute partitioning to the water-rich phase. On the contrary, increasing values of the solute characteristic volume, the solute vapor pressure and the solubility parameter of CO 2 tend to raise the K-factor, that is, to favor the solute partitioning to the CO 2 -rich phase.

Curiosity at Gale crater, Mars: characterization and analysis of the Rocknest sand shadow.

PubMed

Blake, D F; Morris, R V; Kocurek, G; Morrison, S M; Downs, R T; Bish, D; Ming, D W; Edgett, K S; Rubin, D; Goetz, W; Madsen, M B; Sullivan, R; Gellert, R; Campbell, I; Treiman, A H; McLennan, S M; Yen, A S; Grotzinger, J; Vaniman, D T; Chipera, S J; Achilles, C N; Rampe, E B; Sumner, D; Meslin, P-Y; Maurice, S; Forni, O; Gasnault, O; Fisk, M; Schmidt, M; Mahaffy, P; Leshin, L A; Glavin, D; Steele, A; Freissinet, C; Navarro-González, R; Yingst, R A; Kah, L C; Bridges, N; Lewis, K W; Bristow, T F; Farmer, J D; Crisp, J A; Stolper, E M; Des Marais, D J; Sarrazin, P

2013-09-27

The Rocknest aeolian deposit is similar to aeolian features analyzed by the Mars Exploration Rovers (MERs) Spirit and Opportunity. The fraction of sand <150 micrometers in size contains ~55% crystalline material consistent with a basaltic heritage and ~45% x-ray amorphous material. The amorphous component of Rocknest is iron-rich and silicon-poor and is the host of the volatiles (water, oxygen, sulfur dioxide, carbon dioxide, and chlorine) detected by the Sample Analysis at Mars instrument and of the fine-grained nanophase oxide component first described from basaltic soils analyzed by MERs. The similarity between soils and aeolian materials analyzed at Gusev Crater, Meridiani Planum, and Gale Crater implies locally sourced, globally similar basaltic materials or globally and regionally sourced basaltic components deposited locally at all three locations.

Sulfide chemiluminescence detection

DOEpatents

Spurlin, S.R.; Yeung, E.S.

1985-11-26

A method is described for chemiluminescently determining a sulfide which is either hydrogen sulfide or methyl mercaptan by reacting the sulfide with chlorine dioxide at low pressure and under conditions which allow a longer reaction time in emission of a single photon for every two sulfide containing species, and thereafter, chemiluminescently detecting and determining the sulfide. The invention also relates not only to the detection method, but the novel chemical reaction and a specifically designed chemiluminescence detection cell for the reaction. 4 figs.

Apparatus for use in sulfide chemiluminescence detection

DOEpatents

Spurlin, Stanford R.; Yeung, Edward S.

1987-01-01

A method of chemiluminescently determining a sulfide which is either hydrogen sulfide or methyl mercaptan by reacting the sulfide with chlorine dioxide at low pressure and under conditions which allow a longer reaction time in emission of a single photon for every two sulfide containing species, and thereafter, chemiluminescently detecting and determining the sulfide. The invention also relates not only to the detection method, but the novel chemical reaction and a specifically designed chemiluminescence detection cell for the reaction.

Evidence for extreme partitioning of copper into a magmatic vapor phase.

PubMed

Lowenstern, J B; Mahood, G A; Rivers, M L; Sutton, S R

1991-06-07

The discovery of copper sulfides in carbon dioxide- and chlorine-bearing bubbles in phenocryst-hosted melt inclusions shows that copper resides in a vapor phase in some shallow magma chambers. Copper is several hundred times more concentrated in magmatic vapor than in coexisting pantellerite melt. The volatile behavior of copper should be considered when modeling the volcanogenic contribution of metals to the atmosphere and may be important in the formation of copper porphyry ore deposits.

Remedial Investigation Concept Plan for Picatinny Arsenal. Volume 2. Descriptions of and Sampling Plans for Remedial Investigation Sites

DTIC Science & Technology

1991-03-22

by sulfur dioxide to convert hexavalent chromium into trivalent chromium , and by sodium hydroxide to promote precipitation. After being transferred...Regulations COD chemical oxygen demand Cr chromium CTF chlorine trifluoride Cu copper 2,4-D 2,4-dichlorophenoxyaoetic acid 11DCE 1,1...the Site. Inorganic results for surface soil showed elevated values for arsenic, cadmium, chromium , lead, and zinc (Table 2.1). These levels are to be

Role of Chlorine Dioxide in N-Nitrosodimethylamine Formation from Oxidation of Model Amines.

PubMed

Gan, Wenhui; Bond, Tom; Yang, Xin; Westerhoff, Paul

2015-10-06

N-Nitrosodimethylamine (NDMA) is an emerging disinfection byproduct, and we show that use of chlorine dioxide (ClO2) has the potential to increase NDMA formation in waters containing precursors with hydrazine moieties. NDMA formation was measured after oxidation of 13 amines by monochloramine and ClO2 and pretreatment with ClO2 followed by postmonochloramination. Daminozide, a plant growth regulator, was found to yield 5.01 ± 0.96% NDMA upon reaction with ClO2, although no NDMA was recorded during chloramination. The reaction rate was estimated to be ∼0.0085 s(-1), and on the basis of our identification by mass spectrometry of the intermediates, the reaction likely proceeds via the hydrolytic release of unsymmetrical dimethylhydrazine (UDMH), with the hydrazine structure a key intermediate in NDMA formation. The presence of UDMH was confirmed by gas chromatography-mass spectrometry analysis. For 10 of the 13 compounds, ClO2 preoxidation reduced NDMA yields compared with monochloramination alone, which is explained by our measured release of dimethylamine. This work shows potential preoxidation strategies to control NDMA formation may not impact all organic precursors uniformly, so differences might be source specific depending upon the occurrence of different precursors in source waters. For example, daminozide is a plant regulator, so drinking water that is heavily influenced by upstream agricultural runoff could be at risk.

Effectiveness of disinfectant treatments for inactivating Piscirickettsia salmonis.

PubMed

Muniesa, A; Escobar-Dodero, J; Silva, N; Henríquez, P; Bustos, P; Perez, A M; Mardones, F O

2018-03-08

This short communication investigated in vitro differences between commercial disinfectants types (n = 36), doses of application, and time of action in the elimination of Piscirickettsia salmonis, the most important bacterium affecting farmed salmon in Chile. Seven different treatments were examined, including active and inactive chlorine dioxides, glutaraldehyde, hypochlorite disinfectants and detergents, peracetic acid, peroxides and other miscellaneous methods A 3 replicate set of each of the sample groups was stored at 20 °C and 95% relative humidity and retested after 1, 5 and 30 min with varying doses (low, recommended and high doses). Multiple comparison tests were performed for the mean log CFU/ml among different disinfectant types, dose (ppm) and time of exposure (minutes) on the reduction of P. salmonis. Overall, disinfection using peracetic acid, peroxides, and both active and inactive chlorine dioxides caused significantly higher reduction of >7.5 log CFU/ml in samples, compared to other tested sanitizers. The lowest reduction was obtained after disinfection with hypochlorite detergents. As expected, as doses and time of action increase, there was a significant reduction of the overall counts of P. salmonis. However, at lowest doses, only use of paracetic acids resulted in zero counts. Implementation of effective protocols, making use of adequate disinfectants, may enhance biosecurity, and ultimately, mitigate the impact of P. salmonis in farmed salmon. Copyright © 2018. Published by Elsevier B.V.

Thermal electron attachment to chlorinated alkenes in the gas phase

NASA Astrophysics Data System (ADS)

Wnorowski, K.; Wnorowska, J.; Michalczuk, B.; Jówko, A.; Barszczewska, W.

2017-01-01

This paper reports the measurements of the rate coefficients and the activation energies of the electron capture processes with various chlorinated alkenes. The electron attachment processes in the mixtures of chlorinated alkenes with carbon dioxide have been investigated using a Pulsed Townsend technique. This study has been performed in the temperature range (298-378) K. The obtained rate coefficients more or less depended on temperature in accordance to Arrhenius equation. The activation energies (Ea's) were determined from the fit to the experimental data points with function ln(k) = ln(A) - Ea/kBT. The rate coefficients at 298 K were equal to 1.0 × 10-10 cm3 s-1, 2.2 × 10-11 cm3 s-1, 1.6 × 10-9 cm3 s-1, 4.4 × 10-8 cm3 s-1, 2.9 × 10-12 cm3 s-1 and 7.3 × 10-12 cm3 s-1 and activation energies were: 0.27 eV, 0.26 eV, 0.25 eV, 0.21 eV, 0.55 eV and 0.42 eV, for trans-1,2-dichloroethylene, cis-1,2-dichloroethylene, trichloroethylene, tetrachloroethylene, 2-chloropropene, 3-chloropropene respectively.

Cleaning and disinfection of equipment for gastrointestinal endoscopy. Report of a Working Party of the British Society of Gastroenterology Endoscopy Committee.

PubMed

1998-04-01

Two per cent glutaraldehyde is the most commonly used disinfectant in endoscopy units within the UK. Unfortunately adverse reactions to glutaraldehyde are common among endoscopy personnel and the Health and Safety Commission has recommended substantial reductions in atmospheric levels of glutaraldehyde in order to comply with the Control of Substances Hazardous to Health Regulations, 1994. The Working Party addressed ways of eliminating or minimising exposure to glutaraldehyde in endoscopy units by reviewing alternative disinfectants and the use of automated washer/disinfectors. Alternatives to glutaraldehyde must be at least as microbicidal as glutaraldehyde, non-irritating and compatible with endoscope components and decontamination equipment. Peracetic acid is a highly effective disinfectant and may be a suitable alternative to glutaraldehyde. Peracetic acid has a vinegary-like odour and is claimed to be less irritating than glutaraldehyde. Experience with this agent remains relatively limited and the Working Party recommends that peracetic acid should be used in sealed or exhaust ventilated facilities until further experience is obtained. It is considerably more expensive than glutaraldehyde, is less stable and large volumes have to be stored. It causes cosmetic (but not functional) damage to endoscopes and is not compatible with some washer/ disinfectors. Chlorine dioxide is a powerful oxidising agent and highly effective as a disinfectant. Once activated it must be stored in sealed containers with little head space. Fumes cause irritation and sealed or exhaust ventilated facilities are necessary. The agent may damage some metallic and polymer components of endoscopes and automated washer/disinfectors and compatibility should be established with equipment manufacturers before the agent is used. Other disinfectants such as peroxygen compounds and quaternary ammonium derivatives are less suitable because of unsatisfactory mycobactericidal and/or virucidal activity, or incompatibility with endoscopes and automated washer/disinfectors. Alcohol is effective but, on prolonged contact, is damaging to lens cements. It is also flammable and therefore unsuitable for use in large quantities in automated systems. Superoxidised water (Sterilox) is an electrochemical solution (anolyte) containing a mixture of radicals with strong oxidising properties. It is highly microbicidal when freshly generated, provided items are thoroughly clean and strict generation criteria are met--that is, current, pH, redox potential. It seems to be safe for users and provided field trials substantiate laboratory efficacy tests, and the agent is non-damaging, it too may become an alternative to glutaraldehyde. When 2% glutaraldehyde is used for manual and automated disinfection, 10 minutes' immersion is recommended for endoscopes before the session and between patients. This will destroy vegetative bacteria and viruses (including hepatitis B virus (HBV) and HIV). A five minute contact period is recommended for 0.35% peracetic acid and for chlorine dioxide (1100 ppm av ClO2), but if immersed for 10 minutes sporicidal activity will also be achieved. At the end of each session 20 minutes' immersion in glutaraldehyde or five minutes in peracetic acid or chlorine dioxide is recommended. Microbiological studies show that 20 minutes of exposure to 2% glutaraldehyde destroys most organisms, including Mycobacterium tuberculosis. The Working Party concludes therefore that immersion of the endoscope in 2% glutaraldehyde for 20 minutes is sufficient for endoscopy involving patients with AIDS and other immunodeficiency states or pulmonary tuberculosis. Similarly, 20 minutes' immersion is recommended at the start of the list and between cases for endoscopic retrograde cholangiopancreatography (ERCP) when high level disinfection is required. Cleaning and disinfection of endoscopes should be undertaken by trained staff in a dedicated room. Thorough cleaning with detergent

Mechanism of chlorine inactivation of DNA-containing parvovirus H-1.

PubMed Central

Churn, C C; Bates, R C; Boardman, G D

1983-01-01

An investigation was undertaken to determine the effect of chlorine on a small DNA-containing enteric virus. Parvovirus H-1 was exposed to sodium hypochlorite in a phosphate-buffered saline solution at pH 7. Then, the whole virion, the protein capsid, or the nucleic acid was subjected to analysis. The sedimentation rate of the chlorine-treated whole virus decreased from 110S to 43S. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the virus demonstrated the formation of higher-molecular-weight aggregates resulting from covalent cross-linking of the capsid proteins. Electron microscopic examination revealed that the DNA was extruded as a taillike structure which remained attached to the virus particle. Furthermore, the DNA was intact and still capable of in vitro replication. The adsorption of the chlorine-treated virions to host cells was inhibited, presumably due to the effect of chlorine on the particular spatial arrangement of the capsid proteins required for adsorption. Specific sites on these proteins had become highly reactive, indicating that the initial action of chlorine on parvovirus H-1 was on the viral capsid. Images PMID:6660876

Algicidal and Sanitizing Properties of Armazide1

PubMed Central

Antonides, H. J.; Tanner, W. S.

1961-01-01

Algicidal and sanitizing properties of Armazide, a new swimming pool additive, consisting of 12% w/v each of dodecylamine hydrochloride, trimethyl alkyl ammonium chloride, and methyl alkyl dipolyoxypropylene ammonium methyl sulfate in solution, were evaluated by laboratory techniques against algae and sewage. Results indicated it to be highly effective in low concentrations especially in conjunction with low concentrations of chlorine. Swimming pool field tests were found to confirm the laboratory findings. Various treatment levels and methods are described for swimming pools using treatments based upon the actual condition of the pool and water. The use of the product permitted a reduction in chlorine residual in pools resulting in greatly reduced requirements for chlorinating chemicals along with absence of irritation, odor, and other undesirable results usually associated with standard pool chlorination methods. PMID:13861802

Medical toxicology and public health-update on research and activities at the centers for disease control and prevention and the agency for toxic substances and disease registry.

PubMed

Snook, Curtis P; Cardarelli, John; Mickelsen, R Leroy; Mattorano, Dino; Nalipinski, Michael

2008-12-01

An extensive review of CDC epidemiological responses to human outbreaks of anthrax from occupational settings between the years of 1950 and 2001 documented a variety of approaches to mitigation and decontamination [2]. These approaches included taking no action, burning contaminated materials, chlorinating water supplies, instituting administrative and engineering controls and PPE, vaccinating potentially exposed individuals, and in 2 instances, fumigating with formaldehyde vapor (now considered to be a human carcinogen). Secondary contamination of a worker's home was documented in 1 case, but not felt to be clinically significant to warrant any decontamination efforts. In response to the B. anthracis attacks in 2001, chlorine dioxide fumigation, vaporous hydrogen peroxide fumigation, and a combination of HEPA vacuuming, cleaning, and bleach application were all techniques used successfully to clean B. anthracis spore contamination.

Ozone response to a CO2 doubling - Results from a stratospheric circulation model with heterogeneous chemistry

NASA Technical Reports Server (NTRS)

Pitari, G.; Palermi, S.; Visconti, G.; Prinn, R. G.

1992-01-01

A spectral 3D model of the stratosphere has been used to study the sensitivity of polar ozone with respect to a carbon dioxide increase. The lower stratospheric cooling associated with an imposed CO2 doubling may increase the probability of polar stratospheric cloud (PSC) formation and this affect ozone. The ozone perturbation obtained with the inclusion of a simple parameterization for heterogeneous chemistry on PSCs is compared to that relative to a pure homogeneous chemistry. In both cases the temperature perturbation is determined by a CO2 doubling, while the total chlorine content is kept at the present level. It is shown that the lower temperature may increase the depth and the extension of the ozone hole by extending the area amenable to PSC formation. It may be argued that this effect, coupled with an increasing amount of chlorine, may produce a positive feedback on the ozone destruction.

UV/chlorine as an advanced oxidation process for the degradation of benzalkonium chloride: Synergistic effect, transformation products and toxicity evaluation.

PubMed

Huang, Nan; Wang, Ting; Wang, Wen-Long; Wu, Qian-Yuan; Li, Ang; Hu, Hong-Ying

2017-05-01

Benzalkonium chlorides (BACs), as typical cationic surfactants and biocides widely applied in household and industrial products, have been frequently detected as micropollutants in many aquatic environments. In this study, the combination of UV irradiation and chlorine (UV/chlorine), a newly interested advanced oxidation process, was used to degrade dodecylbenzyldimethylammonium chloride (DDBAC). UV/chlorine showed synergistic effects on DDBAC degradation comparing to UV irradiation or chlorination alone. Radical quenching experiments indicated that degradation of DDBAC by UV/chlorine involved both UV photolysis and radical species oxidation, which accounted for 48.4% and 51.6%, respectively. Chlorine dosage and pH are essential parameters affecting the treatment efficiency of UV/chlorine. The pseudo first order rate constant (k obs, DDBAC ) increased from 0.046 min -1 to 0.123 min -1 in response to chlorine dosage at 0-150 mg/L, and the degradation percentage of DDBAC within 12 min decreased from 81.4% to 56.6% at pH 3.6-9.5. Five main intermediates were identified and semi-quantified using HPLC-MS/MS and a possible degradation pathway was proposed. The degradation mechanisms of DDBAC by UV/chlorine included cleavage of the benzyl-nitrogen bond and hydrogen abstraction of the alkyl chain. Trichloromethane (TCM), chloral hydrate (CH), trichloropropanone (TCP), dichloropropanone (DCP) and dichloroacetonitrile (DCAN) were detected using GC-ECD. The formation of chlorinated products increased rapidly initially, then decreased (TCM, TCP, DCP and DCAN) or remained stable (CH) with extended treatment. The actual formation of TCM peaked at 30 min (50.3 μg/L), while other chlorinated products did not exceed 10 μg/L throughout the process. Based on the luminescent bacterial assay, DDBAC solution underwent almost complete detoxification subjected to UV/chlorine treatment for 120 min, which is more effective than UV irradiation or chlorination alone. Copyright © 2017 Elsevier Ltd. All rights reserved.

The corrosion effect of ozonated seawater solution on titanium in polymer generated crevice environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leveillee, S.Y.

1998-01-01

Two different tests were designed to evaluate the reaction of various polymers and grade-2 titanium in ozonated seawater in conjunction with a comparative analysis in an aerated seawater solution. The first was a weight loss test measuring the weight change of Polyvinyl chloride (PVC), Polyethylene and Teflon{trademark} in both ozonated and aerated artificial seawater baths. The second test was designed to induce crevice corrosion on the titanium test samples using various crevice generating materials in both ozonated and aerated solutions. The materials used to create the crevices were grade-2 titanium washers, PVC, Polyethylene, Saran and Teflon{trademark}. The weight loss testmore » showed that all three polymers lost weight in the ozonated bath. The results of the titanium washer crevice test provided no indication of corrosion or surface discoloration in either the ozonated or aerated solutions. Energy dispersive spectrometry (EDS) analysis found no fluorine, chlorine or other corrosion product. The PVC samples in the aerated bath also showed no signs of corrosion, but the PVC samples in the ozonated tank had light brown rings of surface discoloration. One of the ozonated PVC samples did show evidence of chlorine in the corrosion product. The outer circumference of the ozonated PVC washers exhibited the same type bleaching effect as in the weight loss samples, but the whitening of these samples were more pronounced. The polyethylene samples under aeration showed no discoloration or presence of fluorine or chlorine. The polyethylene crevice samples in the ozonated solution all exhibited the distinct brilliant blue color of titanium oxide. Fluorine was found in the corrosion product on only one of the samples. Chlorine was found on the surface of one of the other corrosion coupons. The results of the Teflon{trademark} crevice samples substantiated the previous Rensselaer study.« less

Adsorption of Pd(II) complexes from chloride solutions obtained by leaching chlorinated spent automotive catalysts on ion exchange resin Diaion WA21J.

PubMed

Shen, Shaobo; Pan, Tonglin; Liu, Xinqiang; Yuan, Lei; Zhang, Yongjian; Wang, Jinchao; Guo, Zhanchen

2010-05-01

It was found that Rh, Pd and Pt contained in the spent ceramic automotive catalysts could be effectively extracted by dry chlorination with chlorine. In order to concentrate Pd(II) contained in the chloride solution obtained from the dry chlorination process, thermodynamic and kinetics studies for adsorption of Pd(II) complexes from the chloride solutions on anionic exchange resin Diaion WA21J were carried out. It was found that Pd, Pt, Rh, Al, Fe, Si, Zn and Pb from the chloride solution could be adsorbed on the resin. The isothermal adsorption of Pd(II) was found to fit Freundlich, Langmuir and Dubinin-Kaganer-Radushkevich models under the adsorption conditions. The adsorption of Pd(II) on the resin was favorable according to the values of 1/n and R(L) from Freundlich and Langmuir adsorption isotherms, respectively. The maximum monolayer adsorption capacities Q(max) based on Langmuir adsorption isotherms were 5.70, 4.84 and 4.05 mg/g and the corresponding value X(m) based on Dubinin-Kaganer-Radushkevich were 5.55, 4.69 and 4.01 mg/g at temperatures 18 degrees C, 28 degrees C and 40 degrees C, respectively. The apparent adsorption energies (E(ad)) based on Dubinin-Kaganer-Radushkevich isotherm were -15.43, -16.22 and -23.57 kJ/mol for the temperatures 18 degrees C, 28 degrees C and 40 degrees C, respectively. Chemical adsorption was a main mechanism involved in the adsorption process. Pd(II) adsorption on the resin could be accelerated by increasing the adsorption temperature. The adsorption of Pd(II) from the chloride solution on the resin underwent pseudo-first order kinetic process and the apparent adsorption activation energy E(a) was 15.0 kJ/mol. The intra-particle diffusion was a main rate controlling step in the Pd(II) adsorption process under the adsorption conditions. Copyright 2010 Elsevier Inc. All rights reserved.

Heterogeneous interactions of chlorine nitrate, hydrogen chloride, and nitric acid with sulfuric acid surfaces at stratospheric temperatures

NASA Technical Reports Server (NTRS)

Tolbert, Margaret A.; Rossi, Michel J.; Golden, David M.

1988-01-01

The heterogeneous interactions of ClONO2, HCl, and HNO3 with sulfuric acid surfaces were studied using a Knudsen cell flow reactor. The surfaces studied, chosen to simulate global stratospheric particulate, were composed of 65-75 percent H2SO4 solutions at temperatures in the range -63 to -43 C. Heterogeneous loss, but not reaction, of HNO3 and HCl occurred on these surfaces; the measured sticking coefficients are reported. Chlorine nitrate reacted on the cold sulfuric acid surfaces, producing gas-phase HOCl and condensed HNO3. CLONO2 also reacted with HCl dissolved in the 65-percent H2SO4 solution at -63 C, forming gaseous Cl2. In all cases studied, the sticking and/or reaction coefficients were much larger for the 65-percent H2SO4 solution at -63 C than for the 75-percent solution at -43 C.

Dry-spraying of ascorbic acid or acetaminophen solutions with supercritical carbon dioxide

NASA Astrophysics Data System (ADS)

Wubbolts, F. E.; Bruinsma, O. S. L.; van Rosmalen, G. M.

1999-03-01

Carbon dioxide is a very poor solvent for many organic compounds, which makes it a good anti-solvent. When a solution is sprayed into carbon dioxide vapour the anti-solvent reduces the solubility within several tens of milliseconds and the solute precipitates. Two distinct regions can be identified, below and above the mixture critical pressure. Below this critical pressure the yield remains relatively low and the process is not well controlled. Above the critical pressure small crystals are obtained of about 2 μm with a yield of 90%.

Reducing carbon dioxide to products

DOEpatents

Cole, Emily Barton; Sivasankar, Narayanappa; Parajuli, Rishi; Keets, Kate A

2014-09-30

A method reducing carbon dioxide to one or more products may include steps (A) to (C). Step (A) may bubble said carbon dioxide into a solution of an electrolyte and a catalyst in a divided electrochemical cell. The divided electrochemical cell may include an anode in a first cell compartment and a cathode in a second cell compartment. The cathode may reduce said carbon dioxide into said products. Step (B) may adjust one or more of (a) a cathode material, (b) a surface morphology of said cathode, (c) said electrolyte, (d) a manner in which said carbon dioxide is bubbled, (e), a pH level of said solution, and (f) an electrical potential of said divided electrochemical cell, to vary at least one of (i) which of said products is produced and (ii) a faradaic yield of said products. Step (C) may separate said products from said solution.

Urea degradation by electrochemically generated reactive chlorine species: products and reaction pathways.

PubMed

Cho, Kangwoo; Hoffmann, Michael R

2014-10-07

This study investigated the transformation of urea by electrochemically generated reactive chlorine species (RCS). Solutions of urea with chloride ions were electrolyzed using a bismuth doped TiO2 (BiOx/TiO2) anode coupled with a stainless steel cathode at applied anodic potentials (Ea) of either +2.2 V or +3.0 V versus the normal hydrogen electrode. In NaCl solution, the current efficiency of RCS generation was near 30% at both potentials. In divided cell experiments, the pseudo-first-order rate of total nitrogen decay was an order of magnitude higher at Ea of +3.0 V than at +2.2 V, presumably because dichlorine radical (Cl2(-)·) ions facilitate the urea transformation primary driven by free chlorine. Quadrupole mass spectrometer analysis of the reactor headspace revealed that N2 and CO2 are the primary gaseous products of the oxidation of urea, whose urea-N was completely transformed into N2 (91%) and NO3(-) (9%). The higher reaction selectivity with respect to N2 production can be ascribed to a low operational ratio of free available chlorine to N. The mass-balance analysis recovered urea-C as CO2 at 77%, while CO generation most likely accounts for the residual carbon. In light of these results, we propose a reaction mechanism involving chloramines and chloramides as reaction intermediates, where the initial chlorination is the rate-determining step in the overall sequence of reactions.

Mass Spectrometry Identification of N-Chlorinated Dipeptides in Drinking Water.

PubMed

Huang, Guang; Jiang, Ping; Li, Xing-Fang

2017-04-04

We report the identification of N-chlorinated dipeptides as chlorination products in drinking water using complementary high-resolution quadrupole time-of-flight (QTOF) and quadrupole ion-trap mass spectrometry techniques. First, three model dipeptides, tyrosylglycine (Tyr-Gly), tyrosylalanine (Tyr-Ala), and phenylalanylglycine (Phe-Gly), reacted with sodium hypochlorite, and these reaction solutions were analyzed by QTOF. N-Cl-Tyr-Gly, N,N-di-Cl-Tyr-Gly, N-Cl-Phe-Gly, N,N-di-Cl-Phe-Gly, N-Cl-Tyr-Ala, and N,N-di-Cl-Tyr-Ala were identified as the major products based on accurate masses, 35 Cl/ 37 Cl isotopic patterns, and MS/MS spectra. These identified N-chlorinated dipeptides were synthesized and found to be stable in water over 10 days except N,N-di-Cl-Phe-Gly. To enable sensitive detection of N-chlorinated dipeptides in authentic water, we developed a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method with multiple reaction monitoring (MRM) mode. N-Cl-Tyr-Gly, N,N-di-Cl-Tyr-Gly, N-Cl-Phe-Gly, N-Cl-Tyr-Ala, and N,N-di-Cl-Tyr-Ala along with their corresponding dipeptides were detected in authentic tap water samples. The dipeptides were clearly detected in the raw water, but the N-chlorinated dipeptides were at background levels. These results suggest that the N-chlorinated dipeptides are produced by chlorination. This study has identified N-chlorinated dipeptides as new disinfection byproducts in drinking water. The strategy developed in this study can be used to identify chlorination products of other peptides in drinking water.

FISSION PRODUCT REMOVAL FROM ORGANIC SOLUTIONS

DOEpatents

Moore, R.H.

1960-05-10

The decontamination of organic solvents from fission products and in particular the treatment of solvents that were used for the extraction of uranium and/or plutonium from aqueous acid solutions of neutron-irradiated uranium are treated. The process broadly comprises heating manganese carbonate in air to a temperature of between 300 and 500 deg C whereby manganese dioxide is formed; mixing the manganese dioxide with the fission product-containing organic solvent to be treated whereby the fission products are precipitated on the manganese dioxide; and separating the fission product-containing manganese dioxide from the solvent.

Toxicity evaluation of surface water treated with different disinfectants in HepG2 cells.

PubMed

Marabini, Laura; Frigerio, Silvia; Chiesara, Enzo; Radice, Sonia

2006-01-01

It is well known that water disinfection through chlorination causes the formation of a mixture of disinfection by-products (DBPs), many of which are genotoxic and carcinogenic. To demonstrate the formation of such compounds, a pilot water plant supplied with water from Lake Trasimeno was set up at the waterworks of Castiglione del Lago (PG, Italy). The disinfectants, continuously added to pre-filtered lake water flowing into three different basins, were sodium hypochlorite, chlorine dioxide and peracetic acid, an alternative disinfectant used until now for disinfecting waste waters, but not yet studied for a possible use in drinking water treatment. The aim of this study was to evaluate the formation during the disinfection processes of some toxic compounds that could explain the genotoxic effects of drinking waters. Differently treated waters were concentrated by solid-phase adsorption on silica C(18) columns and toxicity was assessed in a line of human hepatoma cells (HepG2), a metabolically competent cellular line very useful for human risk evaluation. The seasonal variability of the physical-chemical water characteristics (AOX, UV 254 nm, potential formation of THM, pH and temperature) made indispensable experimentation with water samples taken during the various seasons. Autumn waters cause greater toxicity compared to those of other seasons, in particular dilution of the concentrate at 0.5l equivalent of disinfected waters with chlorine dioxide and peracetic acid causes a 55% reduction in cellular vitality while the cellular vitality is over 80% with the all other water concentrates. Moreover it is very interesting underline that non-cytotoxic quantities of the autumnal water concentrates cause, after 2h treatment, a decrease in GSH and a statistically significant increase in oxygen radicals, while after prolonged treatment (24h) cause a GSH increase, without variations in the oxygen radical content. This phenomenon could be interpreted as the cellular adaptation response to an initial oxidative stress.

Application of an electrochemical chlorine-generation system combined with solar energy as appropriate technology for water disinfection.

PubMed

Choi, Jusol; Park, Chan Gyu; Yoon, Jeyong

2013-02-01

Affordable water disinfection is key to reducing the waterborne disease experienced worldwide where resources are limited. A simple electrochemical system that can generate chlorine as a disinfectant from the electrolysis of sodium chloride is an appropriate technology to produce clean water, particularly if driven by solar energy. This study examined the affordability of an electrochemical chlorine generation system using solar energy and developed the necessary design information for its implementation. A two-electrode batch reactor, equipped with commercial IrO(2)-coated electrodes and a solar panel (approximate area 0.2 m(2)), was used to produce chlorine from a 35g/L solution of NaCl. Within 1 h, sufficient chlorine (0.8 g) was generated to produce clean drinking water for about 80 people for 1 day (target microorganism: Escherichia coli; daily drinking water requirement: 2 L per person; chlorine demand: 4 mg/L; solar power: 650 W/m(2) in Seoul, Korea. Small household batteries were demonstrated to be a suitable alternative power source when there is insufficient solar irradiation. Using a 1 m(2) solar panel, the reactor would take only 15 min in Seoul, Korea, or 7 min in the tropics (solar power 1300 W/m(2)), to generate 1 g of chlorine. The solar-powered electrochemical chlorine generation system for which design information is provided here is a simple and affordable way to produce chlorine with which to convert contaminated water into clean drinking water.

Chlorination of low-band-gap polymers: Toward high-performance polymer solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mo, Daize; Wang, Huan; Chen, Hui

Here, halogenation is an effective way to tune the energy levels of organic semiconducting materials. To date, fluorination of organic semiconducting materials to fabricate polymer solar cells (PSCs) has been used far more than chlorination; however, fluorine exchange reactions suffer from low yields and the resulting fluorinated polymer always comes with higher price, which will greatly hinder their commercial applications. Herein, we designed and synthesized a series of chlorinated donor-acceptor (D-A) type polymers, in which benzo[1,2-b:4,5- b]dithiophene and chlorinated benzothiadiazole units are connected by thiophene π-bridges with an asymmetric alkyl chain. These chlorinated polymers showed deep highest occupied molecular orbitalmore » energy levels, which promoted the efficiency of their corresponding PSCs by increasing the device open circuit voltage. The asymmetric alkyl chain on the thiophene moieties gave the final polymer sufficient solubility for solution processing and strong π-π stacking in films allowed for high mobility. Although the introduction of a large chlorine atom increased the torsion angle of the polymer backbone, the chlorinated polymers maintained high crystallinity and a favorable backbone orientation in the blended films. These factors contributed to respectable device performances from thick-film devices, which showed PCEs as high as 9.11% for a 250 nm-thick active layer. These results demonstrate that chlorination is a promising method to fine tune the energy levels of conjugated polymers, and chlorinated benzothiadiazole may be a versatile building block in materials for efficient solar energy conversion.« less

Chlorination of low-band-gap polymers: Toward high-performance polymer solar cells

DOE PAGES

Mo, Daize; Wang, Huan; Chen, Hui; ...

2017-03-08

Here, halogenation is an effective way to tune the energy levels of organic semiconducting materials. To date, fluorination of organic semiconducting materials to fabricate polymer solar cells (PSCs) has been used far more than chlorination; however, fluorine exchange reactions suffer from low yields and the resulting fluorinated polymer always comes with higher price, which will greatly hinder their commercial applications. Herein, we designed and synthesized a series of chlorinated donor-acceptor (D-A) type polymers, in which benzo[1,2-b:4,5- b]dithiophene and chlorinated benzothiadiazole units are connected by thiophene π-bridges with an asymmetric alkyl chain. These chlorinated polymers showed deep highest occupied molecular orbitalmore » energy levels, which promoted the efficiency of their corresponding PSCs by increasing the device open circuit voltage. The asymmetric alkyl chain on the thiophene moieties gave the final polymer sufficient solubility for solution processing and strong π-π stacking in films allowed for high mobility. Although the introduction of a large chlorine atom increased the torsion angle of the polymer backbone, the chlorinated polymers maintained high crystallinity and a favorable backbone orientation in the blended films. These factors contributed to respectable device performances from thick-film devices, which showed PCEs as high as 9.11% for a 250 nm-thick active layer. These results demonstrate that chlorination is a promising method to fine tune the energy levels of conjugated polymers, and chlorinated benzothiadiazole may be a versatile building block in materials for efficient solar energy conversion.« less

Apparatus for use in sulfide chemiluminescence detection

DOEpatents

Spurlin, S.R.; Yeung, E.S.

1987-01-06

A method is described for chemiluminescently determining a sulfide which is either hydrogen sulfide or methyl mercaptan by reacting the sulfide with chlorine dioxide at low pressure and under conditions which allow a longer reaction time in emission of a single photon for every two sulfide containing species, and thereafter, chemiluminescently detecting and determining the sulfide. The invention also relates not only to the detection method, but the novel chemical reaction and a specifically designed chemiluminescence detection cell for the reaction. 4 figs.

Method of generating chemiluminescent light

DOEpatents

Spurlin, S.R.; Yeung, E.S.

1986-03-11

A method of chemiluminescently determining a sulfide which is either hydrogen sulfide or methyl mercaptan by reacting the sulfide with chlorine dioxide at low pressure and under conditions which allow a longer reaction time in emission of a single photon for every two sulfide containing species, and thereafter, chemiluminescently detecting and determining the sulfide. The invention also relates not only to the detection method, but the novel chemical reaction that generates chemiluminescent light and a specifically designed chemiluminescence detection cell for the reaction. 4 figs.

Method of generating chemiluminescent light

DOEpatents

Spurlin, Stanford R.; Yeung, Edward S.

1986-01-01

A method of chemiluminescently determining a sulfide which is either hydrogen sulfide or methyl mercaptan by reacting the sulfide with chlorine dioxide at low pressure and under conditions which allow a longer reaction time in emission of a single photon for every two sulfide containing species, and thereafter, chemiluminescently detecting and determining the sulfide. The invention also relates not only to the detection method, but the novel chemical reaction that generates chemiluminescent light and a specifically designed chemiluminescence detection cell for the reaction.

Chlorine Dioxide Fumigation of Subway Materials ...

EPA Pesticide Factsheets

Report This bench scale study observed that a six (6) log reduction in viable spores of a suitable B. anthracis surrogate can be obtained for subway infrastructure materials by ClO2 fumigation if the temperature is at or above 24 °C combined with RH greater than 75%. No six log reduction in viable spores was observed at realistic (winter) temperatures in a subway environment (11-13 °C and 70-80% RH) for periods of fumigation that are otherwise efficacious at 24 °C/ 75% RH.

Material Compatibility for Historic Items Decontaminated with ...

EPA Pesticide Factsheets

Report This project continued research of the effects of decontamination methods for biological agents on materials identified as representative of types of irreplaceable objects or works of art found in museums and/or archive settings. In the previous research, surrogate materials were checked for compatibility with four decontamination methods: chlorine dioxide, hydrogen peroxide vapor, methyl bromide, and ethylene oxide gas. This project investigated the effects of gamma irradiation, which has also been shown to be an effective decontamination method for biological agents, on the surrogate test materials.

Inactivation efficiency of plasmid-encoded antibiotic resistance genes during water treatment with chlorine, UV, and UV/H2O2.

PubMed

Yoon, Younggun; Chung, Hay Jung; Wen Di, Doris Yoong; Dodd, Michael C; Hur, Hor-Gil; Lee, Yunho

2017-10-15

This study assessed the inactivation efficiency of plasmid-encoded antibiotic resistance genes (ARGs) both in extracellular form (e-ARG) and present within Escherichia coli (intracellular form, i-ARG) during water treatment with chlorine, UV (254 nm), and UV/H 2 O 2 . A quantitative real-time PCR (qPCR) method was used to quantify the ARG damage to amp R (850 bp) and kan R (806 bp) amplicons, both of which are located in the pUC4K plasmid. The plate count and flow cytometry methods were also used to determine the bacterial inactivation parameters, such as culturability and membrane damage, respectively. In the first part of the study, the kinetics of E. coli inactivation and ARG damage were determined in phosphate buffered solutions. The ARG damage occurred much more slowly than E. coli inactivation in all cases. To achieve 4-log reduction of ARG concentration at pH 7, the required chlorine exposure and UV fluence were 33-72 (mg × min)/L for chlorine and 50-130 mJ/cm 2 for UV and UV/H 2 O 2 . After increasing pH from 7 to 8, the rates of ARG damage decreased for chlorine, while they did not vary for UV and UV/H 2 O 2 . The i-ARGs mostly showed lower rates of damage compared to the e-ARGs due to the protective roles of cellular components against oxidants and UV. The contribution of OH radicals to i-ARG damage was negligible in UV/H 2 O 2 due to significant OH radical scavenging by cellular components. In all cases, the ARG damage rates were similar for amp R versus kan R , except for the chlorination of e-ARGs, in which the damage to amp R occurred faster than that to kan R . Chlorine and UV dose-dependent ARG inactivation levels determined in a wastewater effluent matrix could be reasonably explained by the kinetic data obtained from the phosphate buffered solutions and the expected oxidant (chlorine and OH radicals) demands by water matrix components. These results can be useful in optimizing chlorine and UV-based disinfection systems to achieve ARG inactivation. Copyright © 2017 Elsevier Ltd. All rights reserved.

A comparative study of the processes of generation of singlet oxygen upon irradiation of aqueous preparations on the basis of chlorin e6 and coproporphyrin III

NASA Astrophysics Data System (ADS)

Bagrov, I. V.; Belousova, I. M.; Gorelov, S. I.; Dobrun, M. V.; Kiselev, V. M.; Kislyakov, I. M.; Kris'ko, A. V.; Kris'ko, T. K.

2017-02-01

The photosensitizing ability of an agent based on chlorin e6 (Photoditazin), which is used for photodynamic diagnosis and therapy, is compared with that of a new preparation on the basis of coproporphyrin III in the environment of a phosphate buffer and a simulated biological environment (albumin solution). The efficiency of singlet-oxygen production was estimated by EPR spectroscopy and spectroscopy in the UV and visible ranges with the use of "chemical traps" of singlet oxygen. By irradiating drugs with LED emission centered at λmax = 520 nm, we determined the quantum yield of singlet-oxygen production in a buffer solution; the obtained values are 0.60 and 0.37 for chlorine and coproporphyrin, respectively. The steady-state concentration of singlet oxygen upon irradiation of solutions of the studied photosensitizers with concentrations of 12-43 μM and the density of radiation power within the 6-96 W/cm2 region was found to be in the region of 1010-1011 molecules/cm3. It is shown that the introduction into the solution of egg albumin (0.1%) reduces the sensitizing properties of the two drugs by two to three times, while the efficiencies of the preparations with respect to singlet-oxygen production become almost identical (0.19 and 0.17).

Development of a novel wet oxidation process for hazardous and mixed wastes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dhooge, P.M.

1994-12-31

Many DOE waste streams and remediates contain complex and variable mixtures of organic compounds, toxic metals, and radionuclides. These materials are often dispersed in organic or inorganic matrices, such as personal protective equipment, various sludges, soils, and water. The over all objective of the effort described here is to develop a novel catalytic wet oxidation process for the treatment of these multi-component wastes, with the aim of providing a versatile, non-thermal method which will destroy hazardous organic compounds while simultaneously containing and concentrating toxic and radioactive metals for recovery or disposal in a readily stabilized matrix. The DETOX process usesmore » a unique combination of metal catalysts to increase the rate of oxidation of organic materials. The metal catalysts are in the form of salts dissolved in a dilute acid solution. A typical catalyst composition is 60% ferric chloride, 3--4% hydrochloric acid, 0.13% platinum ions, and 0.13% ruthenium ions in a water solution. The catalyst solution is maintained at 423--473 K. Wastes are introduced into contact with the solution, where their organic portion is oxidized to carbon dioxide and water. If the organic portion is chlorinated, hydrogen chloride will be produced as a product. The process is a viable alternative to incineration for the treatment of organic mixed wastes. Estimated costs for waste treatment using the process are from $2.50/kg to $25.00/kg, depending on the size of the unit and the amount of waste processed. Process units can be mobile for on-site treatment of wastes. Results from phase 1 and 2, design and engineering studies, are described.« less

Bactericidal activity of electrolyzed acid water from solution containing sodium chloride at low concentration, in comparison with that at high concentration.

PubMed

Kiura, Hiromasa; Sano, Kouichi; Morimatsu, Shinichi; Nakano, Takashi; Morita, Chizuko; Yamaguchi, Masaki; Maeda, Toyoyuki; Katsuoka, Yoji

2002-05-01

Electrolyzed strong acid water (ESW) containing free chlorine at various concentrations is becoming to be available in clinical settings as a disinfectant. ESW is prepared by electrolysis of a NaCl solution, and has a corrosive activity against medical instruments. Although lower concentrations of NaCl and free chlorine are desired to eliminate corrosion, the germicidal effect of ESW with low NaCl and free-chlorine concentrations (ESW-L) has not been fully clarified. In this study, we demonstrated that ESW-L possesses bactericidal activity against Mycobacteria and spores of Bacillus subtilis. The effect was slightly weaker than that of ESW containing higher NaCl and free-chlorine concentrations (ESW-H), but acceptable as a disinfectant. To clarify the mechanism of the bactericidal activity, we investigated ESW-L-treated Pseudomonas aeruginosa by transmission electron microscopy, a bacterial enzyme assay and restriction fragment length polymorphism pattern (RFLP) assay. Since the bacterium, whose growth was completely inhibited by ESW-L, revealed the inactivation of cytoplasmic enzyme, blebs and breaks in its outer membrane and remained complete RFLP of DNA, damage of the outer membrane and inactivation of cytoplasmic enzyme are the important determinants of the bactericidal activity.

The application of UV LEDs for differential optical absorption spectroscopy

NASA Astrophysics Data System (ADS)

Geiko, Pavel P.; Smirnov, Sergey S.; Samokhvalov, Ignatii V.

2018-04-01

Modern UV LEDs represent a potentially very advantageous alternative to thermal light sources, in particular xenon arc lamps, which are the most common light sources in trace gas-analyzers. So, the light-emitting diodes are very attractive for use of as light sources for Long Path Differential Optical Absorption Spectroscopy (DOAS) measurements of trace gases in the open atmosphere. Recent developments in fibre-coupling telescope technology and the availability of ultraviolet light emitting diodes have now allowed us to construct a portable, long path DOAS instrument for use at remote locations and specifically for measuring degassing from active volcanic systems. First of all, we are talking about the measurement of sulphur dioxide, carbon disulphide and, oxides of chlorine and bromine. The parallel measurements of sulfur dioxide using a certified gas analyzer, were conducted and showed good correlation.

Studies on the potent bacterial mutagen, 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone: aqueous stability, XAD recovery and analytical determination in drinking water and in chlorinated humic acid solutions.

PubMed

Meier, J R; Knohl, R B; Coleman, W E; Ringhand, H P; Munch, J W; Kaylor, W H; Streicher, R P; Kopfler, F C

1987-12-01

3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) was detected by gas chromatography/mass spectrometry in drinking water samples from 3 locations in the U.S.A., and also in a chlorinated humic acid solution. MX appears to account for a significant proportion of the mutagenicity of these samples, as measured in the Ames test using strain TA100 without metabolic activation. Studies on recovery of MX from spiked water samples by XAD-2/8 resin adsorption/acetone elution indicated that sample acidification prior to resin adsorption was essential to the effective recovery of MX. The stability of MX in aqueous solution was pH and temperature dependent. At 23 degrees C the order of stability, based on persistence of mutagenic activity was found to be: pH 2 greater than pH 4 greater than pH 8 greater than pH 6. The half-life at pH 8 and 23 degrees C was 4.6 days. One of the degradation products has been tentatively identified as 2-chloro-3-(dichloromethyl)-4-oxo-2-butenoic acid, an open form of MX which appears to be in the "E" configuration. Overall, these results suggest that MX is formed during water chlorination as a result of reaction of chlorine with humic substances, and that a substantial fraction of the MX formed is likely to persist throughout the distribution system.

Residual Viral and Bacterial Contamination of Surfaces after Cleaning and Disinfection

PubMed Central

Tuladhar, Era; Hazeleger, Wilma C.; Koopmans, Marion; Zwietering, Marcel H.; Beumer, Rijkelt R.

2012-01-01

Environmental surfaces contaminated with pathogens can be sources of indirect transmission, and cleaning and disinfection are common interventions focused on reducing contamination levels. We determined the efficacy of cleaning and disinfection procedures for reducing contamination by noroviruses, rotavirus, poliovirus, parechovirus, adenovirus, influenza virus, Staphylococcus aureus, and Salmonella enterica from artificially contaminated stainless steel surfaces. After a single wipe with water, liquid soap, or 250-ppm free chlorine solution, the numbers of infective viruses and bacteria were reduced by 1 log10 for poliovirus and close to 4 log10 for influenza virus. There was no significant difference in residual contamination levels after wiping with water, liquid soap, or 250-ppm chlorine solution. When a single wipe with liquid soap was followed by a second wipe using 250- or 1,000-ppm chlorine, an extra 1- to 3-log10 reduction was achieved, and except for rotavirus and norovirus genogroup I, no significant additional effect of 1,000 ppm compared to 250 ppm was found. A reduced correlation between reduction in PCR units (PCRU) and reduction in infectious particles suggests that at least part of the reduction achieved in the second step is due to inactivation instead of removal alone. We used data on infectious doses and transfer efficiencies to estimate a target level to which the residual contamination should be reduced and found that a single wipe with liquid soap followed by a wipe with 250-ppm free chlorine solution was sufficient to reduce the residual contamination to below the target level for most of the pathogens tested. PMID:22941071

Residual viral and bacterial contamination of surfaces after cleaning and disinfection.

PubMed

Tuladhar, Era; Hazeleger, Wilma C; Koopmans, Marion; Zwietering, Marcel H; Beumer, Rijkelt R; Duizer, Erwin

2012-11-01

Environmental surfaces contaminated with pathogens can be sources of indirect transmission, and cleaning and disinfection are common interventions focused on reducing contamination levels. We determined the efficacy of cleaning and disinfection procedures for reducing contamination by noroviruses, rotavirus, poliovirus, parechovirus, adenovirus, influenza virus, Staphylococcus aureus, and Salmonella enterica from artificially contaminated stainless steel surfaces. After a single wipe with water, liquid soap, or 250-ppm free chlorine solution, the numbers of infective viruses and bacteria were reduced by 1 log(10) for poliovirus and close to 4 log(10) for influenza virus. There was no significant difference in residual contamination levels after wiping with water, liquid soap, or 250-ppm chlorine solution. When a single wipe with liquid soap was followed by a second wipe using 250- or 1,000-ppm chlorine, an extra 1- to 3-log(10) reduction was achieved, and except for rotavirus and norovirus genogroup I, no significant additional effect of 1,000 ppm compared to 250 ppm was found. A reduced correlation between reduction in PCR units (PCRU) and reduction in infectious particles suggests that at least part of the reduction achieved in the second step is due to inactivation instead of removal alone. We used data on infectious doses and transfer efficiencies to estimate a target level to which the residual contamination should be reduced and found that a single wipe with liquid soap followed by a wipe with 250-ppm free chlorine solution was sufficient to reduce the residual contamination to below the target level for most of the pathogens tested.

Conversion of Carbon Dioxide into Ethanol by Electrochemical Synthesis Method Using Cu-Zn Electrode

NASA Astrophysics Data System (ADS)

Riyanto; Ramadan, S.; Fariduddin, S.; Aminudin, A. R.; Hayatri, A. K.

2018-01-01

Research on conversion of carbon dioxide into ethanol has been done. The conversion process is carried out in a sodium bicarbonate electrolyte solution in an electrochemical synthesis reactor. As cathode was used Cu-Zn, while as anode carbon was utilized. Variations of voltage, concentration of sodium bicarbonate electrolyte solution and time of electrolysis were performed to determine the optimum conditions to convert carbon dioxide into ethanol. Sample of the electrochemical synthesis process was analyzed by gas chromatography. From the result, it is found that the optimum conditions of the electrochemical synthesis process of carbon dioxide conversion into ethanol are voltage, concentration of sodium bicarbonate electrolyte solution and time of electrolysis are 3 volts, 0.4 M and 90 minutes with the ethanol concentration of 10.44%.

Precipitated Silica from Pumice and Carbon Dioxide Gas (Co2) in Bubble Column Reactor

NASA Astrophysics Data System (ADS)

Dewati, R.; Suprihatin, S.; Sumada, K.; Muljani, S.; Familya, M.; Ariani, S.

2018-01-01

Precipitated silica from silica and carbon dioxide gas has been studied successfully. The source of silica was obtained from pumice stone while precipitation process was carried out with carbon dioxide gas (CO2). The sodium silicate solution was obtained by extracting the silica from pumice stone with sodium hydroxide (NaOH) solution and heated to 100 °C for 1 h. The carbon dioxide gas is injected into the aqueous solution of sodium silicate in a bubble column reactor to form precipitated silica. m2/g. The results indicate that the products obtained are precipitate silica have surface area in the range of 100 - 227 m2/g, silica concentration more than 80%, white in appearance, and silica concentration reached 90% at pH 7.

[Degradation Kinetics and Formation of Disinfection By-products During Linuron Chlorination in Drinking Water].

PubMed

Ling, Xiao; Hu, Chen-yan; Cheng, Ming; Gu, Jian

2015-05-01

Chlorination degradation of linuron was studied using the common disinfectant sodium hypochlorite, the effects of chlorine dosage, pH value, bromine ion concentrationand temperature were systematically investigated, and the formation characteristics of disinfection by-products (DBPs) during the chlorination reaction was analyzed. The results showed that the chlorination degradation kinetics of linuron by sodium hypochlorite could be well described by the second-order kinetic model. Moreover, pH values had a great impact on the degradation reaction, and the rate constant reached the maximum level at pH 7, and the base elementary reaction rate constants of HOCl and OCl- with linuron were 4.84 x 10(2) L · (mol · h)(-1) and 3.80 x 10(2) L · (mol · h)(-1), respectively. The reaction rate decreased with the addition of bromide ion and increased with increasing temperature. Furthermore, many kinds of disinfection by- products were produced during the chlorination degradation of linuron, including CF, DCAN, TCNM and halogen acetone. Under conditions of different solution pH and different bromide ion concentrations, there would be significant difference in the types and concentrations of disinfection by-products.

Oxidation of formic acid by oxyanions of chlorine and its implications to the Viking Labeled Release experiment

NASA Astrophysics Data System (ADS)

Martinez, P.; Navarro-gonzalez, R.

2013-05-01

The Viking Landers that arrived on Mars in 1976 carried out three biological experiments designed to investigate if there was microbial life. These were the Gas-Exchange, Pyrolitic Release and Labeled Release experiments. The three experiments yielded positive responses but the Labeled Release experiment had a kinetic response indicative of microbial activity. The experiment consisted of adding a broth of nutrients (formic acid, glycolic acid, glycine, D- and L-alanine and D- and L-lactic acid uniformly marked with 14C) to martian soil samples. The results were surprising; the nutrients were consumed releasing radioactive gases in a manner that is compatible by terrestrial microorganisms. The existence of Martian life was contradicted by soil chemical analysis that indicated the absence of organic compounds above the detection limits of parts per billion (ppb). Instead the positive response of the Labeled Release Experiment was attributed to the existence of peroxides and/or superoxides in the Martian soils that destroyed the nutrients upon contact. Recently, the Phoenix mission that landed in the Martian Arctic in 2008 revealed the presence of a highly oxidized form of the element chlorine in the soil: perchlorate. Perchlorate is thought to have formed in the Martian atmosphere by the oxidation of chloride from volcanic sources with ozone. Therefore perchlorate is formed by the stepwise oxidation of hypochlorite, chlorite and chlorate. These oxyanions of chlorine are powerful oxidizers that may exist in the Martian soil and may have reacted with the nutrients of the Labeled Release Experiment. This paper aims to better understand these results by designing experiments to determine the kinetics of decomposition of formic acid to carbon dioxide with different oxidized forms of chlorine by headspace technique in gas chromatography coupled to mass spectrometry (GC / MS). Previous studies done in the laboratory showed that only hypochlorite quantitatively reacted with the formate, this is why we conducted experiments at 20 ° C, 30 ° C and 40 ° C at times 0, 0.1, 0.5, 1, 3 , 5, 10, 20, 30, 40 and 60 min. The resulting kinetics were similar to those obtained by the LR experiment, however the speeds at which reacted in the laboratory were very rapid, almost instantaneous, a comparison of the acquired by the Viking was kinetics days. This may be because in the laboratory we do not used soil samples, Viking used Mars regolith Martian, like a complex matrix that may affect the reaction rate. We conclude that the response obtained by the LR experiment is possibly due to the presence of oxyanions of chlorine, hypochlorite specific which is increased by the dismutations chlorine species in solution, all in combination with other components very likely soil nutrients reacted with isotopically labeled. This project is still ongoing, open a new hypothesis of whether there is microbial life on Mars, since, if the Labeled Release experiment found no biological activity, may have been a chemical oxidation of organic nutrients for sodium hypochlorite .

Transformation mechanism of benzophenone-4 in free chlorine promoted chlorination disinfection.

PubMed

Xiao, Ming; Wei, Dongbin; Yin, Junxia; Wei, Guohua; Du, Yuguo

2013-10-15

The UV-filter BP-4 (2-hydroxy-4-methoxybenzophenone-5-sulfonic acid) has been frequently observed in the environment, showing high potentials to invade drinking water, swimming water, or wastewater reclamation treatment systems. With the help of high performance liquid chromatography-high resolution mass spectrometry and nuclear magnetic resonance spectroscopy, 10 new products from free chlorine-promoted BP-4 disinfection have been disclosed and their possible transformation routes have been investigated. The first route is chlorine substitution of BP-4 and its transformation products, forming mono-, di-, and tri-chlorinated BP-4 analogs. The second is Baeyer-Villiger-Type oxidation, converting diphenyl ketone to phenyl ester derivatives. The third is ester hydrolysis, generating corresponding phenolic and benzoic products. The fourth is decarboxylation, replacing the carboxyl group by chloride in the benzoic-type intermediate. The fifth is desulfonation, degrading the sulfonic group through an alternative chlorine substitution on the benzene ring. Orthogonal experiments have been established to investigate the species transformed from BP-4 at different pH values and free available chlorine (FAC) dosages. The reaction pathways are strongly dependent on pH conditions, while an excessive amount of FAC eliminates BP-4 to the smaller molecules. The initial transformation of BP-4 in chlorination system follows pseudo-first-order kinetics, and its half-lives ranged from 7.48 s to 1.26 × 10(2) s. More importantly, we have observed that the FAC-treated BP-4 aqueous solution might increase the genotoxic potentials due to the generation of chlorinated disinfection by-products. Copyright © 2013 Elsevier Ltd. All rights reserved.

Catalysis of copper corrosion products on chlorine decay and HAA formation in simulated distribution systems.

PubMed

Zhang, Hong; Andrews, Susan A

2012-05-15

This study investigated the effect of copper corrosion products, including Cu(II), Cu(2)O, CuO and Cu(2)(OH)(2)CO(3), on chlorine degradation, HAA formation, and HAA speciation under controlled experimental conditions. Chlorine decay and HAA formation were significantly enhanced in the presence of copper with the extent of copper catalysis being affected by the solution pH and the concentration of copper corrosion products. Accelerated chlorine decay and increased HAA formation were observed at pH 8.6 in the presence of 1.0 mg/L Cu(II) compared with that observed at pH 6.6 and pH 7.6. Further investigation of chlorine decay in the presence of both Suwannee River NOM and Cu(II) indicated that an increased reactivity of NOM with dissolved and/or solid surface-associated Cu(II), rather than chlorine auto-decomposition, was a primary reason for the observed rapid chlorine decay. Copper corrosion solids [Cu(2)O, CuO, Cu(2)(OH)(2)CO(3)] exhibited catalytic effects on both chlorine decay and HAA formation. Contrary to the results observed when in the absence of copper corrosion products, DCAA formation was consistently predominant over other HAA species in the presence of copper corrosion products, especially at neutral and high pH. This study improves the understanding for water utilities and households regarding chlorine residuals and HAA concentrations in distribution systems, in particular once the water reaches domestic plumbing where copper is widely used. Copyright © 2012 Elsevier Ltd. All rights reserved.

Electrophotolysis oxidation system for measurement of organic concentration in water

NASA Technical Reports Server (NTRS)

Winkler, H. E. (Inventor)

1981-01-01

Methods and apparatus for determining organic carbon in aqueous solution are described. The method comprises subjecting the aqueous solution to electrolysis, for generating oxygen from water, and simultaneously to ultraviolet radiation, for oxidation of substantially all organic carbon to carbon dioxide. The carbon dioxide is measured and the value is related to the concentration of organic carbon in the aqueous solution.

Demonstration tests of irrigation water disinfection with chlorine dioxide in open field cultivation of baby spinach.

PubMed

López-Gálvez, Francisco; Gil, Maria I; Meireles, Ana; Truchado, Pilar; Allende, Ana

2018-06-01

Treatments for the disinfection of irrigation water have to be evaluated by demonstration tests carried out under commercial settings taking into account not only their antimicrobial activity but also the potential phytotoxic effects on the crop. The consequences of the treatment of irrigation water with chlorine dioxide (ClO 2 ) used for sprinkler irrigation of baby spinach in two commercial agricultural fields was assessed. Residual ClO 2 levels at the sprinklers in the treated field were always below 1 mg L -1 . ClO 2 treatment provoked limited but statistically significant reductions in culturable Escherichia coli counts (0.2-0.3 log reductions), but not in the viable E. coli counts in water, suggesting the presence of viable but non-culturable cells (VBNC). Although disinfected irrigation water did not have an impact on the microbial loads of Enterobacteriaceae nor on the quality characteristics of baby spinach, it caused the accumulation of chlorates (up to 0.99 mg kg -1 in plants) and the reduction of the photosynthetic efficiency of baby spinach. Low concentrations of ClO 2 are effective in reducing the culturable E. coli present in irrigation water but it might induce the VBNC state. Presence of disinfection by-products and their accumulation in the crop must be considered to adjust doses in order to avoid crop damage and chemical safety risks. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Factors affecting the formation of iodo-trihalomethanes during oxidation with chlorine dioxide.

PubMed

Guo, Wanhong; Shan, Yingchun; Yang, Xin

2014-01-15

Effects of water characteristics, reaction time, temperature, bromide and iodide ion concentrations, oxidant doses, and pH on formation of iodinated trihalomethanes (I-THM) during oxidation of iodide-containing water with chlorine dioxide (ClO2) were investigated. Among the water samples collected from ten water sources, iodoform (CHI3) was the predominant I-THM and trace amount of chlorodiiodomethane (CHClI2) was occasionally found. CHI3 yields correlated moderately with specific UV absorbance (SUVA) (R(2)=0.79), indicating that hydrophobic aromatic content were important precursors. Longer reaction time led to continued formation of CHI3. I-THM containing bromide was also found in waters containing both bromide and iodide, but CHI3 was dominant. The formation of CHI3 was higher at 25°C than 5°C and 35°C. CHI3 formation showed an increase followed by a decrease trend with increasing ClO2 doses and iodide concentrations and the highest yields occurred at iodide to ClO2 molar ratios of 1-2. pH 8 resulted in the highest CHI3 formation. It should be noted that a high iodide concentration was spiked to waters before adding ClO2 and the results may not reflect the formation yields of iodinated THMs in real conditions, but they provide information about formation trend of I-THM during oxidation of ClO2. Copyright © 2013 Elsevier B.V. All rights reserved.

Tolerance of dormant and active cells in Pseudomonas aeruginosa PA01 biofilm to antimicrobial agents.

PubMed

Kim, Jaeeun; Hahn, Ji-Sook; Franklin, Michael J; Stewart, Philip S; Yoon, Jeyong

2009-01-01

The aim of the study was to determine the susceptibility of active and dormant cell populations from Pseudomonas aeruginosa biofilms to non-antibiotic antimicrobial agents such as chlorine, hydrogen peroxide and silver ions in comparison with antibiotics. Active cells in colony biofilm were differentially labelled by induction of a green fluorescent protein (GFP). Active and dormant cells were sorted in phosphate buffered solution by flow cytometry. Reductions in viability were determined with plate counts. The spatial pattern of metabolic activity in colony biofilm was verified, and the active and dormant cells were successfully sorted according to the GFP intensity. Active cells had bigger cell size and higher intracellular density than dormant cells. While dormant cells were more tolerant to tobramycin and silver ions, active cells were more tolerant to chlorine. Metabolically active cells contain denser intracellular components that can react with highly reactive oxidants such as chlorine, thereby reducing the available concentrations of chlorine. In contrast, the concentrations of silver ions and hydrogen peroxide were constant during treatment. Aerobically grown stationary cells were significantly more tolerant to chlorine unlike other antimicrobial agents. Chlorine was more effective in inactivation of metabolically inactive dormant cells and also more effective under anaerobic conditions. The high oxidative reactivity and rapid decay of chlorine might influence the different antimicrobial actions of chlorine compared with antibiotics. This study contributes to understanding the effects of dormancy and the presence of oxygen on the susceptibility of P. aeruginosa biofilm to a wide range of antimicrobial agents.

Dechlorination of short chain chlorinated paraffins by nanoscale zero-valent iron.

PubMed

Zhang, Zhi-Yong; Lu, Mang; Zhang, Zhong-Zhi; Xiao, Meng; Zhang, Min

2012-12-01

In this study, nanoscale zero-valent iron (NZVI) particles were synthesized and used for the reductive dehalogenation of short chain chlorinated paraffins (SCCPs) in the laboratory. The results show that the dechlorination rate of chlorinated n-decane (CP(10)) by NZVI increased with decreased solution pH. Increasing the loading of NZVI enhanced the dechlorination rate of CP(10). With an increase in temperature, the degradation rate increased. The reduction of CP(10) by NZVI was accelerated with increasing the concentration of humic acid up to 15 mg/L but then was inhibited. The dechlorination of CP(10) within the initial 18 h followed pseudo-first order rate model. The formation of intermediate products indicates a stepwise dechlorination pathway of SCCPs by NZVI. The carbon chain length and chlorination degree of SCCPs have a polynominal impact on dechlorination reactions. Copyright © 2012 Elsevier B.V. All rights reserved.

THE RESPONSE OF SOME HEALTH PHYSICS INSTRUMENTS TO SODIUM-24 AND CHLORINE- 38 ACTIVITIES IN POLYTHENE MANPHANTOMS AND THE HUMAN BODY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peabody, C.O.

1963-12-01

Measurements were made of the response of five commonly used health physics instruments when held near polythene man-phantoms filled with aqueous solutions containing sodium-24 and chlorine-38. The ratios of the wholebody chlorine-38 and sodium-24 activities are calculated for various periods of accidental human irradiation by neutrons. These ratios and the phantom results are used to estimate the response of the five instruments when held near the human body at various times after irradiation. Relative contributions of the chlorine-38 and sodium-24 to the instrument indications are listed. The tabulated data enable the instrument readings to be converted to wholebody sodium- 24more » activity at the time of irradiation. This may be used as a quick estimate of the degree of neutron irradiation. (auth)« less