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Sample records for monochloramine chlorine dioxide

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

    OpenAIRE

    Korich, D. G.; Mead, J R; Madore, M S; Sinclair, N A; Sterling, C R

    1990-01-01

    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% inactiv...

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

    Energy Technology Data Exchange (ETDEWEB)

    Korich, D.G.; Mead, J.R.; Madore, M.S.; Sinclair, N.A.; Sterling, C.R. (Univ. of Arizona, Tucson (USA))

    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 times 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.

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

    Science.gov (United States)

    Korich, D G; Mead, J R; Madore, M S; Sinclair, N A; Sterling, C R

    1990-01-01

    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 times 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. PMID:2339894

  4. Inactivation of simian rotavirus SA11 by chlorine, chlorine dioxide, and monochloramine.

    OpenAIRE

    Berman, D; Hoff, J C

    1984-01-01

    The kinetics of inactivation of simian rotavirus SA11 by chlorine, chlorine dioxide, and monochloramine were studied at 5 degrees C with a purified preparation of single virions and a preparation of cell-associated virions. Inactivation of the virus preparations with chlorine and chlorine dioxide was studied at pH 6 and 10. The monochloramine studies were done at pH 8. With 0.5 mg of chlorine per liter at pH 6, more than 4 logs (99.99%) of the single virions were inactivated in less than 15 s...

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

    OpenAIRE

    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 o...

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

    Science.gov (United States)

    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

  7. Cellular response of the amoeba Acanthamoeba castellanii to chlorine, chlorine dioxide, and monochloramine treatments.

    Science.gov (United States)

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

    2011-07-01

    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.

  8. Monochloramine and chlorine dioxide for controlling Legionella pneumophila contamination: biocide levels and disinfection by-product formation in hospital water networks.

    Science.gov (United States)

    Marchesi, Isabella; Ferranti, Greta; Bargellini, Annalisa; Marchegiano, Patrizia; Predieri, Guerrino; Stout, Janet E; Borella, Paola

    2013-12-01

    Legionella colonization in hospital hot water distribution networks was evaluated following 36 months of continuous treatment with monochloramine and compared with chlorine dioxide. Nitrite, nitrate, chlorite, chlorate, bromide, trihalomethanes and haloacetic acids as well as the biocide concentration at sampled points were measured. Only 8/84 samples treated with monochloramine were found contaminated and after the first 8 months of treatment no Legionella was isolated. Chlorine dioxide was associated with a strong reduction in Legionella contamination compared to pre-treatment, but differences according to the device were observed. Monochloramine between 2 and 3 mg l(-1) and chlorine dioxide between 0.50 and 0.70 mg l(-1) were needed to control Legionella colonization. Comparing no- and post-flush samples, a higher frequency of no-flush positive samples was noted using chlorine dioxide, suggesting an increased risk for patients when they open the tap. No increase in chlorite levels and no water nitrification occurred by using monochloramine. Chlorite at levels exceeding the limit requested for drinking water was measured when chlorine dioxide was applied. In conclusion, we highlight that continuous injection of monochloramine should be considered as an effective alternative to chlorine dioxide in controlling legionellae contamination inside hospital water distribution systems.

  9. 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.

    Science.gov (United States)

    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.

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

    OpenAIRE

    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 wer...

  11. Synergetic Inactivation of Microorganisms in Drinking Water by Short-term Free Chlorination and Subsequent Monochloramination

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    To introduce synergetic inactivation of microorganisms in drinking water by short-term free chlorination for less than 15 minutes followed by monochloramination. Methods Indicator microorganisms such as Escherichia coli,Staphylococcus aureus, Candida albicans, and spores of Bacillus subtilis were used to assess the efficiency of sequential chlorination and free chlorination. Results The sequential chlorination was more efficient in inactivating these microorganisms than free chlorination, indicating that synergy was provided by free chlorine and monochloramine. Ammonia addition time, temperature and pH had influences on this synergy. Conclusion The possible mechanism of this synergy might involve three aspects: free chlorine causing sublethal injury to microorganisms and monochloramine further inactivating them; different ability of free chlorine and monochloramine to penetrate and inactivate microorganism congeries; and higher concentration of residual chlorine in sequential chlorination than in free chlorination.

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

    Science.gov (United States)

    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

  13. Chlorination or monochloramination: Balancing the regulated trihalomethane formation and microbial inactivation in marine aquaculture waters

    KAUST Repository

    Sanawar, Huma

    2017-08-15

    Disinfection methods like chlorination are increasingly used to sanitize the water, equipment, tools and surfaces in aquaculture facilities. This is to improve water quality, and to maintain a hygienic environment for the well-being of aquatic organisms. However, chlorination can result in formation of regulated disinfection byproducts (DBPs) that can be carcinogenic and toxic. This study aims to evaluate if an optimal balance can be achieved between minimal regulated DBP formation and effective microbial inactivation with either chlorination or monochloramination for application in the Red Sea aquaculture waters. Upon chlorination, the concentration of total trihalomethanes (THMs), primarily bromoform, exceeded the regulatory limit of 80μg/L even at the lowest tested concentration of chlorine (1mg/L) and contact time (1h). Comparatively, regulated THMs concentration was only detectable at 30μg/L level in one of the three sets of monochloraminated marine aquaculture waters. The average log reduction of antibiotic-resistant bacteria (ARB) by chlorine ranged from 2.3-log to 3.2-log with different contact time. The average log reduction of ARB by monochloramine was comparatively lower at 1.9 to 2.9-log. Although viable Staphylococcus aureus was recovered from monochloraminated samples as opposed to chlorinated samples, the abundance of S. aureus was not high enough to result in any significant microbial risks. Both chlorination and monochloramination did not provide any significant improvement in the reduction of antibiotic resistance genes (ARGs). This study demonstrates that a systematic evaluation is needed to determine the optimal disinfectant required to balance both microbial and chemical risks. Compared to chlorine, monochloramine may be a more appropriate disinfection strategy for the treatment of aquaculture effluents prior to discharge or for recirculatory use in the aquaculture facility.

  14. Reaction products of chlorine dioxide.

    OpenAIRE

    Stevens, A A

    1982-01-01

    Inspection of the available literature reveals that a detailed investigation of the aqueous organic chemistry of chlorine dioxide and systematic identification of products formed during water disinfection has not been considered. This must be done before an informed assessment can be made of the relative safety of using chlorine dioxide as a disinfectant alternative to chlorine. Although trihalomethanes are generally not formed by the action of chlorine dioxide, the products of chlorine dioxi...

  15. Reaction products of chlorine dioxide.

    OpenAIRE

    Stevens, A. A.

    1982-01-01

    Inspection of the available literature reveals that a detailed investigation of the aqueous organic chemistry of chlorine dioxide and systematic identification of products formed during water disinfection has not been considered. This must be done before an informed assessment can be made of the relative safety of using chlorine dioxide as a disinfectant alternative to chlorine. Although trihalomethanes are generally not formed by the action of chlorine dioxide, the products of chlorine dioxi...

  16. Chlorine dioxide and hemodialysis

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R.P. (Dartmouth Coll., Hanover, NH (USA). Dept. of Pharmacology and Toxicology)

    1989-05-01

    Because it has little or no tendency to generate carcinogenic trihalomethanes such as chloroform, chlorine dioxide is an attractive alternative to chlorine for drinking water disinfection. There are, however, concerns about its acute toxicity, and the toxic effects of its by-products, chlorite and chlorate. The human experience with chlorine dioxide in both controlled, prospective studies and in actual use situations in community water supplies have as yet failed to reveal adverse health effects. The EPA has recommended standards of 0.06 mg/L for chlorine dioxide and standards of 0.007 mg/L for chlorite and chlorate in drinking water. Among groups who may be at special risk from oxychlorines in drinking water are patients who must undergro chronic extracorporeal hemodialysis. Although even units for home hemodialysis are supposed to be equipped with devices which effectively remove oxychlorines, there is a always a possibility of operator error or equipment failure. When the equipment is adequately maintained, it is likely that dialysis patients will have more intensive exposures from drinking water than from dialysis fluids despite the much larger volumes of water that are involved in dialysis. This paper discusses a hemodialysis and the standards and effects of oxychlorines. 90 refs., 2 tabs.

  17. Reaction products of chlorine dioxide.

    Science.gov (United States)

    Stevens, A A

    1982-01-01

    Inspection of the available literature reveals that a detailed investigation of the aqueous organic chemistry of chlorine dioxide and systematic identification of products formed during water disinfection has not been considered. This must be done before an informed assessment can be made of the relative safety of using chlorine dioxide as a disinfectant alternative to chlorine. Although trihalomethanes are generally not formed by the action of chlorine dioxide, the products of chlorine dioxide treatment of organic materials are oxidized species, some of which also contain chlorine. The relative amounts of species types may depend on the amount of chlorine dioxide residual maintained and the concentration and nature of the organic material present in the source water. The trend toward lower concentrations of chlorinated by-products with increasing ClO2 concentration, which was observed with phenols, has not been observed with natural humic materials as measured by the organic halogen parameter. Organic halogen concentrations have been shown to increase with increasing chlorine dioxide dose, but are much lower than those observed when chlorine is applied. Aldehydes have been detected as apparent by-products of chlorine dioxide oxidation reactions in a surface water that is a drinking water source. Some other nonchlorinated products of chlorine dioxide treatment may be quinones and epoxides. The extent of formation of these moieties within the macromolecular humic structure is also still unknown. PMID:7151750

  18. Susceptibility of Legionella strains to the chlorinated biocide, monochloramine.

    Science.gov (United States)

    Jakubek, Delphine; Guillaume, Carole; Binet, Marie; Leblon, Gérard; DuBow, Michael; Le Brun, Matthieu

    2013-01-01

    Members of the Legionella genus find suitable conditions for their growth and survival in nuclear power plant cooling circuits. To limit the proliferation of Legionella pathogenic bacteria in nuclear power plant cooling circuits, and ensure that levels remain below regulatory thresholds, monochloramine treatment can be used. Although the treatment is highly effective, i.e. it reduces Legionella numbers by over 99%, Legionella bacteria can still be detected at low concentrations and rapid re-colonisation of circuits can occur after the treatment has ceased. The aim of this study was to develop an in vitro methodology for determining the intrinsic susceptibility of L. pneumophila strains, collected from various nuclear power plant cooling circuits subjected to different treatment conditions. The methodology was developed by using an original approach based on response surface methodology (RSM) combined with a multifactorial experimental design. The susceptibility was evaluated by the Ct factor. The susceptibility of environmental strains varies widely and is, for some strains, greater than that of known tolerant species; however, strain susceptibility was not related to treatment conditions. Selection pressure induced by monochloramine use did not result in the selection of more tolerant Legionella strains and did not explain the detection of Legionella during treatment or the rapid re-colonisation of cooling circuits after disinfection has ceased.

  19. Comparison of electrochemical method with ozonation, chlorination and monochloramination in drinking water disinfection

    Energy Technology Data Exchange (ETDEWEB)

    Li Hongna, E-mail: lihongna@gmail.com [Department of Environmental Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871 (China); Zhu Xiuping [Department of Environmental Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871 (China); Ni Jinren, E-mail: nijinren@iee.pku.edu.cn [Department of Environmental Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871 (China)

    2011-11-30

    Highlights: > Electrochemical, O{sub 3}, NaClO and NH{sub 2}Cl were compared at respective optimal condition. > Disinfection efficacy was similar for different bacteria in electrolysis. > Harsh Bacillus was inactivated more difficult in O{sub 3}, NaClO and NH{sub 2}Cl system. > Efficient disinfection of electrolysis was attributed to nonselectivity of {center_dot}OH. > Cell surface damage was more obvious in electrochemical process than the others. - Abstract: Electrochemical process in chloride-free electrolytes was proved to be powerful in disinfection due to the strong oxidants produced in the electrolysis and no formation of disinfection byproducts (DBPs). In this study, disinfection experiments were conducted by electrochemical treatment compared with ordinary and advanced methods (ozonation, chlorination and monochloramination), with Escherichia coli (E. coli) K-12, Staphylococcus aureus (S. aureus) A106, Bacillus subtilis (BST) and an isolated Bacillus as the representative microorganisms. Firstly, factor tests were performed on E. coli to obtain the optimal conditions of the four disinfection procedures. At their respective optimal condition, CT (concentration of disinfectant x contact time) value of a 4-log E. coli inactivation was 33.5, 1440, 1575, 1674 mg min L{sup -1} for electrochemical process, ozonation, chlorination and monochloramination, respectively. It was demonstrated that the disinfection availability was in the following order: electrochemical process > ozonation > chlorination > monochloramination, which could be attributed to the hydroxyl radical generated in the electrolysis, with strong oxidizing ability and non-selectivity compared with the other three disinfectants. Moreover, the disinfection efficacy of the four disinfection procedures was compared for four different bacteria. It was found that the disinfection efficacy was similar for the selected four bacteria in electrochemical process, while in the other three treatments

  20. Comparison of the efficacy of free residual chlorine and monochloramine against biofilms in model and full scale cooling towers.

    Science.gov (United States)

    Türetgen, Irfan

    2004-04-01

    The presence of microbial cells on surfaces results in the formation of biofilms, which may also give rise to microbiologically influenced corrosion. Biofilms accumulate on all submerged industrial and environmental surfaces. The efficacy of disinfectants is usually evaluated using planktonic cultures, which often leads to an underestimate of the concentration required to control a biofilm. The aim of this study was to investigate the efficacy of monochloramine on biofilms developed in a cooling tower. The disinfectants selected for the study were commercial formulations recommended for controlling microbial growth in cooling towers. A cooling tower and a laboratory model recirculating water system were used as biofilm reactors. Although previous studies have evaluated the efficacy of free chlorine and monochloramine for controlling biofilm growth, there is a lack of published data concerning the use monochloramine in cooling towers. Stainless steel coupons were inserted in each tower basin for a period of 30 d before removal. Monochloramine and free chlorine were tested under identical conditions on mixed biofilms which had been allowed to grow on coupons. Monochloramine was found to be significantly more effective than free chlorine against cooling tower biofilms.

  1. Kinetics of the oxidation of cylindrospermopsin and anatoxin-a with chlorine, monochloramine and permanganate.

    Science.gov (United States)

    Rodríguez, Eva; Sordo, Ana; Metcalf, James S; Acero, Juan L

    2007-05-01

    Cyanobacteria produce toxins that may contaminate drinking water sources. Among others, the presence of the alkaloid toxins cylindrospermopsin (CYN) and anatoxin-a (ANTX) constitutes a considerable threat to human health due to the acute and chronic toxicity of these compounds. In the present study, not previously reported second-order rate constants for the reactions of CYN and ANTX with chlorine and monochloramine and of CYN with potassium permanganate were determined and the influence of pH and temperature was established for the most reactive cases. It was found that the reactivity of CYN with chlorine presents a maximum at pH 7 (rate constant of 1265 M(-1)s(-1)). However, the oxidation of CYN with chloramine and permanganate are rather slow processes, with rate constants <1 M(-1)s(-1). The first chlorination product of CYN was found to be 5-chloro-CYN (5-Cl-CYN), which reacts with chlorine 10-20 times slower than the parent compound. The reactivity of ANTX with chlorine and chloramines is also very low (k<1M(-1)s(-1)). The elimination of CYN and ANTX in surface water was also investigated. A chlorine dose of 1.5 mg l(-1) was enough to oxidize CYN almost completely. However, 3 mg l(-1) of chlorine was able to remove only 8% of ANTX, leading to a total formation of trihalomethanes (TTHM) at a concentration of 150 microg l(-1). Therefore, chlorination is a feasible option for CYN degradation during oxidation and disinfection processes but not for ANTX removal. The permanganate dose required for CYN oxidation is very high and not applicable in waterworks.

  2. Efficacy of chlorine dioxide mouthwash against halitosis

    Science.gov (United States)

    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 (pChlorine dioxide mouthwash is effective in addressing halitosis.

  3. Improved method generates more chlorine dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, R.W.; Kosinski, A.J.; Baker, R.J.

    1980-10-01

    The addition of acid can greatly improve the chlorine-chlorite process and enhance the use of chlorine dioxide as an alternative to chlorine for disinfection. The process is economical for use in taste and odor control, and for manganese, oxidation. The maximum yield is obtained using no excess chlorine, and the amount of unreacted sodium chlorite and chlorine in the product stream is reduced. (1 diagram, 4 graphs, 9 references)

  4. The photoreactivity of chlorine dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Vaida, V. [Univ. of Colorado, Boulder, CO (United States); Simon, J.D. [Univ. of California, San Diego, La Jolla, CA (United States)

    1995-06-09

    Determining the detailed photoreactivity of radicals that are of importance in atmospheric processes requires information from both laboratory and field measurements and theoretical calculations. Laboratory experiments and quantum calculations have been used to develop a comprehensive understanding of the photoreactivity of chlorine dioxide (OClO). The photoreactivity is strongly dependent on the medium (gas phase, liquid solution, or cryogenic matrix). These data reveal details of the complex chemistry of OClO. The potential role of this radical in stratospheric ozone depletion is discussed in accord with these laboratory measurements. 53 refs., 4 figs.

  5. [Comparison of the quality and toxicity of wastewater after chlorine and chlorine dioxide disinfections].

    Science.gov (United States)

    Wang, Li-sha; Zhang, Tong; Hu, Hong-ying

    2005-11-01

    The effects of chlorine and chlorine dioxide disinfections on quality and toxicity of wastewater were compared. The experiment results showed that chlorine disinfection had no obvious effect on wastewater color, while chlorine dioxide disinfection decreased wastewater color observably. The DOC of wastewater did not change much after chlorine and chlorine dioxide disinfections. Chlorine disinfection significantly increased UV230 of wastewater and chlorine dioxide disinfection slightly decreased UV230 of wastewater. When the disinfectants dosage was 30 mg/L, UV230 increased about 0.7 cm(-1) after chlorine disinfection and decreased about 0.05 cm(-1) after chlorine dioxide disinfection. The acute toxicity of wastewater increased with increasing disinfectants dosage for both chlorine and chlorine dioxide disinfections and the acute toxicity after chlorine disinfection is much stronger than that after chlorine dioxide disinfection. The genotoxicity of wastewater increased slightly after chlorine disinfection and decreased slightly after chlorine dioxide disinfection.

  6. Chlorine dioxide and by-products in water distribution systems

    OpenAIRE

    Ferreira, Francisco Cardoso

    1991-01-01

    Chlorine dioxide is used as both a pre-oxidant and/or a post-disinfectant in several water treatment plants in the United States. Chlorine dioxide is associated with its byproducts chlorite and chlorate. Chlorine dioxide, chlorine, chlori te and chlorate were sampled in four distribution systems where chlorine dioxide is used for disinfection purposes: Charleston, WV, Columbus, GA, New Castle, PA, and Skagit, WA. The fate of chlorine dioxide and its by-products in dist...

  7. Inactivation of Chironomid Larvae with Chlorine Dioxide and Chlorine

    Institute of Scientific and Technical Information of China (English)

    SUN Xin-bin; CUI Fu-yi

    2008-01-01

    Chironomid larvae propagate prolifically in eutrophic water body and they cannot be exterminated by conventional disinfection process.The inactivation effects of chlorine and chlorine dioxide on Chironomid larvae were investigated and some boundary values in practice were determined under conditions of various oxidant dosage,organic precursor concentration and pH value.In addition,removal effect of differmt pre-oxidation combined with coagulation process on Chironomid larvae in law water was evaluated.It was found that chlorine dioxide possessed better inactivation effect than chlorine.Complete inactivation of Chironomid larvae in raw water was resulted by 1.5mg/L of chlorine dioxide with 30min of contact time. Additionally,the ocgallic precursor concentration,pH value had little influence on the inactivation effect.The coagulation jar test showed that Chironomid larvae in the raw water could be completely ronxwed by chlorine dioxide pre-oxidation in combination with the omgulation process at chlorine dioxide dosage of 0.8 mg/L.

  8. Electron affinity of chlorine dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Babcock, L.M.; Pentecost, T.; Koppenol, W.H. (Louisiana State Univ., Baton Rouge (USA))

    1989-12-14

    The flowing afterglow technique was used to determine the electron affinity of chlorine dioxide. A value of 2.37 {plus minus} 0.10 eV was found by bracketing between the electron affinities of HS* and SF{sub 4} as a lower limit and that of NO{sub 2} as an upper limit. This value is in excellent agreement with 2.32 eV predicted from a simple thermodynamic cycle involving the reduction potential of the ClO{sub 2}/ClO{sub 2}{sup {minus}} couple and a Gibbs hydration energy identical with that of SO{sub 2}{sup {sm bullet}{minus}}.

  9. Disinfection kinetics of murine norovirus using chlorine and chlorine dioxide.

    Science.gov (United States)

    Lim, Mi Young; Kim, Ju-Mi; Ko, Gwangpyo

    2010-05-01

    We determined the disinfection efficiency of chlorine and chlorine dioxide (ClO(2)) using murine norovirus (MNV) and coliphage MS2 as surrogates for human norovirus. Experiments were performed in oxidant demand-free buffer (pH 7.2) at 5 degrees C and 20 degrees C. The extent of virus inactivation by a disinfectant was quantified using three different analytical methods: plaque, short template real-time TaqMan reverse transcriptase-polymerase chain reaction (RT-PCR), and long template RT-PCR assays. Rapid inactivation of MNV by both chlorine and chlorine dioxide was observed by the plaque assay. According to the efficiency factor Hom model, Ct values of 0.314mg/Lmin and 0.247mg/Lmin were required for a 4-log reduction of MNV at 5 degrees C by chlorine and chlorine dioxide, respectively. Lower Ct values were required at 20 degrees C. Both long template and short template RT-PCR assays significantly underestimated the virus inactivation compared to the plaque assay. Our study demonstrates that adequate treatment of water with either chlorine or ClO(2) is likely to effectively control the waterborne transmission of human norovirus.

  10. Gaseous, chlorine-free chlorine dioxide for drinking water

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, G. [Miami Univ., Oxford, OH (United States); Rosenblatt, A. [CDG Technology Inc., New York, NY (United States)

    1996-11-01

    The benefits of applying chlorine dioxide (ClO{sub 2}) for the oxidative treatment of drinking water are well established. Chlorine dioxide treated finished water typically has substantially lower trihalomethane (THM) levels because ClO{sub 2} will not form chlorinated organic species as a by-product of disinfection. The THMs that are formed are probably due to chlorine from the generator or chlorine used to maintain a post-disinfection residual. An emerging regulatory issue concerning the formation of disinfection by-products (DBPs) is causing the water industry to set standards for the generation and delivery of ClO{sub 2}. The Federal Register (11 February 1994) contains language developed to limit the production of the unwanted inorganic by-products chlorite (ClO{sub 2}{sup -}), chlorate (ClO{sub 3}{sup -}), and bromate (BrO{sub 3}{sup -}) ions by requiring utilities to maintain high (95%) generation efficiencies and by limiting the amount of excess Cl{sub 2} that can be used during the generation process. The efficiency and excess Cl{sub 2} regulations may be problematic for utilities that over-chlorinate to attain chlorine dioxide high yields. Many utilities will have to decide either to reduce the amount of Cl{sub 2} used to react with sodium chlorite (NaClO{sub 2}), thereby increasing the ClO{sub 2}{sup -} residual in finished water, or over-chlorinate to increase yields and surpass the excess Cl{sub 2} limits.

  11. Chlorine dioxide treatment for zebra mussel control

    Energy Technology Data Exchange (ETDEWEB)

    Rybarik, D. [Dairyland Power Cooperative, La Crosse, WI (United States); Byron, J. [Nalco Chemical Company, Naperville, IL (United States); Germer, M. [Rio Linda Chemical Company, Sacramento, CA (United States)

    1995-06-01

    Chlorine is recognized and commonly used biocide for power plant cooling water and service water treatment programs, including the control of zebra mussels. Chlorine dioxide has recently become a popular method of zebra mussel control because of its economy, safety, environmental acceptability, and effectiveness when compared to other mussel control methods. This control technique was recently demonstrated at Dairyland Power Cooperative`s Alma Generating Station on the east bank of the upper Mississippi River in Alma, Wisconsin. The project was assisted with EPRI Tailored Collaboration Program funds. The Dairyland Power Alam Generating Station consists of five generating units that utilize raw, untreated Mississippi River water for condenser, circulating, and service water supplies. The first units were built in 1947, with the final and largest unit being completed in 1960. Total station generating capacity is 200 MW. Because of recent increases in the zebra mussel density at the station intake, Dairyland Power selected the team of Nalco and Rio Linda to perform a chlorine dioxide treatment of the station`s new water systems to eradicate and control the mussels before their presence created operational difficulties. This paper will present the results of the treatment including treatment theory, design and construction of the treatment system, the method of chlorine dioxide generation, treatment concentration, analytical methods o monitoring chlorine dioxide generation, residuals and trihalomethane (THM) concentrations, protocol for monitoring treatment mortality, and the effects of chlorine dioxide and detoxification on other water chemistry parameters and equipment materials. The goal of this paper is to inform and assist users with establishing consistent and uniform practices for safely utilizing and monitoring chlorine dioxide in the eradication and control of zebra mussels.

  12. Method and apparatus for producing chlorine dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Santillie, P.W.; Ramras, D.M.

    1984-05-29

    A continuous method and apparatus are described for the efficient production of gaseous chlorine dioxide by the reaction between gaseous sulfur dioxide and an aqueous solution of a metallic chlorate. The chlorate solution and a highly concentrated sulfur dioxide gas are introduced into a packed columnar chamber at closely adjacent locations at the bottom of the chamber so as to flood the chamber and maximize both the contact area and contact time of the two reactants. Throughout the reaction the chamber is subjected to high vacuum imposed by an eductor which exhausts the chlorine dioxide gas and spent reactants. For use of the chlorine dioxide to produce potable water or treat foodstuffs, the chlorine dioxide and spent reactants are exhausted from the chamber separately by respective eductors substantially balanced with respect to each other to impose comparable vacuums upon the chamber. Because of the high efficency of the reaction, substantial heat is generated therefrom which is absorbed by a coolant flowing through a jacket surrounding the chamber. The flow rate of the coolant and flow rate of the reactants into the chamber are porportional due to the dependency of the reactant flow rate on the coolant flow rate.

  13. Reactions of aqueous chlorine and chlorine dioxide with model food compounds.

    OpenAIRE

    Fukayama, M Y; Tan, H; Wheeler, W B; Wei, C I

    1986-01-01

    Chlorine and chlorine dioxide (ClO2), common disinfecting and bleaching chemicals used in the food industry, are potent oxidizing and chlorinating agents. Unfortunately, little is known about the nature of the reactions of chlorine with organic food constituents. This presentation reviews published information concerning the reactions of chlorine gas (Cl2[g]), aqueous chlorine, and ClO2 with model food compounds, the fate of chlorine during the chlorination of specific food products, and the ...

  14. Photoabsorption and photoionization of chlorine dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Flesch, R.; Ruehl, E.; Hottmann, K.; Baumgaertel, H. (Freie Universitaet Berlin (Germany))

    1993-01-28

    Photoprocesses of chlorine dioxide in the near-UV have become highly important for stratospheric photoprocesses at high latitudes, especially in Antarctica. Chlorine dioxide has been identified among other absorbers because of its specific absorption cross section in the near-UV. Possible contributions of chlorine dioxide photochemistry to polar ozone depletion have been discussed recently. The high-resolution He I photoelectron spectrum and the absolute (vacuum-UV) absorption cross section (6-25 eV) as well as the ionic fragmentation of chlorine dioxide (OCIO) are reported. The photoelectron spectrum is interpreted in terms of exchange splitting effects of the various singlet and triplet cation states as well as by comparison to chemically related molecules. The vacuum-UV absorption spectrum shows different Rydberg series converging to the cation states. These Rydberg series and their vibrational progressions are assigned by term value arguments, dipole selection rules, and comparison with the photoelectron spectrum. Photoionization mass spectrometry is used for measurements of the ionization and fragmentation threshold of OCIO. The major fragment is ClO[sup +] which occurs above 13.4 eV. Thermomechanical data such as heats of formation and bond dissociation energies are derived. No evidence for isomerization of OClO[sup +] is found, as observed for the electronically excited neutral molecule. 54 refs., 6 figs., 7 tabs.

  15. Inhibitor treatment program for chlorine dioxide corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Edmondson, J.G.; Holder, E.P.

    1991-11-12

    This patent describes a method of inhibiting corrosion by chlorine dioxide in oil field waterflood systems by adding a sufficient amount of a corrosion inhibiting composition. It comprises a phosphonate, a copolymer consisting of repeating units of acrylic acid/allyl hydroxy propyl sulfonate ether, and a permangante.

  16. A comparison of chlorinated organic material produced by chlorine and chlorine dioxide bleaching

    Energy Technology Data Exchange (ETDEWEB)

    McKaque, A.B.; Reeve, D.W. [Univ. of Toronto (Canada)

    1995-12-31

    Chlorine and chlorine dioxide react differently with pulp during bleaching and produce different types of organic by-products. The main differences are the large reduction in the amount of AOX (adsorbable organic halogen) in the effluent and EOX (extractable organic halogen) in the pulp. This talk reviews the differences in the amounts and types of chlorinated organic by-products produced by the two different bleaching agents.

  17. Method of improving formation permeability using chlorine dioxide

    Energy Technology Data Exchange (ETDEWEB)

    McDougall, L.A.; Williams, D.A.

    1991-07-16

    This patent describes a method of treating a sandstone formation containing clays or silicates. It comprises injection a treating liquid into the formation comprising an aqueous solution of: from 50 to 4,200 ppm chlorine dioxide and from 1 to 85 volume percent of carbon dioxide; permitting the chlorine dioxide to react with material in the formation; and thereafter injecting into the formation an acid solution capable of dissolving the reaction products of chlorine dioxide and the clays and silicates.

  18. Disinfectants: Chlorine and chlorine dioxide. (Latest citations from the Life Sciences Collection database). Published Search

    Energy Technology Data Exchange (ETDEWEB)

    1993-05-01

    The bibliography contains citations concerning the antimicrobial properties of chlorine and chlorine dioxide. The use of chlorine for the inactivation of viruses, bacteria, and fungi in wastewater treatment plants is discussed, including the mode of action and factors influencing inactivation. The use of chlorine dioxide as an alternative to chlorine disinfection in swimming pools and water supplies, and possible adverse effects are also discussed. (Contains a minimum of 157 citations and includes a subject term index and title list.)

  19. Efficiency of Chlorine Dioxide as a Bactericide1

    Science.gov (United States)

    Benarde, Melvin A.; Israel, Bernard M.; Olivieri, Vincent P.; Granstrom, Marvin L.

    1965-01-01

    We found chlorine dioxide to be a more effective disinfectant than chlorine in sewage effluent at pH 8.5. Chlorine dioxide was also found to be a more stable bactericide in relation to pH in the range studied. Images Fig. 1 PMID:5325940

  20. Hydraulic fracturing with chlorine dioxide cleanup

    Energy Technology Data Exchange (ETDEWEB)

    Williams, D.A.; Newlove, J.C.; Horton, R.L.

    1990-10-23

    This patent describes a method for fracturing a subterranean formation penetrated by a wellbore. It comprises: injecting a fracturing fluid into the formation to form a vertical fracture therein, the fracturing fluid being gelled with a polymer selected from guar, guar derivatives, acrylamide, acrylamide derivatives, cellulose, cellulose derivatives, and mixtures thereof and crosslinked with an organometallic crosslinking compound and having temperature stability above about 175{degrees} F.; packing the fracture with particulate propping agent; backflowing fluids from the formation through the propped fracture to remove a portion of the polymer; injecting at matrix rates sufficient aqueous solution of chlorine dioxide down the wellbore and into the propped fracture to penetrate at least 60 feet of the propped fracture length and contact polymer in the fracturing fluid and polymer residue in the propped fracture and on the fracture walls, the amount of the chlorine dioxide in the aqueous medium being sufficient to degrade polymer in the fracturing fluid and polymer residue; permitting the chlorine dioxide to remain in contact with the polymer in the fracturing fluid and with the polymer residue on the fracture walls and in the fracture for sufficient time to degrade the polymer thereby reducing the fracturing fluid viscosity and dissolving portions of the polymer residue; and flowing formation fluid from the formation through the propped fracture and into the wellbore to remove substantial portions of the polymer and degraded polymer from the fracture.

  1. High resolution spectrophotometry for identification of chlorine dioxide in concentrated chlorine solutions.

    Science.gov (United States)

    Gauw, R D; Emmert, G L; Bubnis, B; Gordon, G

    1999-12-06

    Electrolyzed salt brine generators hold great promise for water disinfection in small communities and remote locations. Electrolysis cell liquors have been reported to contain chlorine, chlorine dioxide and ozone. High resolution spectrophotometry was used to observe the presence (or absence) of a unique spectral absorbance pattern present in solutions containing 1-2 mg/l chlorine dioxide.

  2. The removal of phenols from oily wastewater by chlorine dioxide

    OpenAIRE

    Hsu, Chung-Jung

    1988-01-01

    Treatability studies were performed on oily wastewaters produced by petroleum and canning industries. Chlorine dioxide was used for the removal of phenolic compounds from these oily wastewaters. Most of phenolic compounds can be destroyed by chlorine dioxide within 15 minutes if CI02-to-phenol ratios of higher than 5.0 are provided. Factors such as pH, temperature, and COD have little effect on phenol removal. The effectiveness of chlorine dioxide treatment depends critic...

  3. Mechanisms of inactivation of poliovirus by chlorine dioxide and iodine.

    OpenAIRE

    Alvarez, M.E.; O'Brien, R.T.

    1982-01-01

    Chlorine dioxide and iodine inactivated poliovirus more efficiently at pH 10.0 than at pH 6.0. Sedimentation analyses of viruses inactivated by chlorine dioxide and iodine at pH 10.9 showed that viral RNA separated from the capsids, resulting in the conversion of virions from 156S structures to 80S particles. The RNAs release from both chlorine dioxide- and iodine-inactivated viruses cosedimented with intact 35S viral RNA. Both chlorine dioxide and iodine reacted with the capsid proteins of p...

  4. Reactions of tetracycline antibiotics with chlorine dioxide and free chlorine.

    Science.gov (United States)

    Wang, Pei; He, Yi-Liang; Huang, Ching-Hua

    2011-02-01

    Tetracyclines (TCs) are a group of widely used antibiotics that have been frequently found in the aquatic environment. The potential reactions of TCs with common water disinfection oxidants such as chlorine dioxide (ClO(2)) and free available chlorine (FAC) have not been studied in depth and are the focus of this study. The oxidation kinetics of tetracycline, oxytetracycline, chlorotetracycline and iso-chlorotetracycline by ClO(2) and FAC are very rapid (with large apparent second-order rate constants k(app) = 2.24 × 10(5)-1.26 × 10(6) M(-1) s(-1) with ClO(2) and k(app) = 1.12 × 10(4)-1.78 × 10(6) M(-1) s(-1) with FAC at pH 7.0) and highly dependent on pH. Species-specific rate constants are obtained by kinetic modeling that incorporates pH-speciation of TCs and the oxidants (for FAC), and reveal that TCs primarily react with ClO(2) and FAC by their unprotonated dimethylamino group and deprotonated phenolic-diketone group. The modest difference in reactivity among the four TCs toward the oxidants is consistent with expectation and can be explained by structural influences on the two reactive moieties. Product evaluation shows that oxidation of TCs by ClO(2) leads to (hydr)oxylation and breakage of TC molecules, while oxidation of TCs by FAC leads to chlorinated and (hydr)oxylated products without any substantial ring breakage. Results of this study indicate that rapid transformation of TCs by oxidants such as ClO(2) and FAC under water and wastewater treatment conditions can be expected. © 2010 Elsevier Ltd. All rights reserved.

  5. Chlorine Dioxide Induced Multiple Chemical Sensitivity: MMPI Validity Problems.

    Science.gov (United States)

    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…

  6. Chlorine Dioxide Induced Multiple Chemical Sensitivity: MMPI Validity Problems.

    Science.gov (United States)

    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…

  7. N-nitrosamine formation by monochloramine, free chlorine, and peracetic acid disinfection with presence of amine precursors in drinking water system.

    Science.gov (United States)

    West, Danielle M; Wu, Qihua; Donovan, Ariel; Shi, Honglan; Ma, Yinfa; Jiang, Hua; Wang, Jianmin

    2016-06-01

    In this study, the formation of eight N-nitrosamines, N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine, N-nitrosomethylamine, N-nitrosodi-n-propylamine, N-nitrosodi-n-butylamine, N-Nitrosopiperidine, N-Nitrosopyrrolidine, N-Nitrosomorpholine, were systematically evaluated with respect to seven N-nitrosamine precursors (dimethylamine, trimethylamine, 3-(dimethylaminomethyl)indole, 4-dimethylaminoantipyrine, ethylmethylamine, diethylamine, dipropylamine) and three disinfectants (monochloramine, free chlorine, peracetic acid) under variable dosages, exposure times, and pH in a drinking water system. Without the presence of the seven selected N-nitrosamine precursors N-nitrosamine formation was not observed under any tested condition except very low levels of N-Nitrosopyrrolidine under some conditions. With selected N-nitrosamine precursors present N-nitrosamines formed at different levels under different conditions. The highest N-nitrosamine formation was NDMA with a maximum concentration of 1180 ng/L by monochloramine disinfection with precursors present; much lower levels of N-nitrosamines were formed by free chlorine disinfection; and no detectable level of N-nitrosamines were observed by peracetic acid disinfection except low level of N-Nitrosodi-n-propylamine under some conditions. NDMA formation was not affected by pH while four other N-nitrosamine formations were slightly affected by sample pH tested between 7 and 9, with formation decreasing with increasing pH. Monochloramine exposure time study displayed fast formation of N-nitrosamines, largely formed in four hours of exposure and maximized after seven days. This was a systematic study on the N-nitrosamine formation with the seven major N-nitrosamine precursors presence and absence under different conditions, including peracetic acid disinfection which has not been studied elsewhere.

  8. Ultrafast measurements of chlorine dioxide photochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Ludowise, P.D.

    1997-08-01

    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. Chapter 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

  9. Electric plasma discharge combustion synthesis of chlorine dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Dotson, R. L.; Geren, G. W.

    1984-09-18

    A process for the production of chlorine dioxide comprises feeding an inert gas to a reaction zone and applying an electrical discharge to the inert gas to produce a high temperature plasma. Chlorine gas and oxygen gas are supplied simultaneously to the reaction zone and reacted in the plasma to produce a gaseous mixture comprised of chlorine dioxide, chlorine, oxygen and inert gas, the molar ratio of oxygen to chlorine in the reaction zone being at least about 2.5;1. The gaseous mixture is recovered from the reaction zone. Chlorine dioxide, which may be recovered as a gas or reacted to produce an alkali metal chlorite, is employed as a bleaching agent and a water treatment agent.

  10. Removal effect on Mesocyclops leukarti and mutagenicity with chlorine dioxide

    Institute of Scientific and Technical Information of China (English)

    ZUO Jin-long; CUI Fu-yi; QU Bo; ZHU Gui-bing

    2006-01-01

    Mesocyclops leukarti of zooplankton propagates excessively in eutrophic water body and it cannot be effectively inactivated by the conventional drinking water treatment process. In order to tackle this problem, a study of removal effect on Mesocyclops leukarti with chlorine dioxide in a waterworks was performed. The results showed that Mesocyclops leukarti could be effectively removed from water by 1.0 mg/L chlorine dioxide preoxidation combined with the conventional drinking water treatment process.Higher oxidizability and molecular state of chlorine dioxide in water is the key to the inactivation of Mesocyclops leukarti. The chlorite, disinfection by-products (DBPs) of chlorine dioxide, was stable at 0.45 mg/L, which is lower than that critical value of the USEPA. GC-MS examination showed that the quantity of organic substance in the water treated by chlorine dioxide obviously decreased. Ames test further revealed that the mutagenicity was reduced by chlorine dioxide with respect to prechlorine. The propagation ofMesocyclops leukarti can be inactivated effectively and safely by chlorine dioxide pre-oxidation.

  11. Aqueous reactions of chlorine dioxide with hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Rav-Acha, C.; Choshen, E.

    1987-11-01

    In contrast to mechanisms proposed earlier in the literature, according to which chlorine dioxide (ClO/sub 2/) reacts with various hydrocarbons in aqueous media by abstracting allylic or benzylic hydrogens, it is shown that ClO/sub 2/ reacts with olefins through initial electron transfer. Hydrocarbons that can undergo facile oxidation, such as polycyclic aromatic hydrocarbons (PAH) and some olefins, react with ClO/sub 2/ quite rapidly, while saturated aliphatic hydrocarbons, some aromatic hydrocarbons, and olefins substituted with electron-withdrawing groups remain unreactive. This was substantiated by comparing the reactivities toward ClO/sub 2/ of a variety of hydrocarbons, including aliphatic and aromatic hydrocarbons, saturated and unsaturated acids, PAH, or cyclic and acyclic olefins. The results were supported by a detailed kinetic and product study of the reaction between ClO/sub 2/ and some model compounds.

  12. Chlorine Dioxide Gas Treatment of Cantaloupe and Residue Analysis

    OpenAIRE

    Kaur, Simran

    2013-01-01

    Chlorine dioxide is a selective oxidant and powerful antimicrobial agent. Previous work has shown that treatment of cantaloupe with chlorine dioxide gas at 5 mg/L for 10 minutes results in a 4.6 and 4.3 log reduction of E. coli O157:H7 and L. monocytogenes respectively. A significant reduction (p Current analytical methods for chlorine dioxide and chloroxyanions are only applicable to aqueous samples. Some of these methods have been used to determine surface residues in treated products by...

  13. Reactions of aqueous chlorine and chlorine dioxide with model food compounds.

    Science.gov (United States)

    Fukayama, M Y; Tan, H; Wheeler, W B; Wei, C I

    1986-01-01

    Chlorine and chlorine dioxide (ClO2), common disinfecting and bleaching chemicals used in the food industry, are potent oxidizing and chlorinating agents. Unfortunately, little is known about the nature of the reactions of chlorine with organic food constituents. This presentation reviews published information concerning the reactions of chlorine gas (Cl2[g]), aqueous chlorine, and ClO2 with model food compounds, the fate of chlorine during the chlorination of specific food products, and the potential toxicity of the reaction products. Fatty acids and their methyl esters react with chlorine with the degree of incorporation corresponding to their degree of unsaturation. Aqueous chlorine oxidizes and chlorinates lipids and amino acids much more readily than ClO2. Several amino acids are highly susceptible to oxidation and chlorination by chlorine compounds. Reactions of chlorine and ClO2 with several food products, including flour and shrimp, have also been characterized. In one model system, 99% of Cl2(g) either reacted with components of flour or was consumed by oxidation/chlorination reactions. The lipids extracted from the chlorinated flour contained significant amounts of chlorine. Exposure of shrimp to hypochlorous acid (HOCl) solution resulted in significant incorporation of chlorine into the edible portion. Although significant quantities of chlorine can be incorporated into specific model compounds and food products, the health risks associated with exposure to chlorinated organic products are unknown. Preliminary studies using the Ames Salmonella/microsome mutagenicity assay indicate that the reaction products from mixtures of aqueous chlorine and various lipids or tryptophan are nonmutagenic. Nevertheless, additional studies are warranted, so that the toxicological significance of these reaction products can be understood more fully. PMID:3545804

  14. MULTISPECTRAL IDENTIFICATION OF CHLORINE DIOXIDE BYPRODUCTS IN DRINKING WATER

    Science.gov (United States)

    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...

  15. MULTISPECTRAL IDENTIFICATION OF CHLORINE DIOXIDE DISINFECTION BYPRODUCTS IN DRINKING WATER

    Science.gov (United States)

    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...

  16. MULTISPECTRAL IDENTIFICATION OF CHLORINE DIOXIDE BYPRODUCTS IN DRINKING WATER

    Science.gov (United States)

    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...

  17. Zebra mussel control using periodic chlorine dioxide treatments

    Energy Technology Data Exchange (ETDEWEB)

    Tsou, J. [Electric Power Research Institute, Palo Alto, CA (United States); Coyle, J. [Central Illinois Public Service, Merdosia, IL (United States); Crone, D. [Illinois Power Company, Alton, IL (United States)] [and others

    1996-08-01

    This paper summarizes the EPRI report (TR-105202) on the same topic as well as presents changes in current thinking on the suitability (applicability) of chlorine dioxide for fouling control. Chlorine dioxide was tested as a zebra mussel biocide at two steam electric generating stations in Illinois and one in Indiana. The purpose of these studies was to determine the efficacy of chlorine dioxide in killing zebra mussels and to develop site specific treatment programs for the three utilities. The Electric Power Research Institute (EPRI) Zebra Mussel Consortium sponsored the testing of this recent use of chlorine dioxide. The raw water system at Central Illinois Public Service`s Meredosia Station, on the Illinois River, received applications of chlorine dioxide in April, July, and September 1994. The raw water system at Illinois Power Company`s Wood River Station, on the Mississippi River, received applications in July 1993, January, April, May, July, and September 1994. The Gallagher Station, on the Ohio River, was treated in July and October 1994. Chlorine dioxide was generated on-site and injected into the water intake structure. Both cooling and service water systems were treated at the facilities. 6 refs., 13 figs.

  18. Kinetics and mechanism of the chlorine dioxide-trithionate reaction.

    Science.gov (United States)

    Cseko, György; Horváth, Attila K

    2012-03-22

    The trithionate-chlorine dioxide reaction has been studied spectrophotometrically in a slightly acidic medium at 25.0 ± 0.1 °C in acetate/acetic acid buffer monitoring the decay of chlorine dioxide at constant ionic strength (I = 0.5 M) adjusted by sodium perchlorate. We found that under our experimental conditions two limiting stoichiometries exist and the pH, the concentration of the reactants, and even the concentration of chloride ion affects the actual stoichiometry of the reaction that can be augmented by an appropriate linear combination of these limiting processes. It is also shown that although the formal kinetic order of trithionate is strictly one that of chlorine dioxide varies between 1 and 2, depending on the actual chlorine dioxide excess and the pH. Moreover, the otherwise sluggish chloride ion, which is also a product of the reaction, slightly accelerates the initial rate of chlorine dioxide consumption and may therefore act as an autocatalyst. In addition to that, overshoot-undershoot behavior is also observed in the [(·)ClO(2)]-time curves in the presence of chloride ion at chlorine dioxide excess. On the basis of the experiments, a 13-step kinetic model with 6 fitted kinetic parameter is proposed by nonlinear parameter estimation. © 2012 American Chemical Society

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

    OpenAIRE

    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 ...

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

    OpenAIRE

    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 ...

  1. Advantages and disadvantages of chemical oxidation and disinfection by ozone and chlorine dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Fiessinger, F.; Richard, Y.; Montiel, A.; Musquere, P.

    1981-04-01

    Ozone and chlorine dioxide present definite advantages and disadvantages over chlorination. Chlorination, particularly for the removal of ammonia and the maintenance of a disinfectant residual in the distribution system has decisive advantages and will be difficult to replace. Ozone and chlorine dioxide seem to produce fewer carcinogenic by-products but the risk for acute toxicity, especially from the chlorites which follow chlorine dioxide, is higher than with chlorine. Chlorine dioxide and more particularly ozone should be considered as useful complements to chlorination, but no strong oxidative treatment should be applied before most of the organic matter has been removed.

  2. Fast detection of lead dioxide (PbO2) in chlorinated drinking water by a two-stage iodometric method.

    Science.gov (United States)

    Zhang, Yan; Zhang, Yuanyuan; Lin, Yi-Pin

    2010-02-15

    Lead dioxide (PbO(2)) is an important corrosion product associated with lead contamination in drinking water. Quantification of PbO(2) in water samples has been proven challenging due to the incomplete dissolution of PbO(2) in sample preservation and digestion. In this study, we present a simple iodometric method for fast detection of PbO(2) in chlorinated drinking water. PbO(2) can oxidize iodide to form triiodide (I(3)(-)), a yellow-colored anion that can be detected by the UV-vis spectrometry. Complete reduction of up to 20 mg/L PbO(2) can be achieved within 10 min at pH 2.0 and KI = 4 g/L. Free chlorine can oxidize iodide and cause interference. However, this interference can be accounted by a two-stage pH adjustment, allowing free chlorine to completely react with iodide at ambient pH followed by sample acidification to pH 2.0 to accelerate the iodide oxidation by PbO(2). This method showed good recoveries of PbO(2) (90-111%) in chlorinated water samples with a concentration ranging from 0.01 to 20 mg/L. In chloraminated water, this method is limited due to incomplete quenching of monochloramine by iodide in neutral to slightly alkaline pH values. The interference of other particles that may be present in the distribution system was also investigated.

  3. Selective determination of chlorine dioxide using gas diffusion flow injection analysis

    Energy Technology Data Exchange (ETDEWEB)

    Hollowell, D.A.; Pacey, G.E.; Gordon, G.

    1985-12-01

    An automated absorbance technique for the determination of aqueous chlorine dioxide has been developed by utilizing gas diffusion flow injection analysis. A gas diffusion membrane is used to separate the donor (sampling) stream from the acceptor (detecting) stream. The absorbance of chlorine dioxide is monitored at 359 nm. The first method uses distilled water as the acceptor stream and gives a detection limit of 0.25 mg/L chlorine dioxide. This system is over 550 times more selective for chlorine dioxide than chlorine. To further minimize chlorine interference, oxalic acid is used in the acceptor stream. The detection limit for this system is 0.45 mg/L chlorine dioxide. This second system is over 5400 times more selective for chlorine dioxide than chlorine. Both methods show excellent selectivity for chlorine dioxide over iron and manganese compounds, as well as other oxychlorinated compounds such as chlorite and perchlorate ions. 18 references, 7 figures, 3 tables.

  4. Application of chlorine dioxide as an oilfield facilities treatment fluid

    Energy Technology Data Exchange (ETDEWEB)

    Romaine, J.; Strawser, T.G.; Knippers, M.L.

    1995-11-01

    Both mechanical and chemical treatments are used to clean water flood injection distribution systems whose efficiency has been reduced as a result of plugging material such as iron sulfide sludge. Most mechanical treatments rely on uniform line diameter to be effective, while chemical treatments require good contact with the plugging material for efficient removal. This paper describes the design and operation of a new innovative application using chlorine dioxide for the removal of iron sulfide sludge from water flood injection distribution systems. This technology has evolved from the use of chlorine dioxide in well stimulation applications. The use of chlorine dioxide for continuous treatment of injection brines will also be discussed. Exxon USA`s Hartzog Draw facility in Gillette, Wyoming was the site for the application described. 4,500 barrels of chlorine dioxide was pumped in three phases to clean sixty-six miles of the water flood distribution system. Results indicate that chlorine dioxide was effective in cleaning the well guard screens, the injection lines, frac tanks used to collect the treatment fluids and the injection wells.

  5. Chlorine dioxide project allows Stora to clean up, use hardwoods

    Energy Technology Data Exchange (ETDEWEB)

    Butters, G.

    1988-10-01

    Effluent fouling into the Strait of Canso between Nova Scotia mainland and Cape Breton Island has caused Stora Forest Industries Ltd. to develop a $5.6 million solution to its chlorine and acid problems. In 1987, Stora produced about 160,000 tonnes of market pulp where their resource base increasingly consisted of hardwood. The company uses hardwood chips for a growing percentage of its annual pulp production and for its hog fuel boiler, but became faced with having to use more local hardwoods which contributes to the resin problem. Their solution was to construct a 12-tpd chlorine dioxide generator, a process using dry sodium chlorate added to concentrated H/sub 2/SO/sub 4/, The products are chlorine dioxide and highly concentrated sulphuric acid resulting from the elimination of water at the starting point. This will eliminate the acid effluent from the generator and the sulphuric acid will be recycled to the top of the chlorine dioxide generation process. In the new process, ClCO/sub 2/ replaces 70% of the chlorine in the first stage, with 100% substitution a goal. In addition to eliminating the chlorine, other benefits include an increase in pulp production, a nominal increase in pulp strength, lower production costs, and an economic incentive to harvest the area's mixed-wood stands.

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

    Science.gov (United States)

    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)

  7. Chlorine dioxide water disinfection: a prospective epidemiology study

    Energy Technology Data Exchange (ETDEWEB)

    Michael, G.E.; Miday, R.K.; Bercz, J.P.; Miller, R.G.; Greathouse, D.G.; Kraemer, D.F.; Lucas, J.B.

    1981-01-01

    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.

  8. Kinetics and Mechanism of Bacterial Disinfection by Chlorine Dioxide1

    Science.gov (United States)

    Benarde, Melvin A.; Snow, W. Brewster; Olivieri, Vincent P.; Davidson, Burton

    1967-01-01

    Survival data are presented for a fecal strain of Escherichia coli exposed to three concentrations of chlorine dioxide at four temperatures. Chick's first-order reaction equation is generalized to a pseudo nth-order model. Nonlinear least squares curve-fitting of the survival data to the nth order model was performed on an analogue computer. The data were observed to follow fractional order kinetics with respect to survival concentration, with an apparent activation energy of 12,000 cal/mole. Initial experiments support the thesis that the mechanism of chlorine dioxide kill occurs via disruption of protein synthesis. Images Fig. 1 Fig. 2 Fig. 3 PMID:5339839

  9. Oxidation of pharmaceuticals by chlorine dioxide in biologically treated wastewater

    DEFF Research Database (Denmark)

    Hey, G.; Grabic, R.; Ledin, A.

    2012-01-01

    Biologically treated wastewater spiked with a mixture of 56 active pharmaceutical ingredients (APIs) was treated with 0–20mg/L chlorine dioxide (ClO2) solution in laboratory-scale experiments. Wastewater effluents were collected from two wastewater treatment plants in Sweden, one with extended......O2, while in high COD effluent a significant increase in API oxidation was observed after treatment with 8mg/L ClO2. This study illustrates the successful degradation of several APIs during treatment of wastewater effluents with chlorine dioxide....

  10. Reactions of polynuclear aromatic hydrocarbons with chlorine and chlorine dioxide in coal tar lined pipes

    Energy Technology Data Exchange (ETDEWEB)

    Merkel, T.; Maier, M.; Sacher, F.; Maier, D. [University of Karlsruhe, Karlsruhe (Germany). Engler Bunte Institut

    1997-12-31

    In the presence of disinfectants, PAH are remobilised from the coal tar lining of water distribution mains. Reactions of the PAH with chlorine and chlorine dioxide can lead to chlorinated PAH that might show higher mutagenic effects that the parent PAH. Detection limits in the lower nanogram-per-litre level for the determination of PAH and chlorinated PAH were achieved by using solid phase micro extraction and a gas chromatographic mass spectrometric device. Thus, the reactions of four PAH (anthracene, fluoranthene, fluorene and phenanthrene) with chlorine and chlorine dioxide under conditions and at concentrations of common practice in the drinking water distribution system could be investigated. In batch experiments with demineralised and drinking water at pH 7, the concentrations of fluoranthene, fluorene and phenanthrene remained constant, whereas anthracene reacted quantitatively with both disinfectants. The reaction of anthracene followed by pseudo-first order kinetics. In these reactions no chlorinated products could be detected, only monohydroxyanthracene and anthraquinone were identified. The toxic effect of a set of chlorinated and oxidised PAH was also examined.

  11. An unusual case of reversible acute kidney injury due to chlorine dioxide poisoning.

    Science.gov (United States)

    Bathina, Gangadhar; Yadla, Manjusha; Burri, Srikanth; Enganti, Rama; Prasad Ch, Rajendra; Deshpande, Pradeep; Ch, Ramesh; Prayaga, Aruna; Uppin, Megha

    2013-09-01

    Chlorine dioxide is a commonly used water disinfectant. Toxicity of chlorine dioxide and its metabolites is rare. In experimental studies, it was shown that acute and chronic toxicity were associated with insignificant hematological changes. Acute kidney injury due to chlorine dioxide was not reported. Two cases of renal toxicity due to its metabolites, chlorate and chlorite were reported. Herein, we report a case of chlorine dioxide poisoning presenting with acute kidney injury.

  12. Safety of water treatment by chlorine dioxide oxidation of aromatic hydrocarbons commonly found in water

    Energy Technology Data Exchange (ETDEWEB)

    Taymaz, K.; Williams, D.T.; Benoit, F.M.

    1979-01-01

    The safety of water treatment by chlorine dioxide oxidation of aromatic hydrocarbons commonly found in water and industrial wastewaters in the US was studied by observing the reactions of naphthalene and methylnaphthalenes in essentially chlorine-free, aqueous chlorine dioxide solutions. Naphthalene and methylnaphthalenes yielded chlorinated derivatives and oxidation products. Further research is recommended.

  13. The effects of low level chlorination and chlorine dioxide on biofouling control in a once-through service water system

    Energy Technology Data Exchange (ETDEWEB)

    Garrett, W.E. Jr. [Alabama Power Co./GSC No. 8, Birmingham, AL (United States); Laylor, M.M. [Univ. of Alabama, Birmingham, AL (United States)

    1995-06-01

    Continuous chlorination has been successfully used for the control of Corbicula at a nuclear power plant located on the Chattahoochee River in southeastern Alabama, since 1986. The purpose of this study was to investigate further minimization of chlorine usage and determine if chlorine dioxide is a feasible alternative. Four continuous biocide treatments were evaluated for macro and microfouling control effectiveness, operational feasibility, and environmental acceptability. One semi-continuous chlorination treatment was also evaluated for macrofouling control effectiveness. Higher treatment residuals were possible with chlorine dioxide than with chlorination due to the river discharge limitations. At the levels tested, continuous chlorine dioxide was significantly more effective in providing both macro and microfouling control. Semi-continuous chlorination was just as effective as continuous chlorination for controlling macrofouling. The Corbicula treatment programs that were tested should all provide sufficient control for zebra mussels. Chlorine dioxide was not as cost effective as chlorination for providing macrofouling control. The semi-continuous treatment save 50% on chemical usage and will allow for the simultaneous treatment of two service water systems. Chlorite levels produced during the chlorine dioxide treatments were found to be environmentally acceptable. Levels of trihalomethanes in the chlorinated service water were less than the maximum levels allowed in drinking water.

  14. The effect of chlorine dioxide on polymeric packaging materials

    Science.gov (United States)

    Chlorine dioxide (ClO2), with its high oxidizing capacity and broad disinfecting property, is used frequently as a disinfectant in many applications. As a biocide in food applications, it showed a microbial inactivating capacity against many important pathogenic and spoilage microorganisms, located ...

  15. Effects of chlorine and chlorine dioxide on human rotavirus infectivity and genome stability.

    Science.gov (United States)

    Xue, Bin; Jin, Min; Yang, Dong; Guo, Xuan; Chen, Zhaoli; Shen, Zhiqiang; Wang, Xinwei; Qiu, Zhigang; Wang, Jingfeng; Zhang, Bin; Li, Junwen

    2013-06-15

    Despite the health risks posed by waterborne human rotavirus (HRV), little information is available concerning the effectiveness of chlorine or chlorine dioxide (ClO2), two common disinfectants of public water sources, against HRV and their effects on its genome remain poorly understood. This study investigated the effects of chlorine and ClO2 on purified HRV by using cell culture and RT-PCR to assess virus infectivity and genetic integrity, respectively. The disinfection efficacy of ClO2 was found to be higher than that of chlorine. According to the efficiency factor Hom model, Ct value (mg/L min) ranges required for a 4-log reduction of HRV at 20 °C by chlorine and ClO2 were 5.55-5.59 and 1.21-2.47 mg/L min, respectively. Detection of the 11 HRV genome segments revealed that damage to the 1227-2354 bp of the VP4 gene was associated with the disappearance of viral infectivity by chlorine. However, no complete accordance between culturing and RT-PCR assays was observed after treatment of HRV with ClO2. These results collectively indicate that the current practice of chlorine disinfection may be inadequate to manage the risk of waterborne HRV infection, and offer the potential to monitor the infectivity of HRV adapting PCR-based protocols in chlorine disinfection. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Efficacy of chlorine dioxide tablets on inactivation of cryptosporidium oocysts.

    Science.gov (United States)

    Murphy, Jennifer L; Haas, Charles N; Arrowood, Michael J; Hlavsa, Michele C; Beach, Michael J; Hill, Vincent R

    2014-05-20

    The ability of chlorine dioxide (ClO2) to achieve 2-log inactivation of Cryptosporidium in drinking water has been documented. No studies have specifically addressed the effects of ClO2 on C. parvum oocyst infectivity in chlorinated recreational water venues (e.g., pools). The aim of this research was to determine the efficacy of ClO2 as an alternative to existing hyperchlorination protocols that are used to achieve a 3-log inactivation of Cryptosporidium in such venues. To obtain a 3-log inactivation of C. parvum Iowa oocysts, contact times of 105 and 128 min for a solution containing 5 mg/L ClO2 with and without the addition of 2.6 mg/L free chlorine, respectively, were required. Contact times of 294 and 857 min for a solution containing 1.4 mg/L ClO2 with and without the addition of 3.6 mg/L free chlorine, respectively, were required. The hyperchlorination control (21 mg/L free chlorine only) required 455 min for a 3-log inactivation. Use of a solution containing 5 mg/L ClO2 and solutions containing 5 or 1.4 mg/L ClO2 with the addition of free chlorine appears to be a promising alternative to hyperchlorination for inactivating Cryptosporidium in chlorinated recreational water venues, but further studies are required to evaluate safety constraints on use.

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

    OpenAIRE

    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 scatte...

  18. Thermal diffusion of chlorine in uranium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Pipon, Y.; Toulhoat, N.; Moncoffre, N.; Jaffrezic, H.; Gavarini, S. [Inst. de Physique Nucleaire de Lyon (IPNL), Villeurbanne (France); Martin, P. [Commissariat a l' Energie Atomique (CEA), Centre de Cadarache, DEN/DEC/SESC/LLCC, Saint-Paul lez Durance (France); Raimbault, L. [Centre d' Informatique Geologique (CIG), Ecole des Mines, Fontainebleau (France); Scheidegger, A.M. [Lab. for Waste Management, Nuclear Energy and Safety Dept. (NES), Paul Scherrer Inst. Villigen PSI (Switzerland)

    2006-07-01

    In a nuclear reactor, isotopes such as {sup 35}Cl present as impurities in the nuclear fuel are activated by thermal neutron capture. During interim storage or geological disposal of nuclear fuel, the activation products such as {sup 36}Cl may be released from the fuel to the geo/biosphere and contribute to the ''instant release fraction'' as they are likely to migrate in defects and grain boundaries. In order to differentiate diffusion mechanisms due to ''athermal'' processes during irradiation from thermally activated diffusion, both irradiation and thermal effects must be assessed. This work concerns the measurement of the thermal diffusion coefficient of chlorine in UO{sub 2}. {sup 37}Cl was implanted at a 10{sup 13} at/cm{sup 2} fluence in depleted UO{sub 2} samples which were then annealed in the 900-1200 C temperature range and finally analyzed by secondary ion mass spectrometry (SIMS) to obtain {sup 37}Cl depth profiles. The migration process appears to be rather complex, involving mechanisms such as atomic, grain boundary, directed diffusion along preferential patterns as well as trapping into sinks before successive effusion. However, using a diffusion model based on general equation of transport, apparent diffusion coefficients could be calculated for 1000 and 1100 C and a mean activation energy of 4.3 eV is proposed. This value is one of the lowest values compared to those found in literature for other radionuclides pointing out a great ability of chlorine to migrate in UO{sub 2} at relatively low temperatures. In order to unequivocally determine the diffusion behaviour of both implanted and pristine chlorine before and after thermal annealing, the structural environment of chlorine in UO{sub 2} was examined using micro X-ray fluorescence (micro-XRF) and micro X-ray absorption spectroscopy (micro-XAS). (orig.)

  19. Inactivation of human and simian rotaviruses by chlorine dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu-Shiaw (Brookhaven National Lab., Upton, NY (USA)); Vaughn, J.M. (Univ. of New England College of Medicine, Biddeford, ME (USA))

    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 were 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.

  20. Inactivation of human and simian rotaviruses by chlorine dioxide.

    Science.gov (United States)

    Chen, Y S; Vaughn, J M

    1990-01-01

    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 degrees 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(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 at neutral pH, and the sensitivities to chlorine dioxide were 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. PMID:2160222

  1. Oxidative elimination of cyanotoxins: comparison of ozone, chlorine, chlorine dioxide and permanganate.

    Science.gov (United States)

    Rodríguez, Eva; Onstad, Gretchen D; Kull, Tomas P J; Metcalf, James S; Acero, Juan L; von Gunten, Urs

    2007-08-01

    As the World Health Organization (WHO) progresses with provisional Drinking Water Guidelines of 1 microg/L for microcystin-LR and a proposed Guideline of 1 microg/L for cylindrospermopsin, efficient treatment strategies are needed to prevent cyanotoxins such as these from reaching consumers. A kinetic database has been compiled for the oxidative treatment of three cyanotoxins: microcystin-LR (MC-LR), cylindrospermopsin (CYN), and anatoxin-a (ANTX) with ozone, chlorine, chlorine dioxide and permanganate. This kinetic database contains rate constants not previously reported and determined in the present work (e.g. for permanganate oxidation of ANTX and chlorine dioxide oxidation of CYN and ANTX), together with previously published rate constants for the remaining oxidation processes. Second-order rate constants measured in pure aqueous solutions of these toxins could be used in a kinetic model to predict the toxin oxidation efficiency of ozone, chlorine, chlorine dioxide and permanganate when applied to natural waters. Oxidants were applied to water from a eutrophic Swiss lake (Lake Greifensee) in static-dose testing and dynamic time-resolved experiments to confirm predictions from the kinetic database, and to investigate the effects of a natural matrix on toxin oxidation and by-product formation. Overall, permanganate can effectively oxidize ANTX and MC-LR, while chlorine will oxidize CYN and MC-LR and ozone is capable of oxidizing all three toxins with the highest rate. The formation of trihalomethanes (THMs) in the treated water may be a restriction to the application of sufficiently high-chlorine doses.

  2. Study on metal corrosion caused by chlorine dioxide of various purities

    Institute of Scientific and Technical Information of China (English)

    崔崇威; 黄君礼; 许晶

    2004-01-01

    Weight lost method was used to comparatively study the corrosion behavior of four different metals under the dosage of chlorine dioxide, chlorine and their mixture respectively. The experimental results indicated that chlorine causes the most serious corrosion of carbon steel, and the higher the concentration of chlorine, the more serious the corrosion. On the contras, metals corrosion is the least serious in the case of chlorine dioxide.The results further revealed that chlorine dioxide is the most effective water treatment reagent, making it the best choice to use extensively in circulated cooling water disinfection and corrosion control.

  3. Chemisorption of chlorine and sulfur dioxide on zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    Vinokurov, A.A.; Derlyukova, L.E.; Evdokimov, V.I.

    1987-03-10

    The chemisorption of sulfur dioxide and chlorine on the surface of zinc oxide and the change in the electric conductivity of ZnO during the chemisorption process were studied. It was shown that both gases induce a negative charging of the surface of zinc oxide. The kinetics of the chemisorption of Cl/sub 2/ and SO/sub 2/ is described by the Zel'dovich-Roginskii equation. The mutual influence of sulfur dioxide and chlorine during successive chemisorption was investigated. It was shown that the nature of the mutual influence depends on the temperature and the sequence of action of the gases. The results obtained were analyzed from the standpoint of the electronic theory of chemisorption on semiconductors.

  4. Chlorine dioxide remediation of a virus-contaminated manufacturing facility.

    Science.gov (United States)

    Lutgen, Mark

    2011-01-01

    CONFERENCE PROCEEDING Proceedings of the PDA/FDA Adventitious Viruses in Biologics: Detection and Mitigation Strategies Workshop in Bethesda, MD, USA; December 1-3, 2010 Guest Editors: Arifa Khan (Bethesda, MD), Patricia Hughes (Bethesda, MD) and Michael Wiebe (San Francisco, CA) Chlorine dioxide fumigation was successfully used to decontaminate a virally contaminated biotech manufacturing facility. Addressing safety, product quality, and corrosion risks were important factors in planning the building fumigation. Studies were performed to define the conditions in which minute mouse virus (MMV) is inactivated by chlorine dioxide and to understand equipment and facility risks. Written plans and procedures documented activities necessary to safely fumigate the building and requalify it to manufacture commercial product.

  5. Treatment of algae-induced tastes and odors by chlorine, chlorine dioxide and permanganate

    OpenAIRE

    Buffin, Lisa Webster

    1992-01-01

    Chlorine (C12(sq»' chlorine dioxide (Cl02 ) and potassium permanganate (KMn04) were evaluated as oxidants for the removal of grassy and cucumber odors associated with the pure compounds, cis-3-hexenol and trans-2, cis-6-nonadienal, respectively, and for the removal of fishy odors associated with a culture of an alga, Synura petersenii. The effects of the oxidants on the pure compounds were assessed both by Flavor Profile Analysis (FPA) and gas chromatography/mass spectrometry (GC/MS). The ef...

  6. Chlorine dioxide against bacteria and yeasts from the alcoholic fermentation

    Science.gov (United States)

    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

  7. Antibacterial effect of chlorine dioxide and hyaluronate on dental biofilm

    OpenAIRE

    Al-bayaty, F.; Taiyeb-ali, T.; Abdulla, M. A.; Hashim, F.

    2010-01-01

    The objective of this study is to investigate antimicrobial action of chlorine dioxide (ClO(2)) gel and hyaluronate gel (Gengigel (R)) on dental biofilm. Pooled supra and subgingival dental biofilm were obtained from healthy individuals and incubated aerobically and anaerobically. Plaque bacteria investigated including Streptococcus constellatus, Streptococcus mitis, Eikenella corrodens, Fusobacterium nucleatum, dental plaque pool samples (aerobic and anaerobic) and Staphylococcus aureus and ...

  8. Inactivation of Salmonella on Eggshells by Chlorine Dioxide Gas.

    Science.gov (United States)

    Kim, Hyobi; Yum, Bora; Yoon, Sung-Sik; Song, Kyoung-Ju; Kim, Jong-Rak; Myeong, Donghoon; Chang, Byungjoon; Choe, Nong-Hoon

    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.

  9. Reduction of chlorine dioxide emissions from a Mathieson generator

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, R.

    1998-03-01

    Chlorine dioxide emissions from the ClO{sub 2} Mathison generator at Crestbrook Forest Industries was studied to determine whether changes would be necessary to meet emission restrictions. The effect of water temperature, packing height and chlorine dioxide gas concentration on emissions was determined using the gas sample data and mass transfer equations for the absorption tower and scrubber. Operation of the generator was discovered to have a significant effect on final chlorine dioxide emissions. Final solutions were evaluated based on ensuring compliance as well as minimizing capital cost. The order in which the changes should be performed to ensure compliance was determined to be (1) change in permit restrictions, (2) better operation of the generator, (3) converting the scrubber to operate with water, and (4) souring the vented gas with SO{sub 2} before being scrubbed with caustic. This would reduce emissions to near zero. However, this solution would be effective only if the SO{sub 2} addition were carefully controlled to ensure that no sodium sulphite was produced. 2 refs., 8 figs.

  10. Evaluation of chlorine dioxide gas residues on selected food produce.

    Science.gov (United States)

    Trinetta, Valentina; Vaidya, Nirupama; Linton, Richard; Morgan, Mark

    2011-01-01

    In recent years, the consumption of fresh fruits and vegetables has greatly increased, and so has its association with contamination of several foodborne pathogens (Listeria, Salmonella, and Escherichia coli). Hence, there is a need to investigate effective sanitizer systems for produce decontamination. Chlorine dioxide (ClO(2)), a strong oxidizing gas with broad spectrum and sanitizing properties, has previously been studied for use on selected fruits and vegetables. ClO(2) gas treatments show great potential for surface pathogen reduction; however its use from a residue safety standpoint has yet to be assessed. Thus, the objective of this study was to evaluate residues of ClO(2), chlorite, chlorate, and chloride on selected fresh produce surfaces after treatment with ClO(2) gas. A rinse procedure was used and water samples were analyzed by N, N-diethyl-p-phenylenediamine and ion chromatography method (300.0). Seven different foods--tomatoes, oranges, apples, strawberries, lettuce, alfalfa sprouts, and cantaloupe--were analyzed after ClO(2) treatment for surface residues. Very low residues were detectable for all the food products except lettuce and alfalfa sprouts, where the measured concentrations were significantly higher. Chlorine dioxide technology leaves minimal to no detectable chemical residues in several food products, thus result in no significant risks to consumers. Practical Application: Potential for chlorine dioxide gas treatments as an effective pathogen inactivation technology to produce with minimal risk for consumers.

  11. Efficacy and Safety Evaluation of a Chlorine Dioxide Solution.

    Science.gov (United States)

    Ma, Jui-Wen; Huang, Bin-Syuan; Hsu, Chu-Wei; Peng, Chun-Wei; Cheng, Ming-Long; Kao, Jung-Yie; Way, Tzong-Der; Yin, Hao-Chang; Wang, Shan-Shue

    2017-03-22

    In this study, a chlorine dioxide solution (UC-1) composed of chlorine dioxide was produced using an electrolytic method and subsequently purified using a membrane. UC-1 was determined to contain 2000 ppm of gaseous chlorine dioxide in water. The efficacy and safety of UC-1 were evaluated. The antimicrobial activity was more than 98.2% reduction when UC-1 concentrations were 5 and 20 ppm for bacteria and fungi, respectively. The half maximal inhibitory concentrations (IC50) of H1N1, influenza virus B/TW/71718/04, and EV71 were 84.65 ± 0.64, 95.91 ± 11.61, and 46.39 ± 1.97 ppm, respectively. A 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test revealed that the cell viability of mouse lung fibroblast L929 cells was 93.7% at a 200 ppm UC-1 concentration that is over that anticipated in routine use. Moreover, 50 ppm UC-1 showed no significant symptoms in a rabbit ocular irritation test. In an inhalation toxicity test, treatment with 20 ppm UC-1 for 24 h showed no abnormality and no mortality in clinical symptoms and normal functioning of the lung and other organs. A ClO₂ concentration of up to 40 ppm in drinking water did not show any toxicity in a subchronic oral toxicity test. Herein, UC-1 showed favorable disinfection activity and a higher safety profile tendency than in previous reports.

  12. The effect of photochemical dissociation on downwind chlorine dioxide plume concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Michalowicz, R.; Alp, E. [Bovar Environmental, Toronto, Ontario (Canada)

    1997-12-31

    The pulp and paper industry handles toxic gases which may present an inherent hazard to the safety of the general public in the surrounding area. One such toxic gas that may pose a hazard is chlorine dioxide. Spills of chlorine dioxide solution result in the gassing off of toxic clouds of chlorine dioxide. Under daytime dry conditions, chlorine dioxide decomposes photolytically to form chlorine and oxygen and intermediates, chlorine trioxide and chlorine hexoxide. Air dispersion modeling of chlorine dioxide releases which does not properly account for its photochemical decomposition will lead to overly conservative hazard zone estimates. Under these conditions, risk control measures and emergency response evacuation zones based on such estimates will be unnecessarily expensive, perhaps prohibitive. This paper investigates the photolytic rate of dissociation of chlorine dioxide under various atmospheric conditions. It was found that modeling based on the decomposition of chlorine dioxide gas, resulted in downwind distances to TLV-Short Term Exposure Limits which are considerably shorter than modeling based on chlorine dioxide dispersion with no decomposition.

  13. Toxicity of chlorine dioxide to early life stages of marine organisms

    Energy Technology Data Exchange (ETDEWEB)

    Hose, J.E.; Di Fiore, D.; Parker, H.S.; Sciarrotta, T.

    1989-03-01

    With increasing interest in minimizing exposure to chlorine, many electric generating and water treatment plants are exploring the use of alternative biocides such as chlorine dioxide. Unlike chlorine, chlorine dioxide does not react with ambient organic compounds to form potentially carcinogenic trihalomethanes such as chloroform. However, the toxicity of chlorine dioxide to aquatic organisms has received little study. No information exists on chlorine toxicity to marine organisms. Furthermore, West Coast electric power stations usually discharge chlorine intermittently once or twice daily and substantial mixing of receiving water occurs between treatments. Therefore, this study sought to obtain information on chlorine dioxide toxicity using an exposure schedule typical of generating stations which discharge into the marine environment. Early life history stages of a plant, invertebrate and fish were tested since these stages are generally acknowledged to be most sensitive to toxicants and are the stages that are most likely to be exposed to the effluent.

  14. SIMULTANEOUS DETERMINATION OF CHLORINE DIOXIDE AND HYPOCHLOROUS ACID IN BLEACHING SYSTEM

    Directory of Open Access Journals (Sweden)

    Qiang Wang

    2011-04-01

    Full Text Available This study has demonstrated a rapid spectroscopic method for the determination of chlorine dioxide and hypochlorous acid concentrations in the pulp bleaching processes. It was found that chlorine dioxide and hypochlorous acid have an isosbestic wavelength of 295 nm. The soluble lignin in such a system is the main interference, but can be corrected by determining the absorbances at 295 nm, 380 nm, and 480 nm. Thus, based on the spectroscopic measurements at 295 nm (the isosbestic point wavelength for chlorine dioxide and hypochlorous acid, 380 nm (absorbance wavelength of chlorine dioxide and 480 nm (the acid soluble lignin absorbance wavelength, the chlorine dioxide and hypochlorous acid concentrations in the bleaching process can be quantified. However, hypochlorous acid was not detected in the real bleaching effluent for its low content. The present method is simple, rapid, accurate, and has the potential for on-line monitoring of the chlorine dioxide bleaching process.

  15. Comparative efficacy of chlorine and chlorine dioxide regimes for condenser slime control in seawater cooled heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Murthy, P.S.; Veeramani, P.; Ershath, M.; Rajamohan, R.; Harinath, Y.V.; Mohan, T.V.K.; Venugopalan, V.P. [BARC Facilities, Water and Steam Chemistry Div., Kalpakkam, Tamil nadu (India)

    2010-07-01

    Chlorination has long been used as an effective and economic biocide for biofouling control in seawater cooling systems. However, the efficacy of chlorine is reduced in the presence of organic content of seawater and the inability of chlorine to effectively penetrate biofilms. Chlorine dioxide is being projected as a possible alternative to chlorine. Experiments were carried out with the help of a seawater circulating facility, in which direct comparison of the efficacy of the two biocides was possible using test condenser tube assemblies. The test condenser tubes made of titanium, SS 316L and Cu-Ni 90/10 were dosed with chlorine and chlorine dioxide. Each dose was evaluated for 30 days. Continuous and intermittent additions of chlorine (0.38 - 0.45 mg L{sup -1} TRO) and chlorine dioxide (0.4 - 0.5 mg L{sup -1}) were used, along with control. The flow velocity in the tubes was maintained at 1.5 m/s. Results of the study showed that the efficacy of the biocide to control biofilms depended on the biocide and the material. Continuous chlorination resulted in 75% reduction of viable counts on titanium, followed by 24% reduction on CuNi and 6% reduction on SS 316L surfaces, as compared to the control. When compared to continuous chlorination, increase in bacterial density in the tubes was observed at different regimes of intermittent chlorination. On SS 316L and Cu-Ni surfaces, intermittent chlorination for 1h, once every 3 h, appeared to give adequate protection. Continuous addition of chlorine dioxide resulted in 99% reduction of viable counts on titanium surfaces, followed by 28% reduction on SS 316 L surfaces and 52% reduction on Cu-Ni surfaces, as compared to the controls. The data indicate that the efficacy of biocides to control biofilms depend on not only the biocide and its frequency of application but also the material of construction. (author)

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

    Science.gov (United States)

    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.

  17. A comparison of iodinated trihalomethane formation from chlorine, chlorine dioxide and potassium permanganate oxidation processes.

    Science.gov (United States)

    Zhang, Tian-Yang; Xu, Bin; Hu, Chen-Yan; Lin, Yi-Li; Lin, Lin; Ye, Tao; Tian, Fu-Xiang

    2015-01-01

    This study compared the formation of iodinated trihalomethanes (I-THMs) from iodide-containing raw waters oxidized by chlorine, chlorine dioxide (ClO₂) and potassium permanganate (KMnO₄) at different oxidant concentrations, reaction times, pHs, initial iodide concentrations and bromide to iodide mass ratios. Among the six investigated I-THMs, iodoform was the major species formed during the oxidation using chlorine, ClO₂ and KMnO₄. When oxidant concentration increased from 0.1 to 3.0 mg/L, the formation of I-THMs increased and then decreased for chlorine and ClO₂, but kept increasing for KMnO₄. As the reaction time went by, I-THM concentration increased to a plateau within 10 h (ClO₂ within only 1 h, especially) for all the three oxidants. I-THM formation gradually increased from pH 3.0 to 9.0 and remained stable at pH values higher than 7.5 for chlorine; however, for ClO₂ and KMnO₄ the highest I-THM formation showed at pH 7.0 and 7.5, respectively. As initial iodide concentration increased from 20 to 800 μg/L, the total amount and species of I-THMs increased for the three oxidants. Iodide contributed to I-THM formation much more significantly than bromide.

  18. Photochemical ozone and nitric oxide formation in air-nitrogen dioxide mixtures containing sulfur dioxide or chlorine

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, J.S.; Springer, G.S.; Stedman, D.H.

    1980-01-01

    The effects of sulfur dioxide and chlorine on ozone and nitric oxide concentrations in nitrogen dioxide-air mixtures were studied. The presence of 0-10 ppM SO/sub 2/ produced no change in the air mixture. Addition of 1-15 ppm chlorine increased the ozone concentration in the air mixture. A reaction model describing the interactions of chlorine and NO/sub 2/ is presented. (1 diagram, 6 graphs, 30 references, 3 tables)

  19. Reversed flow injection spectrophotometric determination of low residuals of chlorine dioxide in water using chlorophenol red

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A novel,simple,rapid,sensitive and highly selective flow injection procedure for the spectrophotometrie determination of chlorine dioxide in the presence of other chlorine species,viz,free chlorine,chlorite,chlorate and hypoehlorite,is developed.The method is based on the discoloration reaction between chlorine dioxide and chlorophenol red and can overcome the shortcomings existed in direct speetrophotometrie determination for chlorine dioxide owing to the serious interference of free and combined chlorine.The procedure gave a linear calibration graph over the range 0-0.71 mg/L of chlorine dioxide.With a detection limit of 0.024 mg/L and a sample throughput of 60 samples/h.

  20. Efficacy and Safety Evaluation of a Chlorine Dioxide Solution

    Directory of Open Access Journals (Sweden)

    Jui-Wen Ma

    2017-03-01

    Full Text Available In this study, a chlorine dioxide solution (UC-1 composed of chlorine dioxide was produced using an electrolytic method and subsequently purified using a membrane. UC-1 was determined to contain 2000 ppm of gaseous chlorine dioxide in water. The efficacy and safety of UC-1 were evaluated. The antimicrobial activity was more than 98.2% reduction when UC-1 concentrations were 5 and 20 ppm for bacteria and fungi, respectively. The half maximal inhibitory concentrations (IC50 of H1N1, influenza virus B/TW/71718/04, and EV71 were 84.65 ± 0.64, 95.91 ± 11.61, and 46.39 ± 1.97 ppm, respectively. A 3-(4,5-Dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT test revealed that the cell viability of mouse lung fibroblast L929 cells was 93.7% at a 200 ppm UC-1 concentration that is over that anticipated in routine use. Moreover, 50 ppm UC-1 showed no significant symptoms in a rabbit ocular irritation test. In an inhalation toxicity test, treatment with 20 ppm UC-1 for 24 h showed no abnormality and no mortality in clinical symptoms and normal functioning of the lung and other organs. A ClO2 concentration of up to 40 ppm in drinking water did not show any toxicity in a subchronic oral toxicity test. Herein, UC-1 showed favorable disinfection activity and a higher safety profile tendency than in previous reports.

  1. Efficacy and Safety Evaluation of a Chlorine Dioxide Solution

    Science.gov (United States)

    Ma, Jui-Wen; Huang, Bin-Syuan; Hsu, Chu-Wei; Peng, Chun-Wei; Cheng, Ming-Long; Kao, Jung-Yie; Way, Tzong-Der; Yin, Hao-Chang; Wang, Shan-Shue

    2017-01-01

    In this study, a chlorine dioxide solution (UC-1) composed of chlorine dioxide was produced using an electrolytic method and subsequently purified using a membrane. UC-1 was determined to contain 2000 ppm of gaseous chlorine dioxide in water. The efficacy and safety of UC-1 were evaluated. The antimicrobial activity was more than 98.2% reduction when UC-1 concentrations were 5 and 20 ppm for bacteria and fungi, respectively. The half maximal inhibitory concentrations (IC50) of H1N1, influenza virus B/TW/71718/04, and EV71 were 84.65 ± 0.64, 95.91 ± 11.61, and 46.39 ± 1.97 ppm, respectively. A 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test revealed that the cell viability of mouse lung fibroblast L929 cells was 93.7% at a 200 ppm UC-1 concentration that is over that anticipated in routine use. Moreover, 50 ppm UC-1 showed no significant symptoms in a rabbit ocular irritation test. In an inhalation toxicity test, treatment with 20 ppm UC-1 for 24 h showed no abnormality and no mortality in clinical symptoms and normal functioning of the lung and other organs. A ClO2 concentration of up to 40 ppm in drinking water did not show any toxicity in a subchronic oral toxicity test. Herein, UC-1 showed favorable disinfection activity and a higher safety profile tendency than in previous reports. PMID:28327506

  2. Effects of chlorine or chlorine dioxide during immersion chilling on recovery of bacteria from broiler carcasses and chiller water

    Science.gov (United States)

    A study was conducted to determine the microbiological impact of immersion chilling broiler carcasses with chlorine or chlorine dioxide. Eviscerated, pre-chill commercial broiler carcasses were cut into left and right halves along the keel bone, and each half was rinsed (HCR) in 100 mL of 0.1% pept...

  3. Effects of chlorine and chlorine dioxide on mutagenic activity of Lake Kinnereth water

    Energy Technology Data Exchange (ETDEWEB)

    Guttman-Bass, N.; Bairey-Albuquerque, M.; Ulitzur, S.; Chartrand, A.; Rav-Acha, C.

    1987-03-01

    Water from Lake Kinnereth (Israel) was tested for the presence of mutagenic activity, with and without disinfection by chlorine and chlorine dioxide. The samples were assayed for activity with two Ames Salmonella typhimurium tester strains, TA 104 and TA 100, and by a luminescent genotoxic assay with a dark mutant strain of Photobacterium fischeri. The water concentrates were mutagenic in strain TA 104 and in the luminescent assay, reaching positive mutagenic activities in the equivalent of 20 mL of water. Chlorination did not greatly affect the net mutagenic activity, although ClO/sub 2/ apparently reduced it. Humic acids were isolated from lake sediment and were assayed with and without disinfection in distilled water and in lake water from which the organic components were removed. The humic acids were mutagenic in both test systems, and treatment with Cl/sub 2/ generally decreased the net activity. ClO/sub 2/ also tended to decrease the mutagenic activity, and cytotoxic effects were observed in some of the samples. Conversely, commercial humic acid was mutagenic only after chlorination on strain TA 100. 54 references, 3 figures, 6 tables.

  4. Analysis of the sporicidal activity of chlorine dioxide disinfectant against Bacillus anthracis (Sterne strain)

    Science.gov (United States)

    Chatuev, B.A.; Peterson, J.W.

    2009-01-01

    Summary Routine surface decontamination is an essential hospital and laboratory procedure, but the list of effective, noncorrosive disinfectants that kill spores is limited. We investigated the sporicidal potential of an aqueous chlorine dioxide solution and encountered some unanticipated problems. Quantitative bacteriological culture methods were used to determine the log10 reduction of Bacillus anthracis (Sterne strain) spores following 3 min exposure to various concentrations of aqueous chlorine dioxide solutions at room temperature in sealed tubes, as well as spraying onto plastic and stainless steel surfaces in a biological safety cabinet. Serial 10-fold dilutions of the treated spores were then plated on 5% sheep blood agar plates, and the survivor colonies were enumerated. Disinfection of spore suspensions with aqueous chlorine dioxide solution in sealed microfuge tubes was highly effective, reducing the viable spore counts by 8 log10 in only 3 min. By contrast, the process of spraying or spreading the disinfectant onto surfaces resulted in only a 1 log10 kill because the chlorine dioxide gas was rapidly vaporised from the solutions. Full potency of the sprayed aqueous chlorine dioxide solution was restored by preparing the chlorine dioxide solution in 5% bleach (0.3% sodium hypochlorite). The volatility of chlorine dioxide can cause treatment failures that constitute a serious hazard for unsuspecting users. Supplementation of the chlorine dioxide solution with 5% bleach (0.3% sodium hypochlorite) restored full potency and increased stability for one week. PMID:20061062

  5. Analysis of the sporicidal activity of chlorine dioxide disinfectant against Bacillus anthracis (Sterne strain).

    Science.gov (United States)

    Chatuev, B M; Peterson, J W

    2010-02-01

    Routine surface decontamination is an essential hospital and laboratory procedure, but the list of effective, noncorrosive disinfectants that kill spores is limited. We investigated the sporicidal potential of an aqueous chlorine dioxide solution and encountered some unanticipated problems. Quantitative bacteriological culture methods were used to determine the log(10) reduction of Bacillus anthracis (Sterne strain) spores following 3min exposure to various concentrations of aqueous chlorine dioxide solutions at room temperature in sealed tubes, as well as spraying onto plastic and stainless steel surfaces in a biological safety cabinet. Serial 10-fold dilutions of the treated spores were then plated on 5% sheep blood agar plates, and the survivor colonies were enumerated. Disinfection of spore suspensions with aqueous chlorine dioxide solution in sealed microfuge tubes was highly effective, reducing the viable spore counts by 8log(10) in only 3min. By contrast, the process of spraying or spreading the disinfectant onto surfaces resulted in only a 1log(10) kill because the chlorine dioxide gas was rapidly vaporised from the solutions. Full potency of the sprayed aqueous chlorine dioxide solution was restored by preparing the chlorine dioxide solution in 5% bleach (0.3% sodium hypochlorite). The volatility of chlorine dioxide can cause treatment failures that constitute a serious hazard for unsuspecting users. Supplementation of the chlorine dioxide solution with 5% bleach (0.3% sodium hypochlorite) restored full potency and increased stability for one week.

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

    Science.gov (United States)

    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...

  7. Potential Use of Chlorine Dioxide to Control Diseases in Ornamental Plant Production Systems

    Science.gov (United States)

    Research is being done to evaluate uses of chlorine dioxide in ornamental plant production systems. Chlorine dioxide has been shown to control spread of Fusarium oxysporum during the hot water treatment of daffodils and should provide replacement of formaldehyde which was used in the past. By dipp...

  8. 49 CFR 173.229 - Chloric acid solution or chlorine dioxide hydrate, frozen.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Chloric acid solution or chlorine dioxide hydrate, frozen. 173.229 Section 173.229 Transportation Other Regulations Relating to Transportation PIPELINE AND... Than Class 1 and Class 7 § 173.229 Chloric acid solution or chlorine dioxide hydrate, frozen. When the...

  9. Photochemical reactions among formaldehyde, chlorine, and nitrogen dioxide in air

    Energy Technology Data Exchange (ETDEWEB)

    Hanst, P.L.; Gay, B.W. Jr.

    1977-11-01

    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 technique by use of folded light paths up to 504 m. With an excess of NO/sub 2/ over Cl/sub 2/, the reaction products included O/sub 3/, CO, HNO/sub 3/,N/sub 2/O/sub 5/, HCl, and nitryl chloride (ClNO/sub 2/). When chlorine exceeded NO/sub 2/, the principal product was peroxy nitric acid (HOONO/sub 2/). Peroxy formyl nitrate, nitrous acid, and chlorine nitrate were not seen. The nitryl chloride was stable even with the ultraviolet lights on. The peroxy nitric acid disappeared from the cell with a half-life of about 10 min. Formyl radicals (HCO), unlike acetyl radicals, did not combine with O/sub 2/ and NO/sub 2/ by addition. HCO reacted with O/sub 2/ to yield CO and HO/sub 2/. The HO/sub 2/ will then add to NO/sub 2/ to yield HOONO/sub 2/. If NO is present, the HO/sub 2/ will prefer to react with it, oxidizing it to NO/sub 2/.

  10. Chlorine isotope separation using an hydrous zirconium dioxide exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Heumann, K.G.; Baier, K.; Wibmer, G.

    1980-05-01

    Hydrous zirconium dioxide is used in column experiments for separating the halide ions as well as for isotope fractionation of chlorine. The preparation of the zirconium dioxide particles is carried out by homogeneous hydrolysis of a zirconyl chloride solution using hexamethylenetetramine. The separation order of the halides is I/sup -/, Br/sup -/ and Cl/sup -/ in contrast to the inverse separation order using a strongly basic anion exchange resin. In chlorine isotope separation experiments an enrichment of /sup 35/Cl/sup -/ is found in the first fractions, whereas the last fractions show a significant enrichment of /sup 37/Cl/sup -/. This also indicates an inversion of the isotope separation compared with a strongly basic anion exchange resin. A dependence of the isotope fractionation on the concentration of the NaNO/sub 3/ solution used as eluant is found. With increasing concentration the isotope fractionation decreases. Using a 0.5 M NaNO/sub 3/ solution the elementary separation effect was calculated epsilon done on different tantalum parts to determine the amount of dissolved hydrogen.

  11. Chlorine isotope separation using an hydrous zirconium dioxide exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Heumann, K.G.; Baier, K.; Wibmer, G.

    1980-05-01

    Hydrous zirconium dioxide is used in column experiments for separating the halide ions as well as for isotope fractionation of chlorine. The preparation of the zirconium dioxide particles is carried out by homogeneous hydrolysis of a zirconyl chloride solution using hexamethylenetetramine. The separation order of the halides is I/sup -/, Br/sup -/ and Cl/sup -/ in contrast to the inverse separation order using a strongly basic anion exchange resin. In chlorine isotope separation experiments an enrichment of /sup 35/Cl/sup -/ is found in the first fractions, whereas the last fractions show a significant enrichment of /sup 37/Cl/sup -/. This also indicates an inversion of the isotope separation compared with a strongly basic anion exchange resin. A dependence of the isotope fractionation on the concentration of the NaNO/sub 3/ solution used as eluant is found. With increasing concentration the isotope fractionation decreases. Using a 0.5 M NaNO/sub 3/ solution the elementary separation effect was calculated epsilon = 6,1 x 10/sup -4/. This is one of the highest isotope fractionations known in a chloride isotope exchange system. The results show that the electrolyte behaviour of isotopes is comparable to that of a series of homologous elements.

  12. Immobilization of chlorine dioxide modified cells for uranium absorption.

    Science.gov (United States)

    He, Shengbin; Ruan, Binbiao; Zheng, Yueping; Zhou, Xiaobin; Xu, Xiaoping

    2014-11-01

    There has been a trend towards the use of microorganisms to recover metals from industrial wastewater, for which various methods have been reported to be used to improve microorganism adsorption characteristics such as absorption capacity, tolerance and reusability. In present study, chlorine dioxide(ClO2), a high-efficiency, low toxicity and environment-benign disinfectant, was first reported to be used for microorganism surface modification. The chlorine dioxide modified cells demonstrated a 10.1% higher uranium adsorption capacity than control ones. FTIR analysis indicated that several cell surface groups are involved in the uranium adsorption and cell surface modification. The modified cells were further immobilized on a carboxymethylcellulose(CMC) matrix to improve their reusability. The cell-immobilized adsorbent could be employed either in a high concentration system to move vast UO2(2+) ions or in a low concentration system to purify UO2(2+) contaminated water thoroughly, and could be repeatedly used in multiple adsorption-desorption cycles with about 90% adsorption capacity maintained after seven cycles.

  13. Potential biodefense model applications for portable chlorine dioxide gas production.

    Science.gov (United States)

    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.

  14. Chlorine dioxide reaction with selected amino acids in water

    Energy Technology Data Exchange (ETDEWEB)

    Navalon, Sergio; Alvaro, Mercedes [Department of Chemistry, Universidad Politecnica de Valencia, Camino de Vera S/N, 46022 Valencia (Spain); Garcia, Hermenegildo, E-mail: hgarcia@qim.upv.es [Department of Chemistry, Universidad Politecnica de Valencia, Camino de Vera S/N, 46022 Valencia (Spain)

    2009-05-30

    Chlorine dioxide is a hypochlorite alternative disinfectant agent. In this context, we have determined the products formed in the reaction of ClO{sub 2} with selected amino acids as model compounds that can be present in natural waters. The reaction of tryptophane, histidine and tyrosine (10 ppm each) with ClO{sub 2} were studied at molar ratios ranging from 0.25 to 4 in the presence or absence of oxygen. It was found that in the absence of oxygen adding substoichiometric amounts of ClO{sub 2} creates products that are structurally similar to the starting amino acids. Through a series of cascade reactions the initial product distribution gradually evolves toward simple, small carbon chain products that are far from the starting amino acid. The reaction product distribution revealed that chlorine dioxide can attack the electron-rich aromatic moieties as well as the nitrogen atom lone electron pair. Our study is relevant to gain knowledge on the reaction mechanism of ClO{sub 2} with ubiquitous amino acids present in natural waters.

  15. Change in genotoxicity of wastewater during chlorine dioxide and chlorine disinfections and the influence of ammonia nitrogen

    Institute of Scientific and Technical Information of China (English)

    WANG Lisha; HU Hongying; WANG Chao; Koichi Fujie

    2007-01-01

    The effects of chlorine dioxide and chlorine disinfections on the genotoxicity of different biologically treated sewage wastewater samples were studied by umu-test.The experiment results showed that when chlorine dioxide dosage was increased from 0 to 30 mg/L,the genotoxicity of wastewater first decreased rapidly and then tended to be stable,while when the chlorine dosage was increased from 0 to 30 mg/L,the genotoxicity of wastewater changed diversely for different samples.It was then found that ammonia nitrogen did not affect the change of genotoxicity during chlorine dioxide disinfection of wastewater,while it greatly affected the change of genotoxicity during chlorine disinfection of wastewater.When the concentration of ammonia nitrogen was low(<10-20mg/L),the genotoxicity of wastewater decreased after chlorine disinfection,and when the concentration of ammonia nitrogen was high(>10-20 mg/L),the genotoxicity of wastewater increased after chlorine disinfection.

  16. 40 CFR 141.544 - What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection?

    Science.gov (United States)

    2010-07-01

    ..., 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...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2015-01-01

    This study aims to explore the effects of encapsulation of chlorine dioxide in a hydrophilic biodegradable polymer gelatin to reduce its release rate. 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). 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. 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.

  19. [Study on synergistic effect of bactericidal effect of chlorine dioxide solution by surfactant].

    Science.gov (United States)

    Wang, Kuitao; Tian, Vuena; Gu, Na; Zhang, Congjing; Niu, Jiajing

    2013-03-01

    To study the effect of gemini fluorocarbon, sodium p-perfluorous nonenoxybenzene sulfonate and sodium dodecyl sulfate on the chlorine dioxide solution sterilization to object surface. Pure chlorine dioxide solution as the reference disinfectant, carrier quantitative bactericidal test and simulated test on-site were used to carry out laboratory observation according to The disinfection technical specifications (2002). Carrier quantitative bactericidal test showed that the addition dosage of gemini fluoronates, sodium dodecyl sulfate surfactant and perfluorinated the nonene oxy benzene sulfonate in disinfectant solution were 60, 60 and 40 mg/L respectively, the killing log value of Staphylococcus aureus exposed to the disinfectant solution containing chlorine dioxide 50 mg/L for 10 mm were all more than 3; and the addition dosage of gemini fluorinates, sodium dodecyl sulfate and perfluorinated the nonene oxy benzene sulfonate in disinfectant solution were 60 mg/L, the killing log value of Escherichia coli exposed to the disinfectant solution containing chlorine dixoxide 20 mg/L for 10 min were all more than 3. The bactericidal effect of the mixture use of surfactant and chlorine dioxide was better than the single use of chlorine dioxide. The simulated test on-site showed that the killing log value of Escherichia coli exposed to the disinfectant solution containing perfluorinated the nonene oxy benzene sulfonate 40 mg/L and chlorine dioxide 20 mg/L for 15 min was more than 3. Surface active agent on germicidal efficacy of chlorine dioxide solution had synergistic action.

  20. 组合氯化消毒工艺的卤代消毒副产物生成特性%Disinfection By-products Reduction of Combined Disinfection by Chlorine and Monochloramines in Distribution System

    Institute of Scientific and Technical Information of China (English)

    刘静; 陈超; 张晓健

    2009-01-01

    比较4种单独使用氯或组合氯化消毒工艺在较长管网停留时的卤代消毒副产物生成情况.4种工艺为单独游离氯消毒、氯胺消毒、清水池游离氯消毒后转氯胺的先氯后氨消毒、短时游离氯后转氯胺的顺序氯化消毒工艺.结果表明,游离氯消毒工艺在管网停留时间长时,卤代消毒副产物会持续大量的生成,而一氯胺消毒工艺生成的卤代消毒副产物量很低.目前使用较为普遍的先氯后氨消毒工艺与游离氯消毒相比,可以降低卤代消毒副产物的生成量,管网停留24 h时,三卤甲烷的生成量降低了9.6%,卤乙酸的生成量减低了42%.但是先氯后氨消毒工艺由于游离氯接触时间约为2 h,卤代消毒副产物已经大量生成.短时游离氯后转氯胺的顺序氯化消毒工艺,由于控制了游离氯的接触时间,可以在保障消毒工艺灭活微生物效果的同时更为有效地控制卤代消毒副产物,管网停留24 h时,三卤甲烷的生成量与单独游离氯消毒工艺相比降低了48%,卤乙酸的生成量减低了72%.因此,顺序氯化消毒工艺可以更好地控制卤代消毒副产物的生成,提高水质安全性.%Halogen disinfection by-products of four chlorined disinfection processes with long contact time in distribution system was compared in the work. These four disinfection processes are free chlorine, monochloramines, free chlorine disinfection in clearwelles while chloramines in distribution system, sequential chlorination disinfection with short-term free chlorine plus chloramines. According to the research, free chlorine generates most trihalomethanes(THMs) and haloacetic acids (HAAs) both in clearwells and distribution system, while monochloramines barely yield halogen DBPs. Free chlorine disinfection in clearwelles while chloramines in distribution system could reduce 9.6% of THMs and 42% of HAAs in 24 h contact time of distribution system compared with free chlorine. But free

  1. [Study on pipe material's influence on chlorine dioxide drinking water disinfection].

    Science.gov (United States)

    He, Tao; Yue, Yinling; Ling, Bo; Zhang, Lan

    2010-09-01

    To study the pipe material's influence on chlorine dioxide drinking water disinfection. 0.8 mg/L chlorine dioxide solution was injected into 5 kinds of pipes respectively, PPR, PVC-U, Steel with Zinc coating, copper and PE pipes. Dipped free from light for 48 hours and the concentrations of chlorine dioxide, chlorite and chlorate were tested from samples taken from each kind of pipe at 1, 2, 3, 4, 5, 6, 12, 24 and 48 hours respectively. Chlorine dioxides decay rates in the water dipping the pipes increase as the dipping time increases and the decay of chlorine dioxide mainly occurs within 6 hours after the dipping. But for different pipe, the influence of decay differs. The consumption of chlorine dioxide of the metal pipes is more than that of the plastic pipes. And with 2 hours after the dipping experiment begins, the concentrations of the chlorite of the copper pipe and of the steel with zinc coating pipe increase quickly and reach the maximum concentration. But then the chlorite concentration decreases greatly. After dipped 24 hours, the chlorite in the water in the pipe can not be detected. For other plastic piples, all the chlorite concentrations in the dipping water increase as the dipping time increase. Compared with the start of the dipping experiment, the chlorate concentration in the dipping water of each pipe has no obvious change. The material of the water transportation pipe does have influence on chlorine dioxide drinking water disinfection.

  2. Clinical evaluation of chlorine dioxide for disinfection of dental instruments.

    Science.gov (United States)

    Watamoto, Takao; Egusa, Hiroshi; Sawase, Takashi; Yatani, Hirofumi

    2013-01-01

    This study aimed to clinically evaluate the disinfection efficacy of chlorine dioxide (ClO2) for used dental instruments. An imprint culture technique demonstrated that ultrasonic cleaning of intraorally applied dental mirrors in 0.02% ClO2 for 10 minutes resulted in compete removal of microorganisms for 10 subjects. Hepatitis C virus (HCV) RNA was detected by real-time polymerase chain reaction on periodontal curettes after subgingival scaling in four HCV-infected patients and was completely removed by the same treatment procedure. Therefore, the combination of ultrasonic cleaning with ClO2 may provide an alternative to toxic disinfectants, such as glutaraldehyde and sodium hypochlorite, for disinfecting dental instruments.

  3. Oxidation of phenol and hydroquinone by chlorine dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Wajon, J.E.; Rosenblatt, D.H.; Burrows, E.P.

    1982-07-01

    Rates of reaction of chlorine dioxide with phenol and with hydroquinone were determined with a stopped-flow spectrophotometer in the pH range 4-8. Second-order rate constants increase with increasing pH, consistent with a mechanism in which both the free phenol and the more reactive phenoxide anion react with ClO/sub 2/. Removal of an electron from the substrate by ClO/sub 2/ to form a phenoxyl radical and ClO/sub 2//sup -/ ion is the rate-determining step. Subsequently, in the case of hydroquinone, ClO/sub 2/ removes another electron from the radical, forming p-benzoquinone and another ClO/sub 2//sup -/ ion. In the case of phenol, ClO/sub 2/ adds to the phenoxyl radical para to the oxygen, and p-benzoquinone is formed with concomitant release of HOCl. The mechanism for phenol reaction accounts for (i) the immediate formation of p-benzoquinone without apparent intermediacy of hydroquinone, (ii) the chlorination observed in solutions containing excess phenol, and (iii) the production of only 0.5 mol of ClO/sub 2//sup -//mol of ClO/sub 2/ consumed.

  4. Bench and Full Scale Study of Removal Effect and Mutagenicity on Mesocyclops Leukarti with Chlorine Dioxide

    Institute of Scientific and Technical Information of China (English)

    ZUO Jin-long; YANG Wei; LIU Yan-an; LIN Tao

    2006-01-01

    Mesocyclops Leukarti of zooplankton propagates excessively in eutrophic water body and it can not be effectively inactivated by the conventional process in drinking waterworks for its special surface structure. In this paper, a study of removal efficiency on Mesocyclops Leukarti with chlorine dioxide in a drinking waterworks was performed.Bench scale results showed that chlorine dioxide is more effective against Mesocyclops Leukarti. And Mesocyclops Leukarti could be effectively removed from water by 1.0 mg/L chlorine dioxide preoxidation cooperated with the conventional process during the full scale study. The chlorite, by-preduct of prechlorine dioxide, was constant at 0.45 mg/L after filtration, which was lower than the critical value of the USEPA. GC-MS examination and Ames test showed that the quantity of organics and the mutagenicity in the water treated by chlorine dioxide is obviously less than that of prechlorination.

  5. Core-level excitation and fragmentation of chlorine dioxide

    Science.gov (United States)

    Flesch, R.; Plenge, J.; Rühl, E.

    2006-03-01

    Inner-shell excitation and fragmentation of chlorine dioxide (OClO) in the Cl 2p- and O 1s-excitation regime is reported. The electronic structure of the element-selectively excited radical is studied by X-ray absorption and total cation yields. A comparison of both approaches allows us to estimate the absolute photoionization cross-section and the ionization yield near the Cl 2p- and O 1s-absorption edges. The latter quantity is characteristically enhanced in core-ionization continua. We observe below both core-absorption edges intense core-to-valence-transitions. These are assigned in comparison with related work on core-excited sulfur dioxide. These results give clear evidence that the highest molecular orbital of OClO is half-filled. High-resolution spectra recorded in the Cl 2p-regime show evidence for Rydberg transitions. The extrapolation of the term values of the low-lying Rydberg states allows us to derive the Cl 2p-ionization energy of OClO. Fragmentation of core-excited OClO is reported. Photoelectron-photoion-coincidence (PEPICO) spectra are recorded, indicating that singly and doubly charged fragments are formed. Fission of the doubly and multiply charged OClO leads to singly charged fragments. These are measured by photoion-photoion-coincidence (PIPICO) spectra, where characteristic changes in intensity of the fission channels in the Cl 2p- and O 1s-continuum are observed.

  6. Comparison of chlorine and chlorine dioxide toxicity of fathead minnows and bluegill

    Energy Technology Data Exchange (ETDEWEB)

    Wilde, E.W.; Soracco, R.J.; Mayack, L.A.; Shealy, R.L.; Broadwell, T.L.; Steffen, R.F.

    1983-01-01

    The comparative toxicity of total residual chlorine (TRC) and chlorine dioxide (ClO/sub 2/) was evaluated by conducting 96 h flow-through bioassays with three types of fish. The fish were subjected to an intermittent exposure regime in which biocide residuals were present for approximately 2-h periods beginning at 0, 24, 48 and 72 h into the tests. These conditions simulated the antifouling procedure (1 h day/sup -1/ biocide addition) used to control biofouling of nuclear reactor heat exchangers at the Savannah River Plant near Aiken, South Carolina. LC/sub 50/ values showed that ClO/sub 2/ was approximately 2 to 4 times more toxic than TRC to: (1) juvenile and 1-year-old fathead minnows (Pimphales promelas); and (2) young-of-the-year bluegill (Lepomis macrochirus). The TRC mean 96-h LC/sub 50/ values were: 0.08 mg l/sup -1/ for juvenile fathead minnows, 0.35 mg l/sup -1/ for adult fathead minnows and 0.44 mg l/sup -1/ for young-of-the-year bluegills. The ClO/sub 2/ mean LC/sub 50/ values were: 0.02 mg l/sup -1/ for juvenile fathead minnows, 0.17 mg l/sup -1/ for adult fathead minnows and 0.15 mg l/sup -1/ for young-of-the-year bluegills. 31 references, 1 figure, 3 tables.

  7. Chlorine dioxide as phenol and H2S scavenger - formation of halogenated phenols and subsequent environmental risk

    Energy Technology Data Exchange (ETDEWEB)

    Melbye, Alf G.; Faksness, Liv-Guri; Knudsen, Boerre Leif

    2006-03-15

    Formation of halogenated phenols as side products from treatment of produced water with aqueous chlorine dioxide has been investigated. The literature describes formation of halogenated hydrocarbons in effluent treatment using chlorine, hypochlorite and chlorine dioxide. A new chlorine dioxide product, originally intended as a H2S scavenger in the oil and gas industry, has been tested both as a phenol scavenger and H2S-scavenger for produced water applications. The concern about the possible formation of halogenated by-products initiated laboratory testing of chlorine dioxide as phenol and H2S scavenger for produced water applications. The tests also included synthetic matrixes containing phenols, and the tests show that halogenated phenols, mainly brominated species, are found in produced water after treatment with chlorine dioxide. Due to potential environmental risk from halogenated organic contaminants, the use of chlorine dioxide as phenol and H2S scavenger is not recommended. (Author)

  8. Sterilization of hydrogen peroxide resistant bacterial spores with stabilized chlorine dioxide.

    Science.gov (United States)

    Friedline, Anthony; Zachariah, Malcolm; Middaugh, Amy; Heiser, Matt; Khanna, Neeraj; Vaishampayan, Parag; Rice, Charles V

    2015-01-01

    Bacillus pumilus SAFR-032 spores isolated from a clean room environment are known to exhibit enhanced resistance to peroxide, desiccation, UV radiation and chemical disinfection than other spore-forming bacteria. The survival of B. pumilus SAFR-032 spores to standard clean room sterilization practices requires development of more stringent disinfection agents. Here, we report the effects of a stabilized chlorine dioxide-based biocidal agent against spores of B. pumilus SAFR-032 and Bacillus subtilis ATCC 6051. Viability was determined via CFU measurement after exposure. Chlorine dioxide demonstrated efficacy towards sterilization of spores of B. pumilus SAFR-032 equivalent or better than exposure to hydrogen peroxide. These results indicate efficacy of chlorine dioxide delivered through a stabilized chlorine dioxide product as a means of sterilization of peroxide- and UV-resistant spores.

  9. Evaluation of Chlorine Dioxide Irrigation Solution on the Microhardness and Surface Roughness of Root Canal Dentin.

    Science.gov (United States)

    Ballal, Nidambur Vasudev; Khandewal, Deepika; Karthikeyan, Saravana; Somayaji, Krishnaraj; Foschi, Federico

    2015-12-01

    The aim of this study was to evaluate the effect of chlorine dioxide and various other more common irrigation solutions on the microhardness and surface roughness of root canal dentin. Fifty human maxillary central incisors were sectioned longitudinally and treated for 1 minute with 5 ml of the following aqueous solutions (v/v%): Group 1: 13.8% chlorine dioxide, Group 2: 17% ethylene diamine tetraacetic acid (EDTA). Group 3: 7% maleic acid, Group 4: 2.5% sodium hypochlorite (5 ml/min), Group 5: Saline (control). Specimens were subjected to microhardness and surface roughness testing. Chlorine dioxide and sodium hypochlorite reduced the microhardness more than other test agents. The highest surface roughness was produced with maleic acid. Chlorine dioxide should be used cautiously during chemomechanical preparation of the root canal system in order to prevent untoward damage to the teeth.

  10. Antimicrobial effect of chlorine dioxide on Actinobacillus actinomycetemcomitans in diabetes mellitus rats treated with insulin

    Directory of Open Access Journals (Sweden)

    Tantin Ermawati

    2012-03-01

    Full Text Available Background: Periodontitis is a chronic inflammatory disease of periodontal tissues. Etiology of periodontal disease includes Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans which is the most predominant disease-causing bacteria found in the gingival sulcus. Periodontitis can be exacerbated by the systemic disease, such as diabetes mellitus considered as a metabolic disease characterized by hyperglycemia due to insulin deficiency. Treatment of periodontitis is then required in patients with type I diabetes to avoid radical reaction that can not only cause bleeding, but can also prevent infection, as a result, topical antimicrobial therapy and blood glucose control are required. Topical antimicrobial chlorine dioxide is a disinfectant that is effective in killing A. actinomycetemcomitans. Purpose: This study is aimed to determine the effects of topical antimicrobial chlorine dioxide gel or rinse on the number of A. actinomycetemcomitans in DM rats treated with insulin. Methods: 20 three month old male Wistar rats with weight of 170–200 grams were divided into four groups. First, periodontitis and DM were manipulated into all groups through aloksan injection with dose of 170 mg/kg. Those rats in group I were treated with insulin and chlorine dioxide gel, those in group II were treated with insulin and chlorine dioxide rinse, those in group III were treated with insulin only, and those in group IV were without treatment. In the third and seventh weeks, the number of A. actinomycetemcomitans was measured. The data was tested by using One-Way ANOVA test followed by LSD test. Results: The study showed that chlorine dioxide gel has a greater ability in reducing the number of A. actinomycetemcomitans than chlorine dioxide rinse although both are antimicrobials. Conclusion: It can be concluded that the use of chlorine dioxide gel can more effective to decrease the number of A. actinomycetemcomitans than chlorine dioxide rinse in DM rats

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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...

  13. Evaluation of chlorine dioxide gas treatment to inactivate Salmonella enterica on mungbean sprouts.

    Science.gov (United States)

    Prodduk, Vara; Annous, Bassam A; Liu, Linshu; Yam, Kit L

    2014-11-01

    Although freshly sprouted beans and grains are considered to be a source of nutrients, they have been associated with foodborne outbreaks. Sprouts provide good matrices for microbial localization and growth due to optimal conditions of temperature and humidity while sprouting. Also, the lack of a kill step postsprouting is a major safety concern. The objective of this work was to evaluate the effectiveness of chlorine dioxide gas treatment to reduce Salmonella on artificially inoculated mungbean sprouts. The effectiveness of gaseous chlorine dioxide (0.5 mg/liter of air) with or without tumbling (mechanical mixing) was compared with an aqueous chlorine (200 ppm) wash treatment. Tumbling the inoculated sprouts during the chlorine dioxide gas application for 15, 30, and 60 min reduced Salmonella populations by 3.0, 4.0, and 5.5 log CFU/g, respectively, as compared with 3.0, 3.0, and 4.0 log CFU/g reductions obtained without tumbling, respectively. A 2.0 log CFU/g reduction in Salmonella was achieved with an aqueous chlorine wash. The difference in microbial reduction between chlorine dioxide gas versus aqueous chlorine wash points to the important role of surface topography, pore structure, bacterial attachment, and/or biofilm formation on sprouts. These data suggested that chlorine dioxide gas was capable of penetrating and inactivating cells that are attached to inaccessible sites and/or are within biofilms on the sprout surface as compared with an aqueous chlorine wash. Consequently, scanning electron microscopy imaging indicated that chlorine dioxide gas treatment was capable of penetrating and inactivating cells attached to inaccessible sites and within biofilms on the sprout surfaces.

  14. Evaluation of the use of chlorine dioxide to control zebra mussels

    Energy Technology Data Exchange (ETDEWEB)

    Tsou, J. [Electric Power Research Institute, Palo Alto, CA (United States); Coyle, J. [Central Illinois Public Service, Meredosia, IL (United States); Pallo, S. [Illinois Power Company, Clinton, IL (United States)] [and others

    1995-06-01

    Chlorine dioxide was tested as a zebra mussel biocide at two steam electric generating stations in Illinois. The purpose of these studies was to determine the efficacy of chlorine dioxide in killing zebra mussels and to develop site specific treatment programs for the two utilities. The Electric Power Research Institute (EPRI) Zebra Mussel Consortium sponsored the testing of this recent use of chlorine dioxide. The raw water system at Central Illinois Public Service`s Meredosia Station, on the Illinois River, received two to four day applications of chlorine dioxide in April, July, and September 1994. The raw water system at Illinois Power Company`s Wood River Station, on the Mississippi River, received two to four day applications in July 1993, January, April, May, July, and September 1994. Chlorine dioxide was generated on-site and injected into the water intake structure, in front of or just behind the traveling screens, at both power stations. Both cooling and service water systems were treated at the facilities. Various water quality parameters, including residual chlorine in the discharge effluent, were measured during the studies. Residual chlorine was neutralized with sodium bisulfite prior to discharge at both plants. Bioboxes, containing healthy zebra mussels, were placed at various strategic locations throughout the power stations. Control bioboxes were also placed in the rivers, upstream of the chlorine dioxide injection locations. Results of the chlorine dioxide applications varied from 35 percent to 100 percent. These varied results appear to be related to seasonal water temperature differences, water quality, and/or plant design. Mortality differences were also noted in bioboxes which contained zebra mussels imported from Lake Erie and those which contained local mussels. These and other data are presented.

  15. Influence of drinking water treatments on chlorine dioxide consumption and chlorite/chlorate formation.

    Science.gov (United States)

    Sorlini, Sabrina; Gialdini, Francesca; Biasibetti, Michela; Collivignarelli, Carlo

    2014-05-01

    Disinfection is the last treatment stage of a Drinking Water Treatment Plant (DWTP) and is carried out to maintain a residual concentration of disinfectant in the water distribution system. Chlorine dioxide (ClO2) is a widely used chemical employed for this purpose. The aim of this work was to evaluate the influence of several treatments on chlorine dioxide consumption and on chlorite and chlorate formation in the final oxidation/disinfection stage. A number of tests was performed at laboratory scale employing water samples collected from the DWTP of Cremona (Italy). The following processes were studied: oxidation with potassium permanganate, chlorine dioxide and sodium hypochlorite, coagulation/flocculation with ferric chloride and aluminum sulfate, filtration and adsorption onto activated carbon. The results showed that the chlorine dioxide demand is high if sodium hypochlorite or potassium permanganate are employed in pre-oxidation. On the other hand, chlorine dioxide leads to the highest production of chlorite and chlorate. The coagulation/flocculation process after pre-oxidation shows that chlorine dioxide demand decreases if potassium permanganate is employed as an oxidant, both with ferric chloride and aluminum sulfate. Therefore, the combination of these processes leads to a lower production of chlorite and chlorate. Aluminum sulfate is preferable in terms of the chlorine dioxide demand reduction and minimization of the chlorite and chlorate formation. Activated carbon is the most effective solution as it reduced the chlorine dioxide consumption by about 50% and the DBP formation by about 20-40%. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Water Quality Impacts of Pure Chlorine Dioxide Pretreatment at the Roanoke County (Virginia) Water Treatment Plant

    OpenAIRE

    Ellenberger, Christine Spada

    1999-01-01

    WATER QUALITY IMPACTS OF PURE CHLORINE DIOXIDE PRETREATMENT AT THE ROANOKE COUNTY (VIRGINIA) WATER TREATMENT PLANT by Christine S. Ellenberger Dr. Robert C. Hoehn, Chairman (ABSTRACT) Chlorine dioxide (ClO2) was included in the Spring Hollow Water Treatment Plant (Roanoke County, Virginia) to oxidize manganese and iron, prevent tastes and odors, and avoid the formation of excessive halogenated disinfection by-products. A state-of-the-art, gas:solid ClO2 generation system ...

  17. Corrosion of stainless steels by sulphur dioxide and chlorine in atmospheric conditions

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, S.; Dhirendra, Dr.; Sanyal, B.; Pandey, G.N.

    1982-10-01

    This paper deals with the effect of sulphur dioxide and chlorine on stainless steels (AISI 304 and 321) under different atmospheric conditions. 70% RH value was found to be critical giving maximum corrosion. Potassium dichromate has been found to be a suitable passivating agent for protection against corrosion due to chlorine. (5 refs.)

  18. Chloroxyanion residues in cantaloupe and tomatoes after chlorine dioxide gas sanitation

    Science.gov (United States)

    Chlorine dioxide gas is effective at cleansing fruits and vegetables of bacterial pathogens and(or) rot organisms, but few data are available on chemical residues remaining subsequent to chlorine gas treatment. Therefore, studies were conducted to quantify chlorate and perchlorate residues after tom...

  19. Full-scale study of removal effect on Cyclops of zooplankton with chlorine dioxide

    Institute of Scientific and Technical Information of China (English)

    LIN Tao; CUI Fu-yi; LIU Dong-mei; AN Dong

    2004-01-01

    Cyclops of zooplankton propagated excessively in eutrophic water body and could not be effectively inactivated by the conventional disinfections process like chlorination due to its stronger resistance to oxidation. In this paper, a full-scale study of chlorine dioxide preoxidation cooperating with routine clarification process for Cyclops removal was conducted in a waterworks. The experimental results were compared with that of the existing prechlorination process in several aspects: including the Cyclops removal efficiencies of water samples taken from the outlets of sedimentation tank and sand filter and the security of drinking water etc. The results showed that chlorine dioxide might be more effective to inactivate Cyclops than chlorine and Cyclops could be thoroughly removed from water by pre-dosing chlorine dioxide process. The GC-MS examination and Ames test further showed that the sort and amount of organic substance in the treated water by chlorine dioxide preoxidation were evidently less than that of prechlorination and the mutagenicity of drinking water treated by pre-dosing chlorine dioxide was substantially reduced compared with prechlorination.

  20. Pilot-scale study of removal effect on Chironomid larvae with chlorine dioxide

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Chironomid larvae propagated excessively in eutrophic water body and could not be effectively inactivated by the conventional disinfection process like chlorination due to its stronger resistance to oxidation. In this paper, a pilot-scale study of chlorine dioxide preoxidation cooperating with routine clarification process for Chironomid larvae removal was conducted in Shenzhen Waterworks in Guangdong Province, China. The experimental results were compared with that of the existing prechlorination process in several aspects, including the Chironomid larvae removal efficiencies of water samples taken from the outlets of sedimentation tank, sand filter, the security of drinking water and so on. The results showed that chlorine dioxide might be more effective to inactivate Chironomid larvae than chlorine and Chironomid larvae could be thoroughly removed from water by pre-dosing chlorine dioxide process. The GC-MS examination and Ames test further showed that the sort and amount of organic substance in the treated water by chlorine dioxide preoxidation were evidently less than that ofprechlorination and the mutagenicity of drinking water treated by pre-dosing chlorine dioxide was substantially reduced compared with prechlorination.

  1. Establishment and Early Succession of Bacterial Communities in Monochloramine-treated Drinking Water Biofilms

    Science.gov (United States)

    The use of monochloramine as drinking water disinfectant is increasing because it forms lower levels of traditional disinfection by-products compared to free-chlorine. However, little is known about the bacterial succession within biofilms in monochloramine-treated systems. The d...

  2. Changes in Biofilm Community Structure Associated with Monochloramine-treated Drinking Water Biofilms

    Science.gov (United States)

    Monochloramine is increasingly used as a drinking water disinfectant because it forms lower levels of traditional disinfectant by-products compared to free-chlorine disinfection treatment. The use of monochloramine has been shown to increase ammonia-oxidizing bacteria and the pr...

  3. Chloroxyanion Residue Quantification in Cantaloupes Treated with Chlorine Dioxide Gas.

    Science.gov (United States)

    Kaur, Simran; Smith, David J; Morgan, Mark T

    2015-09-01

    Previous studies show that treatment of cantaloupes with chlorine dioxide (ClO2) gas at 5 mg/liter for 10 min 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 Escherichia coli O157:H7 and Listeria monocytogenes, respectively. However, this treatment could result in the presence of chloroxyanion residues, such as chloride (Cl(-)), chlorite (ClO2(-)), chlorate (ClO3(-)), and perchlorate (ClO4(-)), which, apart from chloride, are a toxicity concern. Radiolabeled chlorine dioxide ((36)ClO2) gas was used to describe the identity and distribution of chloroxyanion residues in or on cantaloupe subsequent to fumigation with ClO2 gas at a mean concentration of 5.1 ± 0.7 mg/liter for 10 min. Each treated cantaloupe was separated into rind, flesh, and mixed (rind and flesh) sections, which were blended and centrifuged to give the corresponding sera fractions. Radioactivity detected, ratio of radioactivity to mass of chlorite in initial ClO2 gas generation reaction, and distribution of chloroxyanions in serum samples were used to calculate residue concentrations in flesh, rind, and mixed samples. Anions detected on the cantaloupe were Cl(-) (∼ 90%) and ClO3(-) (∼ 10%), located primarily in the rind (19.3 ± 8.0 μg of Cl(-)/g of rind and 4.8 ± 2.3 μg of ClO3(-)/g of rind, n = 6). Cantaloupe flesh (∼ 200 g) directly exposed to(36)ClO2 gas treatment showed the presence of only Cl(-) residues (8.1 ± 1.0 μg of Cl(-)/g of flesh, n = 3). Results indicate chloroxyanion residues Cl(-) and ClO3(-) are only present on the rind of whole cantaloupes treated with ClO2 gas. However during cutting, residues may be transferred to the fruit flesh. Because Cl(-) is not toxic, only ClO3(-) would be a toxicity concern, but the levels transferred from rind to flesh are very low. In the case of fruit flesh directly exposed to ClO2 gas, only nontoxic Cl(-) was detected. This

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

    Science.gov (United States)

    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.

  5. Decontamination of a hospital room using gaseous chlorine dioxide: Bacillus anthracis, Francisella tularensis, and Yersinia pestis.

    Science.gov (United States)

    Lowe, John J; Gibbs, Shawn G; Iwen, Peter C; Smith, Philip W; Hewlett, Angela L

    2013-01-01

    This study assessed the efficacy of gaseous chlorine dioxide for inactivation of Bacillus anthracis, Francisella tularensis, and Yersinia pestis in a hospital patient care suite. Spore and vegetative cells of Bacillus anthracis Sterne 34F2, spores of Bacillus atrophaeus ATCC 9372 and vegetative cells of both Francisella tularensis ATCC 6223 and Yersinia pestis A1122 were exposed to gaseous chlorine dioxide in a patient care suite. Organism inactivation was then assessed by log reduction in viable organisms postexposure to chlorine dioxide gas compared to non-exposed control organism. Hospital room decontamination protocols utilizing chlorine dioxide gas concentrations of 377 to 385 ppm maintained to exposures of 767 ppm-hours with 65% relative humidity consistently achieved complete inactivation of B. anthracis and B. atrophaeus spores, as well as vegetative cells of B. anthracis, F. tularensis, and Y. pestis. Decrease in exposure (ppm-hours) and relative humidity (8 log reductions in organisms. Up to 10-log reductions were achieved in a hospital room with limited impact on adjacent areas, indicating chlorine dioxide concentrations needed for decontamination of highly concentrated (>6 logs) organisms can be achieved throughout a hospital room. This study translates laboratory chlorine dioxide fumigation studies applied in a complex clinical environment.

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

    Science.gov (United States)

    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 population...

  7. The synergistic effect of Escherichia coli inactivation by sequential disinfection with low level chlorine dioxide followed by free chlorine.

    Science.gov (United States)

    Yang, Wu; Yang, Dong; Zhu, Sui-Yi; Chen, Bo-Yan; Huo, Ming-Xin; Li, Jun-Wen

    2012-12-01

    To the best of our knowledge, there was little information available on pathogen removal using low level disinfectant followed by free chlorine in sequential disinfection (SD). This study investigated Escherichia coli inactivation by four types of disinfection: single step disinfection (SSD), SD, traditional sequential disinfection (TSD) and mixed disinfectant disinfection (MDD). Results indicated that SD had higher ability to inactivate E. coli than the others, indicating there was a positive synergistic effect on chlorine disinfection by prior dosing with a low level of chlorine dioxide (ClO(2)). The ONPG assay suggested that the permeability of cell wall rather than the viability of E. coli were changed under 0.02 mg/l ClO(2) treatment. The coexistence of residual ClO(2) and free chlorine also plays an active synergistic effect. Additionally, temperature had a positive effect on E. coli inactivation in SD, while inactivation was reduced in alkaline compared to neutral and acidic conditions.

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

    Science.gov (United States)

    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.

  9. Very Low Energy Electron Scattering from Ozone and Chlorine Dioxide

    Science.gov (United States)

    Gulley, R. J.; Field, T. A.; Steer, W. A.; Mason, N. J.; Ziesel, J. P.; Lunt, S. L.; Field, D.

    1998-10-01

    Total cross-sections are reported for the scattering of electrons from ozone (O_3) and chlorine dioxide (OClO) for energies in the range of 9 meV to 10 eV. The measurements were made in transmission experiments using a synchrotron photoionization apparatus with an energy resolution in the incident electron beam of ~ 3.5 meV (FWHM). The cross section for O3 shows strong rotational scattering at low energy, through the presence of the permanent dipole moment of O_3. Superposed on this strong scattering signal, there is evidence of a weak structure around 50 meV associated with dissociative attachment. A shape resonance, known from earlier work at ~ 4 meV, is also observed. Electron scattering from OClO is dominated by rotationally inelastic scattering decreasing from a peak at essentially zero eV to an energy of 40 meV, where p-wave attachment becomes more important, peaking at 50--60 meV and extending to several hundred meV.

  10. Etching Rate of Silicon Dioxide Using Chlorine Trifluoride Gas

    Science.gov (United States)

    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.

  11. Chlorine dioxide-facilitated oxidation of the azo dye amaranth.

    Science.gov (United States)

    Nadupalli, S; Koorbanally, N; Jonnalagadda, S B

    2011-10-27

    The oxidation reaction of amaranth (trisodium 2-hydroxy-1-(4-sulfonato-1-naphthylazo)naphthalene-3,6-disulfonate or AM(-)) by chlorine dioxide (ClO(2)) in aqueous conditions was investigated in detail. The major reaction products immediately after decolorization of AM(-) were 1,2-naphthoquinone disulfonate sodium salt and 1,4-napthalenedione. The reaction had first-order dependence on both AM(-) and ClO(2). The rate-limiting step involved the reaction between AM(-) and OH(-) ions. The role of hydroxide ion as a catalyst was established. The second-order rate constant increased with pH, from (19.8 ± 0.9) M(-1) s(-1) at pH 7.0, (97.1 ± 2.3) M(-1) s(-1) at pH 8.0 to (132.5 ± 2.8) M(-1) s(-1) at pH 9.0. In the pH range of 6.0-7.5, the catalytic constant for OH(-) ion was 4.0 × 10(9) M(-2) s(-1). The energy and entropy of activation values for the reaction were 50.0 kJ mol(-1) and -658.7 J K(-1) mol(-1), respectively. A probable reaction mechanism was elucidated and was validated by simulations.

  12. Degradation of microcystin-RR in water by chlorine dioxide

    Institute of Scientific and Technical Information of China (English)

    JI Ying; HUANG Jun-li; FU Jiao; WU Ming-song; CUI Chong-wei

    2008-01-01

    Due to the potent hepatotoxicity and tumor-promoting activity of microcystins, a successful removal of these toxins during drinking water treatment processes is of increasing concern. The oxidation kinetics of MC-RR by chlorine dioxide (C1O2)was studied with HPLC and characterization of the reacdon products was performed with UV-spectrometry, TOC and LC-MS. Our experimental results show that the oxidation process is a second order overall and a first order with respect to C1O2 and MC-RR.The activation energy of MC-RR degradation by C1O2 is 53.07 kJ/mol. The rate constant k of the action can be increased by increasing temperature and decreasing pH value and ranged from 6. 11x102 L/(mol.min) to 5.29x 102 L/(mol-min) at pH from 3.44 to 10.41 at 10 ℃. Reaction products were determined to be organic and volatile, because they could be almost removed from aqueous solution by heating for 15 min at 60 ℃. In addition, the main oxidation products have m/z values of 1072 and are identified as dihydroxy isomers of MC-RR.

  13. Impact of combining chlorine dioxide and chlorine on DBP formation in simulated indoor swimming pools.

    Science.gov (United States)

    Kim, Daekyun; Ates, Nuray; Kaplan Bekaroglu, Sehnaz Sule; Selbes, Meric; Karanfil, Tanju

    2017-08-01

    The main objective of this study was to assess the combined use of chlorine dioxide (ClO2) and chlorine (Cl2) on the speciation and kinetics of disinfection by-product (DBP) formation in swimming pools using synthetic pool waters prepared with a body fluid analog (BFA) and/or fresh natural water. At 1:25 (mass ratio) of ClO2 to Cl2, there was no significant reduction in the formation of trihalomethanes (THMs) and haloacetic acids (HAAs) for both BFA solution and natural water compared to the application of Cl2 alone. When the mass ratio of ClO2 to Cl2 increased to 1:1, substantial decreases in both THMs and HAAs were observed in the natural water, while there was almost no change of DBP formations in the BFA solution. Haloacetonitriles and halonitromethanes levels in both water matrices remained similar. In the presence of bromide, the overall DBP formation increased in both BFA solution and natural water. For the DBP formation kinetics, after 72hr of contact time, very low formation of THMs and HAAs was observed for the use of ClO2 only. Compared to Cl2 control, however, applying the 1:1 mixture of ClO2/Cl2 reduced THMs by >60% and HAAs by >50%. Chlorite was maintained below 1.0mg/L, while the formation of chlorate significantly increased over the reaction time. Finally, in a bench-scale indoor pool experiment, applying ClO2 and Cl2 simultaneously produced less THMs compared to Cl2 control and kept chlorite at <0.4mg/L, while HAAs and chlorate accumulated over 4-week operation period. Copyright © 2017. Published by Elsevier B.V.

  14. Removal of hexenuronic acid by xylanase to reduce adsorbable organic halides formation in chlorine dioxide bleaching of bagasse pulp.

    Science.gov (United States)

    Nie, Shuangxi; Wang, Shuangfei; Qin, Chengrong; Yao, Shuangquan; Ebonka, Johnbull Friday; Song, Xueping; Li, Kecheng

    2015-11-01

    Xylanase-aided chlorine dioxide bleaching of bagasse pulp was investigated. The pulp was pretreated with xylanase and followed a chlorine dioxide bleaching stage. The ATR-FTIR and XPS were employed to determine the surface chemistry of the control pulp, xylanase treated and chlorine dioxide treated pulps. The hexenuronic acid (HexA) could obviously be reduced after xylanase pretreatment, and the adsorbable organic halides (AOX) were reduced after chlorine dioxide bleaching. Compared to the control pulp, AOX could be reduced by 21.4-26.6% with xylanase treatment. Chlorine dioxide demand could be reduced by 12.5-22% to achieve the same brightness. The ATR-FTIR and XPS results showed that lignin and hemicellulose (mainly HexA) were the main source for AOX formation. Xylanase pretreatment could remove HexA and expose more lignin, which decreased the chlorine dioxide demand and thus reduced formation of AOX.

  15. Chloroxyanion Residues in Cantaloupe and Tomatoes after Chlorine Dioxide Gas Sanitation.

    Science.gov (United States)

    Smith, D J; Ernst, W; Herges, G R

    2015-11-04

    Chlorine dioxide gas is effective at cleansing fruits and vegetables of bacterial pathogens and(or) rot organisms, but little data are available on chemical residues remaining subsequent to chlorine gas treatment. Therefore, studies were conducted to quantify chlorate and perchlorate residues after tomato and cantaloupe treatment with chlorine dioxide gas. Treatments delivered 50 mg of chlorine dioxide gas per kg of tomato (2-h treatment) and 100 mg of gas per kg of cantaloupe (6-h treatment) in sealed, darkened containers. Chlorate residues in tomato and cantaloupe edible flesh homogenates were less than the LC-MS/MS limit of quantitation (60 and 30 ng/g respectively), but were 1319 ± 247 ng/g in rind + edible flesh of cantaloupe. Perchlorate residues in all fractions of chlorine dioxide-treated tomatoes and cantaloupe were not different (P > 0.05) than perchlorate residues in similar fractions of untreated tomatoes and cantaloupe. Data from this study suggest that chlorine dioxide sanitation of edible vegetables and melons can be conducted without the formation of unwanted residues in edible fractions.

  16. Selective chlorine dioxide determination using gas-diffusion flow injection analysis with chemiluminescent detection

    Energy Technology Data Exchange (ETDEWEB)

    Hollowell, D.A.; Gord, J.R.; Gordon, G.; Pacey, G.E.

    1986-06-01

    An automated chemiluminescent technique has been developed utilizing the advantages of gas-diffusion flow injection analysis. A gas-diffusion membrane separates the donor (sampling) stream from the acceptor (detecting) stream and removes ionic interferences. A novel chemiluminescence flow-through detector cell is used to measure the concentration of chlorine dioxide as a function of the intensity of the chemiluminescence produced from its reaction with luminol. The chemiluminescent reagent merges with the analyte directly in front of the photomultiplier tube in order to maximize the sensitivity of the system. The detection limit for chlorine dioxide is approximately 5 ppb. The method is over 1500 times more selective for chlorine dioxide than for chlorine on a mole basis. This method eliminates interference from iron and manganese compounds, as well as other oxychlorinated compounds such as chlorite ion and chlorate ion.

  17. [Comparison of the effects of chlorine dioxide, sodium hypochlorite and their combination on simulative water disinfection].

    Science.gov (United States)

    Wang, Ying; Li, Na; Lu, Yi; Wang, Yazhou

    2008-05-01

    To compare the effects of disinfection of chlorine dioxide (ClO2), sodium hypochlorite(NaClO) and their combination (ClO + NaClO) on simulative water samples. The simulative water samples containing 5.0 x 10(4) - 5.0 x 10(5) cfu/100ml Escherichia coli were prepared in laboratory and disinfected by different doses of chlorine dioxide, sodium hypochlorite and their combination for 60, 60, 30 + 60 min respectively. The kill ratio for Escherichia coli, and the residual chlorine dioxide, and the product of chlorite ion (ClO2-) and total residual chlorine were detected and compared by the membrane filter(MF) technique and electrometric titration. The minimum effective dosage (MED) for disinfect of simulative water samples were 0.4 mg/L of chlorine dioxide, 0.5 mg/L of sodium hypochlorite, and the 0.1 mg/L + 0.3 mg/L or 0.2 mg/L + 0.2 mg/L of their combination. By comparision with disinfection of ClO2 and NaClO alone, the residual chlorine dioxide increased 13.43% - 166.67% in simulative water sample under disinfection by the combination of ClO2 + NaClO, While chlorite ion decreased 13.11% - 19.97% and total residual chlorine increased 9.34% - 40.15%. The combination of chlorine dioxide and sodium hypochlorite for disinfection of drinking water could achieve better effect of disinfection and decrease disinfection by-products as well.

  18. Final chlorine dioxide stage at near-neutral pH for bleaching eucalypt pulp

    Directory of Open Access Journals (Sweden)

    Robisnéa A. Ribeiro

    2014-01-01

    Full Text Available It is well known that pH is an important parameter for controlling the eucalyptus pulp bleaching when using the final chlorine dioxide stage, since it affects the effectiveness of the process. Recommendations found in the literature for operating are in the 3.5 to 4.0 range. However, in this paper it was shown that final chlorine dioxide has better performance, with significant brightness gain while also preserving pulp quality, when it is operated at near neutral pH. This result can be explained by the generation of sodium bicarbonate in situ upon adding carbon dioxide at this stage.

  19. Reactions of aqueous chlorine and chlorine dioxide with model food compounds

    Energy Technology Data Exchange (ETDEWEB)

    Fukayama, M.Y.; Tan, H.; Wheeler, W.B.; Wei, C.

    1986-11-01

    This presentation reviews published information concerning the reactions of chlorine gas (CL/sub 2/(g)), aqueous chlorine, and ClO/sub 2/ with model food compounds, the fate of chlorine during the chlorination of specific food products, and the potential toxicity of the reaction products. Fatty acids and their methyl esters react with chlorine with the degree of incorporation corresponding to their degree of unsaturation. Aqueous chlorine oxidizes and chlorinates lipids and amino acids much more readily than ClO/sub 2/. Several amino acids are highly susceptible to oxidation and chlorination by chlorine compounds. Reactions of chlorine and ClO/sub 2/ with several food products, including flour and shrimp, have also been characterized. Although significant quantities of chlorine can be incorporated into specific model compounds and food products, the health risks associated with exposure to chlorinated organic products are unknown. Preliminary studies using the Ames Salmonella/microsome mutagenicity assay indicate that the reaction products from mixtures of aqueous chlorine and various lipids or tryptophan are nonmutagenic. Nevertheless, additional studies are warranted, so that the toxicological significance of these reaction products can be understood more fully.

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

    Directory of Open Access Journals (Sweden)

    DuBois John D

    2009-09-01

    Full Text Available Abstract 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 3 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

  1. Rapid Determination of HAAs Formation Potential of the Reaction of Humic Acid with Chlorine or Chlorine Dioxide

    Institute of Scientific and Technical Information of China (English)

    ZHU Zhi-liang; GE Yuan-xin; ZHANG Rong-hua; MA Hong-mei; HAO Jian-fu

    2007-01-01

    On the basis of gas chromatography(GC) coupled with a short capillary column and an electron capture detector(ECD), a simple and rapid method for the determination of five haloacetic acids(HAAs) in drinking water was developed by the optimization of derivation conditions and the modification of gas chromatographic program. HAAs formation potential(HAAFP) of the reaction of humic acid with chlorine was determined via this method. The major advantages of the method are the simplicity of chromatographic temperature program and the short run time of GC. Dichloroacetic acid(DCAA) and Trichloroacetic acid(TCAA), which were detected in the determination of HAAFP, were rapidly formed in the first 72 h of the reaction of humic acid with chlorine. HAAFP of the reaction of humic acid with chlorine increased with the increase in the concentrations of humic acid and chlorine. The average HAAFP of the reaction of humic acid with chlorine was 39.9 μg/mg TOC under the experimental conditions. When the concentration of humic acid was 4 mg/L, the concentration of HAAs, which were produced in the reaction of humic acid with chorine, may exceed MCL of 60 μg/L HAAs as the water quality standards for urban water supply of China and the first stage of US EPA disinfection/disinfection by-products(D/DBP) rule; when the concentration of humic acid was 2 mg/L, the concentration of HAAs may exceed MCL of 30 μg/L HAAs for the second stage of US EPA D/DBP rule. When humic acid was reacted with chlorine dioxide, only DCAA was detected with a maximum concentration of 3.3 μg/L at a humic acid content of 6 mg/L. It was demonstrated that the substitution of chlorine dioxide for chorine may entirely or partly control the formation of HAAs and effectively reduce the health risk associated with disinfected drinking water.

  2. Transcriptional and phenotypic responses of Listeria monocytogenes to chlorine dioxide.

    Science.gov (United States)

    Pleitner, Aaron M; Trinetta, Valentina; Morgan, Mark T; Linton, Richard L; Oliver, Haley F

    2014-05-01

    Significant food-borne disease outbreaks have occurred from consumption of ready-to-eat foods, including produce, contaminated with Listeria monocytogenes. Challenging food matrices (e.g., cantaloupe, sprouts) with limited processing steps postharvest to reduce pathogen loads have underscored a need for new mitigation strategies. Chlorine dioxide (ClO2) is increasingly being used in produce and other food systems to reduce food-borne pathogen levels. The goal of this study was to characterize the transcriptional response and survival of L. monocytogenes 10403S exposed to ClO2. The transcriptional profile of log-phase cells exposed to 300 mg/liter ClO2 for 15 min was defined by whole-genome microarray. A total of 340 genes were significantly differentially expressed. Among the differentially expressed genes, 223 were upregulated (fold change ≥ 1.5; adjusted P value < 0.05) in role categories responsible for protein fate, cellular processes, and energy metabolism. There were 113 and 16 genes differentially expressed belonging to regulatory networks of σ(B) and CtsR, respectively. We assessed L. monocytogenes 10403S survival after exposure to 100, 300, and 500 mg/liter aqueous ClO2 in brain heart infusion (BHI) broth; there was a significant difference between cells exposed to 500 mg/liter ClO2 and those exposed to all other conditions over time (P value < 0.05). Isogenic ΔsigB and ΔctsR mutants exposed to 300 mg/liter ClO2 were more sensitive to ClO2 than the wild type under the same conditions. These results provide an initial insight into the mechanisms that L. monocytogenes employs to survive sublethal ClO2 and further our understanding of the inactivation mechanisms of this increasingly used sanitizer.

  3. Chlorine Dioxide Gas Sterilization under Square-Wave Conditions

    Science.gov (United States)

    Jeng, David K.; Woodworth, Archie G.

    1990-01-01

    Experiments were designed to study chlorine dioxide (CD) gas sterilization under square-wave conditions. By using controlled humidity, gas concentration, and temperature at atmospheric pressure, standard biological indicators (BIs) and spore disks of environmental isolates were exposed to CD gas. The sporicidal activity of CD gas was found to be concentration dependent. Prehumidification enhanced the CD activity. The D values (time required for 90% inactivation) of Bacillus subtilis subsp. niger ATCC 9372 BIs were estimated to be 1.5, 2.5, and 4.2 min when exposed to CD concentrations of 30, 15, and 7 mg/liter, respectively, at 23°C and ambient (20 to 40%) relative humidity (RH). Survivor tailings were observed. Prehumidification of BIs to 70 to 75% RH in an environmental chamber for 30 min resulted in a D value of 1.6 min after exposure to a concentration of 6 to 7 mg of CD per liter at 23°C and eliminated survivor tailing. Prolonging prehumidification at 70 to 75% RH for up to 16 h did not further improve the inactivation rate. Prehumidification by ultrasonic nebulization was found to be more effective than prehumidification in the environmental chamber, improving the D value to 0.55 min at a CD concentration of 6 to 7 mg/liter. Based on the current observations, CD gas is estimated, on a molar concentration basis, to be 1,075 times more potent than ethylene oxide as a sterilant at 30°C. A comparative study showed B. subtilis var. niger BIs were more resistant than other types of BIs and most of the tested bacterial spores of environmental isolates. PMID:16348127

  4. Evaluation of chlorine dioxide based product as a hatchery sanitizer.

    Science.gov (United States)

    Maharjan, P; Cox, S; Gadde, U; Clark, F D; Bramwell, K; Watkins, S E

    2016-12-05

    Formaldehyde is commonly used to overcome contaminants introduced by hatching eggs or water supply in the hatcher cabinets. However, health risks associated with its use make economical alternatives important. This project evaluated a chlorine dioxide based product (CDBP) (0.3% concentrate) as a hatchery sanitizer in decontaminating microbial populations on the shell surface of hatching eggs (>18 d old), as well as its impact on hatchability and chick performance. Hatchers (0.20 m(2)) designed to hold approximately 50 eggs and equipped with circulation fans, heaters, and thermostats were used for the evaluation. For each of the 2 trials conducted, 450 hatching eggs were obtained and incubated in a common setter. Eggs used in trial 1 were floor eggs whereas in trial 2 nest eggs were used. On d 18 of incubation, eggs were removed from the setter, and viable eggs were randomly allocated to 9 hatchers. Pre-treatment egg rinse samples (10 eggs per hatcher) were collected for initial microbial analysis. Three hatchers were treated with CDBP and 3 hatchers with a formaldehyde based product (FBP). Three untreated hatchers served as control (C). Prior to hatch, 10 eggs/incubator, not previously rinsed, were used for post treatment microbial counts. The hatched chicks were reared until d 21 in floor pens with a common starter diet. For the CDBP treated eggs, hatchability and chick performance (weight gains, mortality, and FCR on d 7 and d 21) were similar to the other treatments. The application rate of CDBP evaluated in this study was not an effective antimicrobial alternative to formaldehyde for sanitizing hatching eggs in hatcher cabinets prior to hatch.

  5. Development of chlorine dioxide-related by-product models for drinking water treatment.

    Science.gov (United States)

    Korn, Caroline; Andrew, Robert C; Escobar, Michael D

    2002-01-01

    Factorial experiments were conducted using source waters from seven drinking water treatment plants in Ontario, Canada to develop statistically based model equations capable of predicting chlorine dioxide consumption and chlorite and chlorate formation upon chlorine dioxide application. The equations address raw water quality and operational parameters including pH, temperature, chlorine dioxide concentration, reaction time and water organic content (as described by non-purgeable organic carbon x ultraviolet absorbance measured at 254 nm, NPOC x UV254). Terms describing two-factor interaction effects were also included, improving the accuracy of the predictive equations in fitting measured response concentrations as evaluated through internal and external validations. Nearly 80% of the predictions for chlorine dioxide consumption and chlorite formation were observed to be within 20% of the measured levels. Over 90% of the predicted chlorate levels were within +/- 0.1 mg/L of the measured levels. Chlorine dioxide concentration and NPOC x UV254 were key parameters when developing the predictive models.

  6. Lethality of chlorine, chlorine dioxide, and a commercial produce sanitizer to Bacillus cereus and Pseudomonas in a liquid detergent, on stainless steel, and in biofilm.

    Science.gov (United States)

    Kreske, Audrey C; Ryu, Jee-Hoon; Pettigrew, Charles A; Beuchat, Larry R

    2006-11-01

    Many factors that are not fully understood may influence the effectiveness of sanitizer treatments for eliminating pathogens and spoilage microorganisms in food or detergent residues or in biofilms on food contact surfaces. This study was done to determine the sensitivities of Pseudomonas cells and Bacillus cereus cells and spores suspended in a liquid dishwashing detergent and inoculated onto the surface of stainless steel to treatment with chlorine, chlorine dioxide, and a commercial produce sanitizer (Fit). Cells and spores were incubated in a liquid dishwashing detergent for 16 to 18 h before treatment with sanitizers. At 50 microg/ml, chlorine dioxide killed a significantly higher number of Pseudomonas cells (3.82 log CFU/ml) than did chlorine (a reduction of 1.34 log CFU/ml). Stainless steel coupons were spot inoculated with Pseudomonas cells and B. cereus cells and spores, with water and 5% horse serum as carriers. Chlorine was more effective than chlorine dioxide in killing cells and spores of B. cereus suspended in horse serum. B. cereus biofilm on stainless steel coupons that were treated with chlorine dioxide or chlorine at 200 microg/ml had total population reductions (vegetative cells plus spores) of > or = 4.42 log CFU per coupon; the number of spores was reduced by > or = 3.80 log CFU per coupon. Fit (0.5%) was ineffective for killing spot-inoculated B. cereus and B. cereus in biofilm, but treatment with mixtures of Fit and chlorine dioxide caused greater reductions than did treatment with chlorine dioxide alone. In contrast, when chlorine was combined with Fit, the lethality of chlorine was completely lost. This study provides information on the survival and sanitizer sensitivity of Pseudomonas and B. cereus in a liquid dishwashing detergent, on the surface of stainless steel, and in a biofilm. This information will be useful for developing more effective strategies for cleaning and sanitizing contact surfaces in food preparation and processing

  7. Impact of chlorine dioxide and ozone on the oxidation of NTA during drinking water treatment

    Energy Technology Data Exchange (ETDEWEB)

    Hrubec, J.; ' t Hart, M.J.; Marsman, P.; Luijten, J.A.

    1984-11-01

    The use, as it is proposed, of nitrilotriacetic acid (NTA) for phosphate replacement in detergents will lead to its discharge in surface water at relatively high concentrations. Questions have been raised about potential health hazards related to the uptake and treatment of the NTA containing riverwater for drinking water supply. Degradation of NTA by biological oxidation in waste water treatment systems, soil and surface water under aerobic conditions has been demonstrated many times. However reports on degradation of NTA by chemical oxidation applied in water treatment processes are scarce. The aim of the present investigation was to determine removal of nitrilotriacetic acid upon chlorine, chlorine dioxide and ozone treatment under conditions characteristic for drinking water treatment practice; possible formation of mutagenic substances from the reaction of NTA with these oxidants; and formation of halogenated reaction products of NTA with chlorine and chlorine dioxide.

  8. Chlorine Dioxide Inactivation of Cryptosporidium parvum Oocysts and Bacterial Spore Indicators

    Science.gov (United States)

    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

  9. Chlorine dioxide inactivation of Cryptosporidium parvum oocysts and bacterial spore indicators.

    Science.gov (United States)

    Chauret, C P; Radziminski, C Z; Lepuil, M; Creason, R; Andrews, R C

    2001-07-01

    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 degrees 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 log(10) and 2.0 log(10) 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 log(10) 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.

  10. Chlorine diffusion in uranium dioxide under heavy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Pipon, Y. [Universite Claude Bernard Lyon-1/Institut de Physique Nucleaire de Lyon (IPNL), 4, rue Enrico Fermi, 69622 Villeurbanne cedex (France) and Universite Claude Bernard Lyon-1, Institut Universitaire de Technologie (IUT A), 94, boulevard Niels Bohr, 69622 Villeurbanne cedex (France)]. E-mail: pipon@ipnl.in2p3.fr; Bererd, N. [Universite Claude Bernard Lyon-1/Institut de Physique Nucleaire de Lyon (IPNL), 4, rue Enrico Fermi, 69622 Villeurbanne cedex (France); Universite Claude Bernard Lyon-1, Institut Universitaire de Technologie (IUT A), 94, boulevard Niels Bohr, 69622 Villeurbanne cedex (France); Moncoffre, N. [Universite Claude Bernard Lyon-1/Institut de Physique Nucleaire de Lyon (IPNL), 4, rue Enrico Fermi, 69622 Villeurbanne cedex (France); Peaucelle, C. [Universite Claude Bernard Lyon-1/Institut de Physique Nucleaire de Lyon (IPNL), 4, rue Enrico Fermi, 69622 Villeurbanne cedex (France); Toulhoat, N. [Universite Claude Bernard Lyon-1/Institut de Physique Nucleaire de Lyon (IPNL), 4, rue Enrico Fermi, 69622 Villeurbanne cedex (France); Commissariat a l' Energie Atomique (CEA), DEN/Saclay, 91191 Gif sur Yvette cedex (France); Jaffrezic, H. [Universite Claude Bernard Lyon-1/Institut de Physique Nucleaire de Lyon (IPNL), 4, rue Enrico Fermi, 69622 Villeurbanne cedex (France); Raimbault, L. [Ecole des Mines de Paris, Centre de Geosciences, 35 rue Saint Honore, F-77305 Fontainebleau cedex (France); Sainsot, P. [Institut National des Sciences Appliquees de Lyon (INSA), UMR 5514, F-69621 Villeurbanne cedex (France); Carlot, G. [Commissariat a l' Energie Atomique (CEA), Centre de Cadarache, DEN/DEC/SESC/LLCC, 13108 Saint-Paul lez Durance (France)

    2007-04-15

    The radiation enhanced diffusion of chlorine in UO{sub 2} during heavy ion irradiation is studied. In order to simulate the behaviour of {sup 36}Cl, present as an impurity in UO{sub 2}, {sup 37}Cl has been implanted into the samples (projected range 200 nm). The samples were then irradiated with 63.5 MeV {sup 127}I at two fluxes and two temperatures and the chlorine distribution was analyzed by SIMS. The results show that, during irradiation, the diffusion of the implanted chlorine is enhanced and slightly athermal with respect to pure thermal diffusion. A chlorine gain of 10% accumulating near the surface has been observed at 510 K. This corresponds to the displacement of pristine chlorine from a region of maximum defect concentration. This behaviour and the mean value of the apparent diffusion coefficient found for the implanted chlorine, around 2.5 x 10{sup -14} cm{sup 2} s{sup -1}, reflect the high mobility of chlorine in UO{sub 2} during irradiation with fission products.

  11. Chlorine diffusion in uranium dioxide under heavy ion irradiation

    Science.gov (United States)

    Pipon, Y.; Bérerd, N.; Moncoffre, N.; Peaucelle, C.; Toulhoat, N.; Jaffrézic, H.; Raimbault, L.; Sainsot, P.; Carlot, G.

    2007-04-01

    The radiation enhanced diffusion of chlorine in UO2 during heavy ion irradiation is studied. In order to simulate the behaviour of 36Cl, present as an impurity in UO2, 37Cl has been implanted into the samples (projected range 200 nm). The samples were then irradiated with 63.5 MeV 127I at two fluxes and two temperatures and the chlorine distribution was analyzed by SIMS. The results show that, during irradiation, the diffusion of the implanted chlorine is enhanced and slightly athermal with respect to pure thermal diffusion. A chlorine gain of 10% accumulating near the surface has been observed at 510 K. This corresponds to the displacement of pristine chlorine from a region of maximum defect concentration. This behaviour and the mean value of the apparent diffusion coefficient found for the implanted chlorine, around 2.5 × 10-14 cm2 s-1, reflect the high mobility of chlorine in UO2 during irradiation with fission products.

  12. Evaluation of possible use of disinfectant based on chlorine dioxide in dairy plant

    Directory of Open Access Journals (Sweden)

    Rakić-Martinez Mira

    2009-01-01

    Full Text Available Poor sanitation of food contact surfaces has been a contributing factor in food borne disease outbreaks, especially those involving Listeria monocytogenes, Salmonella spp., Escherichia coli, Staphylococcus aureus etc. The objectives of this study were therefore to: 1. Determine the efficiency of a disinfectant based on chlorine dioxide in suspension in a closed system in a dairy plant. 2. Evaluate the possibility of disinfection of working surfaces with a disinfectant based on chlorine dioxide. In order to determine the germicidal effect of the disinfectant based on chlorine dioxide by suspension test (BSEN 1276:1997; the following test organisms were used: Listeria monocytogenes, Proteus mirabilis, Escherichia coli, Bacillus cereus, Staphylococcus aureus and Pseudomonas aeruginosa clinical isolate. The corrosive properties of the disinfectant based on chlorine dioxide were tested by IDF 077:1977 standard. The efficacy of this disinfectant was investigated in a closed system in a dairy plant. Results indicated a 100% reduction of >108 cfu/ml L. monocytogenes, E. coli, Proteus mirabilis, Pseudomonas aeruginosa, S. aureus, viable count after 1 minute of exposure to 100 ppm of the disinfectant based on chlorine dioxide and 400 ppm for Bacillus cereus. In the presence of 2% skim milk and 4 % skim milk concentrations of 200 and 250 ppm resulted in 100% reduction in numbers of the five of six test microorganisms, respectively. The spore former, Bacillus cereus is less susceptible to the disinfectant. Therefore, the efficient concentration for 100% reduction in viable count after 1 minute exposure was 500 ppm. The corrosive properties of the disinfectant were not determined. In the case of closed system disinfection in a dairy plant, reduction in viable count after 15 minute exposure to 100 ppm of disinfectant based on chlorine dioxide ranged from 80 to 100%.

  13. Kinetics of AOX Formation in Chlorine Dioxide Bleaching of Bagasse Pulp

    Directory of Open Access Journals (Sweden)

    Shuangxi Nie

    2014-07-01

    Full Text Available In this paper, a kinetic model of the first chlorine dioxide bleaching stage (D0 in an elemental chlorine-free (ECF bleaching sequence is presented for bagasse pulps. The model is based on the rate of adsorbable organic halogen (AOX formation. The effects of the chlorine dioxide dosage, the sulfuric acid dosage, and the reaction temperature on the AOX content of wastewater are examined. The reaction of AOX formation could be divided into two periods. A large amount of AOX was formed rapidly within the first 10 min. Ten minutes later, the AOX formation rate significantly decreased. The kinetics could be expressed as: dW⁄dt=660.8•e^(-997.98/T 〖•[ClO〗_2 ]^0.877•[H2SO4 ]^0.355•W^(-1.065, where W is the AOX content, t is the bleaching time (min, T is the temperature (K, [ClO2] is the dosage of chlorine dioxide (kg/odt, and [H2SO4] is the dosage of sulfuric acid (kg/odt. The fit of the experiment results obtained for different temperatures, initial chlorine dioxide dosages, initial sulfuric acid dosages, and AOX content were very good, revealing the ability of the model to predict typical mill operating conditions.

  14. Determination of Chlorine Dioxide and Chlorite in Water Supply Systems by Verified Methods

    Science.gov (United States)

    Tkáčová, Jana; Božíková, Jarmila

    2014-07-01

    This work is dedicated to the development and optimization of appropriate analytical methods for the determination of chlorine dioxide and chlorite in drinking water in order to obtain accurate and correct results in the quality control of drinking water. The work deals with the development and optimization of a method for the determination of chlorine dioxide using chlorophenol red. Furthermore, a new spectrophotometric method for the determination of chlorite via bromometry using methyl orange was developed, optimized and validated. An electrochemical method for the determination of chlorite by flow coulometry was also developed, optimized and validated.

  15. Determination of Chlorine Dioxide and Chlorite in Water Supply Systems by Verified Methods

    Directory of Open Access Journals (Sweden)

    Tkáčová Jana

    2014-07-01

    Full Text Available This work is dedicated to the development and optimization of appropriate analytical methods for the determination of chlorine dioxide and chlorite in drinking water in order to obtain accurate and correct results in the quality control of drinking water. The work deals with the development and optimization of a method for the determination of chlorine dioxide using chlorophenol red. Furthermore, a new spectrophotometric method for the determination of chlorite via bromometry using methyl orange was developed, optimized and validated. An electrochemical method for the determination of chlorite by flow coulometry was also developed, optimized and validated.

  16. Process Development and Design of Chlorine Dioxide Production Based on Hydrogen Peroxide

    Institute of Scientific and Technical Information of China (English)

    陈赟; 江燕斌; 钱宇

    2004-01-01

    This paper presents a process development and design of chlorine dioxide production based on hydrogen peroxide. The process is characterized by cleaner production, high efficiency, and waste minimization. Optimization of process conditions, selection of equipment, and experiment of recycle of waste acid are carried out. The process design is realized in consideration of several aspects such as operation, material, equipment design and safety. An industrialized process flowsheet is developed according to experiment. A pilot testing is carried out to confirm the lab results. Process design of chlorine dioxide production based on hydrogen peroxide is realized.

  17. Effect of chlorine dioxide and sodium hypochlorite on the dissolution of human pulp tissue – An in vitro study

    Science.gov (United States)

    Singh, Sandeep; Sinha, Ramen; Kar, S.K.; Ather, Amber; Limaye, S.N.

    2012-01-01

    Background Organic tissue dissolution is an important property of an irrigant which aids in the success of root canal treatment. Recent studies have advocated the use of Chlorine dioxide as an endodontic irrigant. The aim of this study is to compare the dissolution efficacy of chlorine dioxide and sodium hypochlorite on human pulp tissue. Methods In this study, 2% Sodium hypochlorite, 5% Chlorine dioxide and isotonic saline solution (control) were used. Thirty human pulp tissue specimens were exposed to three test solutions (n = 10) for 30 min following which the loss of weight was compared from the original weight by using a digital analytical balance. Results Sodium hypochlorite was more efficient in dissolving human pulp tissue when compared to Chlorine dioxide. Isotonic saline solution failed to dissolve any of the specimens. Conclusion 5% Chlorine dioxide is capable of dissolving human pulp tissue but sodium hypochlorite was more effective. PMID:24532904

  18. Effect of chlorine dioxide and sodium hypochlorite on the dissolution of human pulp tissue - An in vitro study.

    Science.gov (United States)

    Singh, Sandeep; Sinha, Ramen; Kar, S K; Ather, Amber; Limaye, S N

    2012-10-01

    Organic tissue dissolution is an important property of an irrigant which aids in the success of root canal treatment. Recent studies have advocated the use of Chlorine dioxide as an endodontic irrigant. The aim of this study is to compare the dissolution efficacy of chlorine dioxide and sodium hypochlorite on human pulp tissue. In this study, 2% Sodium hypochlorite, 5% Chlorine dioxide and isotonic saline solution (control) were used. Thirty human pulp tissue specimens were exposed to three test solutions (n = 10) for 30 min following which the loss of weight was compared from the original weight by using a digital analytical balance. Sodium hypochlorite was more efficient in dissolving human pulp tissue when compared to Chlorine dioxide. Isotonic saline solution failed to dissolve any of the specimens. 5% Chlorine dioxide is capable of dissolving human pulp tissue but sodium hypochlorite was more effective.

  19. Molecular size distribution of dissolved organic matter in water of the Pearl River and trihalomethane formation characteristics with chlorine and chlorine dioxide treatments.

    Science.gov (United States)

    Zhao, Zhen-Ye; Gu, Ji-Dong; Fan, Xiao-Jun; Li, Hai-Bo

    2006-06-30

    River water sample was collected from Guangzhou section of the Pearl River to investigate soluble organic fractions and formation of trihalomethane (THMs) after chlorine and chlorine dioxide treatments. The water sample was passed through Amicon YC-05, YM-1, YM-3, YM-10, YM-30, YM-100 and ZM-500 series membranes after a pre-treatment. The molecular weight distribution and the specific ultra-violet absorbance (SUVA(254)) of each fraction obtained from membrane were analyzed, and these fractions were further disinfected with chlorine and chlorine dioxide. The results showed that reverse osmosis (RO) fraction contained mainly dissolved organic matter (DOM) from the water sample, suggesting that the water has been highly contaminated by anthropogenic activities. Meanwhile, the THMs concentration and SUVA(254) increased gradually as the molecular weight of the obtained fractions reduced, indicating that the low molecular weight DOM was the major THMs precursor in the disinfection process with chlorine and chlorine dioxide. The results suggest that THMs in source water of Pearl River could be effectively reduced when pollution of human activity is greatly controlled. Between the two disinfection processes tested, chlorine dioxide produced less THMs than chlorine in this study.

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

    Science.gov (United States)

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

    1982-12-01

    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.

  1. Development and trends in chlorine dioxide bleaching with integrated chlorate electrolysis for the cellulose industry

    Energy Technology Data Exchange (ETDEWEB)

    Wintzer, P.

    1980-05-01

    Rising demand for cellulose and paper and the environmental measures necessary in this branch of industry compel the companies involved to invest large sums. In particular, waste water from bleaching operations causes difficulties in biological waste water purification owing to high chlorolignin content. The sequence of chlorination steps have been optimized for each quality of wood, and the increasing use of chlorine dioxide leads to an expansion of chlorate electrolysis and chlorine dioxide plant at the expense of chlorine. The consumption of chemicals for the various cellulose qualities is considered. During the past 30 years, the Muenchner process for production of ClO/sub 2/ has proved environmentally sound and is being continuously improved. Only hydrochloric acid and water are needed as raw materials. The chlorine formed in this process is converted into hydrochloric acid, hypochlorite, and chlorine water. All steps of the processes require only liquids and gases permitting a favourable, closed mode of operation without by-products or waste salts. New chlorate cells built since 1969 are equipped exclusively with coated titanium anodes (load between 6 and 100 kA) with DC efficiencies of 92 to 95%. Annual world production of sodium chlorate exceeds 1 million tonnes. The rate of increase has long remained steady at 5%.

  2. Intracellular pH Campylobacter jejuni when treated with aqueous chlorine dioxide

    DEFF Research Database (Denmark)

    Smigic, Nada; Rajkovic, Andreja; Arneborg, Nils;

    2011-01-01

    The aim of this study was to investigate the response of Campylobacter jejuni at single-cell level when exposed to different concentrations of chlorine dioxide (ClO2). The parameter of choice, intracellular pH (pHi), was determined by using fluorescence ratio imaging microscopy with a p...

  3. Effect of Chlorine Dioxide Gas on Fungi and Mycotoxins Associated with Sick Building Syndrome

    Science.gov (United States)

    Wilson, S. C.; Wu, C.; Andriychuk, L. A.; Martin, J. M.; Brasel, T. L.; Jumper, C. A.; Straus, D. C.

    2005-01-01

    The growth of indoor molds and their resulting products (e.g., spores and mycotoxins) can present health hazards for human beings. The efficacy of chlorine dioxide gas as a fumigation treatment for inactivating sick building syndrome-related fungi and their mycotoxins was evaluated. Filter papers (15 per organism) featuring growth of Stachybotrys chartarum, Chaetomium globosum, Penicillium chrysogenum, and Cladosporium cladosporioides were placed in gas chambers containing chlorine dioxide gas at either 500 or 1,000 ppm for 24 h. C. globosum was exposed to the gas both as colonies and as ascospores without asci and perithecia. After treatment, all organisms were tested for colony growth using an agar plating technique. Colonies of S. chartarum were also tested for toxicity using a yeast toxicity assay with a high specificity for trichothecene mycotoxins. Results showed that chlorine dioxide gas at both concentrations completely inactivated all organisms except for C. globosum colonies which were inactivated an average of 89%. More than 99% of ascospores of C. globosum were nonculturable. For all ascospore counts, mean test readings were lower than the controls (P < 0.001), indicating that some ascospores may also have been destroyed. Colonies of S. chartarum were still toxic after treatment. These data show that chlorine dioxide gas can be effective to a degree as a fumigant for the inactivation of certain fungal colonies, that the perithecia of C. globosum can play a slightly protective role for the ascospores and that S. chartarum, while affected by the fumigation treatment, still remains toxic. PMID:16151130

  4. Chlorine dioxide and chlorhexidine mouthrinses compared in a 3-day plaque accumulation model

    NARCIS (Netherlands)

    Paraskevas, S.; Rosema, N.A.M.; Versteeg, P.; van der Velden, U.; van der Weijden, G.A.

    2008-01-01

    Background: The aim of this study was to investigate the inhibiting effect of a chlorine dioxide mouthrinse as opposed to a mouthrinse containing chlorhexidine (0.20%) during 3 days of plaque accumulation. Methods: At baseline, all participants (N = 77) received a professional prophylaxis and were r

  5. A comparison of the bleaching effectiveness of chlorine dioxide and hydrogen peroxide on dental composite.

    Science.gov (United States)

    Agnihotry, Anirudha; Gill, Karanjot S; Singhal, Deepak; Fedorowicz, Zbys; Dash, Sambit; Pedrazzi, Vinicius

    2014-01-01

    This study was carried out to verify if composites could be bleached using chlorine dioxide as compared with hydrogen peroxide. 3M ESPE Filtek Z350 Universal Restorative discs were prepared (n=40), with dimensions 5 mm diameter x 2 mm thickness. The discs were divided into 4 groups of 10 discs each. Color assessment was performed by CIEDE2000. The discs were stained with coffee, tea, wine and distilled water (control) solutions for 14 days, 5 hours daily. Color assessment was repeated on stained discs and followed by bleaching of 5 discs from each group using chlorine dioxide and hydrogen peroxide in-office systems. Finally, a last color assessment was performed and compared statistically. DE2000 after bleaching was very close to baseline for both the bleaching agents, although chlorine dioxide showed better results than hydrogen peroxide. After staining, there was a clinically significant discoloration (∆E2000≥3.43) for the tea, coffee and wine groups, and discoloration (∆E2000) was seen more in the wine group as compared to tea and coffee. Overall, the control group (distilled water) had the least color change in the three intervals. After bleaching, the color in all specimens returned close to the baseline. The color differences between bleaching and baseline were less than 3.43 for all groups. The obtained results show that chlorine dioxide is slightly superior to hydrogen peroxide in the bleaching of composites, while maintaining the shade of the composite close to the baseline.

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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.

  8. Chlorine dioxide and chlorhexidine mouthrinses compared in a 3-day plaque accumulation model

    NARCIS (Netherlands)

    Paraskevas, S.; Rosema, N.A.M.; Versteeg, P.; van der Velden, U.; van der Weijden, G.A.

    2008-01-01

    Background: The aim of this study was to investigate the inhibiting effect of a chlorine dioxide mouthrinse as opposed to a mouthrinse containing chlorhexidine (0.20%) during 3 days of plaque accumulation. Methods: At baseline, all participants (N = 77) received a professional prophylaxis and were

  9. Intracellular pH Campylobacter jejuni when treated with aqueous chlorine dioxide

    DEFF Research Database (Denmark)

    Smigic, Nada; Rajkovic, Andreja; Arneborg, Nils

    2011-01-01

    The aim of this study was to investigate the response of Campylobacter jejuni at single-cell level when exposed to different concentrations of chlorine dioxide (ClO2). The parameter of choice, intracellular pH (pHi), was determined by using fluorescence ratio imaging microscopy with a p...

  10. Comparison of chlorine dioxide and dichloroisocyanurate disinfectants for use in the dental setting.

    Science.gov (United States)

    Patel, M; Ebonwu, J; Cutler, E

    2012-08-01

    The aim of this study was to compare the antimicrobial properties of a slow release noncorrosive chlorine dioxide with those of sodium dichloroisocyanurate to establish their possible use in the dental settings. Disinfectant solutions were prepared according to manufacturers' instructions and tested against Staphylococcus aureus ATCC 29213, Pseudomonas aeruginosa ATCC 27853, Streptococcus mutans NCTC 1044, Candida albicans ATCC 90028, Bacillus subtilis ATCC 15244 spores, Mycobacterium tuberculosis ATCC 25177, Mycobacterium avium subsp. avium ATCC 25291 and Hepatitis B virus using the Standard quantitative suspension test. The shelf-lives of the disinfectants were also determined. Both disinfectants killed all the test organisms within 30 seconds. B. subtilis spores were killed in 2 and 2.5 minutes by chlorine dioxide and sodium dichloroisocya nurate respectively. When diluted solutions of these disinfectants were stored in screw cap bottles, they retained their activity for at least 30 days. Chlorine dioxide and sodium dichloroisocyanurate containing disinfectants can be used in the denta settings for surfaces and heat sensitive instruments. However, chlorine dioxide is advantageous because it is non-corrosive and the effective concentration is lower than that recommended for sodium dichloroisocyanurate.

  11. Antimicrobial activity of controlled-release chlorine dioxide gas on fresh blueberries

    Science.gov (United States)

    The effect of chlorine dioxide (ClO2) on the safety and quality of blueberries was studied. In vitro studies revealed that both ClO2 gas fumigation and ClO2 water direct contact killed food pathogen bacterium, Escherichia coli and fruit decay pathogen fungus, Colletotrichum acutatum. In vivo studies...

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

    Science.gov (United States)

    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...

  13. The whitening effect of chlorine dioxide--an in vitro study.

    Science.gov (United States)

    Ablal, M A; Adeyemi, A A; Jarad, F D

    2013-11-01

    The aim of this study was to investigate the whitening properties and rate of bleaching action of chlorine dioxide and compare them with those of hydrogen peroxide of similar concentration. Sixty bovine central incisor crowns were ground and polished until flat surfaces were obtained. The crowns were subjected to extensive staining cycles of artificial saliva, chlorehexidine and tea before being randomly assigned to three groups: chlorine dioxide (ClO2), hydrogen peroxide (H2O2) and deionised water (H2O). The crowns in each group were subjected to seven 2 min exposure cycles in addition to an extra 30 min cycle. CIE LAB spectrophotometric measurements were taken at baseline, after each 2 min, and each extended 30 min bleaching cycle. L* for ClO2 specimens was significantly higher only after the first 2 min cycle (pChlorine dioxide whitens teeth at a faster rate than hydrogen peroxide. Specimens treated with chlorine dioxide were significantly lighter than those treated with hydrogen peroxide at the end of the first 2 min application cycle, however, extended exposures did not enhance color. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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,…

  15. New packaging design for fresh produce with effective distribution of antimicrobial gaseous chlorine dioxide

    Science.gov (United States)

    In the last decade, the potential use of chlorine dioxide (ClO2) as an antimicrobial agent for vapor-phase decontamination to extend the shelf-life of fresh produce has been widely studied. Most of the works focused on the dose of gaseous ClO2 for particular food product and/or specific microorganis...

  16. Application of chlorine dioxide to lessen bacterial contamination during broiler defeathering

    Science.gov (United States)

    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...

  17. Mass Transfer Study of Chlorine Dioxide Gas Through Polymeric Packaging Materials

    Science.gov (United States)

    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...

  18. Influences of packaging design on antimicrobial effects of gaseous chlorine dioxide

    Science.gov (United States)

    Chlorine dioxide (ClO2) gas is an effective surface disinfectant, for it has the ability to reach and inactivate bacterial cells in biofilms which are attached to inaccessible sites on produce surfaces. One of the most promising applications of gaseous ClO2 is to be included in the headspace of foo...

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

    Science.gov (United States)

    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.

  20. USING REDUCING AGENTS TO ELIMINATE CHLORINE DIOXIDE AND CHLORITE ION RESIDUALS IN DRINKING WATER

    Science.gov (United States)

    In an effort to determine the viability of various disinfection alternatives, the Evansville, Ind. Water and Sewer Utility is engaged in a pilot-plant investigation to compare chlorine dioxide and ozone pretreatment. As a result of increased speculation that the total residual c...

  1. Distribution and chemical fate of chlorine dioxide gas during sanitation of tomatoes and cantaloupe

    Science.gov (United States)

    A series of studies was conducted to establish the 1) distribution and chemical fate of 36-ClO2 on tomatoes and cantaloupe; and 2) the magnitude of residues in kilogram quantities of tomatoes and cantaloupe sanitized with a slow-release chlorine dioxide formulation. Tomatoes and cantaloupe were resp...

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  4. Fluorine and chlorine determination in mixed uranium-plutonium oxide fuel and plutonium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Elinson, S.V.; Zemlyanukhina, N.A.; Pavlova, I.V.; Filatkina, V.P.; Tsvetkova, V.T.

    1981-01-01

    A technique of fluorine and chlorine determination in the mixed uranium-plutonium oxide fuel and plutonium dioxide, based on their simultaneous separation by means of pyrohydrolysis, is developed. Subsequently, fluorine is determined by photometry with alizarincomplexonate of lanthanum or according to the weakening of zirconium colouring with zylenol orange. Chlorine is determined using the photonephelometric method according to the reaction of chloride-ion interaction with silver nitrate or by spectrophotometric method according to the reaction with mercury rhodanide. The lower limit of fluorine determination is -6x10/sup -5/ %, of chlorine- 1x10/sup -4/% in the sample of 1g. The relative mean quadratic deviation of the determination result (Ssub(r)), depends on the character of the material analyzed and at the content of nx10/sup -4/ - nx10/sup -3/ mass % is equal to from 0.05 to 0.32 for fluorine and from 0.11 to 0.35 for chlorine.

  5. Examination of the potential of chlorine dioxide for use in zebra mussel veliger control

    Energy Technology Data Exchange (ETDEWEB)

    Rusznak, L.; Smolik, N.; Hale, L.; Freymark, S. [Ashland Chemical Company, Drew Division, Boonton, NJ (United States)

    1995-06-01

    Dreissena polymorpha (zebra mussel) veligers were treated with various concentrations of chlorine dioxide and exposed at several time intervals to determine the effectiveness of this oxidant as a veliger control agent. The direction of this testing was based on previous studies which determined the effectiveness of chlorine dioxide as a molluscicide for adult zebra mussel control. Zebra mussel veligers were collected from the Niagara River shoreline at an untreated site and tested using filtered river water from the same source. All testing was conducted on site at an industrial plant in order to insure the integrity of veligers collected for this study. The plankton wheel method was used to examine the effects of chlorine dioxide. This methodology involves intense microscopic examination of the test organism prior to and after chemical exposure todeterminen molluscicidal efficacy. Veliger mortality was determined based on observations of veliger movement. Typical criteria for the determination of mortality was expanded to include four categories; veliger actively swimming, internal musculature movement, no internal musculature movement observed, however not necessarily indicating a mortality and obviously a mortality. The treatment levels ranged from 0.75 ppm - 2.0 ppm which are considered to simulate treatment levels in actual applications. Mortality levels ranged on average from 16%-42% based on 30 minute or 60 minute exposure times. The determination exposure time was based on water flow time intervals in actural applications. Sodium hypochlorite was also evaluated in order to compare the effectiveness of chlorine dioxide against this known veliger control agent. Testing resulted in chlorine dioxide providing significantly better veliger control than sodium hypochlorite under similar conditions.

  6. Transformation of iopamidol during chlorination.

    Science.gov (United States)

    Wendel, Friedrich M; Lütke Eversloh, Christian; Machek, Edward J; Duirk, Stephen E; Plewa, Michael J; Richardson, Susan D; Ternes, Thomas A

    2014-11-01

    The transformation of the iodinated X-ray contrast media (ICM) iopamidol, iopromide, iohexol, iomeprol, and diatrizoate was examined in purified water over the pH range from 6.5 to 8.5 in the presence of sodium hypochlorite, monochloramine, and chlorine dioxide. In the presence of aqueous chlorine, only iopamidol was transformed. All other ICM did not show significant reactivity, regardless of the oxidant used. Chlorination of iopamidol followed a second order reaction, with an observed rate constant of up to 0.87 M(-1) s(-1) (±0.021 M(-1) s(-1)) at pH 8.5. The hypochlorite anion was identified to be the reactive chlorine species. Iodine was released during the transformation of iopamidol, and was mainly oxidized to iodate. Only a small percentage (less than 2% after 24 h) was transformed to known organic iodinated disinfection byproducts (DBPs) of low molecular weight. Some of the iodine was still present in high-molecular weight DBPs. The chemical structures of these DBPs were elucidated via MSn fragmentation and NMR. Side chain cleavage was observed as well as the exchange of iodine by chlorine. An overall transformation pathway was proposed for the degradation of iopamidol. CHO cell chronic cytotoxicity tests indicate that chlorination of iopamidol generates a toxic mixture of high molecular weight DBPs (LC50 332 ng/μL).

  7. Formation of disinfection byproducts upon chlorine dioxide preoxidation followed by chlorination or chloramination of natural organic matter.

    Science.gov (United States)

    Yang, Xin; Guo, Wanhong; Lee, Wontae

    2013-06-01

    Chlorine dioxide (ClO2) is often used as an oxidant to remove taste, odor and color during water treatment. Due to the concerns of the chlorite formation, chlorination or chloramination is often applied after ClO2 preoxidation. We investigated the formation of regulated and emerging disinfection byproducts (DBPs) in sequential ClO2-chlorination and ClO2-chloramination processes. To clarify the relationship between the formation of DBPs and the characteristics of natural organic matter (NOM), changes in the properties of NOM before and after ClO2 oxidation were characterized by fluorescence, Fourier transform infrared spectroscopy (FTIR), and size and resin fractionation techniques. ClO2 preoxidation destroyed the aromatic and conjugated structures of NOM and transformed large aromatic and long aliphatic chain organics to small and hydrophilic organics. Treatment with ClO2 alone did not produce significant amount of trihalomethanes (THMs) and haloacetic acids (HAAs), but produced chlorite. ClO2 preoxidation reduced THMs, HAAs, haloacetonitriles (HANs) and chloral hydrate (CH) during subsequent chlorination, but no reduction of THMs was observed during chloramination. Increasing ClO2 doses enhanced the reduction of most DBPs except halonitromethanes (HNMs) and haloketones (HKs). The presence of bromide increased the formation of total amount of DBPs and also shifted DBPs to more brominated ones. Bromine incorporation was higher in ClO2 treated samples. The results indicated that ClO2 preoxidation prior to chlorination is applicable for control of THM, HAA and HAN in both pristine and polluted waters, but chlorite formation is a concern and HNMs and HKs are not effectively controlled by ClO2 preoxidation.

  8. Chlorine dioxide disinfection of single and dual species biofilms, detached biofilm and planktonic cells.

    Science.gov (United States)

    Behnke, Sabrina; Camper, Anne K

    2012-01-01

    Disinfection efficacy testing is usually done with planktonic cells or more recently, biofilms. While disinfectants are much less effective against biofilms compared to planktonic cells, questions regarding the disinfection tolerance of detached biofilm clusters remain largely unanswered. Burkholderia cepacia and Pseudomonas aeruginosa were grown in chemostats and biofilm tubing reactors, with the tubing reactor serving as a source of detached biofilm clusters. Chlorine dioxide susceptibility was assessed for B. cepacia and P. aeruginosa in these three sample types as monocultures and binary cultures. Similar doses of chlorine dioxide inactivated samples of chemostat and tubing reactor effluent and no statistically significant difference between the log(10) reductions was found. This contrasts with chlorine, shown previously to be generally less effective against detached biofilm particles. Biofilms were more tolerant and required chlorine dioxide doses ten times higher than chemostat and tubing reactor effluent samples. A second species was advantageous in all sample types and resulted in lower log(10) reductions when compared to the single species cultures, suggesting a beneficial interaction of the species.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  11. Effect of Aloe vera, chlorine dioxide, and chlorhexidine mouth rinses on plaque and gingivitis: A randomized controlled trial.

    Science.gov (United States)

    Yeturu, Sravan Kumar; Acharya, Shashidhar; Urala, Arun Sreenivas; Pentapati, Kalyana Chakravarthy

    2016-01-01

    To evaluate the effect of Aloe vera, chlorine dioxide, and chlorhexidine mouth rinses on plaque and gingivitis in orthodontic treatment. A randomized single-center, single-blind, parallel group, controlled trial was conducted among 90 subjects undergoing fixed orthodontic treatment. The subjects were randomly divided into one of the three study groups (Aloe vera, chlorhexidine, chlorine dioxide). Plaque and gingivitis were assessed using modified Silness and Loe Plaque Index and Gingival Index at baseline and at follow-up after 15 days. Paired t-test and ANOVA with post hoc Dunnett test were used. A p-value of chlorine dioxide with respect to mean reduction in plaque and gingival scores. Chlorine dioxide can be a suitable and economical alternative for chlorhexidine. Further long-term studies are recommended for evaluating their effectiveness.

  12. CHLORINE DIOXIDE BLEACHING OF SODA-ANTHRAQUINONE JUTE PULP TO A VERY HIGH BRIGHTNESS

    Directory of Open Access Journals (Sweden)

    M. Sarwar Jahan

    2010-05-01

    Full Text Available Bleaching of soda-anthraquinone jute pulp by chlorine dioxide (ClO2 was studied to reach a target brightness of above 88% for the purpose of using less bleaching chemicals. The performance of either chlorine dioxide or peroxide in the final bleaching to boost brightness was also studied. The experimental results revealed that the final brightness depended on ClO2 charge in the Do and D1 stages. The brightness reversion was lower when the final stage brightening was done by peroxide. The use of Mg(OH2 in the D1 and D2 stages improved the final brightness due to the formation of less chlorate and chlorite during the Mg(OH2- based ClO2 brightening stages. The strength properties of pulp bleached by peroxide in the final stage was slightly better than that from ClO2 as the final ClO2 bleaching stage.

  13. The use of chlorine dioxide for zebra mussel control - A perspective of treatment histories

    Energy Technology Data Exchange (ETDEWEB)

    Smolik, N.; Rusznak, L.; Anderson, J.; Hale, L. [Ashland Chemical Coman, Drew Division, Booton, NJ (United States)

    1995-06-01

    It is of utmost importance to provide updated performance results of various chemical treatments presently being utilized for zebra mussel control. Zebra mussels have a distinctive ability to endure environmental changes by reproducing effectively and attaching to various hard surfaces. These traits are cause for concern and have resulted in some operating difficulties for industries bordering infested waterways. Various methods are being employed by industries to deal with the problems associated with these species. One of the options is control via chemical treatment. Prior field test studies showed that chlorine dioxide was determined to be an effective molluscicidal agent for adult zebra mussel eradication. Continuous feed of chlorine dioxide at treatment levels ranging from 0.25 - 5.0 ppm above the oxidant demand provided 100% adult zebra mussel mortality which required between 2.9 - 8.8 days of treatment. Previous studies also showed that water temperature was an essential parameter in determining the time required to achieve 100% mortality of adult zebra mussels. Further field applications were undertaken at three electric utility sites located in the midwest. These facilities were concerned with the potential for zebra mussels to reduce efficiency and availability by blocking water flow or plugging equipment. Treatment applications at these facilities consisted of a continuous feed of chlorine dioxide ranging from 0.15 - 0.5 ppm above the oxidant demand. Significant mortality was achieved in monitored mussels tested at each utility in a period ranging from two to four days. This time period was directly related to a number of parameters, with the predominant one being water temperature. Data from these field applications is presented in this paper and confirms that chlorine dioxide is an effective molluscicide for adult zebra mussel control.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  16. Low-temperature decontamination with hydrogen peroxide or chlorine dioxide for space applications.

    Science.gov (United States)

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

    2012-06-01

    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-m(3) 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.

  17. Temperature dependence and mechanism of the reaction between O(3P) and chlorine dioxide

    Science.gov (United States)

    Colussi, A. J.; Sander, S. P.; Fiedl, R. R.

    1992-01-01

    Second-order rate constants for the decay of O(3P) in excess chlorine dioxide, k(II), were measured as a function of total pressure (20-600 Torr argon) and temperature (248-312 K), using flash photolysis-atomic resonance fluorescence. Results indicate that k(II) is pressure dependent with a value, K(b), that is nonzero at zero pressure, and both the third-order rate constant and k(b) have negative temperature dependences.

  18. 基于PMA-定量PCR选择性检测技术的病原菌消毒特性研究%Evaluation of Pathogen Disinfection Efficacy by Chlorine and Monochloramine Disinfection Based on Quantitative PCR Combined with Propidium Monoazide ( PMA-qPCR )

    Institute of Scientific and Technical Information of China (English)

    仝铁铮; 吴舒旭; 李丹; 何苗; 杨天; 施汉昌

    2011-01-01

    A novel detection method of quantitative PCR combined with a DNA intercalating dye propidium monoazide (PMA-qPCR)was developed and then applied to analyze inactivation efficacy of chlorine and monochloramine on E. coli as a representative organism.The results shows that PMA removed 99.94% and 99.99% DNA from non-viable E. coli and Salmonella cells respectively and PMA-qPCR could effectively differentiate viable bacteria from non-viable bacteria; According to the first-order kinetic model, the inactivation coefficients on E. coli obtained by PMA-qPCR were 2.24 L·(mg·min)-1 and 0.0175 L·(mg·min)-1 for chlorine and monochloramine respectively, both of which were lower than those obtained by traditional plating counting method. In order to inactivate 99% of E. coli, the ct values by PMA-qPCR were 0. 9 mg· L-1 · min and more than 100 mg· L-1· min for chlorine and monochloramine while those by plating counting method were only 0.6 mg· L- 1 · min and 20 mg· L - 1 · min, respectively; E. coli concentration detected by conventional qPCR kept almost the same when ct value increased, indicating that conventional qPCR was unable to evaluate inactivation efficacy of both chlorine and monochloramine disinfection. In summary, PMA-qPCR shows to be a promising method for evaluating disinfection efficacy by chlorine and monochloramine more accurately.%建立了一种核酸染料propidium monoazide(PMA)与定量PCR技术联合选择性检测活性病原菌的技术(PMA-qPCR),以大肠杆菌作为模式菌,研究了氯和一氯胺消毒对病原菌的灭活特性.结果表明,PMA染料能够分别去除99.94%和99.99%的来自非活性大肠杆菌和沙门氏菌的DNA,PMA-qPCR技术能够有效区分活性菌与非活性菌;PMA-qPCR技术得到的氯和一氯胺消毒对大肠杆菌的灭活曲线符合一级动力学方程,灭活速率常数分别为2.24 L·(mg·min)和0.017 5 L·(mg·min),低于平板培养法得到的灭活速率常数;当

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  1. Chlorine dioxide: An ideal preprocedural mouthrinse in dental set-up

    Directory of Open Access Journals (Sweden)

    Rajiv Saini

    2015-01-01

    Full Text Available Background: Aerosols generated during ultrasonic scaling is a potential risk factor for cross-contamination in dental settings. The aim of this study is to evaluate and compare the efficacy of commercially available chlorine dioxide as preprocedural mouthrinses in reducing the level of viable bacteria in aerosols. Materials and Methods : This single-center clinical double-blinded study was conducted over a period of 4 months. A total of 80 patients were divided randomly into two groups (A and B of 40 patients each to receive the chlorine dioxide mouthwash and water as preprocedural rinse. The aerosol produced by the ultrasonic unit was collected at five standardized location with respect to the reference point, that is, the mouth of the patient. The blood agar plates were incubated at 37°C for 48 h, and total number of colony-forming units (CFUs was counted and statistically analyzed. Results: The results showed that CFUs in test group A were significantly reduced compared with control group B, P < 0.001 (analysis of variance. The numbers of CFUs were highest in the patient chest area and lowest at the patient front, that is, 6 o′ clock position. Conclusion: This study proves that a regular preprocedural mouthrinse with chlorine dioxide could significantly reduce aerosols generated during professional oral prophylaxis.

  2. Effectiveness of the sulfur(IV) compound, sodium bisulfite, in reducing chlorine, chlorine dioxide, and chlorite toxicity to Daphnia magna in well water and pond water.

    Science.gov (United States)

    Yonkos, L T; Fisher, D J; Burton, D T; Whitekettle, W K; Peterille, J C

    2001-03-01

    Flow-through toxicity tests were conducted with Daphnia magna to determine the residual toxicity of chlorine, chlorine dioxide, and chlorite after treatment with the sulfur(IV) compound sodium bisulfite. Daphnids were exposed separately to 0.5-mg/L concentrations of each of the three compounds without the addition of sodium bisulfite, with a low stoichiometric dose of sodium bisulfite, and with a high stoichiometric dose of sodium bisulfite. Tests were performed in well water with a low total organic carbon (TOC) content and pond water with a high TOC content. Analysis of results indicated that sodium bisulfite did not eliminate the toxicity of chlorine dioxide or chlorite to D. magna. Total residual oxidant (TRO) concentrations were reduced and survival times were extended, but acute toxicity persisted even with a S(IV) concentration 10.0 times the stoichiometric ratio of oxidant. Mortality occurred in chlorine dioxide treatments in which no TRO was detected, indicating that standard analytical (amperometric) techniques may be inadequate to detect toxicity. Sodium bisulfite did succeed in eliminating chlorine toxicity except in pond water receiving a low (3.0x) sodium bisulfite dose. Oxidant reactions with organic substrates may have produced chlorinated residuals that were resistant to S(IV) dechlorination.

  3. Inactivation of three genera of dominant fungal spores in groundwater using chlorine dioxide: Effectiveness, influencing factors, and mechanisms.

    Science.gov (United States)

    Wen, Gang; Xu, Xiangqian; Huang, Tinglin; Zhu, Hong; Ma, Jun

    2017-08-18

    Fungi in aquatic environments received more attention recently; therefore, the characteristics of inactivation of fungal spores by widely used disinfectants are quite important. Nonetheless, the inactivation efficacy of fungal spores by chlorine dioxide is poorly known. In this study, the effectiveness of chlorine dioxide at inactivation of three dominant genera of fungal spores isolated from drinking groundwater and the effects of pH, temperature, chlorine dioxide concentration, and humic acid were evaluated. The inactivation mechanisms were explored by analyzing the leakage of intracellular substances, the increase in extracellular adenosine triphosphate (ATP), deoxyribonucleic acid (DNA), and proteins as well as the changes in spore morphology. The kinetics of inactivation by chlorine dioxide fitted the Chick-Watson model, and different fungal species showed different resistance to chlorine dioxide inactivation, which was in the following order: Cladosporium sp.>Trichoderma sp. >Penicillium sp., which are much more resistant than Escherichia coli. Regarding the three genera of fungal spores used in this study, chlorine dioxide was more effective at inactivation of fungal spores than chlorine. The effect of disinfectant concentration and temperature was positive, and the impact of pH levels (6.0 and 7.0) was insignificant, whereas the influence of water matrices on the inactivation efficiency was negative. The increased concentration of characteristic extracellular substances and changes of spore morphology were observed after inactivation with chlorine dioxide and were due to cell wall and cell membrane damage in fungal spores, causing the leakage of intracellular substances and death of a fungal spore. Copyright © 2017. Published by Elsevier Ltd.

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

    Directory of Open Access Journals (Sweden)

    Qingxia Zhong

    2017-10-01

    Full Text Available 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.

  5. Chemical oxidation of dissolved organic matter by chlorine dioxide, chlorine, and ozone: effects on its optical and antioxidant properties.

    Science.gov (United States)

    Wenk, Jannis; Aeschbacher, Michael; Salhi, Elisabeth; Canonica, Silvio; von Gunten, Urs; Sander, Michael

    2013-10-01

    In water treatment dissolved organic matter (DOM) is typically the major sink for chemical oxidants. The resulting changes in DOM, such as its optical properties have been measured to follow the oxidation processes. However, such measurements contain only limited information on the changes in the oxidation states of and the reactive moieties in the DOM. In this study, we used mediated electrochemical oxidation to quantify changes in the electron donating capacities (EDCs), and hence the redox states, of three different types of DOM during oxidation with chlorine dioxide (ClO2), chlorine (as HOCl/OCl(-)), and ozone (O3). Treatment with ClO2 and HOCl resulted in comparable and prominent decreases in EDCs, while the UV light absorbances of the DOM decreased only slightly. Conversely, ozonation resulted in only small decreases of the EDCs but pronounced absorbance losses of the DOM. These results suggest that ClO2 and HOCl primarily reacted as oxidants by accepting electrons from electron-rich phenolic and hydroquinone moieties in the DOM, while O3 reacted via electrophilic addition to aromatic moieties, followed by ring cleavage. This study highlights the potential of combined EDC-UV measurements to monitor chemical oxidation of DOM, to assess the nature of the reactive moieties and to study the underlying reaction pathways.

  6. Determination of chlorate and chlorite and mutagenicity of seafood treated with aqueous chlorine dioxide.

    Science.gov (United States)

    Kim, J; Marshall, M R; Du, W X; Otwell, W S; Wei, C I

    1999-09-01

    The use of chlorine dioxide (ClO(2)) as a potential substitute for aqueous chlorine to improve the quality of seafood products has not been approved by regulatory agencies due to health concerns related to the production of chlorite (ClO(2)(-)) and chlorate (ClO(3)(-)) as well as possible mutagenic/carcinogenic reaction products. Cubes of Atlantic salmon (Salmo salar) and red grouper (Epinephelus morio) were treated with 20 or 200 ppm aqueous chlorine or ClO(2) solutions for 5 min, and extracts of the treated fish cubes and test solutions were checked for mutagenicity using the Ames Salmonella/microsome assay. No mutagenic activity was detected in the treated fish samples or test solutions with ClO(2). Only the sample treated with 200 ppm chlorine showed weak mutagenic activity toward S. typhimurium TA 100. No chlorite residue was detected in sea scallops, mahi-mahi, or shrimp treated with ClO(2) at 3.9-34.9 ppm. However, low levels of chlorate residues were detected in some of the treated samples. In most cases, the increase in chlorate in treated seafood was time- and dose-related.

  7. Contrasting effects of sulfur dioxide on cupric oxide and chloride during thermochemical formation of chlorinated aromatics.

    Science.gov (United States)

    Fujimori, Takashi; Nishimoto, Yoshihiro; Shiota, Kenji; Takaoka, Masaki

    2014-12-01

    Sulfur dioxide (SO2) gas has been reported to be an inhibitor of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) formation in fly ash. However, other research has suggested little or no inhibitory effect of SO2 gas. Although these studies focused on reactions between SO2 gas and gas-phase chlorine (Cl) species, no attention was paid to thermochemical gas-solid reactions. In this study, we found contrasting effects of SO2 gas depending on the chemical form of copper (CuO vs CuCl2) with a solid-phase inorganic Cl source (KCl). Chlorinated aromatics (PCDD/Fs, polychlorinated biphenyls, and chlorobenzenes) increased and decreased in model fly ash containing CuO + KCl and CuCl2 + KCl, respectively, with increased SO2 injection. According to in situ Cu K-edge and S K-edge X-ray absorption spectroscopy, Cl gas and CuCl2 were generated and then promoted the formation of highly chlorinated aromatics after thermochemical reactions of SO2 gas with the solid-phase CuO + KCl system. In contrast, the decrease in aromatic-Cls in a CuCl2 + KCl system with SO2 gas was caused mainly by the partial sulfation of the Cu. The chemical form of Cu (especially the oxide/chloride ratio) may be a critical factor in controlling the formation of chlorinated aromatics using SO2 gas.

  8. Non-heme manganese catalysts for on-demand production of chlorine dioxide in water and under mild conditions.

    Science.gov (United States)

    Hicks, Scott D; Kim, Doyeon; Xiong, Silei; Medvedev, Grigori A; Caruthers, James; Hong, Seungwoo; Nam, Wonwoo; Abu-Omar, Mahdi M

    2014-03-05

    Two non-heme manganese complexes are used in the catalytic formation of chlorine dioxide from chlorite under ambient temperature at pH 5.00. The catalysts afford up to 1000 turnovers per hour and remain highly active in subsequent additions of chlorite. Kinetic and spectroscopic studies revealed a Mn(III)(OH) species as the dominant form under catalytic conditions. A Mn(III)(μ-O)Mn(IV) dinuclear species was observed by EPR spectroscopy, supporting the involvement of a putative Mn(IV)(O) species. First-order kinetic dependence on the manganese catalyst precludes the dinuclear species as the active form of the catalyst. Quantitative kinetic modeling enabled the deduction of a mechanism that accounts for all experimental observations. The chlorine dioxide producing cycle involves formation of a putative Mn(IV)(O), which undergoes PCET (proton coupled electron-transfer) reaction with chlorite to afford chlorine dioxide. The ClO2 product can be efficiently removed from the aqueous reaction mixture via purging with an inert gas, allowing for the preparation of pure chlorine dioxide for on-site use and further production of chlorine dioxide.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  11. Comparative Antimicrobial Activities of Aerosolized Sodium Hypochlorite, Chlorine Dioxide, and Electrochemically Activated Solutions Evaluated Using a Novel Standardized Assay

    Science.gov (United States)

    Thorn, R. M. S.; Robinson, G. M.

    2013-01-01

    The main aim of this study was to develop a standardized experimental assay to enable differential antimicrobial comparisons of test biocidal aerosols. This study represents the first chlorine-matched comparative assessment of the antimicrobial activities of aerosolized sodium hypochlorite, chlorine dioxide, and electrochemically activated solution (ECAS) to determine their relative abilities to decontaminate various surface-associated health care-relevant microbial challenges. Standard microbiological challenges were developed by surface-associating typed Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis spores, or a clinical methicillin-resistant S. aureus (MRSA) strain on stainless steel, polypropylene, or fabric. All test coupons were subjected to 20-min biocidal aerosols of chlorine-matched (100 ppm) sodium hypochlorite, chlorine dioxide, or ECAS within a standard aerosolization chamber using a commercial humidifier under defined conditions. Biocidal treatment type and material surface had a significant effect on the number of microorganisms recovered from various material surfaces following treatment exposure. Under the conditions of the assay, the order of antimicrobial efficacy of biocidal aerosol treatment was as follows: ECAS > chlorine dioxide > sodium hypochlorite. For all biocides, greater antimicrobial reductions were seen when treating stainless steel and fabric than when treating plastic-associated microorganisms. The experimental fogging system and assay protocol designed within this study were shown capable of differentiating the comparative efficacies of multiple chlorine-matched biocidal aerosols against a spectrum of target organisms on a range of test surface materials and would be appropriate for testing other biocidal aerosol treatments or material surfaces. PMID:23459480

  12. Comparative antimicrobial activities of aerosolized sodium hypochlorite, chlorine dioxide, and electrochemically activated solutions evaluated using a novel standardized assay.

    Science.gov (United States)

    Thorn, R M S; Robinson, G M; Reynolds, D M

    2013-05-01

    The main aim of this study was to develop a standardized experimental assay to enable differential antimicrobial comparisons of test biocidal aerosols. This study represents the first chlorine-matched comparative assessment of the antimicrobial activities of aerosolized sodium hypochlorite, chlorine dioxide, and electrochemically activated solution (ECAS) to determine their relative abilities to decontaminate various surface-associated health care-relevant microbial challenges. Standard microbiological challenges were developed by surface-associating typed Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis spores, or a clinical methicillin-resistant S. aureus (MRSA) strain on stainless steel, polypropylene, or fabric. All test coupons were subjected to 20-min biocidal aerosols of chlorine-matched (100 ppm) sodium hypochlorite, chlorine dioxide, or ECAS within a standard aerosolization chamber using a commercial humidifier under defined conditions. Biocidal treatment type and material surface had a significant effect on the number of microorganisms recovered from various material surfaces following treatment exposure. Under the conditions of the assay, the order of antimicrobial efficacy of biocidal aerosol treatment was as follows: ECAS > chlorine dioxide > sodium hypochlorite. For all biocides, greater antimicrobial reductions were seen when treating stainless steel and fabric than when treating plastic-associated microorganisms. The experimental fogging system and assay protocol designed within this study were shown capable of differentiating the comparative efficacies of multiple chlorine-matched biocidal aerosols against a spectrum of target organisms on a range of test surface materials and would be appropriate for testing other biocidal aerosol treatments or material surfaces.

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

    Science.gov (United States)

    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...

  14. Reduction of tri halomethanes in drinking water using chlorine dioxide as a pre oxidant; Rduccion de trihalometanos en agua potable mediante preoxidacion con dioxido de cloro

    Energy Technology Data Exchange (ETDEWEB)

    Marcian Cervera, V. J.; Monforte Monleon, L.; Ribera Orts, R.; Alvarez Alondiga, I.; Garcia Garrido, J.

    2007-07-01

    The object of the present study is to verify the suitability of using chlorine dioxide as a pre oxidant in the Water Treatment Plant of La Presa (Manises) and El Realon (Picassent), in order to minimize the tri halomethanes formation. To prove the effectiveness of chlorine dioxide, on the tri halomethanes precursors removal by oxidation, many controls and analytics have been done on the two water treatment plants. On the other hand this study also shows the chlorine dioxide generation method used, as well as its high disinfection efficiency, higher than the chlorine. (Author)

  15. [Study on the corn stover lignin oxidized by chlorine dioxide and modified by furfuryl alcohol].

    Science.gov (United States)

    Sun, Yong; Zhang, Jin-ping; Yang, Gang; Li, Zuo-hu

    2007-10-01

    The Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Visible), nuclear magnetic resonance spectroscopy (1H NMR) and TG analysis were used to study the oxidation of corn stover lignin by chloride dioxide and subsequently modified by furfuryl alcohol. The results were as following: The selective oxidation of lignin by chlorine dioxide was obtained by spectroscopy study. FTIR showed that the characteristic absorbance peaks of aromatic units were decreased after chloride dioxide oxidation. The increased absorbance for the band around 1720 cm(-1) corresponding to carbonyl stretching was achieved in the oxidized lignin and the lignin modified with furfuryl alcohol. The ultraviolet-visible spectroscopy showed that the absorbance around 280 nm was largely reduced after the lignin was oxidized. The 1H NMR spectroscopy also showed the decrease of aromatic units and methoxyl group in the oxidized lignin. All these indicated the formation of muconic acid and ester, or quinone derivatives when the lignin was selectively oxidized by chloride dioxide. The modification by furfuryl alcohol made the oxidized lignin more thermally stable.

  16. Reduction of excess sludge production in sequencing batch reactor through incorporation of chlorine dioxide oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Wang Guanghua [Ministry of Education Key Laboratory of Pollution Control and Ecological Remediation for Industrial Agglomeration area, College of Environmental Science and Engineering, South China University of Technology, Guangzhou, 510006 (China); Guangzhou municipal engineering design and research institute, Guangzhou, 510060 (China); Sui Jun [Guangzhou municipal engineering design and research institute, Guangzhou, 510060 (China); Shen Huishan; Liang Shukun [Ministry of Education Key Laboratory of Pollution Control and Ecological Remediation for Industrial Agglomeration area, College of Environmental Science and Engineering, South China University of Technology, Guangzhou, 510006 (China); He Xiangming; Zhang Minju; Xie Yizhong; Li Lingyun [Nanhai Limited Liability Development Company, Foshan, 528200 (China); Hu Yongyou, E-mail: ppyyhu@scut.edu.cn [Ministry of Education Key Laboratory of Pollution Control and Ecological Remediation for Industrial Agglomeration area, College of Environmental Science and Engineering, South China University of Technology, Guangzhou, 510006 (China) and State Key Lab of Pulp and Paper Engineering, College of Light Industry and Food Science, South China University of Technology; Guangzhou, 510640 (China)

    2011-08-15

    In this study, chlorine dioxide (ClO{sub 2}) instead of chlorine (Cl{sub 2}) was proposed to minimize the formation of chlorine-based by-products and was incorporated into a sequencing batch reactor (SBR) for excess sludge reduction. The results showed that the sludge disintegrability of ClO{sub 2} was excellent. The waste activated sludge at an initial concentration of 15 g MLSS/L was rapidly reduced by 36% using ClO{sub 2} doses of 10 mg ClO{sub 2}/g dry sludge which was much lower than that obtained using Cl{sub 2} based on similar sludge reduction efficiency. Maximum sludge disintegration was achieved at 10 mg ClO{sub 2}/g dry sludge for 40 min. ClO{sub 2} oxidation can be successfully incorporated into a SBR for excess sludge reduction without significantly harming the bioreactor performance. The incorporation of ClO{sub 2} oxidation resulted in a 58% reduction in excess sludge production, and the quality of the effluent was not significantly affected.

  17. Formation of disinfection by-products after pre-oxidation with chlorine dioxide or ferrate.

    Science.gov (United States)

    Yang, Xin; Guo, Wanhong; Zhang, Xing; Chen, Feng; Ye, Tingjin; Liu, Wei

    2013-10-01

    The effect of pre-oxidation with chlorine dioxide (ClO2) or ferrate (Fe(VI)) on the formation of disinfection by-products (DBPs) during chlorination or chloramination was tested with natural waters from 12 sources (9 surface waters, 1 groundwater, and 2 wastewater effluents). DBPs investigated included trihalomethanes (THM), chloral hydrate (CH), haloketones (HK), haloacetonitriles (HAN) and trichloronitromethane (TCNM), chlorite and chlorate. Chlorite and chlorate were found in the ClO2-treated waters. Application of 1 mg/L ClO2 ahead of chlorination reduced the formation potential for THM by up to 45% and the formation of HK, HAN and TCNM in most of the samples. The CH formation results were mixed. The formation of CH and HK was enhanced with low doses of Fe(VI) (1 mg/L as Fe), but was greatly reduced at higher doses (20 mg/L Fe). Fe(VI) reduced the formation of THM, HAN and TCNM in most of the samples. Reduced potential for the formation of NDMA was observed in most of the samples after both ClO2 and Fe(VI) pre-oxidation.

  18. Susceptibility of chemostat-grown Yersinia enterocolitica and Klebsiella pneumoniae to chlorine dioxide.

    Science.gov (United States)

    Harakeh, M S; Berg, J D; Hoff, J C; Matin, A

    1985-01-01

    The resistance of bacteria to antimicrobial agents could be influenced by growth environment. The susceptibility of two enteric bacteria, Yersinia enterocolitica and Klebsiella pneumoniae, to chlorine dioxide was investigated. These organisms were grown in a defined medium in a chemostat and the influence of growth rate, temperature, and cell density on the susceptibility was studied. All inactivation experiments were conducted with a dose of 0.25 mg of chlorine dioxide per liter in phosphate-buffered saline at pH 7.0 and 23 degrees C. The results indicated that populations grown under conditions that more closely approximate natural aquatic environments, e.g., low temperatures and growth at submaximal rates caused by nutrient limitation, were most resistant. The conclusion from this study is that antecedent growth conditions have a profound effect on the susceptibility of bacteria to disinfectants, and it is more appropriate to use the chemostat-grown bacteria as test organisms to evaluate the efficacy of a certain disinfectant. PMID:3883899

  19. Characterization of pharmaceuticals and personal care products as N-nitrosodimethylamine precursors during disinfection processes using free chlorine and chlorine dioxide.

    Science.gov (United States)

    Zhang, Ai; Li, Yongmei; Song, Yun; Lv, Juan; Yang, Juan

    2014-07-15

    The worldwide detection of pharmaceuticals and personal care products (PPCPs) in aquatic environment and drinking water has caused wide concern in recent years. The possibility for concurrent formation of N-nitrosodimethylamine (NDMA) during disinfection has become another significant concern for water quality. This study demonstrates that a group of PPCPs containing amine groups can serve as NDMA precursors during free chlorine or chlorine dioxide (ClO2) chlorination processes. Selected PPCPs after screening by NDMA yield were further investigated for NDMA formation conditions. High disinfectant dose and initial PPCP concentration resulted in relatively high NDMA formation potential. Linear kinetic models were developed for NDMA formation during chlorination of selected PPCPs. Although the PPCP precursors were removed significantly during chlorination, they were not completely mineralized based on the total organic carbon (TOC) loss. The existence of another possible pathway for direct formation of NDMA from tertiary amine during chlorination was indicated, in which dimethylamine (DMA) was not involved. It is recommended to control the initial PPCP concentrations prior to disinfection and to shorten the contact time to reduce the NDMA formation. ClO2 is suggested to be a proper disinfectant in order to reduce the NDMA formation.

  20. The effect of chlorine dioxide on the formation of trihalomethanes; Dioxido de cloro y su efecto en la formacion de trihalometanos

    Energy Technology Data Exchange (ETDEWEB)

    Ciurana de Gay, C.

    2000-07-01

    The chlorine dioxide presents a high reactivity with certain organic and inorganic compounds. In the process of making water fit to drink, one of the most valued characteristics of the chlorine dioxide is the oxidation of the precursors of trihalomethanes, that allows their decrease in the drinking water. The generation of the chlorine dioxide is the oxidation of the precursors of trihalomethanes, that allows their decrease in the drinking water. The generation of the chlorine dioxide must be made at the dosage point. Both, the generation and its control can be made in an easy way. Since a few years ago, in the ETAP, in Montfulla, some researches are being carried out in order to decrease the concentration of trihalomethanes. In this work it is exposed the generation the dosage control and the reduction of trihalomethanes obtained through the dosage of the chlorine dioxide at different doses. (Author) 8 refs.

  1. Chlorine

    Science.gov (United States)

    ... but it is also used to make pesticides (insect killers), rubber, and solvents. Chlorine is used in ... the following signs and symptoms may develop: Blurred vision Burning pain, redness, and blisters on the skin ...

  2. A time-resolved resonance Raman study of chlorine dioxide photochemistry in water and acetonitrile

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, S.C.; Philpott, M.P.; Mayer, S.G.; Reid, P.J. [Univ. of Washington, Seattle, WA (United States). Dept. of Chemistry

    1999-07-15

    The photochemistry of chlorine dioxide (OClO) has attracted much interest due to its participation in the atmospheric chlorine reservoir as well as its potential role in stratospheric ozone depletion. Since the environmental impact of OClO arises from its ability to produce atomic chlorine, understanding this phase-dependent reactivity is essential if models capable of predicting the environmental impact of OClO in both homogeneous and heterogeneous settings are to be obtained. The photochemistry of chlorine dioxide (OClO) in water and acetonitrile is investigated using time-resolved resonance Raman spectroscopy. Stokes and anti-Stokes spectra are measured as a function of time following photoexcitation using degenerate pump and probe wavelengths of 390 nm. For aqueous OClO, the time-dependent Stokes intensities are found to be consistent with the re-formation of ground-state OClO by subpicosecond geminate recombination of the primary ClO and O photofragments. This represents the first unequivocal demonstration of primary-photoproduct geminate recombination in the condensed-phase photochemistry of OClO. Anti-Stokes intensity corresponding to the OClO symmetric stretch is observed demonstrating that, following geminate recombination, excess vibrational energy is deposited along this coordinate. Analysis of the anti-Stokes decay kinetics demonstrates that, in water, intermolecular vibrational relaxation occurs with a time constant of {approximately}9 ps. For OClO dissolved in acetonitrile, the Stokes scattering intensities are consistent with a significant reduction in the geminate-recombination quantum yield relative to water. Comparison of the OClO anti-Stokes decay kinetics in acetonitrile and water demonstrates that the rate of intermolecular vibrational relaxation is {approximately}4 times smaller in acetonitrile. Finally, in both solvents the appearance of symmetric-stretch anti-Stokes intensity is significantly delayed relative to geminate recombination. This

  3. Comparing the efficacy of chlorine, chlorine dioxide, and ozone in the inactivation of Cryptosporidium parvum in water from Parana State, Southern Brazil.

    Science.gov (United States)

    Pereira, Juliana Tracz; Costa, Adriana Oliveira; de Oliveira Silva, Márcia Benedita; Schuchard, Wagner; Osaki, Silvia Cristina; de Castro, Edilene Alcântara; Paulino, Rosangela Clara; Soccol, Vanete Thomaz

    2008-12-01

    In the present work, assays were performed to compare the efficacy of hypochlorous acid, chlorine dioxide, and ozone in the inactivation of Cryptosporidium oocyst in public water supply from Brazilian South conditions. Experiments were carried out in samples containing 2 x 10(4) oocysts/ml of C. parvum purified from feces of experimentally contaminated calves. An in vitro excystation method was used to evaluate oocysts' viability and to determine the inactivation rates of hypochlorous acid at 2 ppm, chlorine dioxide at 1, 2, and 5 ppm, and ozone at the doses of 0.18, 0.24, 0.36, 0.48, and 1.44 mg/l. By using hypochlorous acid, the maximum inactivation rate obtained was 49.04% after 120 min. Chlorine dioxide at 5 ppm inactivated 90.56% of oocysts after 90 min of contact. Ozone was the most effective product, rendering an inactivation of 100% with the concentration of 24 mg/l. Resistance of Cryptosporidium to the usual disinfectants and the need for more effective water treatments to prevent waterborne diseases in Brazil are discussed in this manuscript.

  4. 40 CFR 141.535 - What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 22 2010-07-01 2010-07-01 false What if my system uses chloramines, 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...

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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...

  11. Evaluation of disinfection efficiency in pet's hospital by using chlorine dioxide

    Directory of Open Access Journals (Sweden)

    Ching-Shan Hsu

    2016-07-01

    Full Text Available Microbial aerosols could cause various human and animal health problems and their control is becoming a significant scientific and technological topic for consideration. The main objectives of this study were to monitor bioaerosol levels of the pet's hospital and then to perform disinfection efficiency by applying chlorine dioxide. The air quality within these pet's hospitals should satisfy the guidelines specified by the Taiwan Environmental Protection Administration (TEPA. Accordingly, this study performed an experimental investigation into the efficiency of two different gaseous chlorine dioxide (0.3 mg m−3 treatments in disinfecting a local pet's hospital, namely a single, one-off application and a multiple-daily application. In both cases, the ClO2 was applied using strategically-placed aerosol devices. The air quality before and after disinfection was evaluated by measuring the bioaerosol levels of bacteria and fungi. The experimental results found that the average background levels of bacteria and fungi prior to ClO2 disinfection were found to be 2014 ± 1350 and 1002 ± 669 CFU m−3, respectively. A single ClO2 application was found to total disinfected bacteria and fungi concentration levels by as much as 57.3 and 57.6%. By contrast, a multiple-daily ClO2 application was found to total disinfected bacteria and fungi concentration levels by as much as 65.1 and 57.6%. Among the two disinfection methods, the multiple-daily ClO2 application method was found to yield a higher disinfection efficiency for bacteria, i.e., 16.28 ± 0.92%. Thus, using a ClO2 disinfectant to maintain the air quality is of great importance to reduce infectious diseases in the pet's hospital. Therefore, the results suggest that the air quality guidelines prescribed by the TEPA for pet's hospital and other animal facilities can best be achieved by applying chlorine dioxide at regular intervals. The ClO2 aerosol devices can effectively restrain or

  12. Preparation and Evaluation of Novel Solid Chlorine Dioxide-based Disinfectant Powder in Single-pack

    Institute of Scientific and Technical Information of China (English)

    MIN ZHU; LI-SHI ZHANG; XIAO-FANG PEI; XIN XU

    2008-01-01

    Objective To prepare and evaluate novel chlorine dioxide-based disinfectant powder in single-pack that is more convenient for use and iransportation.Methods Orthogonal experiment was performed to determine the recipe of the disinfectant powder.Stability test,suspension quantitative bactericidal test,simulation neld trial,and animal toxicity test were carried out to observe its bactericidal and toxicological effects.Results The orthogonal experiment showed thatthe type of water solution had no effect on the disinfectant powder and the best ratio of sodium chlorite to solid acid was 1:3.Ten grams of the disinfectant powder was fully dissolved in 20 mL water for 2 mill,and diluted to 500 mL in water.After 5-10 min,the concentration of chlorine dioxide(ClO2)solution was 266 mg/L to 276 mg/L.After stored at 54℃ for 14 d,the average concentration of ClO2 was decreased by 5.03%.Suspension quantitative bactericidal test showed that the average killing logarithm(KL)value for both Staphylococcus aureus and Escherichia coli in 100 mg/L ClO2 solution for 2 min was over 5.00.In simulation field trial,the average descending KL value for Escherichia coli in the solution containing 100 mg/L ClO2 for 5min was ovcr 3.00.The mouse acute LD50 in the solution 5 times exceeded 5000 mg/kg.The disinfectant powder was not toxic and irritativeto rabbit skin and had nomutagenic effect on mouse marrow polychrornafic erythrocytes(PCE).Conclusion The stability and bactericidal efficacy of solid chlorine dioxide-based disinfectant powder in single-pack are good.The solution containing 100mg/L ClO2 can kill vegetative forms of bacteria.The concenwation of ClO2 on the disinfecting surface of objects is 100mg/L.The disinfectant powder is not toxic and irritative.

  13. Experimental Study on Combined Disinfection Mechanism of Chlorine Dioxide and Chlorine%二氧化氯和氯联合消毒耦合机制试验研究

    Institute of Scientific and Technical Information of China (English)

    袁一星; 常魁; 高金良; 王慧; 刘盈

    2011-01-01

    分析了铸铁管、钢管和PVC管中不同消毒剂投加量下二氧化氯和氯联合消毒时二者的衰减规律.结果表明,不同管材中二氧化氯和氯联合消毒时二者的衰减速率各不相同,且联合消毒时二氧化氯的衰减速率低于单独采用二氧化氯消毒时的.%The decay of chlorine dioxide and chlorine during combined disinfection with different doses of chlorine dioxide and chlorine in cast iron, steel and PVC pipes was analyzed. The result shows that the decay rates of chlorine dioxide and chlorine during combined disinfection in the pipes with different materials are different, and the decay rate of chlorine dioxide during combined disinfection is less than that of only chlorine dioxide.

  14. MECHANISM OF FUSARIUM TRICINCTUM (CORDA SACC. SPORE INACTIVATION BY CHLORINE DIOXIDE

    Directory of Open Access Journals (Sweden)

    Zhao Chen

    2015-06-01

    Full Text Available The mechanism of Fusarium tricinctum (Corda Sacc. spore inactivation by chlorine dioxide (ClO2 was investigated. During F. tricinctum spore inactivation by ClO2, protein, DNA, and metal ion leakage, enzyme activity, and cell ultrastructure were examined. Protein and DNA leakages were not detected, while there were metal ion leakages of K+, Ca2+, and Mg2+, which were well-correlated with the inactivation rate. The enzyme activities of glucose-6-phosphate dehydrogenase, citrate synthase, and phosphofructokinase were inhibited and were also well-correlated with the inactivation rate. Electron micrographs showed the ultrastructural modifications of spores and demonstrated that spores were heavily distorted and collapsed from their regular structure. Spore surface damage and disruption in inner components was also severe. The metal ion leakage, the inhibition of enzyme activities, and the damage of spore structure were significant in F. tricinctum spore inactivation by ClO2.

  15. Application of highly purified electrolyzed chlorine dioxide for tilapia fillet disinfection.

    Science.gov (United States)

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

    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.

  16. Target Turing patterns and growth dynamics in the chlorine dioxide-iodine-malonic acid reaction.

    Science.gov (United States)

    Preska Steinberg, Asher; Epstein, Irving R; Dolnik, Milos

    2014-04-03

    We study the growth dynamics of Turing patterns in the chlorine dioxide-iodine-malonic acid reaction-diffusion system in response to perturbations with visible light. We describe several mechanisms by which Turing patterns reappear after they are suppressed by illumination with a disc-shaped geometry. We observe that under specific conditions the patterns reorganize from a random configuration of spots and stripes to a set of ordered, concentric rings, which we refer to as target Turing patterns. These patterns closely resemble the unit cells of the Turing hexagonal superlattices known as black eye patterns. However, these target Turing patterns are not part of a larger superlattice structure, and they usually have a larger number of concentric rings. Numerical simulations support the experimental findings.

  17. A coupled chemical burster: The chlorine dioxide-iodide reaction in two flow reactors

    Science.gov (United States)

    Dolnik, Milos; Epstein, Irving R.

    1993-01-01

    The dynamical behavior of the chlorine dioxide-iodide reaction has been studied in a system consisting of two continuous flow stirred tank reactors (CSTRs). The reactors are coupled by computer monitoring of the electrochemical potential in each reactor, which is then used to control the input into the other reactor. Two forms of coupling are employed: reciprocally triggered, exponentially decreasing stimulation, and alternating mass exchange. The reaction, which exhibits oscillatory and excitable behavior in a single CSTR, displays neuronlike bursting behavior with both forms of coupling. Reciprocal stimulation yields bursting in both reactors, while with alternating mass exchange, bursting is observed in one reactor and complex oscillation in the other. A simple model of the reaction gives good agreement between the experimental observations and numerical simulations.

  18. Chlorine dioxide as a disinfectant for Ralstonia solanacearum control in water, storage and equipment

    Directory of Open Access Journals (Sweden)

    Popović Tatjana

    2016-01-01

    Full Text Available Brown rot or bacterial wilt caused by bacterium Ralstonia solanacearum is the main limiting factor in potato production. Quarantine measures are necessary to avoid spread of disease to disease-free areas. R. solanacearum has been shown to contaminate watercourses from which crop irrigation is then prohibited causing further potential losses in yield and quality. The bacteria also spread via surfaces that diseased seed potatoes come into contact with. This study showed bactericidal activity of chlorine dioxide (CIO2 on R. solanacearum for disinfection of water, surface and equipment. The results showed that CIO2 solution at concentration of 2 ppm at 30 minutes of exposure time had bactericidal effect for disinfection of water. For surface and equipment disinfection, concentration of 50 ppm showed total efficacy at 30 min and 5 sec exposure time, respectively. Results suggest that use of CIO2 as a disinfectant has a potential for control of brown rot pathogen in water, storage and equipment.

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

    Science.gov (United States)

    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.

  20. Removal of pharmaceuticals in biologically treated wastewater by chlorine dioxide or peracetic acid

    DEFF Research Database (Denmark)

    Hey, G.; Ledin, Anna; La Cour Jansen, Jes

    2012-01-01

    Removal of six active pharmaceutical ingredients in wastewater was investigated using chlorine dioxide (ClO2) and peracetic acid (PAA) as chemical oxidants. Four non-steroidal anti -inflammatory drugs (ibuprofen, naproxen, diclofenac, and mefenamic acid) and two l ipid regulating agents (gemfibrozi...... compounds, only clofibric acid and ibuprofen were not removed when treated wi th ClO2 up to 20 mg/L. Wi th increasing PAA dose up to 50 mg/L, signi ficant removal of most of the pharmaceutical s was observed except for the wastewater wi th the highest COD. Thi s indicates that chemical oxidation wi th ClO2...... could be used for tertiary treatment at WWTPs for active pharmaceutical ingredients whi le PAA was not sufficiently efficient....

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1986-11-01

    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 (ClO/sub 2/) 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 ClO/sub 2/ ingestion, it seems that ClO/sub 2/ does not cause iodide deficiency of sufficient magnitude to account for the decease in hormonogenesis. Absorption of one or more of iodinated molecules, e.g., nutrient, hormones, or cellular constituents of the alimentary tract having thyromimetic or thyroid inhibitory properties, is a better hypothesis for the effects seen.

  2. Femtosecond pump-probe studies of actinic-wavelength dependence in aqueous chlorine dioxide photochemistry

    Science.gov (United States)

    Bixby, Teresa J.; Bolinger, Joshua C.; Patterson, Joshua D.; Reid, Philip J.

    2009-04-01

    The actinic or photolysis-wavelength dependence of aqueous chlorine dioxide (OClO) photochemistry is investigated using femtosecond pump-probe spectroscopy. Following photoexcitation at 310, 335, and 410 nm the photoinduced evolution in optical density is measured from the UV to the near IR. Analysis of the optical-density evolution illustrates that the quantum yield for atomic chlorine production (ΦCl) increases with actinic energy, with ΦCl=0.16±0.02 for 410 nm excitation and increasing to 0.25±0.01 and 0.54±0.10 for 335 and 310 nm excitations, respectively. Consistent with previous studies, the production of Cl occurs through two channels, with one channel corresponding to prompt (<5 ps) Cl formation and the other corresponding to the thermal decomposition of ClOO formed by OClO photoisomerization. The partitioning between Cl production channels is dependent on actinic energy, with prompt Cl production enhanced with an increase in actinic energy. Limited evidence is found for enhanced ClO production with an increase in actinic energy. Stimulated emission and excited-state absorption features associated with OClO populating the optically prepared A22 surface decrease with an increase in actinic energy suggesting that the excited-state decay dynamics are also actinic energy dependent. The studies presented here provide detailed information on the actinic-wavelength dependence of OClO photochemistry in aqueous solution.

  3. The effect of sulfur dioxide on the formation of molecular chlorine during co-combustion of fuels

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Y.; Xie, W.; Liu, K.; Dicken, L.; Pan, W.-P.; Riley, J.T. [Western Kentucky University, Bowling Green, KY (USA). Combustion Lab., Dept. of Chemistry

    2000-06-01

    This project was designed to evaluate the combustion performance of and emissions from a fluidized bed combustor during the combustion of mixtures of high sulfur and/or high chlorine coals and municipal solid waste (MSW). The effect of sulfur dioxide on the formation of molecular chlorine during co-combustion of fuels was examined in this study. Sulfur dioxide was shown to be an effective inhibitor for the formation of molecular chlorine through the Deacon Reaction and subsequently, the formation of chlorinated organics. Theoretically, co-firing high sulfur coals with MSW will decrease the possibility of polychlorodibenzodioxin/furan (PCDD/F) formation during the combustion process. A mixture of coal and PVC pellets was burned in a 0.1 MW{sub th} bench-scale fluidized bed system at WKU and no detectable amounts of chlorinated organics were found in the flue gas and bed ash. The results from this study indicated the practical effects of using coal as a combustion support fuel when burning MSW. 23 refs., 3 figs., 3 tabs.

  4. Chlorine

    Energy Technology Data Exchange (ETDEWEB)

    Talmage, Sylvia Smith [ORNL

    2009-01-01

    Following a brief description of the use of chlorine as a chemical warfare agent in World War I, this chapter summarizes physical and chemical data and recent clinical and controlled laboratory studies on the irritant and lethal effects of chlorine. The mechanism of toxicity for both irritation and lethal effects is described. The mathematical relationship between concentration and exposure duration for a set endpoint is given for both an irritancy response and mortality. This information can be used to assist in time-scaling for the set endpoint to other exposure durations. Risk assessment addresses the potential for greater effects in sensitive populations such as asthmatics. A concentration of 0.5 ppm for up to 8 hours is a no-adverse-effect concentration in most sensitive subjects; whereas, a concentration of 1.0 ppm induces some sensory irritation and transient changes in respiratory tract airflow parameters. Treatment and intervention of exposed individuals is dependent upon symptoms

  5. Neutron-activated determination of chlorine, using the /sup 35/Cl(n,p)/sup 35/S reaction as the basis, in thin coatings of silicon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Perezhogin, G.A.

    1988-01-10

    The neutron-activation determination of chlorine in thin coatings of silicon dioxide on silicon has been shown to be possible through the use of the /sup 55/Cl(n, P)/sup 35/S reaction. The detection limit of chlorine is 3 x 10/sup -9/ g (5 x 10/sup 13/ atoms).

  6. Kinetics and mechanism of the oxidation of pentathionate ion by chlorine dioxide in a slightly acidic medium.

    Science.gov (United States)

    Xu, Li; Csekő, György; Petz, Andrea; Horváth, Attila K

    2014-02-27

    The chlorine dioxide-pentathionate reaction has been studied at a slightly acidic medium by conventional UV-vis spectroscopy monitoring the absorbance at 430 nm. We have shown that pentathionate was oxidized to sulfate, but chlorate is also a marginal product of the reaction besides the chloride ion. The stoichiometry of the reaction can be established as a linear combination of two limiting stoichiometries under our experimental conditions. Kinetics of the reaction was found to be also complex because initial rate studies revealed that formal kinetic orders of both the hydrogen ion and chlorine dioxide is far from unity. Moreover, log-log plot of the initial rate against pentathionate concentration indicated a nonconstant formal kinetic order. We also observed a significant catalytic effect of chloride ion. Based on our observations and simultaneous evaluation of the kinetic curves, an 11-step kinetic model is obtained with 6 fitted rate coefficients. A relatively simple rate equation has also been derived and discussed.

  7. Progress of Chlorine Dioxide Preparation Method%二氧化氯制备方法研究进展

    Institute of Scientific and Technical Information of China (English)

    吴建春; 杨佳财

    2012-01-01

    二氧化氯是一种具有高氧化性和强消毒性的化合物,本论文介绍了二氧化氯制备的化学法、电解法以及电化学法,并对几种工艺方法的优缺点进行了分析和比较,适合工业化生产的工艺主要是化学法中的氯酸钠法和亚氯酸钠法。%Chlorine dioxide is a high oxidation resistance and strong disinfection compound.This paper introduces the chemical preparation method of dioxide chlorine,electrolysis method and electrochemical method.The advantages and disadvantages of several processing methods were discussed and compared.The process suitable for industrial production is mainly sodium chlorate and sodium chlorite method.

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

    Science.gov (United States)

    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.

  9. Evaluation of chlorine, chlorine dioxide, and a peroxyacetic acid-based sanitizer for effectiveness in killing Bacillus cereus and Bacillus thuringiensis spores in suspensions, on the surface of stainless steel, and on apples.

    Science.gov (United States)

    Kreske, Audrey C; Ryu, Jee-Hoon; Beuchat, Larry R

    2006-08-01

    Chlorine (10 to 200 microg/ml), chlorine dioxide (10 to 200 microg/ml), and a peroxyacetic acid-based sanitizer (40 and 80 microg/ ml) were evaluated for effectiveness in killing spores of Bacillus cereus and Bacillus thuringiensis in suspensions and on the surface of stainless steel and apples. Water and 5% horse serum were used as carriers for spore inoculum applied to the surface of stainless steel coupons, and 5% horse serum was used as a carrier for inoculum applied to apples. Inocula were dried on stainless steel for 5 h and on apples for 22 to 24 h before treating with sanitizers. At the concentrations of sanitizers tested, sensitivities of planktonic B. cereus and B. thuringiensis spores were similar. A portion of the spores surviving treatment with chlorine and, more markedly, chlorine dioxide had decreased tolerance to heat. Planktonic spores of both species were more sensitive to sanitizers than were spores on the surface of stainless steel or apples. At the same concentrations, chlorine was more effective than chlorine dioxide in killing spores in suspension and on stainless steel. The lethality of chlorine dioxide was markedly reduced when inoculum on stainless steel coupons was suspended in 5% horse serum as a carrier rather than water. Chlorine and chlorine dioxide at concentrations of 10 to 100 microg/ml were equally effective in killing spores on apples. Significant reductions of > or = 3.8 to 4.5 log CFU per apple were achieved by treatment with 100 microg/ml of either of the two sanitizers. The peroxyacetic acid sanitizer (40 and 80 microg/ml) was ineffective in killing Bacillus spores in the test systems investigated. Results provide information on the effectiveness of sanitizers commonly used in the food processing industry in killing Bacillus spores in suspension, on a food-contact surface, and on a ready-to-eat food.

  10. Differential oscillator strengths for chlorine dioxide, OClO, produced by electron impact energy-loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Davies, J.A.; Mason, N.J. [University Coll., London (United Kingdom). Dept. of Physics and Astronomy; Marston, G.; Wayne, R.P. [Oxford Univ. (United Kingdom). Physical Chemistry Lab.

    1995-09-28

    Electron impact spectroscopy has been used for the first time to obtain energy-loss spectra for chlorine dioxide, OC10, over an energy range 2.5 {yields} 12.5 eV. The differential oscillator strength (DOS) obtained from the energy-loss spectrum is compared with the DOS obtained from optical measurements. Oscillator strengths for several transitions have been calculated from a summation of the DOS and comparisons are also made with previous optical data. (author).

  11. UV Irradiation Chlorine Dioxide Photocatalytic Oxidation of Simulated Fuchsine Wastewater by UV-Vis and Online FTIR Spectrophotometric Method

    OpenAIRE

    Jie Liu; Chunlei Huai; Na Li; Xiaomei Wang; Laishun Shi

    2012-01-01

    The photocatalyst TiO2/SiO2 was prepared and used for chlorine dioxide photocatalytic oxidation of simulated fuchsine wastewater under UV irradiation. The removal efficiency of fuchsine treated by photocatalytic oxidation process is higher than that of chemical oxidation process. By using UV-Vis and online FTIR analysis technique, the intermediates during the degradation process were obtained. The benzene ring in fuchsine was degraded into quinone and carboxylic acid and finally changed into ...

  12. Monochloramine Cometabolism by Nitrifying Biofilm Relevant ...

    Science.gov (United States)

    Recently, biological monochloramine removal (i.e., cometabolism) by a pure culture ammonia–oxidizing bacteria, Nitrosomonas europaea, and a nitrifying mixed–culture have been shown to increase monochloramine demand. Although important, these previous suspended culture batch kinetic experiments were not representative of drinking water distribution systems where bacteria grow predominantly as biofilm attached to pipe walls or sediments and physiological differences may exist between suspension and biofilm growth. Therefore, the current research was an important next step in extending the previous results to investigate monochloramine cometabolism by biofilm grown in annular reactors under drinking water relevant conditions. Estimated monochloramine cometabolism kinetics were similar to those of ammonia metabolism, and monochloramine cometabolism was a significant loss mechanism (25–40% of the observed monochloramine loss). These results demonstrated that monochloramine cometabolism occurred in drinking water relevant nitrifying biofilm; thus, cometabolism may be a significant contribution to monochloramine loss during nitrification episodes in distribution systems. Investigate whether or not nitrifying biofilm can biologically transform monochloramine under drinking water relevant conditions.

  13. Design of an acid stimulation system with chlorine dioxide for the treatment of water-injection wells

    Energy Technology Data Exchange (ETDEWEB)

    Cavallaro, A.N.; Baigorria, R.; Curci, E. [Repsol YPF, Buenos Aires, (Argentina)

    2000-06-01

    A method to remove solid residues resulting from formation damage in water-injection wells was presented. The method is based on a chemical stimulation system which uses a treatment fluid comprised of hydrochloric acid and chlorine dioxide. This fluid is more effective than conventional acidizing systems in treating the solid residues that get deposited in fractured reservoirs, particularly when the plugging material contains iron sulfide and bacterial agents. This is because of the high oxidative power of chlorine dioxide. Formation damage is a common occurrence in several secondary recovery oilfields in Argentina, resulting in injectivity losses. Internal or external cake formation is usually the mechanism associated with injection performance. The severity of the damage can be determined by examining the parameters such as particle size, shape and composition, injection rates, pore system properties such as permeability, and pore size. Clean-up treatments raise the injection maintenance costs and water treatment substantially. The system presented here differs from past treatments because the chlorine dioxide is not produced in-situ. Core flooding laboratory tests have been conducted which successfully demonstrate the effectiveness of the system in removing solid residues resulting from formation damage. A pilot study will be conducted in the near future. 7 refs., 1 tab., 7 figs.

  14. Prevention of bovine mastitis by a postmilking teat disinfectant containing chlorous acid and chlorine dioxide in a soluble polymer gel.

    Science.gov (United States)

    Oliver, S P; King, S H; Torre, P M; Shull, E P; Dowlen, H H; Lewis, M J; Sordillo, L M

    1989-11-01

    A natural exposure study was conducted in a herd of 150 lactating dairy cows for 18 mo to determine the effectiveness of chlorous acid and chlorine dioxide in a soluble polymer gel as a postmilking teat disinfectant for the prevention of bovine mastitis. Right quarters of cows were dipped in the experimental teat dip after milking machine removal. Left quarters were not dipped and served as within-cow negative controls. The experimental teat dip reduced Staphylococcus aureus infections 67.4%, Streptococcus dysgalactiae infections 63.8%, and Streptococcus uberis infections 27.8%. Overall efficacy of the chlorous acid and chlorine dioxide teat dip against major mastitis pathogens was 52.2%. The experimental teat dip reduced Corynebacterium bovis infections and coagulase-negative staphylococcal infections also by 45.8 and 38.7%, respectively. Overall efficacy against minor mastitis pathogens was 43.4%. Under conditions of this trial, the experimental teat dip containing chlorous acid and chlorine dioxide was effective in preventing new intramammary infections against a variety of mastitis pathogens.

  15. Use of chlorine dioxide in a secondary recovery process to inhibit bacterial fouling and corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Knickrehm, M.; Caballero, E.; Romualdo, P.; Sandidge, J.

    1987-01-01

    A major oil company operates a secondary recovery waterflood in Inglewood, California. The waterflood currently processes 250,000 bbls. per day of produced fluid. The major economic and operational problems associated with a secondary recovery waterflood are: 1) corrosion due to oxygen, carbon dioxide, hydrogen sulfide, and bacteria (sulfate reducers and slime biomass), 2) plugging from deposits due to salts, sulfides, and biofilms. These problems lead to deterioration of water handling equipment, injection lines (surface and subsurface), and decreased water quality resulting in the plugging of injection wells. During the last 8 years the operator has used varying mechanical and chemical technology to solve these problems. From 1978 to 1982 traditional chemical programs were in effect. Over this time period there was a continuing decline in water quality, and a substantial increase in chemical and operational costs. It was determined at that time that the major reason for this was due to microbiological activity. With this in mind, the operator proceeded to test the effects of using Aqueous Chlorine Dioxide in one portion of their water handling facilities. Due to the success of the program it was applied field wide. Presently, the primary problems associated with bacteria have been arrested. Solving one corrosion problem can lead to the onset of another. The operator is now in the process of making a concentrated effort to eliminate the other synergistically related corrosive and plugging agents (O/sub 2/, CO/sub 2/, H/sub 2/S). A field history of the problems, findings, and solutions, are discussed along with an overview of our present direction.

  16. Removal of residual chlorine from Indiana 5 coal by supercritical carbon dioxide extraction

    Energy Technology Data Exchange (ETDEWEB)

    Kocher, B.S.; Azzam, F.O.; Lee, S. (University of Akron, Akron, OH (United States). Dept. of Chemical Engineering)

    1994-01-01

    The perchloroethylene coal desulfurization process has unique advantages as a precombustion coal cleaning process, that include high cleaning efficiencies, mild process conditions, minimal output of undesirable byproducts, and cost effectiveness. However, the use of perchloroethylene in the process renders an important process engineering problem of complete recovery and reuse of perchloroethylene, thus requiring a 'zero discharge' condition of the solvent. Therefore, the treated coal must be stripped of any residual perchloroethylene. Carbon dioxide (CO[sub 2]) in its supercritical state has been investigated for its ability to remove chlorine from Indiana 5 coal, that has been desulfurized by the perchloroethylene (PCE) process. The reduction of Cl content from a PCE treated and filtered coal has been as high as 78% by mass. The experiments have been carried out following a statistical experimental design and the discerning characteristics of the process have been identified. The solvent density and extraction conditions can be tailored in such a way as to optimally remove C from the coal without any detrimental effects on the coal matrix. The supercritical CO[sub 2] extraction process can be successfully implemented to the PCE coal cleaning process by replacing energy intensive steps of steam stripping and vacuum drying. 6 refs., 3 figs., 3 tabs.

  17. On the cause of the tailing phenomenon during virus disinfection by chlorine dioxide.

    Science.gov (United States)

    Sigstam, Thérèse; Rohatschek, Andreas; Zhong, Qingxia; Brennecke, Moritz; Kohn, Tamar

    2014-01-01

    This study investigates the mechanisms underlying the deviation from Chick-Watson kinetics, namely a tailing curve, during the disinfection of viruses by chlorine dioxide (ClO2). Tailing has been previously reported, but is typically attributed to the decay in disinfectant concentration. Herein, it is shown that tailing occurs even at constant ClO2 concentrations. Four working hypothesis to explain the cause of tailing were tested, specifically changes in the solution's disinfecting capacity, aggregation of viruses, resistant virus subpopulations, and changes in the virus properties during disinfection. In experiments using MS2 as a model virus, it was possible to rule out the solution's disinfecting capacity, virus aggregation and the resistant subpopulation as reasons for tailing. Instead, the cause for tailing is the deposition of an adduct onto the virus capsid over the course of the experiment, which protects the viruses. This adduct could easily be removed by washing, which restored the susceptibility of the viruses to ClO2. This finding highlights an important shortcoming of ClO2, namely its self-limiting effect on virus disinfection. It is important to take this effect into account in treatment applications to ensure that the water is sufficiently disinfected before human consumption.

  18. Investigating the phase-dependent photochemical reaction dynamics of chlorine dioxide using resonance Raman spectroscopy

    Science.gov (United States)

    Hayes, Sophia C.; Wallace, Paul M.; Bolinger, Josh C.; Reid, Philip J.

    Recent progress in understanding the phase-dependent reactivity demonstrated by halooxides is outlined. Specifically, resonance Raman intensity analysis (RRIA) and time-resolved resonance Raman (TRRR) studies of chlorine dioxide (OClO) photochemistry in solution are presented. Using RRIA, it has been determined that the excited-state structural evolution that occurs along the asymmetric-stretch coordinate in the gas phase is restricted in solution. The absence of evolution along this coordinate results in the preservation of groundstate symmetry in the excited state. The role of symmetry in defining the reaction coordinate and the solvent-solute interactions responsible for modification of the excited-state potential energy surface are discussed. TRRR studies are presented which demonstrate that geminate recombination of the primary photoproducts resulting in the reformation of ground-state OClO is a central feature of OClO photochemistry in solution. These studies also demonstrate that a fraction of photoexcited OClO undergoes photoisomerization to form ClOO, with the ground-state thermal decomposition of this species resulting in Cl production on the subnanosecond timescale. Finally, time-resolved anti-Stokes experiments are presented which demonstrate that the OClO vibrational-relaxation dynamics are solvent dependent. The current picture of OClO photochemistry derived from these studies is discussed, and future directions for study are outlined.

  19. Lifetime Prediction of Polyethylene Pipes Transporting Drinking Water in the Presence of Chlorine Dioxide

    Science.gov (United States)

    Colin, X.; Audouin, L.; Verdu, J.

    2008-08-01

    A kinetic model for lifetime prediction of polyethylene pipes transporting pressurized water disinfected by chlorine dioxide (DOC) has been elaborated. This model is composed of three sub-models: —A system of differential equations, derived from a realistic mechanistic scheme for radical chain oxidation in the presence of DOC of stabilized polyethylene (PE), giving access to the spatial distribution of structural changes in the pipe wall and its evolution against time of exposure; —The classical Saito's equation to predict the profiles of average molar masses from the spatial distribution of chain scissions and crosslinking events; —An empirical creep equation and an empirical fracture criterion derived from regression curves obtained in pure water. It is assumed that chemical degradation modifies only the time to transition tc between ductile and brittle regimes of failure, and that tc is linked to the weight average molar mass by a power law. By combining these three sub-models, it is possible to predict the time to failure tF under the coupled effects of pressure and chemical degradation. In current use conditions (under 3-12 bars water pressure, at 15 °C, in the presence of 0.15 mg of DOC per liter of water), the model predicts a tF of the order of 15 years against more than 50 years expected lifetime, that agrees well with experimental results.

  20. Effect of chlorine dioxide on cyanobacterial cell integrity, toxin degradation and disinfection by-product formation.

    Science.gov (United States)

    Zhou, Shiqing; Shao, Yisheng; Gao, Naiyun; Li, Lei; Deng, Jing; Zhu, Mingqiu; Zhu, Shumin

    2014-06-01

    Bench scale tests were conducted to study the effect of chlorine dioxide (ClO2) oxidation on cell integrity, toxin degradation and disinfection by-product formation of Microcystis aeruginosa. The simulated cyanobacterial suspension was prepared at a concentration of 1.0×10(6)cells/mL and the cell integrity was measured with flow cytometry. Results indicated that ClO2 can inhibit the photosynthetic capacity of M. aeruginosa cells and almost no integral cells were left after oxidation at a ClO2 dose of 1.0mg/L. The total toxin was degraded more rapidly with the ClO2 dosage increasing from 0.1mg/L to 1.0mg/L. Moreover, the damage on cell structure after oxidation resulted in released intracellular organic matter, which contributed to the formation of trihalomethanes (THMs) and haloacetic acids (HAAs) as disinfection by-products. Therefore, the use of ClO2 as an oxidant for treating algal-rich water should be carefully considered.

  1. Application of chlorine dioxide as an oilfield-facilities-treatment fluid

    Energy Technology Data Exchange (ETDEWEB)

    Romaine, J. [Rio Linda Chemical Co., Inc., Sugar Land, TX (United States); Strawser, T.J. [Exxon Co. USA, Gillette, WY (United States); Knippers, M.L. [Nalco/Exxon Energy Chemicals L.P., Sugar Land, TX (United States)

    1996-02-01

    Both mechanical and chemical treatments are used to clean waterflood-injection distribution systems whose efficiency has been reduced as a result of plugging material, such as iron sulfide (FeS) containing sludge. Most mechanical treatments rely on uniform-line diameter to be effective, while chemical treatments require good contact with the plugging material for efficient removal. This paper describes the design and operation of a new innovative application using chlorine dioxide (ClO{sub 2}) for the removal of FeS sludge from waterflood-injection distribution systems. The use of ClO{sub 2} for continuous treatment of injection brines will also be discussed. Exxon USA`s Hartzog Draw facility in Gillette, WY, was the site for the application described. A total of 4,500 bbl of ClO{sub 2} was pumped in three phases to clean 66 miles of the waterflood-distribution system. Results indicated that ClO{sub 2} was effective in cleaning the well guard screens, the injection lines, and the injection wells. The addition of excess ClO{sub 2} to the frac tanks used to collect the treatment fluids also reduced waste handling and disposal costs.

  2. The uptake of chlorine dioxide by type II polar stratospheric clouds

    Energy Technology Data Exchange (ETDEWEB)

    Brown, L.A. [Univ. of Colorado, Boulder, CO (United States); Graham, J.D.; Roberts, J.T. [Univ. of Minnesota, Minneapolis, MN (United States)

    1995-12-31

    We studied the uptake of chlorine dioxide by type II, ice, Polar Stratospheric Clouds with several experimental techniques. The surface coverage of OClO on amorphous ice was studied using a flow tube apparatus. These experiments determined an upper limit to the surface coverage of 2 x 10{sup 9} molec/cm{sup 2} for an OClO concentration of 6 x 10{sup 10} molec/cm{sup 3}. The first order desorption kinetics of OClO from single crystal. ice surfaces was measured in a UHV chamber using temperature programmed desorption. The activation energy for desorption is 23 kJ/mol with a preexponential of 2 x 10{sup 9} s{sup -1}. The sticking coefficient of OClO to amorphous and crystalline ice at 100 K is 0.8 and 0.6 respectively. Using the sticking coefficient and desorption kinetics, equilibrium surface coverages were calculated for OClO on type II PSCs.

  3. Factors affecting the formation of iodo-trihalomethanes during oxidation with chlorine dioxide.

    Science.gov (United States)

    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.

  4. Reactions of aquacobalamin and cob(II)alamin with chlorite and chlorine dioxide.

    Science.gov (United States)

    Dereven'kov, Ilia A; Shpagilev, Nikita I; Valkai, László; Salnikov, Denis S; Horváth, Attila K; Makarov, Sergei V

    2016-11-19

    Reactions of aquacobalamin (H2O-Cbl(III)) and its one-electron reduced form (cob(II)alamin, Cbl(II)) with chlorite (ClO2(-)) and chlorine dioxide (ClO 2(•) ) were studied by conventional and stopped-flow UV-Vis spectroscopies and matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS). ClO2(-) does not react with H2O-Cbl(III), but oxidizes Cbl(II) to H2O-Cbl(III) as a major product and corrin-modified species as minor products. The proposed mechanism of chlorite reduction involves formation of OCl(-) that modifies the corrin ring during the course of reaction with Cbl(II). H2O-Cbl(III) undergoes relatively slow destruction by ClO 2(•) via transient formation of oxygenated species, whereas reaction between Cbl(II) and ClO 2(•) proceeds extremely rapidly and leads to the oxidation of the Co(II)-center.

  5. Multistate vibronic interactions and nonadiabatic wave packet dynamics in the second photoelectron band of chlorine dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Mahapatra, Susanta; Ritschel, Thomas

    2003-04-15

    We report theoretical investigations on the second photoelectron band of chlorine dioxide molecule by ab initio quantum dynamical methods. This band exhibits a highly complex structure and represents a composite portrait of five excited energetically close-lying electronic states of ClO{sub 2}{sup +}. Much of this complexity is likely to be arising due to strong vibronic interactions among these electronic states - which we address and examine herein. The near equilibrium MRCI potential energy surfaces (PESs) of these five cationic states reported by Peterson and Werner [J. Chem. Phys. 99 (1993) 302] for the C{sub 2v} configuration, are extended for the C{sub s} geometry assuming a harmonic vibration along the asymmetric stretching mode. The strength of the vibronic coupling parameters of the Hamiltonian are calculated by ab initio CASSCF-MRCI method and conical intersections of the PESs are established. The diabatic Hamiltonian matrix is constructed within a linear vibronic coupling scheme and the resulting PESs are employed in the nuclear dynamical simulations, carried out with the aid of a time-dependent wave packet approach. Companion calculations are performed for transitions to the uncoupled electronic states in order to reveal explicitly the impact of the nonadiabatic coupling on the photoelectron dynamics. The theoretical findings are in good accord with the experimental observations. The femtosecond nonradiative decay dynamics of ClO{sub 2}{sup +} excited electronic states mediated by conical intersections is also examined and discussed.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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%.

  8. Turing pattern formation in the chlorine dioxide-iodine- malonic acid reaction-diffusion system

    Science.gov (United States)

    Setayeshgar, Sima

    The formation of localized structures in the chlorine dioxide-idodine-malonic acid (CDIMA) reaction-diffusion system is investigated numerically using a realistic model of this system. We analyze the one-dimensional patterns formed along the gradients imposed by boundary feeds, and study their linear stability to symmetry- breaking perturbations (the Turing instability) in the plane transverse to these gradients. We establish that an often-invoked simple local linear analysis which neglects longitudinal diffusion is inappropriate for predicting the linear stability of these patterns. Using a fully nonuniform analysis, we investigate the structure of the patterns formed along the gradients and their stability to transverse Turing pattern formation as a function of the values of two control parameters: the malonic acid feed concentration and the size of the reactor in the dimension along the gradients. The results from this investigation are compared with existing experimental results. We also verify that the two-variable reduction of the chemical model employed in the linear stability analysis is justified. Finally, we present numerical solution of the CDIMA system in two dimensions which is in qualitative agreement with experiments. This result also confirms our linear stability analysis, while demonstrating the feasibility of numerical exploration of realistic chemical models.

  9. Chlorine dioxide as a treatment for ballast water to control invasive species: shipboard testing.

    Science.gov (United States)

    Maranda, Lucie; Cox, Annie M; Campbell, Robert G; Smith, David C

    2013-10-15

    The efficacy of chlorine dioxide (ClO2) in eliminating organisms present in estuarine ballast water of a containership was determined under actual operating conditions by comparing the survival of planktonic communities present in waters of treated and control ballast tanks. Sampling was via ballast-tank hatches. The treatment (5 mg L(-1)ClO2 without pre-filtration) delivered by a prototype ClO2-generating system was generally effective against planktonic assemblages, although bacterial communities rebounded after a few days. Regardless of temperature, ClO2 was very effective against phytoplankton; the effect was immediate, without resurgence. Some zooplankters in the ≥ 50-μm fraction may survive the biocide, especially those able to find refuge within a protective coating (e.g., cysts, resting eggs, and shells) or in sediment. In order to boost efficacy, a pre-filtration step is recommended (now installed as standard equipment) to lower the intake of the ≥ 50-μm fraction and lessen the challenge posed by this size class.

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

    Science.gov (United States)

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

    2017-08-10

    Chlorine dioxide (ClO2) is a bleaching reagent used in paper industry. Two different types of pretreatment methods were investigated incorporating ClO2 as a secondary reagent: (a) alkaline followed by ClO2 treatment; (b) dilute-sulfuric acid followed ClO2 treatment. In these methods, ClO2 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 ClO2 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. ClO2 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.

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

    Science.gov (United States)

    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.

  12. Removal of pharmaceuticals in biologically treated wastewater by chlorine dioxide or peracetic acid.

    Science.gov (United States)

    Hey, G; Ledin, A; Jansen, J la Cour; Andersen, H R

    2012-01-01

    Removal of six active pharmaceutical ingredients in wastewater was investigated using chlorine dioxide (ClO2) or peracetic acid (PAA) as chemical oxidants. Four non-steroidal anti-inflammatory drugs (ibuprofen, naproxen, diclofenac and mefenamic acid) and two lipid-regulating agents (gemfibrozil and clofibric acid, a metabolite of clofibrate) were used as target substances at 40 microg/L initial concentration. Three different wastewaters types originating from two wastewater treatment plants (WWTPs) were used. One wastewater was collected after extended nitrogen removal in activated sludge, one after treatment with high-loaded activated sludge without nitrification, and one from the final effluent from the same plant where nitrogen removal was made in trickling filters for nitrification and moving-bed biofilm reactors for denitrification following the high-loaded plant. Of the six investigated compounds, only clofibric acid and ibuprofen were not removed when treated with ClO2 up to 20 mg/L. With increasing PAA dose up to 50 mg/L, significant removal of most of the pharmaceuticals was observed except for the wastewater with the highest chemical oxygen demand (COD). This indicates that chemical oxidation with ClO2 could be used for tertiary treatment at WWTPs for active pharmaceutical ingredients, whereas PAA was not sufficiently efficient.

  13. Application of Highly Purified Electrolyzed Chlorine Dioxide for Tilapia Fillet Disinfection

    Directory of Open Access Journals (Sweden)

    Chen-Hsing Yu

    2014-01-01

    Full Text Available 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.

  14. Effect of antecedent growth conditions on sensitivity of Escherichia coli to chlorine dioxide.

    Science.gov (United States)

    Berg, J D; Matin, A; Roberts, P V

    1982-01-01

    Bacterial resistance to inactivation by antibacterial agents that is induced by the growth environment was studied. Escherichia coli was grown in batch culture and in a chemostat, and the following parameters were varied: type of substrate, growth rate, temperature, and cell density during growth. Low doses (0.75 mg/liter) of chlorine dioxide were used to inactivate the cultures. The results demonstrated that populations grown under conditions that more closely approximated natural aquatic environments were more resistant than those grown under commonly employed batch culture conditions. In particular, bacteria grown at submaximal rates were more resistant than their counterparts grown at mumax. The most resistant populations encountered in this study were those grown at D values of 0.02 h-1 and 0.06 h-1 at 25 degrees C. Growth at 15 degrees C led to greater resistance than did growth at 37 degrees C. The conditions that produced relatively resistant phenotypes were much closer to those found in most natural environments than are the typical conditions of batch culture methods. The importance of major physiological changes that can be induced by the antecedent growth environment is discussed in light of the possible modes of action of several disinfectants. PMID:6756305

  15. Ordinary Toxicity of Chlorine Dioxide and By-products Chlorite and Chlorate in Water

    Institute of Scientific and Technical Information of China (English)

    王丽; 常爱敏; 黄君礼

    2003-01-01

    Acute toxicity and accumulated toxicity of chlorine dioxide (C1O2) and by-products chlorite ( C1O-2 ) and chlorate (C1O-3) in water acted on mice are studied by the method of Horn and accumulation coefficient.Subchronic toxicity of the mixture of C1O2 and C1O-2 and ClO-3 in water acted on rat is studied though feeding test for 90 days, including statistical analysis of variance on weight gaining, food utilization efficiency, index of blood and serum, liver (or kidney)to body weight ratio, and histopathological examination on liver and kidney. The results show that aqueous solution of C1O2, NaC1O2 and NaC1O3 (with the concentration of 276. 5 mg/L, 200 mg/L and 200 mg/L respectively) and the mixed aqueous solution of C1O2 with the concentration of 553 mg/L are actually non poisonous, and non-cumulative aqueous solution as well.

  16. In Situ Generation of Chlorine Dioxide for Surface Decontamination of Produce.

    Science.gov (United States)

    Hwang, Cheng-An; Huang, Lihan; Wu, Vivian Chi-Hua

    2017-04-01

    Fresh fruits and vegetables are frequently contaminated with bacterial pathogens and implicated in foodborne illnesses. The objective of this study was to develop a unique surface decontamination method for produce using sodium chlorite and an acid in a sequential treatment. The surfaces of cantaloupe rinds, peels of cucumbers, stem scars of grape tomatoes, and leaves of baby spinach were inoculated with Salmonella or Listeria monocytogenes at 5 to 6 log CFU/g, submerged in 1.6 to 4% sodium chlorite solutions for 10 or 30 min, dried for 20 min, and then soaked in 6 mM hydrogen chloride (HCl) for 10 or 30 min and dried for 20 min. Control samples were treated with deionized water, sodium chlorite, HCl, or a premixed solution of sodium chlorite and HCl for comparison. The control treatments reduced the levels of both pathogens on the samples by only 0.3 to 2.9 log CFU/g, whereas the sequential treatment caused significantly higher reductions (P < 0.05) of 5.1 to 5.6 log CFU/g, effectively eliminating the inoculated pathogens. The more effective decontamination resulting from the sequential treatment was attributed to the in situ formation of chlorine dioxide within the plant tissues under the surface by the reaction between sodium chlorite absorbed by the produce and HCl. These results suggest that the sequential use of sodium chlorite and acid is a potentially effective treatment for elimination of foodborne pathogens on produce.

  17. Oxidation of diclofenac with chlorine dioxide in aquatic environments: influences of different nitrogenous species.

    Science.gov (United States)

    Wang, Yingling; Liu, Haijin; Liu, Guoguang; Xie, Youhai; Ni, Tianjun

    2015-06-01

    The oxidation of diclofenac (DCF), a non-steroidal anti-inflammatory drug and emerging water pollutant, with chlorine dioxide was investigated under simulated water disinfection conditions. The reaction kinetics as functions of the initial concentrations of DCF, different nitrogenous species, and different pE values were experimentally determined. The results demonstrated that DCF reacted rapidly with ClO2, where more than 75 % of DCF (≤3.00 μM) was removed by 18.94 μM ClO2 within 60 s. All of the reactions followed pseudo first-order kinetics with respect to DCF, and the rate constant, k obs, exhibited a significant decrease from 4.21 × 10(-2) to 8.09 × 10(-3) s(-1), as the initial DCF concentration was increased from 1.00 to 5.00 μM. Furthermore, the degradation kinetics of DCF was clearly dependent on nitrogen-containing ion concentrations in the reaction solution. Ammonium and nitrite ions inhibited the DCF degradation by ClO2, whereas nitrate ion clearly initiated its promotion. In contrast, the inhibitory effect of NO2 (-) was more robust than that of NH4 (+). When the values of pE were gradually increased, the transformation of NH4 (+) to NO2 (-), and subsequently to NO3 (-), would occur, the rate constants were initially decreased, and then increased. When NH4 (+) and NO2 (-) coexisted, the inhibitory effect on the DCF degradation was less than the sum of the partial inhibitory effect. However, when NO2 (-) and NO3 (-) coexisted, the actual inhibition rate was greater than the theoretical estimate. These results indicated that the interaction of NH4 (+) and NO2 (-) was antagonistic, while the coexistence of NO2 (-) and NO3 (-) was observed to have a synergistic effect in aqueous environments.

  18. Sanitizing radish seeds by simultaneous treatments with gaseous chlorine dioxide, high relative humidity, and mild heat.

    Science.gov (United States)

    Bang, Jihyun; Choi, Moonhak; Son, Hyeri; Beuchat, Larry R; Kim, Yoonsook; Kim, Hoikyung; Ryu, Jee-Hoon

    2016-11-21

    Sanitizing radish seeds intended for edible sprout production was achieved by applying simultaneous treatments with gaseous chlorine dioxide (ClO2), high relative humidity (RH, 100%), and mild heat (55°C). Gaseous ClO2 was produced from aqueous ClO2 (0.66ml) by mixing sulfuric acid (5% w/v) with sodium chlorite (10 mg/mL) in a sealed container (1.8L). Greater amounts of gaseous ClO2 were measured at 23% RH (144ppm after 6h) than at 100% RH (66ppm after 6h); however, the lethal activity of gaseous ClO2 against naturally occurring mesophilic aerobic bacteria (MAB) on radish seeds was significantly enhanced at 100% RH. For example, when exposed to gaseous ClO2 at 23% RH, the number of MAB on radish seeds decreased from 3.7logCFU/g to 2.6logCFU/g after 6h. However, when exposed to gaseous ClO2 at 100% RH for 6h, the MAB population decreased to 0.7logCFU/g after 6h. Gaseous ClO2 was produced in higher amounts at 55°C than at 25°C, but decreased more rapidly over time at 55°C than at 25°C. The lethal activity of gaseous ClO2 against MAB on radish seeds was greater at 55°C than at 25°C. When radish seeds were treated with gaseous ClO2 (peak concentration: 195ppm) at 100% RH and 55°C, MAB were reduced to populations below the detectable level (0.05) decreased after treatment for 6h. The information reported here will be useful when developing decontamination strategies for producing microbiologically safe radish seed sprouts.

  19. Inactivation of Airborne Bacteria and Viruses Using Extremely Low Concentrations of Chlorine Dioxide Gas.

    Science.gov (United States)

    Ogata, Norio; Sakasegawa, Miyusse; Miura, Takanori; Shibata, Takashi; Takigawa, Yasuhiro; Taura, Kouichi; Taguchi, Kazuhiko; Matsubara, Kazuki; Nakahara, Kouichi; Kato, Daisuke; Sogawa, Koushirou; Oka, Hiroshi

    2016-01-01

    Infectious airborne microbes, including many pathological microbes that cause respiratory infections, are commonly found in medical facilities and constitute a serious threat to human health. Thus, an effective method for reducing the number of microbes floating in the air will aid in the minimization of the incidence of respiratory infectious diseases. Here, we demonstrate that chlorine dioxide (ClO2) gas at extremely low concentrations, which has no detrimental effects on human health, elicits a strong effect to inactivate bacteria and viruses and significantly reduces the number of viable airborne microbes in a hospital operating room. In one set of experiments, a suspension of Staphylococcus aureus, bacteriophage MS2, and bacteriophage ΦX174 were released into an exposure chamber. When ClO2 gas at 0.01 or 0.02 parts per million (ppm, volume/volume) was present in the chamber, the numbers of surviving microbes in the air were markedly reduced after 120 min. The reductions were markedly greater than the natural reductions of the microbes in the chamber. In another experiment, the numbers of viable airborne bacteria in the operating room of a hospital collected over a 24-hour period in the presence or absence of 0.03 ppm ClO2 gas were found to be 10.9 ± 6.7 and 66.8 ± 31.2 colony-forming units/m3 (n = 9, p < 0.001), respectively. Taken together, we conclude that ClO2 gas at extremely low concentrations (≤0.03 ppm) can reduce the number of viable microbes floating in the air in a room. These results strongly support the potential use of ClO2 gas at a non-toxic level to reduce infections caused by the inhalation of pathogenic microbes in nursing homes and medical facilities.

  20. Antimicrobial activity of controlled-release chlorine dioxide gas on fresh blueberries.

    Science.gov (United States)

    Sun, Xiuxiu; Bai, Jinhe; Ference, Christopher; Wang, Zhe; Zhang, Yifan; Narciso, Jan; Zhou, Kequan

    2014-07-01

    The effect of chlorine dioxide (ClO2) gas on the safety and quality of blueberries was studied. In vitro studies revealed that both ClO2 gas fumigation and ClO2 direct contact in water killed food pathogen bacterium Escherichia coli and fruit decay pathogen fungus Colletotrichum acutatum. In vivo studies were conducted using noninoculated berries and berries inoculated with postharvest decay and foodborne pathogens. Berries were inoculated with either E. coli (5.2 log CFU/g) or C. acutatum (3.9 log CFU/g). Inoculated fruit were dried for 2 h at room temperature in a climate-controlled laboratory and packed in perforated commercial clamshells, with or without ClO2 pads, and stored at 10°C for up to 9 days. The effects of ClO2 on microbial populations and fruit firmness were monitored during storage. In the inoculation experiment, treatment with ClO2 reduced populations of E. coli and C. acutatum by 2.2 to 3.3 and 1.3 to 2.0 log CFU/g, respectively. For the noninoculated blueberries, the initial total aerobic bacteria count and the yeast and mold count were 4.2 and 4.1 log CFU/g, respectively. ClO2 treatment reduced total aerobic bacteria count and yeast and mold count by 1.5 to 1.8 and 1.3 to 1.7 log CFU/g, respectively. The firmness of both inoculated and noninoculated blueberries was maintained by ClO2 treatment. Thus, controlled-release ClO2 gas fumigation technology shows promise as an effective and practical antimicrobial agent in commercial clamshell packaging of blueberry and other fruits.

  1. A study of the properties of chlorine dioxide gas as a fumigant.

    Science.gov (United States)

    Shirasaki, Yasufumi; Matsuura, Ayumi; Uekusa, Masashi; Ito, Yoshihiro; Hayashi, Toshiaki

    2016-07-29

    Chlorine dioxide (ClO2) is a strong oxidant that possesses an antimicrobial activity. We demonstrated here that ClO2 gas is easily generated by mixing 3.35% sodium chlorite solution (Purogene) and 85% phosphoric acid at a 10:1 volume ratio without using an expensive machine. In a test room (87 m(3)), experiments were carried out using various amounts of sodium chlorite solution (0.25 ml/m(3) to 20.0 ml/m(3)). The gas concentration increased in a sodium chlorite volume-dependent manner and reached peak values of from 0.8 ppm to 40.8 ppm at 2 h-3 h, and then gradually decreased. No differences in gas concentrations were observed between 0.1 and 2.5 m above the floor, indicating that the gas was evenly distributed. Under high-humidity (approximately 80% relative humidity), colony formation of both Staphylococcus aureus and Escherichia coli was completely inhibited by ClO2 gas exposure at 1.0 ml/m(3) sodium chlorite solution (mean maximal concentration of 3.0 ppm). Exposure at 4.0 ml/m(3) sodium chlorite solution (mean maximal concentration of 10.6 ppm) achieved complete inactivation of Bacillus atrophaeus spores. In contrast, without humidification, the efficacy of ClO2 gas was apparently attenuated, suggesting that the atmospheric moisture is indispensable. Delicate electronic devices (computer, camera, etc.) operated normally, even after being subjected to more than 20 times of fumigation. Considering that our method for gas generation is simple, reproducible, and highly effective at decontaminating microbes, our approach is expected to serve as an inexpensive alternative method for cleaning and disinfecting animal facilities.

  2. Disinfection of herbal spa pool using combined chlorine dioxide and sodium hypochlorite treatment.

    Science.gov (United States)

    Hsu, Ching-Shan; Huang, Da-Ji

    2015-02-01

    The presence of pathogenic microorganisms in public spa pools poses a serious threat to human health. The problem is particularly acute in herbal spas, in which the herbs and microorganisms may interact and produce undesirable consequences. Accordingly, the present study investigated the effectiveness of a combined disinfectant containing chlorine dioxide and sodium hypochlorite in improving the water quality of a public herbal spa in Taiwan. Water samples were collected from the spa pool and laboratory tests were then performed to measure the variation over time of the microorganism content (total CFU and total coliforms) and residual disinfectant content given a single disinfection mode (SDM) with disinfectant concentrations of 5.2 × 10, 6.29 × 10, 7.4 × 10, and 11.4 × 10(-5) N, respectively. Utilizing the experience gained from the laboratory tests, a further series of on-site investigations was performed using three different disinfection modes, namely SDM, 3DM (once every 3 h disinfection mode), and 2DM (once every 2 h disinfection mode). The laboratory results showed that for all four disinfectant concentrations, the CFU concentration reduced for the first 6 h following SDM treatment, but then increased. Moreover, the ANOVA results showed that the sample treated with the highest disinfectant concentration (11.4 × 10(-5) N) exhibited the lowest rate of increase in the CFU concentration. In addition, the on-site test results showed that 3DM and 2DM treatments with disinfectant concentrations in excess of 9.3 × 10 and 5.5 × 10(-5) N, respectively, provided an effective reduction in the total CFU concentration. In conclusion, the experimental results presented in this study provide a useful source of reference for spa businesses seeking to improve the water quality of their spa pools.

  3. Development of an online biosensor for in situ monitoring of chlorine dioxide gas disinfection efficacy

    Energy Technology Data Exchange (ETDEWEB)

    Del Busto-Ramos, M.; Budzik, M.; Corvalan, C.; Morgan, M.; Nivens, D.; Applegate, B. [Purdue Univ., West Lafayette, IN (United States). Dept. of Food Science; Turco, R. [Purdue Univ., West Lafayette, IN (United States). Dept. of Agronomy

    2008-03-15

    A prototype bioluminescence-based biosensor was designed and constructed to evaluate the antimicrobial efficacy of chlorine dioxide (ClO{sub 2}) gas under various treatment conditions. The biosensor consisted of a bioluminescent bioreporter (Pseudomonas fluorescens 5RL), an optical transducer (photomultiplier tube), and a light-tight chamber housing, the bioreporter and the transducer. The bioluminescent recombinant P. fluorescens 5RL in the biosensor allowed for online monitoring of bioluminescence during ClO{sub 2} gas disinfection. Experiments were performed to evaluate the effects of the two key physical parameters associated with ClO{sub 2} disinfection: relative humidity (40, 60, 80%) and ClO{sub 2} gas concentration (0.5, 1.0, 1.6, 2.1 mg/l) on the bioreporter. Results showed that increasing concentrations of ClO{sub 2} gas corresponded to a faster decrease in luminescence. The rates of luminescence decrease from P. fluorescens 5RL, and the log reduction time (LRT, time required to obtain 1-log reduction in luminescence) were calculated for each treatment tested. The LRT values of luminescence were 103, 78, 53, and 35 s for 0.5, 1.0, 1.6, and 2.1 mg/l of ClO{sub 2} gas treatment, respectively, at 78% relative humidity. The gas concentration which caused a tenfold change in LRT (z value) for luminescence of P. fluorescens 5RL was 3.4 mg/l of ClO{sub 2}. The prototype biosensor showed potential for many applications, such as monitoring real-time microbial inactivation and understanding parameters that influence the efficacy of gaseous decontamination procedures. (orig.)

  4. Decontamination of Bacillus subtilis var. niger spores on selected surfaces by chlorine dioxide gas*

    Science.gov (United States)

    Li, Yan-ju; Zhu, Neng; Jia, Hai-quan; Wu, Jin-hui; Yi, Ying; Qi, Jian-cheng

    2012-01-01

    Objective: Chlorine dioxide (CD) gas has been used as a fumigant in the disinfection of biosafety laboratories. In this study, some experiments were conducted to assess the inactivation of spores inoculated on six materials [stainless steel (SS), painted steel (PS), polyvinyl chlorid (PVC), polyurethane (PU), glass (GS), and cotton cloth (CC)] by CD gas. The main aims of the study were to determine the sporicidal efficacy of CD gas and the effect of prehumidification before decontamination on sporicidal efficacy. Methods: Material coupons (1.2 cm diameter of SS, PS, and PU; 1.0 cm×1.0 cm for PVC, GS, and CC) were contaminated with 10 μl of Bacillus subtilis var. niger (ATCC 9372) spore suspension in mixed organic burden and then dried in a biosafety cabinet for 12 h. The spores were recovered by soaking the coupons in 5 ml of extraction liquid for 1 h and then vortexing the liquid for 1 min. Results: The log reductions in spore numbers on inoculated test materials exposed to CD gas [0.080% (volume ratio, v/v) for 3 h] were in the range of from 1.80 to 6.64. Statistically significant differences were found in decontamination efficacies on test material coupons of SS, PS, PU, and CC between with and without a 1-h prehumidification treatment. With the extraction method, there were no statistically significant differences in the recovery ratios between the porous and non-porous materials. Conclusions: The results reported from this study could provide information for developing decontamination technology based on CD gas for targeting surface microbial contamination. PMID:22467366

  5. A pilot study on using chlorine dioxide gas for disinfection of gastrointestinal endoscopes* #

    Science.gov (United States)

    Yi, Ying; Hao, Li-mei; Ma, Shu-ren; Wu, Jin-hui; Wang, Tao; Lin, Song; Zhang, Zong-xing; Qi, Jian-cheng

    2016-01-01

    Objectives: This pilot study of employing chlorine dioxide (CD) gas to disinfect gastrointestinal endoscopes was conducted to meet the expectations of many endoscopy units in China for a high-efficiency and low-cost disinfectant. Methods: An experimental prototype with an active circulation mode was designed to use CD gas to disinfect gastrointestinal endoscopes. One type of testing device composed of polytetrafluoroethylene (PTFE) tubes (2 m long, inner diameter 1 mm) and bacterial carrier containers was used to simulate the channel of the endoscope. PTFE bacterial carriers inoculated with Bacillus atrophaeus with or without organic burden were used to evaluate the sporicidal activity of CD gas. Factors including exposure dosage, relative humidity (RH), and flow rate (FR) influencing the disinfection effect of CD gas were investigated. Moreover, an autoptic disinfecting test on eight real gastrointestinal endoscopes after clinical use was performed using the experimental prototype. Results: RH, exposure dosage, organic burden, and the FR through the channel significantly (P<0.05) affected the disinfection efficacy of CD gas for a long and narrow lumen. The log reduction increased as FR decreased. Treatment with 4 mg/L CD gas for 30 min at 0.8 L/min FR and 75% RH, resulted in complete inactivation of spores. Furthermore, all eight endoscopes with a maximum colony-forming unit of 915 were completely disinfected. The cost was only 3 CNY (0.46 USD) for each endoscope. Conclusions: The methods and results reported in this study could provide a basis for further studies on using CD gas for the disinfection of endoscopes. PMID:27381729

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

    Science.gov (United States)

    Ray, Soumi; Jin, Tony; Fan, Xuetong; Liu, Linshu; Yam, Kit L

    2013-02-01

    A feasibility study was conducted to develop chlorine dioxide (ClO(2) )-releasing packaging films for decontaminating fresh produce. Sodium chlorite and citric acid powder were incorporated into polylactic acid (PLA) polymer. Films made with different amounts of PLA (100 and 300 mg), percentages of reactant (5% to 60%), and ratios of sodium chlorite to citric acid (1:2 or 2:1) were prepared using a solvent casting method. The release of ClO(2) from the resultant films was activated by moisture. Increase of reactants in the films produced more ClO(2) while higher PLA content in the films resulted in less release of ClO(2) . The ratio of sodium chlorite to citric acid and activation temperature (22 °C compared with 10 °C) did not affect the ClO(2) release from the films. Antimicrobial efficacy of ClO(2) released from the films was evaluated using grape tomato as a model food. The results indicate that the films were activated by moisture from tomatoes in the package and the released ClO(2) reduced Salmonella spp. and Escherichia coli O157:H7 inoculated on the tomatoes to undetectable levels (tomato), achieving more than 3 log reduction. The film-treated tomatoes did not show significant changes in color and texture as compared to controls during storage at 10 °C for 21 d. This study demonstrated the technical feasibility for development of gaseous ClO(2) -releasing packaging system to enhance microbial safety and extend shelf life of fresh produce.

  7. Disinfection of indoor air microorganisms in stack room of university library using gaseous chlorine dioxide.

    Science.gov (United States)

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

    2015-02-01

    As with all indoor public spaces in Taiwan, the stack rooms in public libraries should meet the air quality guidelines laid down by the Taiwan Environmental Protection Administration. Accordingly, utilizing a university library in Taiwan for experimental purposes, this study investigates the efficiency of gaseous chlorine dioxide (ClO2) as a disinfection agent when applied using three different treatment modes, namely a single-daily disinfection mode (SIM), a twice-daily disinfection mode (TWM), and a triple-daily disinfection mode (TRM). For each treatment mode, the ClO2 is applied using an ultrasonic aerosol device and is performed both under natural lighting conditions and under artificial lighting conditions. The indoor air quality is evaluated before and after each treatment session by measuring the bioaerosol levels of bacteria and fungi. The results show that for all three disinfection modes, the application of ClO2 reduces the indoor bacteria and fungi concentrations to levels lower than those specified by the Taiwan EPA (i.e., bacteria disinfection process is performed. For each disinfection mode, a better disinfection efficiency is obtained under natural lighting conditions since ClO2 readily decomposes under strong luminance levels. Among the three treatment modes, the disinfection efficiencies of the TWM and TRM modes are very similar under natural lighting conditions and are significantly better than that of the SIM mode. Thus, overall, the results suggest that the TWM treatment protocol represents the most cost-effective and efficient method for meeting the indoor air quality requirements of the Taiwan EPA.

  8. Efficacy of FIT produce wash and chlorine dioxide on pathogen control in fresh potatoes.

    Science.gov (United States)

    Park, E J; Gray, P M; Oh, S W; Kronenberg, J; Kang, D H

    2008-08-01

    A commercial fresh pack potato operation was used as a model to evaluate FIT fruit and vegetable wash effectiveness in reducing levels of microorganisms on potatoes and in flume water. Fresh potatoes were washed in flume water with or without FIT, or treated with a spray bar utilizing either FIT, 9 ppm chlorine dioxide (CIO2), or a water control. Both flume treatments were also evaluated for APC and Gram-negatives. There were no significant differences in reduction of these microorganisms on treated or control potatoes. However, levels of Gram-negative bacteria in FIT-amended flume water were reduced by 5.95 log CFU/g, and the APC was reduced by 1.43 log CFU/g. To validate plant trial findings, this test was repeated using solutions of sterile potato flume water from the fresh pack operation, containing a typical level of dissolved and suspended solids. Treatment solutions prepared with flume water or deionized water containing FIT, 9 ppm CIO2, or a water control were inoculated with E. coli O157:H7, Salmonella Typhimurium, or Pectobacterium carotovorumssp. carotovorum. FIT and ClO2 prepared with deionized water reduced levels of microorganisms by >6.1 to 6.6 log CFU/g to below the detection limit. FIT prepared with flume water reduced levels of all organisms by >6.0 to 6.4 log CFU/g to below the detection limit, whereas ClO2 prepared from flume water reduced bacterial levels of all organisms by only 0.7 to 1.4 log CFU/g. Neither FIT nor ClO2 was particularly efficacious against E. coli O157:H7, S. Typhimurium, APC, yeasts, or molds on potato surfaces.

  9. Disinfection of Penicillium-infected Wheat Seed by Gaseous Chlorine Dioxide

    Directory of Open Access Journals (Sweden)

    Young-ah Jeon

    2015-06-01

    Full Text Available Seeds of wheat (Triticum aestivum L. cv. Olgeurumil were infected with Penicillium sp. at mean infection rate of 83%. Penicillium sp. was detected in endosperm with bran but not in embryo. Gaseous chlorine dioxide (ClO2 effectively inhibited growth of Penicillium sp. at concentration of 5 to 20 mg/ml. As treatment duration was extended from 1 to 3 h, growth of Penicillium sp. was completely suppressed even at 10 mg/ml. There was no significant reduction in the incidence of Penicillium sp. at 30% relative humidity (RH. However, the incidence of Penicillium sp. was 27.7% at 50% RH, further those were 3.5% and 0.2% at 70% and 80% RH, respectively. Seed germination was not affected by ClO2 treatment at all the RH conditions. Water-soaked seeds (30% seed moisture content showed a drastic reduction in the incidence of Penicillium sp. when treated at more than 10 mg/ml of ClO2. The incidences of Penicillium sp. were 3.3, 1.8 and 1.2% at 10, 15 and 20 mg/ml, respectively. The incidence of Penicillium sp. in dry seeds with 9.7% seed moisture content did not reduce when treated with 5 and 10 mg/ml at 50% RH although it tended to decrease as ClO2 concentration increased to 20 mg/ml. Seed germination was not affected by ClO2 treatment at the tested concentrations. These results indicated that gaseous ClO2 was effective disinfectant to wheat seeds infected with Penicillium sp. and that the effectiveness of ClO2 strongly increased when moisture content around or inside of the seed was increased.

  10. Chlorine dioxide oxidation of Escherichia coli in water - A study of the disinfection kinetics and mechanism.

    Science.gov (United States)

    Ofori, Isaac; Maddila, Suresh; Lin, Johnson; Jonnalagadda, Sreekantha B

    2017-06-07

    This study investigated the kinetics and mechanism of chlorine dioxide (ClO2) inactivation of a Gram-negative bacteria Escherichia coli (ATCC 35218) in oxidant demand free (ODF) water in detail as a function of disinfectant concentration (0.5-5.0 mg/L), water pH (6.5-8.5), temperature variations (4-37°C) and bacterial density (10(5)-10(7) cfu/mL). The effects of ClO2 on bacterial cell morphology, outer membrane permeability, cytoplasmic membrane disruption and intracellular enzymatic activity were also studied to elucidate the mechanism of action on the cells. Increasing temperature and disinfectant concentration were proportional to the rate of cell killing, but efficacy was found to be significantly subdued at 0.5 mg/L and less dependent on the bacterial density. The bactericidal efficiency was higher at alkaline pH of 8 or above as compared to neutral and slightly acidic pH of 7 and 6.5 respectively. The disinfection kinetic curves followed a biphasic pattern of rapid inactivation within the initial 2 min which were followed by a tailing even in the presence of residual biocide. The curves were adequately described by the Cavg Hom model. Transmission Electron Microscopy images of the bacteria cells exposed to lethal concentrations of ClO2 indicated very little observable morphological damage to the outer membranes of the cells. ClO2 however was found to increase the permeability of the outer and cytoplasmic membranes leading to the leakage of membrane components such as 260 nm absorbing materials and inhibiting the activity of the intracellular enzyme β-D-galactosidase. It is suggested that the disruption of the cytoplasmic membrane and subsequent efflux of intracellular components result in the inactivation of the Gram-negative bacteria.

  11. A pilot study on using chlorine dioxide gas for disinfection of gastrointestinal endoscopes.

    Science.gov (United States)

    Yi, Ying; Hao, Li-Mei; Ma, Shu-Ren; Wu, Jin-Hui; Wang, Tao; Lin, Song; Zhang, Zong-Xing; Qi, Jian-Cheng

    2016-07-01

    This pilot study of employing chlorine dioxide (CD) gas to disinfect gastrointestinal endoscopes was conducted to meet the expectations of many endoscopy units in China for a high-efficiency and low-cost disinfectant. An experimental prototype with an active circulation mode was designed to use CD gas to disinfect gastrointestinal endoscopes. One type of testing device composed of polytetrafluoroethylene (PTFE) tubes (2 m long, inner diameter 1 mm) and bacterial carrier containers was used to simulate the channel of the endoscope. PTFE bacterial carriers inoculated with Bacillus atrophaeus with or without organic burden were used to evaluate the sporicidal activity of CD gas. Factors including exposure dosage, relative humidity (RH), and flow rate (FR) influencing the disinfection effect of CD gas were investigated. Moreover, an autoptic disinfecting test on eight real gastrointestinal endoscopes after clinical use was performed using the experimental prototype. RH, exposure dosage, organic burden, and the FR through the channel significantly (P<0.05) affected the disinfection efficacy of CD gas for a long and narrow lumen. The log reduction increased as FR decreased. Treatment with 4 mg/L CD gas for 30 min at 0.8 L/min FR and 75% RH, resulted in complete inactivation of spores. Furthermore, all eight endoscopes with a maximum colony-forming unit of 915 were completely disinfected. The cost was only 3 CNY (0.46 USD) for each endoscope. The methods and results reported in this study could provide a basis for further studies on using CD gas for the disinfection of endoscopes.

  12. Decontamination of Bacillus subtilis var.niger spores on selected surfaces by chlorine dioxide gas

    Institute of Scientific and Technical Information of China (English)

    Yan-ju LI; Neng ZHU; Hai-quan JIA; Jin-hui WU; Ying YI; Jian-cheng QI

    2012-01-01

    Objective:Chlorine dioxide (CD) gas has been used as a fumigant in the disinfection of biosafety laboratories.In this study,some experiments were conducted to assess the inactivation of spores inoculated on six materials [stainless steel (SS),painted steel (PS),polyvinyl chlorid (PVC),polyurethane (PU),glass (GS),and cotton cloth (CC)] by CD gas.The main aims of the study were to determine the sporicidal efficacy of CD gas and the effect of prehumidification before decontamination on sporicidal efficacy.Methods:Material coupons (1.2 cm diameter of SS,PS,and PU; 1.0 cm×1.0 cm for PVC,GS,and CC) were contaminated with 10 μl of Bacillus subtilis var.niger(ATCC 9372) spore suspension in mixed organic burden and then dried in a biosafety cabinet for 12 h.The spores were recovered by soaking the coupons in 5 ml of extraction liquid for 1 h and then vortexing the liquid for 1 min.Results:The log reductions in spore numbers on inoculated test materials exposed to CD gas [0.080% (volume ratio,v/v) for 3 h]were in the range of from 1.80 to 6.64.Statistically significant differences were found in decontamination efficacies on test material coupons of SS,PS,PU,and CC between with and without a 1-h prehumidification treatment.With the extraction method,there were no statistically significant differences in the recovery ratios between the porous and non-porous materials.Conclusions:The results reported from this study could provide information for developing decontamination technology based on CD gas for targeting surface microbial contamination.

  13. Epidemiological review on chlorine dioxide; Il biossido di cloro: efficacia e aspetti epidemiologici

    Energy Technology Data Exchange (ETDEWEB)

    Sansebastiano, G. [Parma Univ. (Italy). Fac. di Agraria; Zoni, R.; Mezzetta, S.

    1998-04-01

    The Hygiene Institute of the University of Parma carried out inactivation test on poliovirus l, Coxsachievirus B3 and Echovirus 7, using Chlorine dioxide at varying pH values and varying temperatures. The results high lightened the high virus killing potential of ClO{sub 2} and that this was more active under slightly more alkaline conditions and at temperatures higher than 20 C degrees. The literature relating to experimental and analytical epidemiological studies carried out on man were also surveyed so as to evaluate the toxic effects of ClO{sub 2} and ClO{sub 2}{sup -}. This survey found no evidence of any significant changes in hematologic parameters (red cells, hemoglobin, average-cell volume, average cell concentration) or in total cholesterol, HDL, apolipoprotein B, methaemoglobin and thyroid hormones. [Italiano] L`Istituto di Igiene dell`Universita` di Parma ha condotto test di inattivazione su Poliovirus l, Coxsakcievirus B3 ed Echovirus 7, usando biossido di cloro a diversi valori di pH e temperatura. i risultati hanno evidenziato l`elevato potere di inattivazione del ClO{sub 2} e che questo e` piu` attivo in condizioni lievemente alcaline ed a temperature superiori a 20 gradi C. E` stata rivista la letteratura relativa a studi di epidemiologia analitica e sperimentale condotti sull`uomo per valutare gli effetti tossici di ClO{sub 2} e ClO{sub 2}{sup -}. Tali controlli non hanno evidenziato alcun cambiamento nei parametri ematologici (globuli rossi, emoglobina, volume cellulare medio, concentrazione cellulare media) come anche nel colesterolo totale, HDL, apolipoproteina B, metaemoglobina ed ormoni tiroidei.

  14. Degradation of anthracene, pyrene and benzo[a]anthracene in aqueous solution by chlorine dioxide

    Institute of Scientific and Technical Information of China (English)

    LIU Jinquan; HUANG Junli; SU Liqiang; CAO Xiangyu; JI Ying

    2006-01-01

    Polycyclic aromatic hydrocarbons (PAHs) constitute an important group of micropollutants, which are known to be mutagenic, carcinogenic and/or co-carcinogenic and relatively persistent in the environment. The effects of chlorine dioxide (ClO2) on the degradation of anthracene (ANTH), pyrene (PYR) and benzo[a]anthracene (BaA) in aqueous solution were investigated using high performance liquid chromatography (HPLC). In preliminary experiments, it was observed that ClO2 could remove these three PAHs effectively within a short time. Several factors including reaction time, the concentration of ClO2 and pH of the reaction mixture influencing the degradation ratio of PAHs have been studied by batch experiments. The results showed that the degradation ratio of PAHs was affected by reaction time and the concentration of ClO2 instead of pH. The degradation ratio of ANTH, PYR and BaA could reach their maximum as approximately 99.0%, 67.5% and 89.5%, respectively, under the condition as follows: reaction time 30, 60 and 120 min, the concentration of ClO2 0.1, 0.4 and 0.5 mmol·L-1, and pH 7.2. ANTH was selected as the representative to study the reaction mechanism with ClO2. The oxidation products formed in the reaction of ANTH with ClO2 were tentatively identified by gas chromatography-mass spectrometry (GC-MS), and the results showed that the main product was 9, 10-anthraquinone, which could be biodegraded more easily and quickly than ANTH. Through analyzing the reaction properties of ANTH and ClO2, the possible pathway for the ANTH-ClO2 reaction was proposed based on the theory of single electron transfer (SET).

  15. Shelf-life extension of minimally processed carrots by gaseous chlorine dioxide.

    Science.gov (United States)

    Gómez-López, V M; Devlieghere, F; Ragaert, P; Debevere, J

    2007-05-10

    Chlorine dioxide (ClO(2)) gas is a strong oxidizing and sanitizing agent that has a broad and high biocidal effectiveness and big penetration ability; its efficacy to prolong the shelf-life of a minimally processed (MP) vegetable, grated carrots (Daucus carota L.), was tested in this study. Carrots were sorted, their ends removed, hand peeled, cut, washed, spin dried and separated in 2 portions, one to be treated with ClO(2) gas and the other to remain untreated for comparisons. MP carrots were decontaminated in a cabinet at 91% relative humidity and 28 degrees C for up to 6 min, including 30 s of ClO(2) injection to the cabinet, then stored under equilibrium modified atmosphere (4.5% O(2), 8.9% CO(2), 86.6% N(2)) at 7 degrees C for shelf-life studies. ClO(2) concentration in the cabinet rose to 1.33 mg/l after 30 s of treatment, and then fell to nil before 6 min. The shelf-life study included: O(2) and CO(2) headspace concentrations, microbiological quality (mesophilic aerobic bacteria, psychrotrophs, lactic acid bacteria, and yeasts), sensory quality (odour, flavour, texture, overall visual quality, and white blushing), and pH. ClO(2) did not affect respiration rate of MP carrots significantly (alphacarrots was not impaired significantly (alphaview. The shelf-life extension was limited to one day due to the restricted effect of the ClO(2) treatment on yeast counts. Nevertheless, ClO(2) seems to be a promising alternative to prolong the shelf-life of grated carrots.

  16. Comparative toxicities of oxygen, ozone, chlorine dioxide, and chlorine bleaching filtrates - microtox toxicities of raw and processed filtrates

    Energy Technology Data Exchange (ETDEWEB)

    Ard, T.A.; McDonough, T.J.

    1995-12-31

    It has claimed that effluents from the bleaching of kraft pulp with chlorine and its compounds have deleterious effects on the aquatic environment. It has been further suggested that bleaching without the use of chlorine or its compounds will produce innocuous effluents. To obtain information on the validity of these claims, we have conducted a laboratory study of the toxicity of filtrates from chlorine-based and nonchlorine bleaching processes. We have also examined two related issues. The first is whether any toxicants generated during bleaching are rendered harmless (by neutralization, storage, and biological treatment) before being discharged to the environment. The second related issue is whether any toxicity observed in mill effluents actually originates in the bleaching process, as opposed to being due to raw material components or compounds formed during the pulping step that precedes bleaching. Several conclusions were drawn from this study. (1) There is a background level of toxicity which originates in the oxygen stage, process steps prior to bleaching, or in the wood raw material. It is decreased by neutralization and storage, but residual toxicity may still be detected after two weeks. (2) If the sum of the first and second stage toxicities is taken as an indicator of overall toxicity, the untreated filtrates may be ranked as follows: Control (Background) > D(EO) > Z(EO) > C(EO). However, these toxicities are of no importance in regard to environmental effects because of their ephemeral nature and the likelihood of their being reduced or eliminated prior to effluent discharge. Evidence for this statement is the ease with which all except the C(EO) were detoxified by neutralization and storage. (3) After neutralization and storage for two weeks at room temperature the ranking of toxicities becomes: C(EO) > D(EO) > Z(EO) > Background. The last three are similar in magnitude.

  17. Removal of NO from flue gas by aqueous chlorine-dioxide scrubbing solution in a lab-scale bubbling reactor

    Energy Technology Data Exchange (ETDEWEB)

    Deshwal, Bal Raj [Department of Chemistry, A.I.J.H.M. College, Rohtak 124001, Haryana (India); Jin, Dong Seop; Lee, Si Hyun; Moon, Seung Hyun [Korea Institute of Energy Research, Daejon 305 600 (Korea, Republic of); Jung, Jong Hyeon [Department of Environmental Engineering, Sorabol College, Kyungbuk - 780 711 (Korea, Republic of); Lee, Hyung Keun [Korea Institute of Energy Research, Daejon 305 600 (Korea, Republic of)], E-mail: hklee@kier.re.kr

    2008-02-11

    The present study attempts to clean up nitric oxide from the simulated flue gas using aqueous chlorine-dioxide solution in the bubbling reactor. Chlorine-dioxide is generated by chloride-chlorate process. Experiments are carried out to examine the effect of various operating variables like input NO concentration, presence of SO{sub 2}, pH of the solution and NaCl feeding rate on the NO{sub x} removal efficiency at 45 deg. C. Complete oxidation of nitric oxide into nitrogen dioxide occurred on passing sufficient ClO{sub 2} gas into the scrubbing solution. NO is finally converted into nitrate and ClO{sub 2} is reduced into chloride ions. A plausible reaction mechanism concerning NO{sub x} removal by ClO{sub 2} is suggested. DeNO{sub x} efficiency increased slightly with the increasing input NO concentration. The presence of SO{sub 2} improved the NO{sub 2} absorption but pH of solution showed marginal effect on NO{sub 2} absorption. NO{sub x} removal mechanism changed when medium of solution changed from acidic to alkaline. A constant NO{sub x} removal efficiency of about 60% has been achieved in the wide pH range of 3-11 under optimized conditions.

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

    Science.gov (United States)

    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.

  19. Comparative evaluation of 15% ethylenediamine tetra-acetic acid plus cetavlon and 5% chlorine dioxide in removal of smear layer: A scanning electron microscope study

    Directory of Open Access Journals (Sweden)

    Sandeep Singh

    2013-01-01

    Full Text Available Aims: The purpose of this study was to compare the efficacy of smear layer removal by 5% chlorine dioxide and 15% Ethylenediamine Tetra-Acetic Acid plus Cetavlon (EDTAC from the human root canal dentin. Materials >and Methods : Fifty single rooted human mandibular anterior teeth were divided into two groups of 20 teeth each and control group of 10 teeth. The root canals were prepared till F3 protaper and initially irrigated with 2% Sodium hypochlorite followed by 1 min irrigation with 15% EDTAC or 5% Chlorine dioxide respectively. The control group was irrigated with saline. The teeth were longitudinally split and observed under Scanning electron microscope SEM (×2000. Statistical Analysis Used: The statistical analysis was done using General Linear Mixed Model. Results : At the coronal thirds, no statistically significant difference was found between 15% EDTAC and 5% Chlorine dioxide in removing smear layer. In the middle and apical third region 15% EDTAC showed better smear layer removal ability than 5% Chlorine dioxide. Conclusion : Final irrigation with 15% EDTAC is superior to 5% chlorine dioxide in removing smear layer in the middle and apical third of radicular dentin.

  20. Comparative evaluation of 15% ethylenediamine tetra-acetic acid plus cetavlon and 5% chlorine dioxide in removal of smear layer: A scanning electron microscope study

    Science.gov (United States)

    Singh, Sandeep; Arora, Vimal; Majithia, Inderpal; Dhiman, Rakesh Kumar; Kumar, Dinesh; Ather, Amber

    2013-01-01

    Aims: The purpose of this study was to compare the efficacy of smear layer removal by 5% chlorine dioxide and 15% Ethylenediamine Tetra-Acetic Acid plus Cetavlon (EDTAC) from the human root canal dentin. Materials and Methods Fifty single rooted human mandibular anterior teeth were divided into two groups of 20 teeth each and control group of 10 teeth. The root canals were prepared till F3 protaper and initially irrigated with 2% Sodium hypochlorite followed by 1 min irrigation with 15% EDTAC or 5% Chlorine dioxide respectively. The control group was irrigated with saline. The teeth were longitudinally split and observed under Scanning electron microscope SEM (×2000). Statistical Analysis Used: The statistical analysis was done using General Linear Mixed Model. Results: At the coronal thirds, no statistically significant difference was found between 15% EDTAC and 5% Chlorine dioxide in removing smear layer. In the middle and apical third region 15% EDTAC showed better smear layer removal ability than 5% Chlorine dioxide. Conclusion: Final irrigation with 15% EDTAC is superior to 5% chlorine dioxide in removing smear layer in the middle and apical third of radicular dentin. PMID:23853455

  1. 二氧化氯在饮用水消毒工艺中的应用%Application of Chlorine Dioxide in Disinfect Drinking Water

    Institute of Scientific and Technical Information of China (English)

    方火明

    2012-01-01

    As a disinfectant for drinking water, chlorine dioxide was widely applied in drinking water treatment. The properties and disinfection mechanisms of chlorine dioxide were introduced. Application scope and advantages of chlorine dioxide in drinking water treatment were analyzed. The problems of chlorine dioxide as a disinfectant were also discussed. The result showed that chlorine dioxide as a new type of disinfectant in drinking water treatment had a wide application prospect.%二氧化氯作为饮用水消毒剂应用越来越广泛。介绍了二氧化氯的理化性质、消毒机理;分析了其在饮用水处理领域的应用范围和优缺点,讨论了二氧化氯作为水消毒剂时存在的问题。研究结果表明二氧化氯作为一种新型的消毒剂在饮用水处理中有广阔的应用前景。

  2. Formation Rule of Chlorine Dioxide Disinfection By-products%二氧化氯消毒副产物的生成规律研究

    Institute of Scientific and Technical Information of China (English)

    张盛军; 张大钰; 董燕; 王永芳

    2013-01-01

    According to chlorite excessive phenomenon in chlorine dioxide sterilization of drinking water, Xiaoqinghe River and Darning Lake water were selected to study the relationship between chlorine dioxide consumption and chlorite production in the disinfection process. The removal of COD by chlorine dioxide was assessed. The results showed that chlorite production was positively correlated with chlorine dioxide consumption, and had no direct relation with chlorine dioxide dosage and COD concentration in water.%针对二氧化氯在饮用水消毒过程中出现的副产物亚氯酸盐超标现象,以小清河水和大明湖水为处理对象,研究了在消毒过程中二氧化氯的消耗量与亚氯酸盐的产生量之间的关系,同时测定了二氧化氯对COD的去除情况.结果表明,副产物亚氯酸盐的产生量与二氧化氯的消耗量呈正相关关系,而与二氧化氯的投加量及水体中的COD浓度没有直接关系.

  3. Comparative evaluation of 15% ethylenediamine tetra-acetic acid plus cetavlon and 5% chlorine dioxide in removal of smear layer: A scanning electron microscope study.

    Science.gov (United States)

    Singh, Sandeep; Arora, Vimal; Majithia, Inderpal; Dhiman, Rakesh Kumar; Kumar, Dinesh; Ather, Amber

    2013-01-01

    The purpose of this study was to compare the efficacy of smear layer removal by 5% chlorine dioxide and 15% Ethylenediamine Tetra-Acetic Acid plus Cetavlon (EDTAC) from the human root canal dentin. Fifty single rooted human mandibular anterior teeth were divided into two groups of 20 teeth each and control group of 10 teeth. The root canals were prepared till F3 protaper and initially irrigated with 2% Sodium hypochlorite followed by 1 min irrigation with 15% EDTAC or 5% Chlorine dioxide respectively. The control group was irrigated with saline. The teeth were longitudinally split and observed under Scanning electron microscope SEM (×2000). The statistical analysis was done using General Linear Mixed Model. At the coronal thirds, no statistically significant difference was found between 15% EDTAC and 5% Chlorine dioxide in removing smear layer. In the middle and apical third region 15% EDTAC showed better smear layer removal ability than 5% Chlorine dioxide. Final irrigation with 15% EDTAC is superior to 5% chlorine dioxide in removing smear layer in the middle and apical third of radicular dentin.

  4. Oxidative transformation of micropollutants during municipal wastewater treatment: comparison of kinetic aspects of selective (chlorine, chlorine dioxide, ferrate VI, and ozone) and non-selective oxidants (hydroxyl radical).

    Science.gov (United States)

    Lee, Yunho; von Gunten, Urs

    2010-01-01

    Chemical oxidation processes have been widely applied to water treatment and may serve as a tool to minimize the release of micropollutants (e.g. pharmaceuticals and endocrine disruptors) from municipal wastewater effluents into the aquatic environment. The potential of several oxidants for the transformation of selected micropollutants such as atenolol, carbamazepine, 17 alpha-ethinylestradiol (EE2), ibuprofen, and sulfamethoxazole was assessed and compared. The oxidants include chlorine, chlorine dioxide, ferrate(VI), and ozone as selective oxidants versus hydroxyl radicals as non-selective oxidant. Second-order rate constants (k) for the reaction of each oxidant show that the selective oxidants react only with some electron-rich organic moieties (ERMs), such as phenols, anilines, olefins, and deprotonated-amines. In contrast, hydroxyl radicals show a nearly diffusion-controlled reactivity with almost all organic moieties (k>or=10(9)M(-1) s(-1)). Due to a competition for oxidants between a target micropollutant and wastewater matrix (i.e. effluent organic matter, EfOM), a higher reaction rate with a target micropollutant does not necessarily translate into more efficient transformation. For example, transformation efficiencies of EE2, a phenolic micropollutant, in a selected wastewater effluent at pH 8 varied only within a factor of 7 among the selective oxidants, even though the corresponding k for the reaction of each selective oxidant with EE2 varied over four orders of magnitude. In addition, for the selective oxidants, the competition disappears rapidly after the ERMs present in EfOM are consumed. In contrast, for hydroxyl radicals, the competition remains practically the same during the entire oxidation. Therefore, for a given oxidant dose, the selective oxidants were more efficient than hydroxyl radicals for transforming ERMs-containing micropollutants, while hydroxyl radicals are capable of transforming micropollutants even without ERMs. Besides Ef

  5. 复合二氧化氯消毒剂有效含量的定义%Definition of Available Disinfectant Concentration of Composite Chlorine Dioxide

    Institute of Scientific and Technical Information of China (English)

    陈飒; 李志梅; 苏子行; 郑燕琼

    2012-01-01

    复合二氧化氯在饮用水消毒方面的应用越来越广泛,但消毒剂含量定义的问题一直争论不休.该文提出“总有效氯”为复合二氧化氯作为消毒剂中有效氯含量的定义,即pH在中性条件下,二氧化氯折算成氯的质量浓度乘以1(从ClO2还原到ClO-2,氧化价态变化值为1),再加上氯气质量浓度.“总有效氯”可用国标推荐五步碘量法的第一步(pH=7),方法应用简单、结果稳定、可靠.测定饮用水中余氯用DPD分光光度法比碘量法更好.如果二氧化氯与氯比值为1.0,则国标中的“有效氯”是“总有效氯”的2.3倍.%Application of composite chlorine dioxide in drinking water is wide spread in recent years, but argument about the definition of the concentration of composite chlorine dioxide exists in the circle of water treatment. In the paper, total available chlorine is defined as the sum of the concentration of chlorine and that of chlorine dioxide calculated as Cl because in water, pH=7, ClO2 reduced to ClO2- the change of valence is equal to 1. Total available chlorine of composite chlorine dioxide may be determined with the first step of the five steps iodometric titration method. This procedure is simple, stable and reliable. Residual chlorine in drinking water could be determined by spectrophotometric method with DPD better than by iodometric titration. The effective resident chlorine defined by national standard is 2.3 times of total effective chlorine if the ratio of chlorine dioxide to chlorine is 1.0.

  6. Multifold Increases in Turing Pattern Wavelength in the Chlorine Dioxide-Iodine-Malonic Acid Reaction-Diffusion System

    Science.gov (United States)

    Gaskins, Delora K.; Pruc, Emily E.; Epstein, Irving R.; Dolnik, Milos

    2016-07-01

    Turing patterns in the chlorine dioxide-iodine-malonic acid reaction were modified through additions of sodium halide salt solutions. The range of wavelengths obtained is several times larger than in the previously reported literature. Pattern wavelength was observed to significantly increase with sodium bromide or sodium chloride. A transition to a uniform state was found at high halide concentrations. The observed experimental results are qualitatively well reproduced in numerical simulations with the Lengyel-Epstein model with an additional chemically realistic kinetic term to account for the added halide and an adjustment of the activator diffusion rate to allow for interhalogen formation.

  7. Galerkin analysis of light-induced patterns in the chlorine dioxide-iodine-malonic acid reaction-diffusion system

    Science.gov (United States)

    Ghosh, Pushpita; Sen, Shrabani; Riaz, Syed Shahed; Ray, Deb Shankar

    2009-05-01

    The photosensitive chlorine dioxide-iodine-malonic acid reaction-diffusion system has been an experimental paradigm for the study of Turing pattern over the last several years. When subjected to illumination of varied intensity by visible light the patterns undergo changes from spots to stripes, vice versa, and their mixture. We carry out a nonlinear analysis of the underlying model in terms of a Galerkin scheme with finite number of modes to explore the nature of the stability and existence of various modes responsible for the type and crossover of the light-induced patterns.

  8. Lack of enhanced effect of a chlorine dioxide-based cleaning regimen on environmental contamination with Clostridium difficile spores.

    Science.gov (United States)

    Goldenberg, S D; Patel, A; Tucker, D; French, G L

    2012-09-01

    Spores of Clostridium difficile may play a significant role in transmission of disease within the healthcare environment and are resistant to a variety of detergents and cleaning fluids. A range of environmental cleaning agents has recently become available, many of which claim to be sporicidal. We investigated the effect of changing to a chlorine dioxide-based cleaning regimen on C. difficile environmental contamination and patient infection rates. The prevalence of environmental contamination was unaffected with a rate of 8% (9/120) before and 8% (17/212) following the change. Rates of patient infection were also unchanged during these periods.

  9. Enhanced chlorine dioxide decay in the presence of metal oxides: Relevance to drinking water distribution systems

    KAUST Repository

    Liu, Chao

    2013-07-19

    Chlorine dioxide (ClO2) decay in the presence of typical metal oxides occurring in distribution systems was investigated. Metal oxides generally enhanced ClO2 decay in a second-order process via three pathways: (1) catalytic disproportionation with equimolar formation of chlorite and chlorate, (2) reaction to chlorite and oxygen, and (3) oxidation of a metal in a reduced form (e.g., cuprous oxide) to a higher oxidation state. Cupric oxide (CuO) and nickel oxide (NiO) showed significantly stronger abilities than goethite (α-FeOOH) to catalyze the ClO2 disproportionation (pathway 1), which predominated at higher initial ClO2 concentrations (56-81 μM). At lower initial ClO2 concentrations (13-31 μM), pathway 2 also contributed. The CuO-enhanced ClO2 decay is a base-assisted reaction with a third-order rate constant of 1.5 × 10 6 M-2 s-1 in the presence of 0.1 g L -1 CuO at 21 ± 1 C, which is 4-5 orders of magnitude higher than in the absence of CuO. The presence of natural organic matter (NOM) significantly enhanced the formation of chlorite and decreased the ClO 2 disproportionation in the CuO-ClO2 system, probably because of a higher reactivity of CuO-activated ClO2 with NOM. Furthermore, a kinetic model was developed to simulate CuO-enhanced ClO 2 decay at various pH values. Model simulations that agree well with the experimental data include a pre-equilibrium step with the rapid formation of a complex, namely, CuO-activated Cl2O4. The reaction of this complex with OH- is the rate-limiting and pH-dependent step for the overall reaction, producing chlorite and an intermediate that further forms chlorate and oxygen in parallel. These novel findings suggest that the possible ClO2 loss and the formation of chlorite/chlorate should be carefully considered in drinking water distribution systems containing copper pipes. © 2013 American Chemical Society.

  10. Effects of food composition on the inactivation of foodborne microorganisms by chlorine dioxide.

    Science.gov (United States)

    Vandekinderen, I; Devlieghere, F; Van Camp, J; Kerkaert, B; Cucu, T; Ragaert, P; De Bruyne, J; De Meulenaer, B

    2009-05-31

    Chlorine dioxide (ClO2) is a strong oxidizing agent that can be applied in solution as well as in the gaseous state. It has bactericidal, fungicidal and viricidal properties. Several food-related microorganisms, including Gram-negative and Gram-positive bacteria, yeasts, mould spores and Bacillus cereus spores were tested for their susceptibility to 0.08 mg/L gaseous ClO2 during 1 min at a relative humidity of 90%. In this screening, the resistance of the different groups of microorganisms towards gaseous ClO2 generally increased in the order Gram-negative bacteria, Gram-positive bacteria, yeasts and mould spores and Bacillus cereus spores. With this treatment, reductions of microbial numbers between 0.1 and 3.5 log cfu/cm2 could be achieved. The effects of the food components starch, fat, protein and NaCl on the antimicrobial activity of gaseous ClO2 were also evaluated. Soluble starch, corn oil, butter, whey protein isolate and NaCl were added in incremental concentrations to portions of an agar medium. Then, plates of the supplemented agars were inoculated with Leuconostoc mesenteroïdes at numbers of 4 log cfu/cm2 and subsequently treated with ClO2. Both soluble starch and NaCl did not have an effect on the antimicrobial efficiency of ClO2. However, butter, corn oil or whey protein in the agar almost eliminated the antimicrobial effect of ClO2. In corn oil-water emulsions treated with gaseous ClO2 the peroxide value increased significantly, indicating the formation of primary oxidation products. Similarly, a treatment with ClO2 increased the protein carbonyl content and induced the transformation of SH-groups to -S-S-groups in whey protein. The findings suggest that gaseous ClO2 will be a highly effective decontaminating agent for carbohydrate-rich foods, but that it would be less effective for the decontamination of high-protein and fatty foods.

  11. 二氧化氯消毒中水实验研究%Study on reclaimed water disinfection with chlorine dioxide

    Institute of Scientific and Technical Information of China (English)

    刘艳娟; 马丽莎; 祝明; 杨雅雯; 赵燕

    2015-01-01

    研究了二氧化氯消毒中水COD与二氧化氯最小投加量的定量关系及确保二氧化氯持续消毒能力的剩余剂量. 结果表明:在室温,COD为15~50 mg/L,浊度为1.00~6.37 NTU,大肠菌群数<106数量级的条件下,中水COD与二氧化氯最小投加量定量关系满足一元线性方程.为保证二氧化氯的持续消毒能力,消毒30 min水样的剩余二氧化氯质量浓度不能低于0.10 mg/L.二氧化氯浓度随时间的衰减规律符合一级反应动力学模型,且随二氧化氯浓度的减小,其衰减速率逐渐减小.%The quantitative relationship between COD of chlorine dioxide used for disinfecting reclaimed water ,and chlorine dioxide minimum dosage,and the residual dosage of ensuring continuous disinfecting capacity of chlorine dioxide have been studied. The results show that under the following conditions:at room temperature,COD is 15-50 mg/L,turbidity 1.00-6.37 NTU,the numbers of colon bacillus<106,the quantitative relationship between reclaimed water COD and the minimum dosage of chlorine dioxide meets the unary linear equation. To ensure the continuous disinfecting capacity of chlorine dioxide,the mass concentration of the residual chlorine dioxide of the water sample which has been disinfected for 30 min,should not be lower than 0.10 mg/L. The rule that chlorine dioxide concentra-tion attenuates with time complies with the first level of reaction kinetics model. Furthermore ,with the decrease of chlorine dioxide concentration,its attenuation rate decreases gradually.

  12. Chlorine Dioxide-Iodide-Methyl Acetoacetate Oscillation Reaction Investigated by UV-Vis and Online FTIR Spectrophotometric Method

    Science.gov (United States)

    Shi, Laishun; Wang, Xiaomei; Li, Na; Liu, Jie; Yan, Chunying

    2012-01-01

    In order to study the chemical oscillatory behavior and mechanism of a new chlorine dioxide-iodide ion-methyl acetoacetate reaction system, a series of experiments were done by using UV-Vis and online FTIR spectrophotometric method. The initial concentrations of methyl acetoacetate, chlorine dioxide, potassium iodide, and sulfuric acid and the pH value have great influence on the oscillation observed at wavelength of 289 nm. There is a preoscillatory or induction period, and the amplitude and the number of oscillations are associated with the initial concentration of reactants. The equations for the triiodide ion reaction rate changing with reaction time and the initial concentrations in the oscillation stage were obtained. Oscillation reaction can be accelerated by increasing temperature. The apparent activation energies in terms of the induction period and the oscillation period were 26.02 KJ/mol and 17.65 KJ/mol, respectively. The intermediates were detected by the online FTIR analysis. Based upon the experimental data in this work and in the literature, a plausible reaction mechanism was proposed for the oscillation reaction. PMID:22454614

  13. Simultaneous removal of SO{sub 2} and NO by wet scrubbing using aqueous chlorine dioxide solution

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Dong-Seop [Flue Gas Treatment Center, Korea Institute of Energy Research, Daejon 305 600 (Korea, Republic of); Deshwal, Bal-Raj [Department of Chemistry, A.I.J.H.M. College, Rohtak 124001, Haryana (India)]. E-mail: deshwalbr@yahoo.com; Park, Young-Seong [Department of Environmental Engineering, Daejon University, Daejon (Korea, Republic of); Lee, Hyung-Keun [Flue Gas Treatment Center, Korea Institute of Energy Research, Daejon 305 600 (Korea, Republic of)

    2006-07-31

    The present study attempts to generate chlorine dioxide (ClO{sub 2}) gas continuously by chlorate-chloride process and to utilize it further to clean up SO{sub 2} and NO {sub x} gases simultaneously from the flue gas in the lab-scale bubbling reactor. Experiments were carried out to examine the effect of various operating parameters like input SO{sub 2} concentration, input NO concentration, pH of the reaction medium, and ClO{sub 2} feeding rate on the SO{sub 2} and NO {sub x} removal efficiencies at 45 deg. C. Complete oxidation of NO into NO{sub 2} occurred on passing sufficient ClO{sub 2} gas into the scrubbing solution. SO{sub 2} removal efficiency of about 100% and NO {sub x} removal efficiency of 66-72% were achieved under optimized conditions. NO {sub x} removal efficiency decreased slightly with increasing pH and NO concentration. Input SO{sub 2} concentration had marginal catalytic effect on NO{sub 2} absorption. No improvement in the NO {sub x} removal efficiency was observed on passing excess of chlorine dioxide in the scrubbing solution.

  14. A Comparison of Wound Healing Rate Following Treatment with Aftamed and Chlorine Dioxide Gels in Streptozotocin-Induced Diabetic Rats

    Science.gov (United States)

    Al-Bayaty, Fouad; Abdulla, Mahmood Ameen

    2012-01-01

    Background and Purpose. This study aimed to evaluate the wound healing activities of Aftamed and chlorine dioxide gels in streptozotocin-induced diabetic rats. Experimental Approach. Forty-eight Sprague Dawley rats were chosen for this study, divided into 4 groups. Diabetes was induced. Two-centimeter-diameter full-thickness skin excision wounds were created. Animals were topically treated twice daily. Groups 1, the diabetic control group, were treated with 0.2 mL of sterile distilled water. Group 2 served as a reference standard were treated with 0.2 mL of Intrasite gel. Groups 3 and 4 were treated with 0.2 mL of Aftamed and 0.2 mL of chlorine dioxide gels respectively. Granulation tissue was excised on the 10th day and processed for histological and biochemical analysis. The glutathione peroxidase ,superoxide dismutase activities and the malondialdehyde (MDA) levels were determined. Results. Aftamed-treated wounds exhibited significant increases in hydroxyproline, cellular proliferation, the number of blood vessels, and the level of collagen synthesis. Aftamed induced an increase in the free radical-scavenging enzyme activity and significantly reduced the lipid peroxidation levels in the wounds as measured by the reduction in the MDA level. Conclusions. This study showed that Aftamed gel is able to significantly accelerate the process of wound healing in diabetic rats. PMID:22666291

  15. Correlation of Conformational Changes and Protein Degradation with Loss of Lysozyme Activity Due to Chlorine Dioxide Treatment.

    Science.gov (United States)

    Ooi, Beng Guat; Branning, Sharon Alyssa

    2016-12-13

    Chlorine dioxide (ClO2) is a potent oxidizing agent used for the treatment of drinking water and decontamination of facilities and equipment. The purpose of this research is to elucidate the manner in which ClO2 destroys proteins by studying the effects of ClO2 on lysozyme. The degree of enzyme activity lost can be correlated to the treatment time and levels of the ClO2 used. Lysozyme activity was drastically reduced to 45.3% of original enzyme activity when exposed to 4.3 mM ClO2 in the sample after 3 h. Almost all activities were lost in 3 h after exposure to higher ClO2 concentrations of up to 16.8 and 21.9 mM. Changes in protein conformation and amount as a result of ClO2 treatment were determined using the Raman spectroscopy and gel electrophoresis. Raman shifts and the alteration of spectral features observed in the ClO2-treated lysozyme samples are associated with loss of the α-helix secondary structure, tertiary structure, and disulfide bond. Progressive degradation of the denatured lysozyme by increasing levels of chlorine dioxide was also observed in gel electrophoresis. Hence, ClO2 can effectively cause protein denaturation and degradation resulting in loss of enzyme activity.

  16. Chlorine Dioxide-Iodide-Methyl Acetoacetate Oscillation Reaction Investigated by UV-Vis and Online FTIR Spectrophotometric Method

    Directory of Open Access Journals (Sweden)

    Laishun Shi

    2012-01-01

    Full Text Available In order to study the chemical oscillatory behavior and mechanism of a new chlorine dioxide-iodide ion-methyl acetoacetate reaction system, a series of experiments were done by using UV-Vis and online FTIR spectrophotometric method. The initial concentrations of methyl acetoacetate, chlorine dioxide, potassium iodide, and sulfuric acid and the pH value have great influence on the oscillation observed at wavelength of 289 nm. There is a preoscillatory or induction period, and the amplitude and the number of oscillations are associated with the initial concentration of reactants. The equations for the triiodide ion reaction rate changing with reaction time and the initial concentrations in the oscillation stage were obtained. Oscillation reaction can be accelerated by increasing temperature. The apparent activation energies in terms of the induction period and the oscillation period were 26.02 KJ/mol and 17.65 KJ/mol, respectively. The intermediates were detected by the online FTIR analysis. Based upon the experimental data in this work and in the literature, a plausible reaction mechanism was proposed for the oscillation reaction.

  17. Enhancing the efficacy of electrolytic chlorination for ballast water treatment by adding carbon dioxide.

    Science.gov (United States)

    Cha, Hyung-Gon; Seo, Min-Ho; Lee, Heon-Young; Lee, Ji-Hyun; Lee, Dong-Sup; Shin, Kyoungsoon; Choi, Keun-Hyung

    2015-06-15

    We examined the synergistic effects of CO2 injection on electro-chlorination in disinfection of plankton and bacteria in simulated ballast water. Chlorination was performed at dosages of 4 and 6ppm with and without CO2 injection on electro-chlorination. Testing was performed in both seawater and brackish water quality as defined by IMO G8 guidelines. CO2 injection notably decreased from the control the number of Artemia franciscana, a brine shrimp, surviving during a 5-day post-treatment incubation (1.8 and 2.3 log10 reduction in seawater and brackish water, respectively at 6ppm TRO+CO2) compared with water electro-chlorinated only (1.2 and 1.3 log10 reduction in seawater and brackish water, respectively at 6ppm TRO). The phytoplankton Tetraselmis suecica, was completely disinfected with no live cell found at >4ppm TRO with and without CO2 addition. The effects of CO2 addition on heterotrophic bacterial growth was not different from electro-chlorination only. Total residual oxidant concentration (TRO) more rapidly declined in electro-chlorination of both marine and brackish waters compared to chlorine+CO2 treated waters, with significantly higher amount of TRO being left in waters treated with the CO2 addition. Total concentration of trihalomethanes (THMs) and haloacetic acids (HAAs) measured at day 0 in brackish water test were found to be 2- to 3-fold higher in 6ppm TRO+CO2-treated water than in 6ppm TRO treated water. The addition of CO2 to electro-chlorination may improve the efficiency of this sterilizing treatment of ballast water, yet the increased production of some disinfection byproducts needs further study.

  18. Formation of Disinfection By-products in Drinking Water With Chlorine Dioxide and Chlorine%二氧化氯与氯对饮用水中消毒副产物形成的研究

    Institute of Scientific and Technical Information of China (English)

    朱明新; 孙轶民; 沈丽娜; 徐炎华; 伏荣进

    2012-01-01

    采用氯和二氧化氯作为消毒剂,用模拟水样和实际水样比较这两种消毒剂的消毒副产物产生量及其消毒效果.实验结果表明:在不同腐殖酸浓度、消毒剂浓度及pH下,氯消毒产生的三氯甲烷都比二氧化氯消毒产生的多;从成本上看,不同二氧化氯制备方法所需的药剂成本都比液氯高,其中过氧化氢法所需的成本较低,是液氯的1.4 ~2.5倍;而盐酸法和亚氯酸钠法所需的成本较高,是液氯的4~5倍.%Disinfecting effect of chlorine and chlorine dioxide has been compared by using simulating water and actual water samples. The result indicates that chlorine disinfection produces more chloroform than chlorine dioxide at the conditions of different humic acid concentration, disinfectants concentration and pH value. From a cost consideration, the pharmaceutical cost used by chlorine dioxide disinfection is higher than chlorine disinfection. The raw material cost of hydrogen peroxide method is lower, while the raw material cost of hydrochloric acid method and sodium chlorite method is higher. Respectively,the cost is 1.4~2.5 times and 4~5 times more than chlorine.

  19. Monochloramine Cometabolism by Nitrifying Biofilm Relevant to Drinking Water

    Science.gov (United States)

    Recently, biological monochloramine removal (i.e., cometabolism) by a pure culture ammonia–oxidizing bacteria, Nitrosomonas europaea, and a nitrifying mixed–culture have been shown to increase monochloramine demand. Although important, these previous suspended culture batch kine...

  20. Monochloramine Cometabolism by Nitrifying Biofilm Relevant to Drinking Water

    Science.gov (United States)

    Recently, biological monochloramine removal (i.e., cometabolism) by a pure culture ammonia–oxidizing bacteria, Nitrosomonas europaea, and a nitrifying mixed–culture have been shown to increase monochloramine demand. Although important, these previous suspended cultur...

  1. Monochloramine Cometabolism by Nitrifying Biofilm Relevant to Drinking Water

    Science.gov (United States)

    Recently, biological monochloramine removal (i.e., cometabolism) by a pure culture ammonia–oxidizing bacteria, Nitrosomonas europaea, and a nitrifying mixed–culture have been shown to increase monochloramine demand. Although important, these previous suspended culture batch kine...

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

    Science.gov (United States)

    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

  3. Effect of Chlorine Dioxide and Ascorbic Acid on Enzymatic Browning and Shelf Life of Fresh-Cut Red Delicious and Granny Smith Apples

    NARCIS (Netherlands)

    Remorini, Damiano; Landi, Marco; Tardelli, Francesca; Lugani, Arianna; Massai, Rossano; Graziani, Giulia; Fogliano, Vincenzo; Guidi, Lucia

    2015-01-01

    In this work, we tested the hypothesis that ascorbic acid (AA) reduces browning of fresh-cut apples (Red Delicious, RD, and Granny Smith, GS), and we investigated the impact of AA on phenylpropanoid metabolism of RD and GS. Apple slices were dipped in a solution of 100mg/L of chlorine dioxide (Cl

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

    Science.gov (United States)

    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.

  5. Effect of Chlorine Dioxide and Ascorbic Acid on Enzymatic Browning and Shelf Life of Fresh-Cut Red Delicious and Granny Smith Apples

    NARCIS (Netherlands)

    Remorini, Damiano; Landi, Marco; Tardelli, Francesca; Lugani, Arianna; Massai, Rossano; Graziani, Giulia; Fogliano, Vincenzo; Guidi, Lucia

    2015-01-01

    In this work, we tested the hypothesis that ascorbic acid (AA) reduces browning of fresh-cut apples (Red Delicious, RD, and Granny Smith, GS), and we investigated the impact of AA on phenylpropanoid metabolism of RD and GS. Apple slices were dipped in a solution of 100mg/L of chlorine dioxide

  6. OBSERVATION ON DISINFECTION EFFICACY OF CHLORINE DIOXIDE IN WATER%二氧化氯对水体消毒效果的观察

    Institute of Scientific and Technical Information of China (English)

    李爱萍; 周景洋; 刘文杰; 董非; 杨彬; 崔树玉; 张岚; 岳银玲

    2011-01-01

    目的 观察二氧化氯对水体中细菌芽孢的杀灭效果及其在水体中的衰减规律.方法 采用滤膜抽滤法,对二氧化氯杀灭水体中枯草杆菌黑色变种芽孢的效果进行了实验.结果 在人工染菌水样中投放二氧化氯浓度为20 mg/L,作用45 min,可使水体中枯草杆菌黑色变种芽孢降至为0 cfu/100 ml.作用5 min,水样中二氧化氯浓度下降率为0.95%;作用30 min后,水样中二氧化氯残留浓度为9.05 mg/L,下降率为54.84%.结论 水体中二氧化氯在较低浓度下,具有良好的杀灭细菌芽孢的效果;水体中二氧化氯持续作用30 min,其浓度下降率约50%左右.%Objective To observe the germicidal efficacy of chlorine dioxide on killing bacterial spores and the decaying rules water. Methods Membrane filtration method was used to observe the germicidal efficacy of chlorine dioxide in killing spores of Bacillus subtilis var. niger in drinking water. Results The spores of B. subtilis var. niger exposed to the solution containing chlorine dioxide 20 mg/L for 45 min decreased to 0 cfu/100ml. The declining rate of residual chlorine dioxide concentration was 0. 95% for 5 min. The residual chlorine dioxide concentration was 9.05 mg/L and the declining rate was 54.84% for 30 min. Conclusion Chlorine dioxide with relatively low concentration in water has good germicidal efficacy on spores. The declining rate is about 50% when the chlorine dioxide keeps on operating for 30 min.

  7. Selective and trace determination of monochloramine in river water by chemical derivatization and liquid chromatography/tandem mass spectrometry analysis.

    Science.gov (United States)

    Kinani, Said; Layousse, Stéphany; Richard, Bertille; Kinani, Aziz; Bouchonnet, Stéphane; Thoma, Astrid; Sacher, Frank

    2015-08-01

    Monochloramine (MCA) may enter the aquatic environment through three main sources: wastewater treatment plant effluents, industrial effluents and thermal power plant wastes. Up to date, there are no available data about the concentration levels of this chemical in river water due to lack of appropriate analytical methods. Therefore, sensitive and selective analytical methods for monochloramine analysis in river water are required to evaluate its environmental fate and its effects on aquatic ecosystems. Thus, in this study we describe a highly specific and sensitive method for monochloramine determination in river water. This method combines chemical derivatization of monochloramine into indophenol followed by liquid chromatography coupled to electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS) analysis. Two precursor-to-product ion transitions were monitored (200→127 and 200→154) in positive ionisation mode, fulfilling the criteria of selectivity, in accordance with the European Legislation requirements (decision 2002/657/EC). Ion structures and fragmentation mechanisms have been proposed to explain the selected transitions. Linearity range, accuracy and precision of the method have been assessed according to the French method validation standard NF T90-210. Detecting the derivatized monochloramine (indophenol) in Multiple Reaction Monitoring (MRM) mode provided a limit of quantification of 40 ng L(-1) equivalent monochloramine. Applied to Loire river water (France), the developed method occasionally detected monochloramine at concentrations less than 300 ng L(-1), which could be explained by punctual discharges of water containing active chlorine upstream of the sampling point. Indeed, it is widely reported in the literature that the addition of chlorine to water containing ammonia (e.g., wastewater effluents and river water) may result in the instantaneous formation of monochloramine. The proposed method is a powerful tool that can be used in

  8. Carbon dioxide-water oxygen isotope fractionation factor using chlorine trifluoride and guanidine hydrochloride techniques

    Energy Technology Data Exchange (ETDEWEB)

    Dugan, J.P. Jr.; Borthwick, J.

    1986-12-01

    A new value for the CO/sub 2/-H/sub 2/O oxygen isotope fractionation factor of 1.04145 +/- 0.000 15 (2sigma) has been determined. The data have been normalized to the V-SMOW/V-SLAP scale and were obtained by measuring isotopic compositions with the guanidine hydrochloride and chlorine trifluoride techniques.

  9. Composite Film of Vanadium Dioxide Nanoparticles and Ionic Liquid-Nickel-Chlorine Complexes with Excellent Visible Thermochromic Performance.

    Science.gov (United States)

    Zhu, Jingting; Huang, Aibin; Ma, Haibin; Ma, Yining; Tong, Kun; Ji, Shidong; Bao, Shanhu; Cao, Xun; Jin, Ping

    2016-11-02

    Vanadium dioxide (VO2), as a typical thermochromic material used in smart windows, is always limited by its weaker solar regulation efficiency (ΔTsol) and lower luminous transmittance (Tlum). Except for common approaches such as doping, coating, and special structure, compositing is another effective method. The macroscopic thermochromic (from colorless to blue) ionic liquid-nickel-chlorine (IL-Ni-Cl) complexes are selected in this paper to be combined with VO2 nanoparticles forming a composite film. This novel scheme demonstrates outstanding optical properties: ΔTsol = 26.45% and Tlum,l = 66.44%, Tlum,h = 43.93%. Besides, the addition of the IL-Ni-Cl complexes endows the film with an obvious color change from light brown to dark green as temperature rises. This splendid visible thermochromic performance makes the composite film superior in function exhibiting and application of smart windows.

  10. Forcing of Turing patterns in the chlorine dioxide-iodine-malonic acid reaction with strong visible light.

    Science.gov (United States)

    Nagao, Raphael; Epstein, Irving R; Dolnik, Milos

    2013-09-26

    We investigate the sensitivity of Turing patterns in the chlorine dioxide-iodine-malonic acid reaction to illumination by strong white light. Intense illumination results in an increase of [I(-)], in contrast to previous studies, which found only decreased [I(-)] for weak and intermediate intensities of illumination. We propose an expanded mechanism to explain the experimental observations. Both experimental and numerical results suggest that [ClO2] is the key parameter that determines whether the high iodide state is obtained under strong illumination. When strong illumination is applied through a spatially periodic mask with black and white stripes, a dark state with high [I(-)] is produced in the illuminated domain and a light state with low [I(-)] forms in the nonilluminated domain. Depending on the black:white ratio of the mask and its wavelength, Turing patterns can coexist with either the light or the dark state in the nonilluminated domain.

  11. Laser flash photolysis of chlorine dioxide: Formation and ultraviolet absorption spectrum of Cl sub 2 O sub 3 sup 1

    Energy Technology Data Exchange (ETDEWEB)

    Colussi, A.J.; Redmond, R.W.; Scaiano, J.C. (National Research Council of Canada, Ottawa, Ontario (Canada))

    1989-06-15

    The kinetics of ClO{sub 2} photodecomposition in trichlorofluoromethane solutions induced by 337.1-nm pulses were investigated under various experimental conditions. Instantaneous photochemical bleaching is followed by a slower bleaching which follows pseudo-first-order kinetics and leads to the formation of a long-lived transient species absorbing up to 330 nm with {lambda}{sub max} {approx} 280 nm. At high concentrations of ClO{sub 2} identical amounts of chlorine dioxide are consumed in both stages, revealing that the latter involves stoichiometric reaction of an initially formed intermediate with excess ClO{sub 2}. Addition of tetramethylethylene, a very efficient oxygen atom quencher, had no detectable effect on the kinetics of ClO{sub 2} decay. The intermediate is therefore identified as ClO and the new species as Cl{sub 2}O{sub 3}, chlorine sesquioxide, formed by reaction 5: ClO + ClO{sub 2} {yields} Cl{sub 2}O{sub 3}.

  12. Chlorine dioxide as an alternative antifouling biocide for cooling water systems: Toxicity to larval barnacle Amphibalanus reticulatus (Utinomi).

    Science.gov (United States)

    Venkatnarayanan, Srinivas; Sriyutha Murthy, P; Kirubagaran, Ramalingam; Venugopalan, Vayalam P

    2017-01-19

    Chlorine dioxide (ClO2) is seen as an effective alternative to chlorine, which is widely used as an antifouling biocide. However, data on its efficacy against marine macrofoulants is scanty. In this study, acute toxicity of ClO2 to larval forms of the fouling barnacle Amphibalanus reticulatus was investigated. ClO2 treatment at 0.1mg/L for 20min elicited 45-63% reduction in naupliar metamorphosis, 70% inhibition of cyprid settlement and 80% inhibition of metamorphosis to juveniles. Increase in concentration to 0.2mg/L did not result in any significant difference in the settlement inhibition or metamorphosis. Treatment with 0.2mg/L of ClO2 elicited substantial reduction in the settlement of barnacle larvae compared to control. The study indicates the possibility of using ClO2 as an alternative antifouling biocide in power plant cooling water systems. However, more work needs to be done on the environmental effects of such switchover, which we are currently undertaking.

  13. Study by XPS of the chlorination of proteins aggregated onto tin dioxide during electrochemical production of hypochlorous acid

    Science.gov (United States)

    Debiemme-Chouvy, Catherine; Haskouri, Sanae; Cachet, Hubert

    2007-04-01

    In solution, hypochlorous acid (HOCl) reacts with organic matter and notably with protein side-chains. In this study, HOCl was produced by an electrochemical way, by oxidation of chloride ions at a transparent tin dioxide electrode in the presence of a protein, the bovine serum albumin (BSA). A thick irregular layer is formed at the electrode when HOCl is produced at the SnO 2 surface. Indeed, SEM analyses show that an important deposit is formed during the anodic polarization of SnO 2 in the presence of chloride ions and proteins. Actually, two phenomena take place on the one hand the chlorination of the proteins due to the reaction of HOCl with some protein side-chains and on the other hand the aggregation of proteins onto the SnO 2 surface. The present X-ray photoelectron spectroscopy study points out the cross-linking of BSA molecules via formation of inter molecular sulfonamide groups. It also shows that the BSA chlorination is due on the one hand to the formation of sulfonyl chloride groups (-SO 2Cl) and on the other hand to formation of chloramine groups ( lbond2 N-Cl). The Cl2p and S2p photo-peak intensities allowed us to quantify the chloramines. It is found that, one BSA entity immobilized onto the SnO 2 surface contains about 50 chloramine groups.

  14. Study by XPS of the chlorination of proteins aggregated onto tin dioxide during electrochemical production of hypochlorous acid

    Energy Technology Data Exchange (ETDEWEB)

    Debiemme-Chouvy, Catherine [Laboratoire Interfaces et Systemes Electrochimiques, UPR 15 du CNRS, UPMC Case Courrier 133-4, Place Jussieu, 75252 Paris Cedex (France)]. E-mail: debiemme@ccr.jussieu.fr; Haskouri, Sanae [Laboratoire Interfaces et Systemes Electrochimiques, UPR 15 du CNRS, UPMC Case Courrier 133-4, Place Jussieu, 75252 Paris Cedex (France); Cachet, Hubert [Laboratoire Interfaces et Systemes Electrochimiques, UPR 15 du CNRS, UPMC Case Courrier 133-4, Place Jussieu, 75252 Paris Cedex (France)

    2007-04-15

    In solution, hypochlorous acid (HOCl) reacts with organic matter and notably with protein side-chains. In this study, HOCl was produced by an electrochemical way, by oxidation of chloride ions at a transparent tin dioxide electrode in the presence of a protein, the bovine serum albumin (BSA). A thick irregular layer is formed at the electrode when HOCl is produced at the SnO{sub 2} surface. Indeed, SEM analyses show that an important deposit is formed during the anodic polarization of SnO{sub 2} in the presence of chloride ions and proteins. Actually, two phenomena take place on the one hand the chlorination of the proteins due to the reaction of HOCl with some protein side-chains and on the other hand the aggregation of proteins onto the SnO{sub 2} surface. The present X-ray photoelectron spectroscopy study points out the cross-linking of BSA molecules via formation of inter molecular sulfonamide groups. It also shows that the BSA chlorination is due on the one hand to the formation of sulfonyl chloride groups (-SO{sub 2}Cl) and on the other hand to formation of chloramine groups ( N-Cl). The Cl2p and S2p photo-peak intensities allowed us to quantify the chloramines. It is found that, one BSA entity immobilized onto the SnO{sub 2} surface contains about 50 chloramine groups.

  15. Method and equipment to eliminate gaseous sulphur dioxide and chlorine components from a gas stream

    Energy Technology Data Exchange (ETDEWEB)

    Dahlstrom, D.A.; Ellison, W.S.; Wilhelm, J.H.

    1977-10-27

    The known method to clean waste gases from coal combustion which besides SO/sub 2/ still contain chlorine compounds by treatment with aqueous washing solutions is improved upon. A combination of two wash systems is suggested which are particularly economical as the washing solutions can be regenerated and recycled into the system. Calcium compounds and sodium sulphite are used, the solids formed are removed from the system. The apparatus is described.

  16. THM reduction on water distribution network with chlorine dioxide as disinfectant; Reduccion de THM en red de distribucion utilizando dioxido de cloro como desinfectante

    Energy Technology Data Exchange (ETDEWEB)

    Ventura, G.; Gorriz, D.; Pascual, E.; Romero, M.

    2009-07-01

    A disinfectant change on water distribution network, by chlorine dioxide in that case, avoids THM formation. In the other hand it creates big doubts about utilization and analytical determination of another oxidant different to chlorine. Just a need to comply the current legislation points us to make a change as the one mentioned above and carried out in DWTP Rio Verde, being managed by Acosol, where the THM formation is been reduced to 80%, according to the new limit of 100{mu}g/l, along the 200 km of the supply network. (Author) 13 refs.

  17. 二氧化氯对水体消毒效果的试验观察%EXPERIMENTAL OBSERVATION ON DISINFECTION EFFECT OF CHLORINE DIOXIDE ON WATER BODY

    Institute of Scientific and Technical Information of China (English)

    刘仲霞; 苏伟东; 诸葛石养; 梁川

    2013-01-01

    目的 观察一种由发生器生产的二氧化氯对水体消毒效果.方法 采用滤膜法和现场消毒试验对某二氧化氯发生器产二氧化氯消毒液对染菌水样中大肠杆菌和现场水样的消毒效果进行观察.结果 该发生器产生的二氧化氯消毒液含量为164.27 mg/L.在污染水样中投入浓度0.2 mg/L的二氧化氯,作用15 min,可使人工染菌水样中大肠杆菌下降至0 cfu/100 ml.在现场自然水样中投入浓度0.5 mg/L二氧化氯,作用30 min,可使水样中自然菌总数、总大肠菌群达到生活饮用水卫生标准规定.结论 该二氧化氯发生器生产的二氧化氯在较低浓度条件下对污染水样和自然水样消毒效果均达到标准要求.%Objective To observe the disinfection effect of chlorine dioxide produced by generator on water body.Methods Filter membrane method and on the spot disinfection test were used to observe the disinfection effect of chlorine dioxide on water contaminated with Escherichia coli and water sampling on the spot.Results The content of chlorine dioxide produced by generator was 164.27 mg/L.The number of Escherichia coli in contaminated water decreased to 0 cfu/100 ml exposed to chlorine dioxide 0.2 mg/L for 15min.While exposed to chlorine dioxide 0.5 mg/L for 30 min in on the spot natural water the number of natural bacteria and total ciliform bacteria could meet the heahh requirements of standard regulation of drinking water.Conclusion The chlorine dioxide produced by generator can meet the standard requirement of disinfection effect in the comparatively low content.

  18. OBSERVATION ON GERMICIDAL PROPERTY OF A CHLORINE DIOXIDE DISINFECTANT POWDER%一种二氧化氯消毒粉的杀菌性能观察

    Institute of Scientific and Technical Information of China (English)

    饶林; 武雪冰; 王长德; 蒋莉

    2012-01-01

    目的 观察一种二氧化氯消毒粉的杀菌性能.方法 用悬液定量杀菌试验和理化测定方法,对该消毒剂性能进行了实验室试验.结果 消毒粉A和B两剂混合,溶解于2L蒸馏水中活化后二氧化氯含量为3 902 mg/L.用浓度为78 mg/L二氧化氯溶液作用5 min,对悬液内金黄色葡萄球菌和大肠杆菌平均杀灭对数值均>5.00.用相同浓度该二氧化氯消毒液对物体表面作擦拭消毒并作用10min,对表面自然菌平均杀灭对数值>1.00.在天然水样中加入该二氧化氯约1.0 mg/L作用30 min,使水样中大肠杆菌下降至0 cfu/100 ml.结论 该二氧化氯消毒粉杀菌效果较好,在较低浓度条件下对物体表面和水体消毒均效果较好.%Objective To evaluate the germicidal efficacy of a chlorine dioxide disinfectant powder. Methods Suspension quantitative germicidal test and physicochemical examination were used to evaluate the disinfectant property in laboratory. Results Powder A and B were compounded, and then were solved in 2 L distilled water for inactivation. The concentration of chlorine dioxide was 3 902 mg/L after inactivation for 20 min. The average killing logarithm value of Staphylococcus aureus and Escherichia coli in the suspension exposed to the disinfection solution with the concentration of chlorine dioxide was 78 mg/L for 5 min were both > 5. 00. And the average killing logarithm value of natural bacteria on material surface was > 1. 0 when scripted with 78 mg/L chlorine dioxide for 10 min. 1. 0 mg/L chlorine dioxide can reduce Escherichia coli added into natural water to 0 cfu /100ml in 30 min. Conclusion The chlorine dioxide disinfectant powder has good germicidal efficacy. It can be used for material surface and water disinfection.

  19. Impact of Chlorine dioxide Gas on the Barrier Properties of Polymeric Packaging Materials

    Science.gov (United States)

    One important criterion of polymeric material selection and packaging design for fresh produce is choosing the material with suitable ratio of carbon dioxide and oxygen permabilities (PCO2/P O2), to the respiratory proportion of the targeted produce. The ratio of [O2] and [CO2] in the head space var...

  20. Oxidation of diclofenac by aqueous chlorine dioxide: identification of major disinfection byproducts and toxicity evaluation.

    Science.gov (United States)

    Wang, Yingling; Liu, Haijin; Liu, Guoguang; Xie, Youhai

    2014-03-01

    Diclofenac (DCF), a synthetic non-steroidal anti-inflammatory drug, is one of the most frequently detected pharmaceuticals in the aquatic environment. In this work, the mechanism and toxicity of DCF degradation by ClO2 under simulated water disinfection conditions were investigated. Experimental results indicate that rapid and significant oxidation of DCF occurred within the first few minutes; however, its mineralization process was longer than its degradation process. UPLC-MS and (1)H NMR spectroscopy were performed to identify major disinfection byproducts that were generated in three tentative degradation routes. The two main routes were based on initial decarboxylation of DCF on the aliphatic chain and hydroxylation of the phenylacetic acid moiety at the C-4 position. Subsequently, the formed aldehyde intermediates were the starting point for further multistep degradation involving decarboxylation, hydroxylation, and oxidation reactions of CN bond cleavage. The third route was based on transient preservation of chlorinated derivatives resulting from electrophilic attack by chlorine on the aromatic ring, which similarly underwent CN bond cleavage. Microtox bioassay was employed to evaluate the cytotoxicity of solutions treated by ClO2. The formation of more toxic mid-byproducts during the ClO2 disinfection process poses a potential risk to consumers.

  1. Development and field testing of a mobile chlorine dioxide generation system for the decontamination of buildings contaminated with Bacillus anthracis

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Joseph P., E-mail: wood.joe@epa.gov [U.S. Environmental Protection Agency, Office of Research and Development, National Homeland Security Research Center, MC-E343-06, Research Triangle Park, NC 27711 (United States); Blair Martin, G., E-mail: martin.blair@epa.gov [U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, MC-E340-C, Research Triangle Park, NC 27711 (United States)

    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{sub 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{sub 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 24 h. 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{sub 2} was generated and routed directly to the scrubber in a 12-h continuous run. Measurement of ClO{sub 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{sub 2} emissions below the limit. Numerous lessons were learned in the field trials of this ClO{sub 2} decontamination technology.

  2. Synergistic effect of chlorine dioxide and drying treatments for inactivating Escherichia coli O157:H7 on radish seeds.

    Science.gov (United States)

    Kim, Hoikyung; Kim, Haeyoung; Bang, Jihyun; Beuchat, Larry R; Ryu, Jee-Hoon

    2010-07-01

    Studies were done to determine whether calcium hypochlorite (Ca(OCl)(2)) and chlorine dioxide (ClO(2)) treatment followed by drying had a synergistic killing effect on microorganisms on radish seeds intended for sprout production. Uninoculated radish seeds and seeds inoculated with Escherichia coli O157:H7 were treated with water, Ca(OCl)(2) (free chlorine concentrations of 50 or 200 microg/ml), or ClO(2) (50 or 200 microg/ml) for 5 min and subsequently dried at 25 degrees C for up to 24 h. Populations of total aerobic bacteria (TAB), molds and yeasts (MY), and E. coli O157:H7 on the seeds treated with Ca(OCl)(2) were not significantly different (P = 0.05) than populations on seeds treated with ClO(2) at the same concentrations. However, populations of microorganisms on seeds treated with ClO(2) decreased more rapidly during drying. Treatment with ClO(2) (200 microg/ml) followed by drying caused reductions in TAB, MY, and E. coli O157:H7 of 3.1, 2.0, and 3.8 log CFU/g, respectively. When seeds were treated with water, Ca(OCl)(2) (50 or 200 microg/ml), and ClO(2) (50 microg/ml) and subsequently dried, reductions in TAB, MY, and E. coli O157:H7 were 0.2 to 2.0, 0.4 to 2.0, and 1.4 to 2.2 log CFU/g, respectively. Results indicate that inactivation of E. coli O157:H7 on radish seeds is greater after treatment with ClO(2) followed by drying than after treatment with Ca(OCl)(2) followed by drying, thus providing a synergistic treatment combination for reducing the safety risk associated with sprouts produced from these seeds.

  3. C4000型分析仪在二氧化氯制备装置中的应用%Application of C4000 analyzer in chlorine dioxide preparation apparatus for pulp bleaching

    Institute of Scientific and Technical Information of China (English)

    王国安; 王志法

    2013-01-01

    This paper introduces the working principle of C4000 chlorine dioxide analyzer and its installation, application, maintenance and precautions in chlorine dioxide preparation system.%  介绍了C4000型二氧化氯分析仪的工作原理及在二氧化氯制备装置中的安装、使用、维护、注意事项等。

  4. Comparative Inactivation of Murine Norovirus and MS2 Bacteriophage by Peracetic Acid and Monochloramine in Municipal Secondary Wastewater Effluent.

    Science.gov (United States)

    Dunkin, Nathan; Weng, ShihChi; Schwab, Kellogg J; McQuarrie, James; Bell, Kati; Jacangelo, Joseph G

    2017-03-07

    Chlorination has long been used for disinfection of municipal wastewater (MWW) effluent while the use peracetic acid (PAA) has been proposed more recently in the United States. Previous work has demonstrated the bactericidal effectiveness of PAA and monochloramine in wastewater, but limited information is available for viruses, especially ones of mammalian origin (e.g., norovirus). Therefore, a comparative assessment was performed of the virucidal efficacy of PAA and monochloramine against murine norovirus (MNV) and MS2 bacteriophage in secondary effluent MWW and phosphate buffer (PB). A suite of inactivation kinetic models was fit to the viral inactivation data. Predicted concentration-time (CT) values for 1-log10 MS2 reduction by PAA and monochloramine in MWW were 1254 and 1228 mg-min/L, respectively. The 1-, 2-, and 3-log10 model predicted CT values for MNV viral reduction in MWW were 32, 47, and 69 mg-min/L for PAA and 6, 13, and 28 mg-min/L for monochloramine, respectively. Wastewater treatment plant disinfection practices informed by MS2 inactivation data will likely be protective for public health but may overestimate CT values for reduction of MNV. Additionally, equivalent CT values in PB resulted in greater viral reduction which indicate that viral inactivation data in laboratory grade water may not be generalizable to MWW applications.

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

    Science.gov (United States)

    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.

  6. Laboratory studies on the reactions between chlorine, sulfur dioxide, and oxygen - Implications for the Venus stratosphere

    Energy Technology Data Exchange (ETDEWEB)

    Demore, W.B.; Leu, M.T.; Smith, R.H.; Yung, Y.L.

    1985-09-01

    Fourier transform IR spectrophotometry is used to monitor the reactants and products in a Venus stratosphere simulation study involving the photolysis of mixtures of Cl/sub 2/ and SO/sub 2/, with and without O/sub 2/ present in an atmosphere of N/sub 2/. When several speculative reactions inferred from these experiments are incorporated by the Yung and DeMore (1982) model of Venus stratospheric chemistry, it emerges that SO/sub 2/Cl/sub 2/ is a key reservoir species for chlorine, and that the reaction between Cl and SO/sub 2/ furnishes an important cycle for the destruction of O/sub 2/ and the conversion of SO/sub 2/ to H/sub 2/SO/sub 4/, thereby providing a possible solution to the photochemistry of the Venus stratosphere. 17 references.

  7. Survival of lactic acid and chlorine dioxide treated Campylobacter jejuni under suboptimal conditions of pH, temperature and modified atmosphere

    DEFF Research Database (Denmark)

    Smigic, Nada; Rajkovic, Andreja; Nielsen, Dennis Sandris;

    2010-01-01

    Campylobacter jejuni cells treated with lactic acid (LA, 3% lactic acid, pH 4.0, 2 min) or chlorine dioxide (ClO(2), 20 ppm, 2 min) were inoculated in Bolton broth (pH 6.0) and incubated under 80% O(2)/20% N(2), 80% CO(2)/20% N(2), air or micro-aerophilic (10% CO(2)/85% N(2)/5% O(2)) atmosphere, at 4 degrees C...

  8. CHLORINE DIOXIDE TREATMENT OF SISAL FIBRE: SURFACE LIGNIN AND ITS INFLUENCES ON FIBRE SURFACE CHARACTERISTICS AND INTERFACIAL BEHAVIOUR OF SISAL FIBRE/PHENOLIC RESIN COMPOSITES

    Directory of Open Access Journals (Sweden)

    Linxin Zhong

    2010-11-01

    Full Text Available This paper describes an investigation of the influences of chlorine dioxide treatment on fibre surface lignin. The fibre surface characteristics and the interfacial behaviour of the sisal fibre/phenolic resin composites were also studied by SEM, AFM, and XPS. The results show that the surface of the untreated fibre contains a large amount of lignin with granular structure and non-granular structure. The surface lignin concentration is up to 51% for the untreated fibre, and then it decreases to 24% and 20% for fibres treated with 1.5 % and 2.0% chlorine dioxide, respectively. The removal of lignin from the fibre surface can enhance the interfacial strength of the composites, giving rise to increases by 36% and 28% in tensile strength and internal bonding strength. These results indicate that the surface properties of single sisal fibres can be tailored to improve the fibre/resin interface. Chlorine dioxide treatment has potential for surface modification of sisal fibre in engineering the interfacial behaviour of composites.

  9. The Biocide Chlorine Dioxide Stimulates Biofilm Formation in Bacillus subtilis by Activation of the Histidine Kinase KinC▿ †

    Science.gov (United States)

    Shemesh, Moshe; Kolter, Roberto; Losick, Richard

    2010-01-01

    Bacillus subtilis forms biofilms in response to signals that remain poorly defined. We report that biofilm formation is stimulated by sublethal doses of chlorine dioxide (ClO2), an extremely effective and fast-acting biocide. ClO2 accelerated biofilm formation in B. subtilis as well as in other bacteria, suggesting that biofilm formation is a widely conserved response to sublethal doses of the agent. Biofilm formation depends on the synthesis of an extracellular matrix that holds the constituent cells together. We show that the transcription of the major operons responsible for the matrix production in B. subtilis, epsA-epsO and yqxM-sipW-tasA, was enhanced by ClO2, in a manner that depended on the membrane-bound kinase KinC. Activation of KinC appeared to be due to the ability of ClO2 to collapse the membrane potential. Importantly, strains unable to make a matrix were hypersensitive to ClO2, indicating that biofilm formation is a defensive response that helps protect cells from the toxic effects of the biocide. PMID:20971918

  10. Experimental Study of Closed System in the Chlorine Dioxide-Iodide-Sulfuric Acid Reaction by UV-Vis Spectrophotometric Method

    Science.gov (United States)

    Li, Na; Shi, Laishun; Wang, Xiaomei; Guo, Fang; Yan, Chunying

    2011-01-01

    The mole ratio r(r = [I−]0/[ClO2]0) has great influence on ClO2-I−-H2SO4 closed reaction system. By changing the initiate concentration of potassium iodide, the curve of absorbance along with the reaction time was obtained at 350 nm and 297 nm for triiodide ion, and 460 nm for iodine. The changing point of the absorbance curve's shape locates at r = 6.00. For the reaction of ClO2-I− in the absence of H2SO4, the curve of absorbance along with the reaction time can be obtained at 350 nm for triiodide ion, 460 nm for iodine. The mole ratio r is equal to 1.00 is the changing point of the curve's shape no matter at which wavelength to determine the reaction. For the reaction of ClO2-I−-H+ in different pH buffer solution, the curve of absorbance along with the reaction time was recorded at 460 nm for iodine. When r is greater than 1.00, the transition point of the curve's shape locates at pH 2.0, which is also the point of producing chlorite or chloride for chlorine dioxide at different pH. When r is less than 1.00, the transition point locates at pH 7.0. PMID:21808646

  11. Experimental Study of Closed System in the Chlorine Dioxide-Iodide-Sulfuric Acid Reaction by UV-Vis Spectrophotometric Method

    Directory of Open Access Journals (Sweden)

    Na Li

    2011-01-01

    Full Text Available The mole ratio r(r=[I−]0/[ClO2]0 has great influence on ClO2-I−-H2SO4 closed reaction system. By changing the initiate concentration of potassium iodide, the curve of absorbance along with the reaction time was obtained at 350 nm and 297 nm for triiodide ion, and 460 nm for iodine. The changing point of the absorbance curve's shape locates at r=6.00. For the reaction of ClO2-I− in the absence of H2SO4, the curve of absorbance along with the reaction time can be obtained at 350 nm for triiodide ion, 460 nm for iodine. The mole ratio r is equal to 1.00 is the changing point of the curve's shape no matter at which wavelength to determine the reaction. For the reaction of ClO2-I−-H+ in different pH buffer solution, the curve of absorbance along with the reaction time was recorded at 460 nm for iodine. When r is greater than 1.00, the transition point of the curve's shape locates at pH 2.0, which is also the point of producing chlorite or chloride for chlorine dioxide at different pH. When r is less than 1.00, the transition point locates at pH 7.0.

  12. Effect of low-concentration chlorine dioxide gas against bacteria and viruses on a glass surface in wet environments.

    Science.gov (United States)

    Morino, H; Fukuda, T; Miura, T; Shibata, T

    2011-12-01

    To evaluate the efficacy of low-concentration chlorine dioxide (ClO(2)) gas against model microbes in the wet state on a glass surface. We set up a test room (39 m(3)) and the ClO(2) gas was produced by a ClO(2) gas generator that continuously releases a constant low-concentration ClO(2) gas. Influenza A virus (Flu-A), feline calicivirus (FCV), Staphylococcus aureus and Escherichia coli were chosen as the model microbes. The low-concentration ClO(2) gas (mean 0.05 ppmv, 0.14 mg m(-3)) inactivated Flu-A and E. coli (>5 log(10) reductions) and FCV and S. aureus (>2 log(10) reductions) in the wet state on glass dishes within 5 h. The treatment of wet environments in the presence of human activity such as kitchens and bathrooms with the low-concentration ClO(2) gas would be useful for reducing the risk of infection by bacteria and viruses residing on the environmental hard surfaces without adverse effects. This study demonstrates that the low-concentration ClO(2) gas (mean 0.05 ppmv) inactivates various kinds of microbes such as Gram-positive and Gram-negative bacteria, enveloped and nonenveloped viruses in the wet state. © 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.

  13. STUDY ON DISINFECTION PROPERTIES OF A CHLORINE DIOXIDE DISINFECTANT%一种二氧化氯消毒剂消毒性能的研究

    Institute of Scientific and Technical Information of China (English)

    王衍德; 李波菊; 陈婷

    2013-01-01

    Objective To study the antiseptic property of a chlorine dioxide disinfectant.Methods Suspension quantitative germicidal test and field disinfection test are used to observe the disinfectant properties in laboratory.Results The average killing logarithm value of Escherichia coli and Staphylococcus aureus in suspension are above 5.00 by the disinfectant water solution containing 121 mg/L chlorine dioxide for 5 minutes.In the energy test of Escherichia coli,the lowest certiffed concentration is 600 mg/L chlorine dioxide.The disinfectant water solution containing 121 mg/L chlorine dioxide is used to spray wood surface until the surface is moist for 20 minutes,and the average killing logarithmic values of natural bacterium on the surface is above 1.00.If the disinfectant water solution containing 121 mg/L chlorine dioxide is used to soak fabrics for 10 minutes,and the average killing logarithmic values of the natural bacterium carried in the fabrics is above 1.00.Conclusion The disinfectant has relatively strong disinfection effect to bacterial vegetative form and natural bacteria on body surface.%目的 研究一种二氧化氯消毒剂的消毒相关性能.方法 采用悬液定量杀菌试验和现场消毒试验,对该消毒剂进行了试验观察.结果 用含二氧化氯121 mg/L该消毒剂水溶液作用5min,对悬液内大肠杆菌和金黄色葡萄球菌的平均杀灭对数值均>5.00.对大肠杆菌的能量试验,其最低合格浓度为600 mg/L二氧化氯.用含二氧化氯121 mg/L消毒液喷洒木质物体表面至其潮湿,作用20 min,对其表面上的自然菌平均杀灭对数值>1.00;浸泡织物10 min,对其携带的自然菌平均杀灭对数值>1.00.结论 该消毒剂对细菌繁殖体和物体表面自然菌均具有较强的杀灭作用.

  14. 二氧化氯空气消毒的效果及评价%Effect of applying natural evaporation of chlorine dioxide on air disinfection

    Institute of Scientific and Technical Information of China (English)

    唐萍; 王艳霞

    2011-01-01

    OBJECTIVE To improve the air quality of the wards and to reduce the incidence of cross-infection in hospitals, and at the same time, to monitor and evaluate the effectiveness of the disinfection by applying the method of natural evaporation of chlorine dioxide to disinfect the air in hospital wards. METHODS In accordance with the requirements of the specifications of disinfection techniques, the natural evaporation water could infused with 200 ml water + 250 mg chlorine dioxide disinfectant tablets, 3 cans were placed in a room which was less than 30cm2; The air of the wards was disinfected through the continuing natural evaporation of chlorine dioxide,and the air in the wards was detected. RESULTS With the continuous functioning of the chlorine dioxide, the TB bacteria and the pathogenic micro-organisms suspended in the air of the wards could be killed with the qualified rates of 98.0%. The continuous monitoring showed that the number of chumps colonies was lower than the standard of Ministry of Health. The effect of the disinfection was satisfactory. CONCLUSION The disinfection effect of applying the method of natural evaporation of chlorine dioxide to disinfect the air in hospital wards is reliable.%目的 应用二氧化氯自然挥发法消毒医院病房的空气,以提高病房空气质量,降低医院交叉感染发生率,同时监测和评价消毒效果.方法按照消毒技术规范的要求,在每间面积<30 m2病房角落里放置3个挥发容器,容器内加入水150 ml+二氧化氯消毒剂250 mg,通过二氧化氯持续自然挥发消毒病房空气,并对病房空气进行检测.结果二氧化氯的持续作用,可杀灭悬浮在病房空气中的结核菌及病原微生物,合格率为98.0%;经持续监测,菌落数低于卫生部的标准;消毒效果满意.结论应用二氧化氯自然挥发进行医院病房空气消毒,其消毒效果可靠.

  15. 气体二氧化氯的光降解规律研究%Research on Photochemical Decomposition of Gaseous Chlorine Dioxide

    Institute of Scientific and Technical Information of China (English)

    崔超; 胡双启; 晋日亚; 张晓宇

    2011-01-01

    为研究气体二氧化氯的光降解规律,利用自行设计的光降解装置,考察不同波长光源、温度和气体二氧化氯初始质量浓度对其降解速率的影响,同时以暗室降解作为参比试验.结果表明:分别在365 nm紫外光、日光、254 nm紫外光以及400~700 nm荧光照射下,相同初始质量浓度的气体二氧化氯的降解速率逐渐下降;当温度在15 ~25℃范围变化时,相同初始质量浓度的气体二氧化氯的日光降解速率基本相同;不同质量浓度的气体二氧化氯在日光照射下,降解速率随气体质量浓度的增加而增大.因此,对气体二氧化氯的光降解起主要作用的波长是在365 nm附近的紫外光;温度对其降解速率基本没有影响;在日光照射下,气体二氧化氯的降解速率与质量浓度的一次方成正比,属于一级反应,其半衰期与初始质量浓度无关,仅与反应速率常数k有关,半衰期约为63 min.%In order to research the laws of the photochemical decomposition of gaseous chlorine dioxide, a systematic experiment has been performed with a photochemical decomposition instrument of self-made. The effects of the wavelength of light sources, temperature, and initial concentration have been studied. The results show that the promoting effects of 365 nm UV, sunlight, 254 nm UV, and fluorescence fall down in turn. The same experiment has been done in the dark as a standard comparison. It is indicates that the ultraviolet light near the visible region plays a key role in the photochemical decomposition of gaseous chlorine dioxide. The temperature doesn't have obvious effect on the decomposition rate over the range of 15 ~25℃. In the sunlight, the decomposition rate is increasing as the initial concentration of chlorine dioxide is increasing. The photochemical decomposition of gaseous chlorine dioxide is first-order reaction and the decomposition rate is proportionate to the concentration of chlorine dioxide

  16. Aqueous chlorine dioxide treatment of horticultural produce: Effects on microbial safety and produce quality - A review.

    Science.gov (United States)

    Praeger, Ulrike; Herppich, Werner B; Hassenberg, Karin

    2016-05-19

    Microbial load on fresh fruit and vegetables causes decay and losses after harvest and may lead to foodborne illness in case of contamination with human pathogens on raw consumed produces. Washing with tap water only marginally reduces microorganisms attached to produce surfaces. Chlorine is widely used for decontamination on fresh horticultural produces. However, due to harmful by-products and the questionable efficacy it has become increasingly challenged. During the last 20 years, the interest to study ClO2 treatments as an alternative sanitation agent for industrially prepared fresh produce has largely increased. For a wide range of commodities, the application of gaseous ClO2 has meanwhile been investigated. In addition, since several years, the interest in aqueous ClO2 treatments has further risen because of the better manageability in postharvest processing lines compared to gaseous application. This article critically evaluated the effects of postharvest application of aqueous ClO2, either alone or in combination with other treatments, on microbial loads for various horticultural produces. In laboratory investigations, application of aqueous ClO2 at concentrations between 3 and 100 ppm effectively reduced counts of natural or inoculated microorganisms (bacteria, yeasts and mold) in the range of 1 and 5 log. However, various effects of ClO2 treatments on produce quality have been described. These mainly comprise implication on sensory and visual attributes. In this context, there is increasing focus on the potential impacts of aqueous ClO2 on relevant nutritional components of produces such as organic acids or phenolic substances.

  17. Efficacy of gaseous chlorine dioxide in inactivating Bacillus cereus spores attached to and in a biofilm on stainless steel.

    Science.gov (United States)

    Nam, Hyegyeong; Seo, Hyun-Sun; Bang, Jihyun; Kim, Hoikyung; Beuchat, Larry R; Ryu, Jee-Hoon

    2014-10-01

    We evaluated the lethal activity of gaseous chlorine dioxide (ClO2) against Bacillus cereus spores attached to and in biofilm formed on a stainless steel surface. Aqueous ClO2 was prepared by mixing sulfuric acid (5% w/v) with sodium chlorite (10mg/mL), and gaseous ClO2 was produced by vaporization of aqueous ClO2 in an air-tight container. The concentration of gaseous ClO2 in the air within the container increased rapidly at first but gradually decreased over time. The lethality of gaseous ClO2 against B. cereus spores attached to stainless steel coupons (SSCs) and in biofilm formed by the pathogen on SSCs was determined. The B. cereus spores attached to SSCs (5.3±0.1logCFU/coupon) were completely inactivated within 1h at 25°C when treated with gaseous ClO2 (peak concentration: 115.3±5.0 parts per million [ppm]). The total number of vegetative cells and spores in biofilm formed by B. cereus on SSCs was 5.9±0.3logCFU/coupon; the spore count was 5.3±0.1logCFU/coupon. The vegetative cells and spores in biofilm were completely inactivated within 6h (peak concentration: 115.3±5.0ppm). Results show that B. cereus spores in biofilms are more resistant to gaseous ClO2 than are attached spores not in biofilms. Gaseous ClO2 was, nevertheless, very effective in killing B. cereus spores in biofilm on the surface of stainless steel. Results show promise for application of gaseous ClO2 to enhance the microbiological safety of foods that may come in contact with stainless steel and possibly other hard surfaces on which B. cereus biofilms have formed.

  18. Combination treatment of chlorine dioxide gas and aerosolized sanitizer for inactivating foodborne pathogens on spinach leaves and tomatoes.

    Science.gov (United States)

    Park, Sang-Hyun; Kang, Dong-Hyun

    2015-08-17

    The objective of this study was to evaluate the antimicrobial effect of chlorine dioxide (ClO2) gas and aerosolized sanitizer, when applied alone or in combination, on the survival of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes inoculated onto spinach leaves and tomato surfaces. Spinach leaves and tomatoes were inoculated with a cocktail of three strains each of the three foodborne pathogens. ClO2 gas (5 or 10 ppmv) and aerosolized peracetic acid (PAA) (80 ppm) were applied alone or in combination for 20 min. Exposure to 10 ppmv of ClO2 gas for 20 min resulted in 3.4, 3.3, and 3.4 log reductions of E. coli O157:H7, S. Typhimurium, and L. monocytogenes on spinach leaves, respectively. Treatment with 80 ppm of aerosolized PAA for 20 min caused 2.3, 1.9, and 0.8 log reductions of E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively. Combined treatment of ClO2 gas (10 ppmv) and aerosolized PAA (80 ppm) for 20 min caused 5.4, 5.1, and 4.1 log reductions of E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively. E. coli O157:H7, S. Typhimurium, and L. monocytogenes on tomatoes experienced similar reduction patterns to those on spinach leaves. As treatment time increased, most combinations of ClO2 gas and aerosolized PAA showed additive effects in the inactivation of the three pathogens. Combined treatment of ClO2 gas and aerosolized PAA produced injured cells of three pathogens on spinach leaves while generally did not produce injured cells of these pathogens on tomatoes. Combined treatment of ClO2 gas (10 ppmv) and aerosolized PAA (80 ppm) did not significantly (p>0.05) affect the color and texture of samples during 7 days of storage.

  19. Inactivation Kinetics and Mechanism of a Human Norovirus Surrogate on Stainless Steel Coupons via Chlorine Dioxide Gas.

    Science.gov (United States)

    Yeap, Jia Wei; Kaur, Simran; Lou, Fangfei; DiCaprio, Erin; Morgan, Mark; Linton, Richard; Li, Jianrong

    2015-10-16

    Acute gastroenteritis caused by human norovirus is a significant public health issue. Fresh produce and seafood are examples of high-risk foods associated with norovirus outbreaks. Food contact surfaces also have the potential to harbor noroviruses if exposed to fecal contamination, aerosolized vomitus, or infected food handlers. Currently, there is no effective measure to decontaminate norovirus on food contact surfaces. Chlorine dioxide (ClO2) gas is a strong oxidizer and is used as a decontaminating agent in food processing plants. The objective of this study was to determine the kinetics and mechanism of ClO2 gas inactivation of a norovirus surrogate, murine norovirus 1 (MNV-1), on stainless steel (SS) coupons. MNV-1 was inoculated on SS coupons at the concentration of 10(7) PFU/coupon. The samples were treated with ClO2 gas at 1, 1.5, 2, 2.5, and 4 mg/liter for up to 5 min at 25°C and a relative humidity of 85%, and virus survival was determined by plaque assay. Treatment of the SS coupons with ClO2 gas at 2 mg/liter for 5 min and 2.5 mg/liter for 2 min resulted in at least a 3-log reduction in MNV-1, while no infectious virus was recovered at a concentration of 4 mg/liter even within 1 min of treatment. Furthermore, it was found that the mechanism of ClO2 gas inactivation included degradation of viral protein, disruption of viral structure, and degradation of viral genomic RNA. In conclusion, treatment with ClO2 gas can serve as an effective method to inactivate a human norovirus surrogate on SS contact surfaces.

  20. Reduction of Salmonella enterica on the surface of eggshells by sequential treatment with aqueous chlorine dioxide and drying.

    Science.gov (United States)

    Choi, Seonyeong; Park, Sunhyung; Kim, Yoonsook; Kim, Byeong-sam; Beuchat, Larry R; Hoikyung, Kim; Ryu, Jee-Hoon

    2015-10-01

    The synergistic effects of sequential treatments with chlorine dioxide (ClO2) and drying in killing Salmonella enterica on the surface of chicken eggshells were investigated. Initial experiments were focused on comparing lethalities of sodium hypochlorite (NaOCl) and ClO2. Eggs surface-inoculated with S. enterica in chicken feces as a carrier were immersed in water, NaOCl (50 or 200 μg/mL), or ClO2 (50 or 200 μg/mL) for 1 or 5 min. For 1-min treatments, lethal activities of sanitizers were not significantly different (P>0.05). However, after treatment with ClO2 for 5 min, reductions of S. enterica were significantly greater (P≤0.05) than reductions after treatment with water or NaOCl. The effect of treatment of eggs with ClO2 or NaOCl, followed by drying at 43% relative humidity and 25 °C for 24 and 48 h, were determined. Populations of S. enterica decreased during drying, regardless of the type of sanitizer treatment. ClO2 treatment, compared to water or NaOCl treatments, resulted in additional reductions of ca. >1.3 log CFU/egg during drying. This indicates that sequential treatments with ClO2 and drying induced synergistic lethal effects against S. enterica on the surface of eggshells. These observations will be useful when selecting a sanitizer to control S. enterica on the surface of eggshells and designing an effective egg sanitization system exploiting the synergistic lethal effects of sanitizer and drying.

  1. Comparisons of the film peeling from the composite oxides of quartz sand filters using ozone, hydrogen peroxide and chlorine dioxide.

    Science.gov (United States)

    Guo, Yingming; Huang, Tinglin; Wen, Gang; Cao, Xin

    2015-08-01

    To solve the problem of shortened backwashing intervals in groundwater plants, several disinfectants including ozone (O3), hydrogen peroxide (H2O2) and chlorine dioxide (ClO2) were examined to peel off the film from the quartz sand surface in four pilot-scale columns. An optimized oxidant dosage and oxidation time were determined by batch tests. Subsequently, the optimized conditions were tested in the four pilot-scale columns. The results demonstrated that the backwashing intervals increased from 35.17 to 54.33 (H2O2) and to 53.67 hr (ClO2) after the oxidation treatments, and the increase of backwashing interval after treatment by O3 was much less than for the other two treatments. Interestingly, the treatment efficiency of filters was not affected by O3 or H2O2 oxidation; but after oxidation by ClO2, the treatment efficiency was deteriorated, especially the ammonia removal (from 96.96% to 24.95%). The filter sands before and after the oxidation were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. Compared with the oxidation by O3 and H2O2, the structures on the surface of filter sands were seriously damaged after oxidation by ClO2. The chemical states of manganese on the surfaces of those treated sands were only changed by ClO2. The damage of the structures and the change of the chemical states of manganese might have a negative effect on the ammonia removal. In summary, H2O2 is a suitable agent for film peeling.

  2. Systematic Evaluation of the Efficacy of Chlorine Dioxide in Decontamination of Building Interior Surfaces Contaminated with Anthrax Spores▿

    Science.gov (United States)

    Rastogi, Vipin K.; Ryan, Shawn P.; Wallace, Lalena; Smith, Lisa S.; Shah, Saumil S.; Martin, G. Blair

    2010-01-01

    Efficacy of chlorine dioxide (CD) gas generated by two distinct generation systems, Sabre (wet system with gas generated in water) and ClorDiSys (dry system with gas generated in air), was evaluated for inactivation of Bacillus anthracis spores on six building interior surfaces. The six building materials included carpet, acoustic ceiling tile, unpainted cinder block, painted I-beam steel, painted wallboard, and unpainted pinewood. There was no statistically significant difference in the data due to the CD generation technology at a 95% confidence level. Note that a common method of CD gas measurement was used for both wet and dry CD generation types. Doses generated by combinations of different concentrations of CD gas (500, 1,000, 1,500, or 3,000 parts per million of volume [ppmv]) and exposure times (ranging between 0.5 and 12 h) were used to evaluate the relative role of fumigant exposure period and total dose in the decontamination of building surfaces. The results showed that the time required to achieve at least a 6-log reduction in viable spores is clearly a function of the material type on which the spores are inoculated. The wood and cinder block coupons required a longer exposure time to achieve a 6-log reduction. The only material showing a clear statistical difference in rate of decay of viable spores as a function of concentration was cinder block. For all other materials, the profile of spore kill (i.e., change in number of viable spores with exposure time) was not dependent upon fumigant concentration (500 to 3,000 ppmv). The CD dose required for complete spore kill on biological indicators (typically, 1E6 spores of Bacillus atrophaeus on stainless steel) was significantly less than that required for decontamination of most of the building materials tested. PMID:20305025

  3. Surrogate testing suggests that chlorine dioxide gas exposure would not inactivate Ebola virus contained in environmental blood contamination.

    Science.gov (United States)

    Lowe, John J; Hewlett, Angela L; Iwen, Peter C; Smith, Philip W; Gibbs, Shawn G

    2015-05-08

    The ability to decontaminate a room potentially containing the Ebola virus is important to healthcare facilities in the United States. Ebola virus remains viable in body fluids, a room that has housed a patient with Ebola virus disease must have all surfaces manually wiped with an approved disinfectant, which increases occupational exposure risk. This study evaluated the efficacy of gaseous chlorine dioxide inactivation of bacterial organisms in blood as Ebola virus surrogates and as the organisms used by the Nebraska Biocontainment Unit to provide the margin of safety for decontamination. Bacillus anthracis, Escherichia coli, Enterococcus faecalis, and Mycobacterium smegmatis blood suspensions that were exposed to ClO2 gas concentrations and exposure limits. The log reduction in Colony Forming Units (CFU) was determined for each bacterial blood suspension. Exposure parameters approximating industry practices for ClO2 environmental decontamination (360ppm concentration to 780 ppm-hrs exposure, 65% relative humidity) as well as parameters exceeding current practice (1116 ppm concentration to 1400 ppm-hrs exposure; 1342ppm concentration to 1487 ppm-hrs exposure) were evaluated. Complete inactivation was not achieved for any of the bacterial blood suspensions tested. Reductions were observed in concentrations of B. anthracis spores (1.3 -3.76 log) and E. faecalis vegetative cells (1.3 log) whereas significant reductions in vegetative cell concentrations for E. coli and M. smegmatis blood suspensions were not achieved. Our results showed that bacteria in the presence of blood were not inactivated using gaseous ClO2 decontamination. ClO2 decontamination alone should not be used for Ebola virus, but decontamination processes should first include manual wiping of potentially contaminated blood; especially for microorganisms as infectious as the Ebola virus.

  4. Disinfection by-products of chlorine dioxide (chlorite, chlorate, and trihalomethanes): Occurrence in drinking water in Qatar.

    Science.gov (United States)

    Al-Otoum, Fatima; Al-Ghouti, Mohammad A; Ahmed, Talaat A; Abu-Dieyeh, Mohammed; Ali, Mohammed

    2016-12-01

    The occurrence of chlorine dioxide (ClO2) disinfection by-products (DBPs) in drinking water, namely, chlorite, chlorate, and trihalomethanes (THMs), was investigated. Two-hundred-ninety-four drinking water samples were collected from seven desalination plants (DPs), four reservoirs (R), and eight mosques (M) distributed within various locations in southern and northern Qatar. The ClO2 concentration levels ranged from 0.38 to <0.02 mg L(-1), with mean values of 0.17, 0.12, and 0.04 mg L(-1) for the DPs, Rs, and Ms, respectively. The chlorite levels varied from 13 μg L(-1) to 440 μg L(-1), with median values varying from 13 to 230 μg L(-1), 77-320 μg L(-1), and 85-440 μg L(-1) for the DPs, Rs, and Ms, respectively. The chlorate levels varied from 11 μg L(-1) to 280 μg L(-1), with mean values varying from 36 to 280 μg L(-1), 11-200 μg L(-1), and 11-150 μg L(-1) in the DPs, Rs, and Ms, respectively. The average concentration of THMs was 5 μg L(-1), and the maximum value reached 77 μg L(-1) However, all of the DBP concentrations fell within the range of the regulatory limits set by GSO 149/2009, the World Health Organization (WHO), and Kahramaa (KM).

  5. Formation of iodinated disinfection by-products during oxidation of iodide-containing waters with chlorine dioxide.

    Science.gov (United States)

    Ye, Tao; Xu, Bin; Lin, Yi-Li; Hu, Chen-Yan; Lin, Lin; Zhang, Tian-Yang; Gao, Nai-Yun

    2013-06-01

    This study was to explore the formation of iodinated disinfection by-products (I-DBPs), including iodoform (CHI3), iodoacetic acid (IAA) and triiodoacetic acid (TIAA), when iodide-containing artificial synthesized waters and raw waters are in contact with chlorine dioxide (ClO2). Among the investigated I-DBPs, CHI3 was the major species during ClO2 oxidation in artificial synthesized waters. Impact factors were evaluated, including the concentrations of ClO2, iodide (I(-)), dissolved organic carbon (DOC) and pH. Formation of CHI3, IAA and TIAA followed an increasing and then decreasing pattern with increased ClO2 or DOC concentration. I-DBPs yield was significantly affected by solution pH. High concentrations of I-DBPs were generated under circumneutral conditions with the maximum formation at pH 8. The increase of I(-) concentration can increase I-DBPs yields, but the increment was suppressed when I(-) concentration was higher than 50 μM. When 100 μg/L I(-)and ClO2 (7.5-44.4 μM) were spiked to the raw water samples from Yangshupu and Minhang drinking water treatment plant, certain amounts of CHI3 and IAA were found under pH 7 and the concentrations were strongly correlated with ClO2 dosage and water qualities, however, no TIAA was detected. Finally, we investigated I-DBPs formation of 18 model compounds, including 4 carboxylic acids, 5 phenols and 8 amino acids, treating with ClO2 when I(-) was present. Results showed that most of these model compounds could form a considerable amount of I-DBPs, especially for propanoic acid, butanoic acid, resorcinol, hydroquinone, alanine, glutamic acid, phenylalanine and serine.

  6. Evaluation of current operating standards for chlorine dioxide in disinfection of dump tank and flume for fresh tomatoes.

    Science.gov (United States)

    Tomás-Callejas, Alejandro; López-Velasco, Gabriela; Valadez, Angela M; Sbodio, Adrian; Artés-Hernández, Francisco; Danyluk, Michelle D; Suslow, Trevor V

    2012-02-01

    Standard postharvest unit operations that rely on copious water contact, such as fruit unloading and washing, approach the criteria for a true critical control point in fresh tomato production. Performance data for approved sanitizers that reflect commercial systems are needed to set standards for audit compliance. This study was conducted to evaluate the efficacy of chlorine dioxide (ClO(2)) for water disinfection as an objective assessment of recent industry-adopted standards for dump tank and flume management in fresh tomato packing operations. On-site assessments were conducted during eight temporally distinct shifts in two Florida packinghouses and one California packinghouse. Microbiological analyses of incoming and washed fruit and dump and flume system water were evaluated. Water temperature, pH, turbidity, conductivity, and oxidation-reduction potential (ORP) were monitored. Reduction in populations of mesophilic and coliform bacteria on fruit was not significant, and populations were significantly higher (P dump tanks but consistently below the detection limit in flumes. Turbidity and conductivity increased with loads of incoming tomatoes. Water temperature varied during daily operations, but pH and ORP mostly remained constant. The industry standard positive temperature differential of 5.5°C between water and fruit pulp was not maintained in tanks during the full daily operation. ORP values were significantly higher in the flume than in the dump tank. A positive correlation was found between ORP and temperature, and negative correlations were found between ORP and turbidity, total mesophilic bacteria, and coliforms. This study provides in-plant data indicating that ClO(2) can be an effective sanitizer in flume and spray-wash systems, but current operational limitations restrict its performance in dump tanks. Under current conditions, ClO(2) alone is unlikely to allow the fresh tomato industry to meet its microbiological quality goals under typical

  7. Characterization of halogenated DBPs and identification of new DBPs trihalomethanols in chlorine dioxide treated drinking water with multiple extractions.

    Science.gov (United States)

    Han, Jiarui; Zhang, Xiangru; Liu, Jiaqi; Zhu, Xiaohu; Gong, Tingting

    2017-08-01

    Chlorine dioxide (ClO2) is a widely used alternative disinfectant due to its high biocidal efficiency and low-level formation of trihalomethanes and haloacetic acids. A major portion of total organic halogen (TOX), a collective parameter for all halogenated DBPs, formed in ClO2-treated drinking water is still unknown. A commonly used pretreatment method for analyzing halogenated DBPs in drinking water is one-time liquid-liquid extraction (LLE), which may lead to a substantial loss of DBPs prior to analysis. In this study, characterization and identification of polar halogenated DBPs in a ClO2-treated drinking water sample were conducted by pretreating the sample with multiple extractions. Compared to one-time LLE, the combined four-time LLEs improved the recovery of TOX by 2.3 times. The developmental toxicity of the drinking water sample pretreated with the combined four-time LLEs was 1.67 times higher than that pretreated with one-time LLE. With the aid of ultra-performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry, a new group of polar halogenated DBPs, trihalomethanols, were detected in the drinking water sample pretreated with multiple extractions; two of them, trichloromethanol and bromodichloromethanol, were identified with synthesized standard compounds. Moreover, these trihalomethanols were found to be the transformation products of trihalomethanes formed during ClO2 disinfection. The results indicate that multiple LLEs can significantly improve extraction efficiencies of polar halogenated DBPs and is a better pretreatment method for characterizing and identifying new polar halogenated DBPs in drinking water. Copyright © 2017. Published by Elsevier B.V.

  8. Chloroacetonitrile and n,2-dichloroacetamide formation from the reaction of chloroacetaldehyde and monochloramine in water.

    Science.gov (United States)

    Kimura, Susana Y; Komaki, Yukako; Plewa, Michael J; Mariñas, Benito J

    2013-01-01

    Combined chlorine is increasingly being used as an alternative disinfectant to free chlorine to maintain a residual in drinking water distribution systems mainly because it would reduce the formation of regulated disinfection byproducts (DBPs) trihalomethanes and haloacetic acids. However, the use of combined chlorine could promote the formation of currently unregulated nitrogenous DBPs (N-DBPs) such as haloacetonitriles and haloacetamides that are found to be more cyto- and genotoxic than regulated DBPs. Monochloramine quickly reacts with chloroacetaldehyde, a DBP formed during primary disinfection with free chlorine, forming and reaching pseudoequilibrium (equilibrium constant K1 = 1.87 × 10(3) M(-1)) with the carbinolamine 2-chloro-1-(chloroamino)ethanol. 2-Chloro-1-(chloroamino)ethanol undergoes slow dehydration to form the imine 1-chloro-2-(chloroimino)ethane that decomposes at a faster rate to chloroacetonitrile. 2-Chloro-1-(chloroamino)ethanol is also oxidized by monochloramine to produce the previously unreported DBP N,2-dichloroacetamide. The carbinolamine dehydration step was found to be acid/base catalyzed (k2(0) = 3.30 × 10(-6) s(-1), k2(H) = 2.43 M(-1) s(-1), k2(OH) = 3.90 M(-1) s(-1)). In contrast, N,2-dichloroacetamide formation was observed to be only base catalyzed (k3(OH) = 3.03 × 10(4) M(-2) s(-1)). N,2-dichloroacetamide cytotoxicity (LC50 = 2.56 × 10(-4) M) was found to be slightly lower compared to that reported for chloroacetamide but higher than those of di- and trichloroacetamide.

  9. Radiation enhanced thermal diffusion of chlorine in uranium dioxide; Diffusion thermique et sous irradiation du chlore dans le dioxyde d'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Pipon, Yves [Ecole doctorale de physique et d' astrophysique, Universite Claude Bernard Lyon-I, Lyon (France)

    2006-12-15

    This work concerns the study of the thermal and radiation enhanced diffusion of {sup 36}Cl in uranium dioxide. It is a contribution to PRECCI programme (research programme on the long-term behaviour of the spent nuclear fuel). {sup 36}Cl is a long lived volatile activation product (T = 300 000 years) able to contribute significantly to the instant release fraction in geological disposal conditions. We simulated the presence of {sup 36}Cl by implanting a quantity of {sup 37}Cl comparable to the impurity content of chlorine in UO{sub 2}. In order to evaluate the diffusion properties of chlorine in the fuel and in particular to assess the influence of the irradiation defects, we performed two kinds of experiments: - the influence of the temperature was studied by carrying out thermal annealings in the temperature range 900 - 1300 deg. C; we showed that implanted chlorine was mobile from temperatures as low as 1000 deg. C and determined a thermal diffusion coefficient D{sub 1000} {sub deg.} {sub C} around 10{sup -16} cm{sup 2}s{sup -1} and deduced an activation energy of 4.3 eV. This value is one of lowest compared to that of volatile fission products such as iodine or the xenon. These parameters reflect the very mobile behaviour of chlorine; - the irradiation effects induced by fission products were studied by irradiating the samples with {sup 127}I (energy of 63.5 MeV). We showed that the implanted chlorine diffusion in the temperature range 30 - 250 deg. C is not purely athermal. In these conditions, the diffusion coefficient D{sub 250} {sub deg.} {sub C} for the implanted chlorine is around 10{sup -14} cm{sup 2}s{sup -1} and the activation energy is calculated to be 0.1 eV. Moreover, at 250 deg. C, we observed an important transport of the pristine chlorine from the bulk towards the surface. This chlorine comes from a zone where the defects are mainly produced by the nuclear energy loss process at the end of iodine range. We showed the importance of the

  10. Thermal diffusion of chlorine in uranium dioxide studied by secondary ion mass spectrometry and X-ray absorption spectroscopy

    Science.gov (United States)

    Pipon, Y.; Toulhoat, N.; Moncoffre, N.; Raimbault, L.; Scheidegger, A. M.; Farges, F.; Carlot, G.

    2007-05-01

    In a nuclear reactor, 35Cl present as an impurity in the nuclear fuel is activated by thermal neutron capture. During interim storage or geological disposal of the nuclear fuel, 36Cl may be released from the fuel to the geo/biosphere and contribute significantly to the 'instant release fraction'. In order to elucidate the diffusion mechanisms, both irradiation and thermal effects must be assessed. This paper deals with the thermal diffusion of chlorine in depleted UO2. For this purpose, sintered UO2 pellets were implanted with 37Cl at an ion fluence of 1013 cm-2 and successively annealed in the 1175-1475 K temperature range. The implanted chlorine is used to simulate the behaviour of the displaced one due to recoil and to interactions with the fission fragments during reactor operation. The behaviour of the pristine and the implanted chlorine was investigated during thermal annealing. SIMS and μ-XAS (at the Cl-K edge) analyses show that: the thermal migration of implanted chlorine becomes significant at 1275 K; this temperature and the calculated activation energy of 4.3 eV points out the great ability of chlorine to migrate in UO2 at relatively low temperatures, the behaviour of the implanted chlorine which aggregates into 'hot spots' during annealing before its effusion is clearly different from that of the pristine one which remains homogenously distributed after annealing, the 'hot spot' and the pristine chlorine seem to be in different structural environments. Both types of chlorine are assumed to have a valence state of -I, the comparison between an U2O2Cl5 reference compound and the pristine chlorine environment shows a contribution of the U2O2Cl5 to the pristine chlorine.

  11. Influence of ultrasound enhancement on chlorine dioxide consumption and disinfection by-products formation for secondary effluents disinfection.

    Science.gov (United States)

    Zhou, Xiaoqin; Zhao, Junyuan; Li, Zifu; Lan, Juanru; Li, Yajie; Yang, Xin; Wang, Dongling

    2016-01-01

    Chlorine dioxide (ClO2) has been promoted as an alternative disinfectant because of its high disinfection efficiency and less formation of organic disinfection by-products (DBPs). However, particle-associated microorganisms could be protected during the disinfection process, which decreases the disinfection efficiency or increases the required dosage. Besides, the formation of inorganic disinfection by-products is a significant concern in environment health. Ultrasound (US)-combined disinfection methods are becoming increasingly attractive because they are efficient and environmentally friendly. In this study, US was introduced as an enhancement method to identify its influence on ClO2 demand reduction and to minimize the production of potential DBPs for secondary effluents disinfection. Fecal coliform was used as an indicator, and DBPs, including trichloromethane (TCM), dichloroacetic acid (DCAA), trichloroacetic acid (TCAA), chlorite (ClO2(-)), and chlorate (ClO3(-)), were analyzed to observe the potential DBPs formation. Results show that US pretreatment could reduce half of ClO2 dosage compared with ClO2 disinfection alone for the same disinfection efficiency, and that an input power density of 2.64 kJ/L pretreatment with the 1.5mg/L ClO2 was enough to meet the discharge requirement in China (i.e., fecal coliform below 1000 CFU/L for Class 1A) for secondary effluent disinfection, and the ClO2(-) concentration in the disinfection effluent was only 1.37 mg/L at the same time. Furthermore, the different effects of US on the two processes (US as pretreatment and simultaneous US/ClO2 disinfection) were also analyzed, including deagglomerating, cell damage, and synergistic disinfection as well as degasing/sonolysis. It was proved that the production of TCM, DCAA, and TCAA was insignificantly influenced with the introduction of US, but US pretreatment did reduce the production of ClO2(-) and ClO3(-) effectually. In general, US pretreatment could be a better option for

  12. Oxidative stress induced by chlorine dioxide as an insecticidal factor to the Indian meal moth, Plodia interpunctella.

    Science.gov (United States)

    Kumar, Sunil; Park, Jiyeong; Kim, Eunseong; Na, Jahyun; Chun, Yong Shik; Kwon, Hyeok; Kim, Wook; Kim, Yonggyun

    2015-10-01

    A novel fumigant, chlorine dioxide (ClO2) is a commercial bleaching and disinfection agent. Recent study indicates its insecticidal activity. However, its mode of action to kill insects is yet to be understood. This study set up a hypothesis that an oxidative stress induced by ClO2 is a main factor to kill insects. The Indian meal moth, Plodia interpunctella, is a lepidopteran insect pest infesting various stored grains. Larvae of P. interpunctella were highly susceptible to ClO2 gas, which exhibited an acute toxicity. Physiological damages by ClO2 were observed in hemocytes. At high doses, the larvae of P. interpunctella suffered significant reduction of total hemocytes. At low doses, ClO2 impaired hemocyte behaviors. The cytotoxicity of ClO2 was further analyzed using two insect cell lines, where Sf9 cells were more susceptible to ClO2 than High Five cells. The cells treated with ClO2 produced reactive oxygen species (ROS). The produced ROS amounts increased with an increase of the treated ClO2 amount. However, the addition of an antioxidant, vitamin E, significantly attenuated the cytotoxicity of ClO2 in a dose-dependent manner. To support the oxidative stress induced by ClO2, two antioxidant genes (superoxide dismutase (SOD) and thioredoxin-peroxidase (Tpx)) were identified from P. interpunctella EST library using ortholog sequences of Bombyx mori. Both SOD and Tpx were expressed in larvae of P. interpunctella especially under oxidative stress induced by bacterial challenge. Exposure to ClO2 gas significantly induced the gene expression of both SOD and Tpx. RNA interference of SOD or Tpx using specific double stranded RNAs significantly enhanced the lethality of P. interpunctella to ClO2 gas treatment as well as to the bacterial challenge. These results suggest that ClO2 induces the production of insecticidal ROS, which results in a fatal oxidative stress in P. interpunctella.

  13. Six-month low level chlorine dioxide gas inhalation toxicity study with two-week recovery period in rats

    Science.gov (United States)

    2012-01-01

    Background Chlorine dioxide (CD) gas has a potent antimicrobial activity at extremely low concentration and may serve as a new tool for infection control occupationally as well as publicly. However, it remains unknown whether the chronic exposure of CD gas concentration effective against microbes is safe. Therefore, long-term, low concentration CD gas inhalation toxicity was studied in rats as a six-month continuous whole-body exposure followed by a two-week recovery period, so as to prove that the CD gas exposed up to 0.1 ppm (volume ratio) is judged as safe on the basis of a battery of toxicological examinations. Methods CD gas at 0.05 ppm or 0.1 ppm for 24 hours/day and 7 days/week was exposed to rats for 6 months under an unrestrained condition with free access to chow and water in a chamber so as to simulate the ordinary lifestyle in human. The control animals were exposed to air only. During the study period, the body weight as well as the food and water consumptions were recorded. After the 6-month exposure and the 2-week recovery period, animals were sacrificed and a battery of toxicological examinations, including biochemistry, hematology, necropsy, organ weights and histopathology, were performed. Results Well regulated levels of CD gas were exposed throughout the chamber over the entire study period. No CD gas-related toxicity sign was observed during the whole study period. No significant difference was observed in body weight gain, food and water consumptions, and relative organ weight. In biochemistry and hematology examinations, changes did not appear to be related to CD gas toxicity. In necropsy and histopathology, no CD gas-related toxicity was observed even in expected target respiratory organs. Conclusions CD gas up to 0.1 ppm, exceeding the level effective against microbes, exposed to whole body in rats continuously for six months was not toxic, under a condition simulating the conventional lifestyle in human. PMID:22348507

  14. Six-month low level chlorine dioxide gas inhalation toxicity study with two-week recovery period in rats

    Directory of Open Access Journals (Sweden)

    Akamatsu Akinori

    2012-02-01

    Full Text Available Abstract Background Chlorine dioxide (CD gas has a potent antimicrobial activity at extremely low concentration and may serve as a new tool for infection control occupationally as well as publicly. However, it remains unknown whether the chronic exposure of CD gas concentration effective against microbes is safe. Therefore, long-term, low concentration CD gas inhalation toxicity was studied in rats as a six-month continuous whole-body exposure followed by a two-week recovery period, so as to prove that the CD gas exposed up to 0.1 ppm (volume ratio is judged as safe on the basis of a battery of toxicological examinations. Methods CD gas at 0.05 ppm or 0.1 ppm for 24 hours/day and 7 days/week was exposed to rats for 6 months under an unrestrained condition with free access to chow and water in a chamber so as to simulate the ordinary lifestyle in human. The control animals were exposed to air only. During the study period, the body weight as well as the food and water consumptions were recorded. After the 6-month exposure and the 2-week recovery period, animals were sacrificed and a battery of toxicological examinations, including biochemistry, hematology, necropsy, organ weights and histopathology, were performed. Results Well regulated levels of CD gas were exposed throughout the chamber over the entire study period. No CD gas-related toxicity sign was observed during the whole study period. No significant difference was observed in body weight gain, food and water consumptions, and relative organ weight. In biochemistry and hematology examinations, changes did not appear to be related to CD gas toxicity. In necropsy and histopathology, no CD gas-related toxicity was observed even in expected target respiratory organs. Conclusions CD gas up to 0.1 ppm, exceeding the level effective against microbes, exposed to whole body in rats continuously for six months was not toxic, under a condition simulating the conventional lifestyle in human.

  15. Effects of Chlorine Dioxide Gas on Postharvest Physiology and Storage Quality of Green Bell Pepper (Capsicum frutescens L. var. Longrum)

    Institute of Scientific and Technical Information of China (English)

    DU Jin-hua; FU Mao-run; LI Miao-miao; XIA Wei

    2007-01-01

    The effects of treatment of chlorine dioxide (ClO2) gas on postharvest physiology and preservation quality of green bell peppers were studied. Green bell peppers were collected in bags and treated with 0, 5, 10, 20, and 50 mg L-1 ClO2 gas at 10 ± 0.5℃ for over 40 d, and the changes in postharvest physiology and preservation quality of the peppers were evaluated during the storage. The inhibition of rot of the peppers was observed for all the tested ClO2 gas treatments. The rot rates of the treated samples were 50% lesser than those of the control after day 40 of storage. The highest inhibitory effect was obtained after 50 mg L-1 ClO2 gas treatment, where the peppers did not decay until day 30 and showed only one-fourth of the rot rate of the control at day 40 of storage. The respiratory activity of the peppers was significantly (P < 0.05) inhibited by 20 and 50 mg L-1 ClO2 treatments, whereas no significant effects on respiratory activity were observed with 5 and 10 mg L-1ClO2 treatments (P> 0.05). Except for 50 mg L-1 ClO2, malondialdenyde (MDA) contents in the peppers treated with 5,10, or 20 mg L-1 ClO2 were not significantly (P>0.05) different from those in the control. Degradation of chlorophyll in the peppers was delayed by 5 mg L-1 ClO2, but promoted by 10, 20, or 50 mg L-1 ClO2. The vitamin C content, titratable acidity,and total soluble solids of the peppers treated by all the tested ClO2 gas did not significantly change during the storage.The results suggested that ClO2 gas treatment effectively delayed the postharvest physiological transformation of green peppers, inhibited decay and respiration, maintained some nutritional and sensory quality, and retarded MDA accumulation.

  16. Removal of ethylene and bioaerosol by chlorine dioxide using a chemical scrubbing system in a fruit and vegetable storage facility.

    Science.gov (United States)

    Chang, Tsu-Hua; Wu, Li-Chun; You, Ya-Ting; Chung, Ying-Chien

    2009-02-15

    Ethylene (C2H4) and bioaerosol are commonly present in the inside atmosphere of postharvest fruit and vegetable storage facilities, which may affect the aging of postharvest fruit and human health. We have assessed the feasibility of chlorine dioxide (ClO2) as the scrubbing solution in a chemical scrubbing tower for simultaneously removing C2H4 and bioaerosol emissions from a gas stream. Parameters such as the ClO2concentration, contact time, and liquid-to-gas (L/G) ratio were examined with the aim of determining the optimal operating conditions. Using the system reported here, the optimal C2H4 removal efficiency was 99.5% when 500 ppm ClO2 was used at a reaction time of 30-60 s under a continuous non-recycle ClO2 flow mode. In terms of C2H4 removal, a greater L/G resulted in a higher C2H4 removal efficiency up to the optimal ratio of 12.5. In terms of the simultaneous removal of C2H4 and bioaerosol, the removal efficiency of C2H4 was 99.2% and those for the bioaersols of Escherichia coli and Staphylococcus aureus were 99.92 and 99.10%, respectively, under a continuous non-recycle flow mode. Our results also indicate that oxidation reduction potential (ORP) can be a valuable indicator for the timing of the replacement of the scrubbing solution in the system under a continuous recycle flow mode. Additional confirmation of the feasibility of the ORP as an indicator of C2H4 and bioaerosol removal in situ was obtained in a 3-month test of our system in continuous recycle flow mode with the periodical replacement of scrubbing solution, ClO2. The removal efficiencies for C2H4, bacterial and fungus aerosol, and total hydrocarbon compounds (THC) were 83.4, 96.8, 96.1, and 76.5%, respectively. Our results prove that ClO2 is an excellent scrubbing solution in the chemical scrubbing tower for the removal of C2H4 emissions and bioaerosol. We demonstrate, for the first time, the feasibility of this system in a fruit and vegetable storage facility.

  17. Acetonitrile and N-Chloroacetamide Formation from the Reaction of Acetaldehyde and Monochloramine.

    Science.gov (United States)

    Kimura, Susana Y; Vu, Trang Nha; Komaki, Yukako; Plewa, Michael J; Mariñas, Benito J

    2015-08-18

    Nitriles and amides are two classes of nitrogenous disinfection byproducts (DBPs) associated with chloramination that are more cytotoxic and genotoxic than regulated DBPs. Monochloramine reacts with acetaldehyde, a common ozone and free chlorine disinfection byproduct, to form 1-(chloroamino)ethanol. Equilibrium (K1) and forward and reverse rate (k1,k-1) constants for the reaction between initial reactants and 1-(chloroamino)ethanol were determined between 2 and 30 °C. Activation energies for k1 and k-1 were 3.04 and 45.2 kJ·mol(-1), respectively, and enthalpy change for K1 was -42.1 kJ·mol(-1). In parallel reactions, 1-(chloroamino)ethanol (1) slowly dehydrated (k2) to (chloroimino)ethane that further decomposed to acetonitrile and (2) was oxidized (k3) by monochloramine to produce N-chloroacetamide. Both reactions were acid/base catalyzed, and rate constants were characterized at 10, 18, and 25 °C. Modeling for drinking water distribution system conditions showed that N-chloroacetamide and acetonitrile concentrations were 5-9 times higher at pH 9.0 compared to 7.8. Furthermore, acetonitrile concentration was found to form 7-10 times higher than N-chloroacetamide under typical monochloramine and acetaldehyde concentrations. N-chloroacetamide cytotoxicity (LC50 = 1.78 × 10(-3) M) was comparable to dichloroacetamide and trichloroacetamide, but less potent than N,2-dichloroacetamide and chloroacetamide. While N-chloroacetamide was not found to be genotoxic, N,2-dichloroacetamide genotoxic potency (5.19 × 10(-3) M) was on the same order of magnitude as chloroacetamide and trichloroacetamide.

  18. 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-)

    DEFF Research Database (Denmark)

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

    2017-01-01

    : performic acid (PFA), peracetic acid (PAA) and chlorine dioxide (ClO2) as well as two by-products of their use: hydrogen peroxide (H2O2) and chlorite. All of the five chemicals investigated showed clear toxicity to the algae with well-defined dose response curves. The EC50 values ranged from 0.16 to 2.9 mg....../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...

  19. 基于过氧化氢制备生产二氧化氯的过程开发研究%Process Development and Design of Chlorine Dioxide Production Based on Hydrogen Peroxide

    Institute of Scientific and Technical Information of China (English)

    陈赟; 江燕斌; 钱宇

    2004-01-01

    This paper presents a process development and design of chlorine dioxide production based on hydrogen peroxide. The process is characterized by cleaner production, high efficiency, and waste minimization. Optimization of process conditions, selection of equipment, and experiment of recycle of waste acid are carried out. The process design is realized in consideration of several aspects such as operation, material, equipment design and safety. An industrialized process flowsheet is developed according to experiment. A pilot testing is carried out to confirm the lab results. Process design of chlorine dioxide production based on hydrogen peroxide is realized.

  20. Germicidal activity of a chlorous acid-chlorine dioxide teat dip and a sodium chlorite teat dip during experimental challenge with Staphylococcus aureus and Streptococcus agalactiae.

    Science.gov (United States)

    Boddie, R L; Nickerson, S C; Adkinson, R W

    1998-08-01

    Three postmilking teat dips were tested for efficacy against Staphylococcus aureus and Streptococcus agalactiae in two separate studies using experimental challenge procedures that were recommended by the National Mastitis Council. The first study evaluated a barrier teat dip product containing chlorous acid-chlorine dioxide as the germicidal agent, and the second study evaluated a sodium chlorite product with a barrier component as well as a sodium chlorite product without a barrier component. The chlorous acid-chlorine dioxide teat dip reduced new intramammary infections (IMI) caused by Staph. aureus by 91.5% and reduced new IMI caused by Strep. agalactiae by 71.7%. The barrier dip containing sodium chlorite reduced new IMI caused by Staph. aureus and Strep. agalactiae by 41.0 and 0%, respectively. The nonbarrier dip containing sodium chlorite reduced new IMI caused by Staph. aureus by 65.6% and reduced new IMI caused by Strep. agalactiae by 39.1%. Teat skin and teat end conditions were evaluated before and after the second study; no deleterious effects among dipped quarters compared with control quarters were noted for the two sodium chlorite products.

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

    Science.gov (United States)

    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.

  2. Preparation of disinfectant containing both chlorine dioxide and chlorine for safe urban reuse%复合二氧化氯的制备及其用于城市污水回用消毒

    Institute of Scientific and Technical Information of China (English)

    樊金红; 王红武; 马鲁铭

    2012-01-01

    在酸性环境中通过NaCl电解协同NaClO2化学氧化方法制备的复合二氧化氯溶液中ClO2和自由氯浓度分别达到70%和20%左右,系统地研究了电流密度(A)、NaClO2与NaCl质量比(B)、电解时间(C)对复合溶液中组分浓度和质量百分数的影响,并将复合溶液用于城市污水二级处理出水的消毒.结果表明,复合溶液中自由氯的浓度主要受因素C和A的影响,ClO2的浓度主要受因素C和B的影响,而A对副产物ClO-2和ClO-3的影响最大.总大肠菌群数在105~108个?L-1的城市污水二级处理出水采用复合溶液消毒时,当其中ClO2投加量为4mg? L-1,自由氯含量不低于1.20 mg?L-1,经30 min接触后出水生物学指标满足GB/T 18920-2002的要求.既降低了消毒剂的使用量,又减少了消毒副产物ClO-2的生成.%To achieve simultaneously maximum disinfection and minimum toxicity a mix disinfectant of chlorine dioxide and chlorine are found to be efficient for disinfection of drinking water and urban reused waste-water. However, transportation and reservation of the mixture may threat to environmental safety. Therefore, on-site preparation is necessary for field use. At present, preparation methods of the mix disinfectant have chemical reduction of sodium chlorate and electrolysis of sodium chloride, and the content of chlorine dioxide in mixture obtained is usually below 30%. To get high chlorine dioxide content, a method for the preparation of the mix disinfectant was proposed : electrolyzing sodium chloride (NaCl) was followed by a chemical oxidation of sodium chlorite (NaClC2) in an undivided electrolysis reactor, in which the content of C1O2 in the mix disinfectant can be controlled. The effect of current density (A), mass ratio of NaCIO2: NaCl (B), electrolysis time (C) on the concentration and mass percentage of CIO2, free chlorine, ClO-2 and C1O-3 was investigated systematically. Under the electrolysis conditions: current density 41. 67-83. 33 A

  3. Chlorine dioxide, seawater

    Energy Technology Data Exchange (ETDEWEB)

    Kreysa, G. (ed.) (Deutsche Gesellschaft fuer Chemisches Apparatewesen, Chemische Technik und Biotechnologie e.V. (DECHEMA), Frankfurt am Main (Germany)); Eckermann, R. (ed.) (Deutsche Gesellschaft fuer Chemisches Apparatewesen, Chemische Technik und Biotechnologie e.V. (DECHEMA), Frankfurt am Main (Germany))

    1992-01-01

    The present work, the DECHEMA Corrosion Handbook, is a translation of the ''DECHEMA-Werkstoff-Tabelle'' incorporating revisions to take account of the most recent developments. It is the result of a painstaking review and evaluation of the literature on corrosion, undertaken by specialists in their field, and contains information and recommendations on the appropriate use of materials of construction and their behavior during the handling and processing of aggressive media. (orig./MM)

  4. Chapter 21. chlorine dioxide

    Science.gov (United States)

    Submerging terminal leafy cuttings of Rhododendron L. 'Gumpo White' ('Gumpo White' azalea) in 50 °C water for 21 min was previously shown to eliminate binucleate Rhizoctonia species, the cause of azalea web blight, from plant tissues. Prior to considering commercial use of this practice, a better un...

  5. Thermal diffusion of chlorine in uranium dioxide studied by secondary ion mass spectrometry and X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pipon, Y. [Institut de Physique Nucleaire de Lyon (IPNL), 4, rue Enrico Fermi, 69622 Villeurbanne cedex (France)]. E-mail: pipon@ipnl.in2p3.fr; Toulhoat, N. [Institut de Physique Nucleaire de Lyon (IPNL), 4, rue Enrico Fermi, 69622 Villeurbanne cedex (France); Commissariat l' Energie Atomique (CEA), DEN/Saclay, 91191 Gif s/Yvette Cedex (France); Moncoffre, N. [Institut de Physique Nucleaire de Lyon (IPNL), 4, rue Enrico Fermi, 69622 Villeurbanne cedex (France); Raimbault, L. [Centre d' Informatique Geologique (CIG), Ecole des Mines, 35 rue Saint Honore, F-77305 Fontainebleau cedex (France); Scheidegger, A.M. [Laboratory for Waste Management, Nuclear Energy and Safety Department (NES), Paul Scherrer Institut CH-5232 Villigen PSI (Switzerland); Farges, F. [Laboratoire des Geomateriaux, Universite de Marne la Vallee, 5 Bd Descartes-Champs S/Marne, 77454 Marne la Vallee cedex 2 (France); Carlot, G. [Commissariat l' Energie Atomique (CEA), Centre de Cadarache, DEN/DEC/SESC/LLCC, 13108 Saint-Paul lez Durance (France)

    2007-05-31

    In a nuclear reactor, {sup 35}Cl present as an impurity in the nuclear fuel is activated by thermal neutron capture. During interim storage or geological disposal of the nuclear fuel, {sup 36}Cl may be released from the fuel to the geo/biosphere and contribute significantly to the 'instant release fraction'. In order to elucidate the diffusion mechanisms, both irradiation and thermal effects must be assessed. This paper deals with the thermal diffusion of chlorine in depleted UO{sub 2}. For this purpose, sintered UO{sub 2} pellets were implanted with {sup 37}Cl at an ion fluence of 10{sup 13}cm{sup -2} and successively annealed in the 1175-1475K temperature range. The implanted chlorine is used to simulate the behaviour of the displaced one due to recoil and to interactions with the fission fragments during reactor operation. The behaviour of the pristine and the implanted chlorine was investigated during thermal annealing. SIMS and {mu}-XAS (at the Cl-K edge) analyses show that: (1) the thermal migration of implanted chlorine becomes significant at 1275K; this temperature and the calculated activation energy of 4.3eV points out the great ability of chlorine to migrate in UO{sub 2} at relatively low temperatures; (2) the behaviour of the implanted chlorine which aggregates into 'hot spots' during annealing before its effusion is clearly different from that of the pristine one which remains homogenously distributed after annealing; (3) the 'hot spot' and the pristine chlorine seem to be in different structural environments. Both types of chlorine are assumed to have a valence state of -I; (4) the comparison between an U{sub 2}O{sub 2}Cl{sub 5} reference compound and the pristine chlorine environment shows a contribution of the U{sub 2}O{sub 2}Cl{sub 5} to the pristine chlorine.

  6. Monochloramine Cometabolism by Nitrifying Biofilm Relevant to Drinking Water

    Data.gov (United States)

    U.S. Environmental Protection Agency — Data for Figures in manuscript. This dataset is associated with the following publication: Wahman , D., J. Maestre, and G. Speitel Jr.. Monochloramine Cometabolism...

  7. 二氧化氯与氯联合消毒对饮用水中消毒副产物的影响%EFFECT OF COMBINED DISINFECTION WITH CHLORINE AND CHLORINE DIOXIDE ON THE FORMATION OF DISINFECTION BY-PRODUCTS IN DRINKING WATER

    Institute of Scientific and Technical Information of China (English)

    叶必雄; 王五一; 杨林生; 王小龙; 魏建荣

    2011-01-01

    In an effect to explore the production mechanisms and characteristics of the by-products in different water disinfection processes,and to investigate the effect of chlorine dioxide on the formation of chlorine by-products,water samples from 4 water plants in a city in China were analyzed.Compared with the water disinfected with chlorine alone,the amount of THMs and HAAs decreased by 74.39% and 40.65%,respectively,in water samples disinfected with both chlorine dioxide and chlorine.Likewise,the amounts of chlorate and chlorite produced by the chlorine dioxide chemical generator was higher than that of the pure chlorine dioxide generator.%为了研究二氧化氯与氯联合消毒工艺过程中消毒副产物的形成规律以及特点,探讨二氧化氯对氯化消毒副产物的控制效果,对我国北方某市使用同一水源的4家水厂消毒工艺进行全面的采样与检测,并对各项消毒副产物检测结果进行了全面的分析.结果表明,二氧化氯与氯联合消毒比单纯液氯消毒形成的三卤甲烷平均降低74.39%,卤乙酸平均降低40.65%.在控制氯酸盐及亚氯酸盐生成方面,使用纯二氧化氯发生器生成的氯酸盐要显著低于化学法复合二氧化氯发生器.

  8. 二氧化氯去除污染物及其动力学研究进展%Research Progress on Kinetics of PoUutants Removal by Chlorine Dioxide

    Institute of Scientific and Technical Information of China (English)

    曹向禹

    2012-01-01

    二氧化氯在消毒杀菌、饮用水净化、工业废水处理和纸浆漂白等领域的应用广泛,是一种极具潜力的绿色氧化剂。本文介绍目前国内外二氧化氯对无机和有机污染物去除的研究现状,并对二氧化氯氧化水中污染物反应动力学的研究进展进行了全面综述,为二氧化氯的应用提供理论指导。%Chlorine dioxide, as a potential green oxidant, is increasingly be used in disinfection, drinking water puritication, industrial wastewater treatment and pulp bleaching process. In the paper, the current research situations of chlorine dioxide in both organic and inorganic pollutants removal were introduced. The internal and external research progress on oxidation kinetics of pollutants in water by chlorine dioxide is summarized comprehensively, which can provide theoretical instruction for application of chlorine dioxide in the furore.

  9. The measures to improve conversion rate of chlorine dioxide in methanol method process%提高甲醇法二氧化氯制备工艺转化率的措施

    Institute of Scientific and Technical Information of China (English)

    徐萃声; 詹磊; 黄丙贵

    2016-01-01

    在强酸性环境下,甲醇可以与氯酸钠发生氧化还原反应,氯酸钠由此被还原而产生二氧化氯,人们将这种二氧化氯制备方法称之为甲醇法。纸浆漂白甲醇法二氧化氯制备系统国产化已经实现,目前已成功运行多套系统。本文分析了影响纸浆漂白甲醇法二氧化氯系统工艺转化率的相关因素,并结合生产实际提出了相应的改进措施。%Methanol can make oxidation-reduction reaction with sodium chlorate under strong acid situation. Sodium chlorate is restored to make chlorine dioxide, which is called methanol method to prepare chlorine dioxide. The methanol method for chlorine dioxide preparation has been localized successfully, which has been well proven in many projects in bleaching plant in pulp industry. In this article were analyzed the relating factors of conversion rate of chlorine dioxide which is used in pulp bleaching process, and was put forward the corresponding improving measures combined with the production practice.

  10. Virucidal Activity of Fogged Chlorine Dioxide- and Hydrogen Peroxide-Based Disinfectants against Human Norovirus and Its Surrogate, Feline Calicivirus, on Hard-to-Reach Surfaces

    Directory of Open Access Journals (Sweden)

    Naim Montazeri

    2017-06-01

    Full Text Available Human norovirus (NoV is the leading cause of foodborne illnesses in the United States. Norovirus is shed in high numbers in the feces and vomitous of infected individuals. Contact surfaces contaminated with bodily fluids harboring infectious virus particles serve as vehicles for pathogen transmission. Environmental stability of NoV and its resistance to many conventional disinfectants necessitate effective inactivation strategies to control the spread of virus. We investigated the efficacy of two commercial disinfectants, hydrogen peroxide (7.5% and a chlorine dioxide (0.2%-surfactant-based product using a fogging delivery system against human NoV GI.6 and GII.4 Sydney strains as well as the cultivable surrogate, feline calicivirus (FCV dried on stainless steel coupons. Log10 reductions in human NoV and FCV were calculated utilizing RNase RT-qPCR and infectivity (plaque assay, respectively. An improved antiviral activity of hydrogen peroxide as a function of disinfectant formulation concentration in the atmosphere was observed against both GII.4 and FCV. At 12.4 ml/m3, hydrogen peroxide achieved a respective 2.5 ± 0.1 and 2.7 ± 0.3 log10 reduction in GI.6 and GII.4 NoV genome copies, and a 4.3 ± 0.1 log10 reduction in infectious FCV within 5 min. At the same disinfectant formulation concentration, chlorine dioxide-surfactant-based product resulted in a respective 1.7 ± 0.2, 0.6 ± 0.0, and 2.4 ± 0.2 log10 reduction in GI.6, GII.4, and FCV within 10 min; however, increasing the disinfectant formulation concentration to 15.9 ml/m3 negatively impacted its efficacy. Fogging uniformly delivered the disinfectants throughout the room, and effectively decontaminated viruses on hard-to-reach surfaces. Hydrogen peroxide delivered by fog showed promising virucidal activity against FCV by meeting the United States EPA 4-log10 reduction criteria for an anti-noroviral disinfectant; however, fogged chlorine dioxide-surfactant-based product did not achieve

  11. Virucidal Activity of Fogged Chlorine Dioxide- and Hydrogen Peroxide-Based Disinfectants against Human Norovirus and Its Surrogate, Feline Calicivirus, on Hard-to-Reach Surfaces.

    Science.gov (United States)

    Montazeri, Naim; Manuel, Clyde; Moorman, Eric; Khatiwada, Janak R; Williams, Leonard L; Jaykus, Lee-Ann

    2017-01-01

    Human norovirus (NoV) is the leading cause of foodborne illnesses in the United States. Norovirus is shed in high numbers in the feces and vomitous of infected individuals. Contact surfaces contaminated with bodily fluids harboring infectious virus particles serve as vehicles for pathogen transmission. Environmental stability of NoV and its resistance to many conventional disinfectants necessitate effective inactivation strategies to control the spread of virus. We investigated the efficacy of two commercial disinfectants, hydrogen peroxide (7.5%) and a chlorine dioxide (0.2%)-surfactant-based product using a fogging delivery system against human NoV GI.6 and GII.4 Sydney strains as well as the cultivable surrogate, feline calicivirus (FCV) dried on stainless steel coupons. Log10 reductions in human NoV and FCV were calculated utilizing RNase RT-qPCR and infectivity (plaque) assay, respectively. An improved antiviral activity of hydrogen peroxide as a function of disinfectant formulation concentration in the atmosphere was observed against both GII.4 and FCV. At 12.4 ml/m(3), hydrogen peroxide achieved a respective 2.5 ± 0.1 and 2.7 ± 0.3 log10 reduction in GI.6 and GII.4 NoV genome copies, and a 4.3 ± 0.1 log10 reduction in infectious FCV within 5 min. At the same disinfectant formulation concentration, chlorine dioxide-surfactant-based product resulted in a respective 1.7 ± 0.2, 0.6 ± 0.0, and 2.4 ± 0.2 log10 reduction in GI.6, GII.4, and FCV within 10 min; however, increasing the disinfectant formulation concentration to 15.9 ml/m(3) negatively impacted its efficacy. Fogging uniformly delivered the disinfectants throughout the room, and effectively decontaminated viruses on hard-to-reach surfaces. Hydrogen peroxide delivered by fog showed promising virucidal activity against FCV by meeting the United States EPA 4-log10 reduction criteria for an anti-noroviral disinfectant; however, fogged chlorine dioxide-surfactant-based product did not achieve a 4-log10

  12. Method to remove poisonous chlorine compounds using supercritical carbon dioxide. Chorinkai tansan gas wo mochiita yudoku enso kagobutsu no jokyoho

    Energy Technology Data Exchange (ETDEWEB)

    Ikushima, Y. (Government Industrial Research Institute, Tohoku, Sendai (Japan))

    1989-12-15

    This paper describes a method to extract and remove selectively poisonous chlorine compounds from aqueous solution using supercritical CO2. This method is characterized in that it extracts and separates only chlorine compounds in short time under a moderate condition, and removes it without a need of whatever post-treatment. The supercritical CO2 pressure was 80 kg/cm[sup 2], and the extraction temperature was 40[degree]C. The supercritical CO2 extracted 70% to 80% by weight of trichloroethylene and tetrachloroethylene in 15 to 30 minutes, almost all of 1,2-dichloroethane and 1,1,1-trichloroethane in one hour, and about 70% by weight of benzil chloride after 90 minutes. When the supercritical CO2 extraction was carried out for a dilute chlorine compound at 1000 ppm for three hours, the concentrations of trichloroethylene and tetrachloroethylene in the aqueous solution decreased down to several ppm, with no other substances than chlorine compounds detected in the extracts. This proves that no water has been extracted at all. 5 figs., 1 tab.

  13. Protein turnover in the breast muscle of broiler chicks and studies addressing chlorine dioxide sanitation of hatching eggs, poultry leg problems and wheat middling diets for laying hens

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, P.H.

    1988-01-01

    Developmental changes occurred in breast muscle Ks measured by {sup 14}C-tyrosine incorporation at 10, 16, 22 and 34 days of age. Protein synthesis rates decreased as the birds matures: 30 to 11.2%/d between 10 and 34 days of age. In a second study birds fed diets low in lysine or protein-energy had reduced fractional rates of protein synthesis and free tyrosine, branched chain and large neutral amino acid concentrations as compared to control birds the same body weight. Artificial weight loading and reduced dietary protein levels were used to study the effects of body weight on the severity of leg deformities in chicks and poults. Experiments investigating the practicality of wheat middlings as an alternate feedstuff for laying hens suggested that high levels in the diet will reduce egg production, feed conversion, hen livability and egg yolk color. Lastly, chlorine dioxide foam and dipping solutions were compared with formaldehyde fumigation for sanitizing hatching eggs.

  14. Development of Combined Dry Heat and Chlorine Dioxide Gas Treatment with Mechanical Mixing for Inactivation of Salmonella enterica Serovar Montevideo on Mung Bean Seeds.

    Science.gov (United States)

    Annous, Bassam A; Burke, Angela

    2015-05-01

    Foodborne outbreaks have been associated with the consumption of fresh sprouted beans. The sprouting conditions of mung bean seeds provide optimal conditions of temperature and relative humidity for any potential pathogenic contaminant on the seeds to grow. The lack of a kill step postsprouting is a major safety concern. Thus, the use of a kill step on the seeds prior to a sprouting step would enhance the safety of fresh sprouts. The objective of this work was to evaluate the effectiveness of the combined thermal and chlorine dioxide gas (3.5 mg/liter of air) treatment with mechanical mixing (tumbling) to eliminate Salmonella on artificially inoculated mung bean seeds. Although no viable Salmonella was recovered from seeds treated in hot water at 60°C for 2 h, these treated seeds failed to germinate. Dry heat treatments (55, 60, or 70°C) for up to 8 h reduced Salmonella populations in excess of 3 log CFU/g. The use of tumbling, while treating the seeds, resulted in up to 1.6 log CFU/g reduction in Salmonella populations compared with no tumbling. Dry heat treatment at 65°C for 18 h with tumbling resulted in a complete inactivation of Salmonella populations on inoculated seeds with low inoculum levels (2.83 log CFU/g) as compared with high inoculum levels (4.75 log CFU/g). The increased reductions in pathogenic populations on the seeds with the use of tumbling could be attributed to increased uniformity of heat transfer and exposure to chlorine dioxide gas. All treated seeds were capable of germinating, as well as the nontreated controls. These results suggest that this combined treatment would be a viable process for enhancing the safety of fresh sprouts.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Sonali Taneja

    2014-01-01

    Full Text Available 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 (ClO 2 and 13% ClO 2 . 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% ClO 2 at 60 minutes. Least amount of tissue dissolving ability was demonstrated by 5% Ca(OCl 2 and 5% ClO 2 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 ClO 2 gradually increased with time and with their increase in concentration.

  17. Use of high-concentration-short-time chlorine dioxide gas treatments for the inactivation of Salmonella enterica spp. inoculated onto Roma tomatoes.

    Science.gov (United States)

    Trinetta, V; Morgan, M T; Linton, R H

    2010-12-01

    Salmonella outbreaks have been recently linked to the consumption of fresh tomatoes. Thus, there is a need to develop systems that reduce the risk of microbial contamination to increase product shelf-life and keep fresh fruit attributes. The objectives of this study were to evaluate high-concentration-short-time chlorine dioxide gas treatments effects on Salmonella-inoculated Roma tomatoes and determine the optimal treatment conditions for microbial inactivation and shelf-life extension. Effects of ClO(2) concentration (2, 5, 8 and 10mg/l) and exposure time (10, 30, 60, 120 and 180 s) on inoculated Roma tomatoes were studied. Salmonella enterica strains, serotype Montevideo, Javiana and Baildon, were used to experimentally inoculate the food product. After ClO(2) treatments, tomatoes were stored at room temperature for 28 days. Inherent microbial population, change in tomato color, and chlorine dioxide gas residuals were evaluated. ANOVA analysis showed that both ClO(2) concentration and treatment time were significant (ptomatoes with 8 mg/l ClO(2) for 60 s, 10 mg/l ClO(2) for 120 s, and 10 mg/l for 180 s, respectively (initial Salmonella population: 6.03±0.11 log CFU/cm(2)). The selected treatments significantly reduced background microflora (pcolor and residual contents were not significantly different (p>0.05), as compared to the control. Results suggest the potential for high-concentration-short-time treatments ClO(2) gas as an effective pathogen inactivation technology for large-scale produce packing operations.

  18. Application of preparation process of high pure chlorine dioxide by electrolysis method in water treatment%电解法制高纯二氧化氯工艺在水处理中的应用

    Institute of Scientific and Technical Information of China (English)

    刘艳霞; 韩瑞雄; 赵红; 周俊波

    2011-01-01

    为了开发经济实用的二氧化氯消毒工艺,对电解法制备高纯二氧化氯工艺在水处理中的运用进行了研究.在最佳条件下,电解氯酸盐自动催化循环制备的二氧化氯纯度可达98%左右.通过二氧化氯杀菌除藻试验,讨论了二氧化氯用量以及原水pH对细菌、叶绿素a、藻类的去除率的影响.结果表明,二氧化氯用量在2 mg/L以上时,3者的去除率均达到90%以上.当二氧化氯用量为2 mg/L、原水pH为6~9时,3者的去除率不发生显著变化,并且二氧化氯的剩余质量浓度均控制在0.5 mg/L以下.消毒成本:生产1 kg二氧化氯成本可以控制在6元以内,当二氧化氯用量在0.5 ~2 mg/L时,1 t水的消毒成本为0.003~ 0.012元.%To develop an economical and practical disinfection technology of chlorine dioxide, the application of preparation process of high pure chlorine dioxide by electrolysis method in water treatment was studied. Under the best conditions, the purity of chlorine dioxide, which was prepared by electrolysis of chlorate solution with auto-catalytic cycling,can reach about 98% . Through the experiments of algae removal and sterilization,the influences of concentration of chlorine dioxide and pH of raw water on the removal rate of bacteria,chlorophyll A ,and algal were discussed. Results showed that when the mass concentration of chlorine dioxide was above 2 mg/L, the removal rates of bacteria, chlorophyll A, and algal could all reached above 90% . When the mass concentration of chlorine dioxide was 2 mg/L and pH of raw water was at 6 ~9,the removal rates of them could not occur significant change, and the mass concentration of residual chlorine dioxide was all under 0. 5 mg/L. Though accounting for the cost of water disinfection, the cost of per kilogram chlorine dioxide in the process can be controlled less than RMB 6 Yuan. When the invested amount of chlorine dioxide was at 0.5 ~2 mg/L,and the cost of per ton water disinfection

  19. 不同环境下二氧化氯消毒剂的消毒效果及其稳定性研究%The research of disinfectant effect and stabilization of chlorine dioxide antiseptic in different environments

    Institute of Scientific and Technical Information of China (English)

    张庆华; 姬素霞; 胡金花; 闫丽; 张鹏; 胡建和; 徐彦召

    2014-01-01

    为了研究不同环境下二氧化氯的消毒效果及其稳定性,试验以大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、白色念珠菌为测试菌株,采用菌悬液定量杀菌试验、压缩雾化法和平板计数的方法,对二氧化氯的杀菌效果进行试验。结果表明:在菌液密度为5×106 CFU/mL的条件下,90 mg/L的二氧化氯作用5 min,即可对测试菌株达到100%的杀灭效果。不同的pH值、温度及不同浓度有机物存在的条件下,二氧化氯同样具有极强的消毒效果。雾化的二氧化氯对空气自然菌及雾化菌液气溶胶的杀灭效果同样可以达到100%。试验表明二氧化氯作为一种高效、稳定的广谱消毒剂具有良好的杀菌效果。%To research the disinfetant effect and stabilization of chlorine dioxide in different environments,the antibacterial activity of chlorine dioxide to Escherichia coli,Staphylococcus aureus,Bacillus subtilis and Manidia albican was tested by quantitative germicidal test,compression atomizing effect and plate counting method.The results showed that chlorine dioxide at 90 mg/L could kill all the bacteria in 5 min.Chlorine dioxide exhibits widely antiseptic properties in multi-environment,despite of the pH value,temperature and organic matter.Chlorine dioxide in gaseous also had the forceful sterilizing effect to the normal air and the theaerosol of bacterial suspension.It indicated that chlorine dioxide with the quality of efficient and stable have the excellent antibacterial activity as an disinfectant.

  20. Feasibility of water disinfection with stabilized chlorine dioxide in small rural drinking water safety project of Guangxi%小型农村安全饮水工程使用稳定二氧化氯进行消毒的可行性

    Institute of Scientific and Technical Information of China (English)

    陆清; 庄健君

    2014-01-01

    An introduction was made on the physical and chemical characteristics of chlorine dioxide, the method and features of water disinfection with chlorine dioxide. The authors analyze the reasons for chlorine dioxide genera-tor not applicable for the small drinking water safety project of Guangxi, and also analyze the feasibility of adopting stabilized chlorine dioxide.%论述了二氧化氯的物理和化学特性及其用于饮水消毒的方法和特点。分析了二氧化氯发生器不适用我区小型农村饮水安全工程的原因,对使用稳定二氧化氯进行了可行性分析。

  1. Control effects of pε and pH on the generation and stability of chlorine dioxide

    Institute of Scientific and Technical Information of China (English)

    PEI Yuan-sheng; WU Xiao-qiang; LUAN Zhao-kun; WANG Tong

    2003-01-01

    A new method, without assistance of activity ratio diagram, was applied to construct the pε-pH diagrams for chlorine system. The optimal pH range for generation of ClO2 by contacting Cl2(g) directly with ClO2- solution is within pH 1.35-1.94, particularly within pH 1.35-4.00 only if minimizing the formation of Cl2. It is unachievable to synthesize pure ClO2 from the reaction of Cl2 and ClO2-. Conversely, ClO2 may be present a variation of stability in different waters owing to the changed pε and pH. ClO2 could be relatively stable if not disproportionate into ClO3-, coexisting with ClO2- (pε17.63 and pH>9.68), Cl2 (pH≤0.92) or Cl- (pH 0.92-9.68). When chlorine system has already reached the ultimate equilibria, ClO2 is a stable species in strongly acid media. As the acidity decreases, ClO2 disproportionates into ClO3- and Cl2. Aqueous ClO2 is unstable within the normal pH range. This work initially, theoretically elucidates the generation and stability of ClO2 by way of the pε-pH diagrams.

  2. 3D Chlorine and Monochloramine Penetration and Nitrifying Biofilm Activity and Viability: Periodic Chlorine Switch Implications

    Science.gov (United States)

    Biofilm formation in drinking water distribution systems has been associated with water quality degradation and may result in non-compliance with existing regulations. United States water utilities report biofilm survival and regrowth despite disinfectant presence, and systems t...

  3. Electrochemical and Integrated Process Opportunities for On-Site/On-Demand Generation of Chlorine Dioxide - Final Report - 08/02/1996 - 08/01/1999

    Energy Technology Data Exchange (ETDEWEB)

    Tatarchuk, Bruce J.; Krishnagopalan, G.; Nickell, Ryan A.

    2000-01-30

    Due to continued evidence of environmental harm from elemental chlorine bleaching, the nation's paper industry continues to search for cost effective alternative bleaching. A practical and cost effective bleaching alternative is chlorine dioxide manufactured entirely from sodium chlorate. Sodium chlorate is produced by the electrolysis of brine in an undivided cell with steel plate cathodes and dimensionally stable anodes. Although the overpotential at the anode is only 50 mV, the cathodic overpotential is 940 mV. Thus, nearly one volt of electricity is wasted in driving hydrogen evolution at the cathode. Auburn University's Center for Microfibrous Materials Manufacturing has demonstrated that high performance, three dimensional, microfibrous electrodes can improve the performance of capacitors, batteries, hybrid power cells, and electrolysis electrodes in a variety of applications. The goal of this research was to apply this technology to a chlorate cell's cathode and reduce the overpotential between 200 and 400 mV. An economic analysis of the industry has shown that for every 100 mV reduction in overpotential, $100 per square meter of electrode can be saved annually. Due to their enhanced surface area over plates, corrosion of microfibrous electrodes is a major issue in this research. Samples based on chromium protection (i.e. stainless steel) have proved unfeasible for chlorate application. However, samples based on stainless steel and nickel show dramatic performance improvements over industry status quo in chlor-alkali application. Building microfibrous electrodes on a titanium base protected with a silver coating alleviates the corrosion problem and provides 100 mV or more of overpotential reduction. Further reduction is realized by impregnating silver-titanium microfibrous mesh with a PVDF binder and dispersed platinum on activated carbon. The resulting electrodes are mechanically sound, active towards hydrogen evolution, and hold promise for

  4. Discussion of the determination of chlorine dioxide in drinking water with colorimetric method%比色法测定饮用水中二氧化氯的含量

    Institute of Scientific and Technical Information of China (English)

    张颖清

    2012-01-01

    The method of chlorine dioxide determination in drinking water with colorimetry is suitable for the measurement above 0. 25mg/L. Because of a good accuracy, it is pretty suitable for the determination of chlorine dioxide in water.%采用比色法测定饮用水中二氧化氯的含量。该方法适合于质量浓度在0.25mg/L以上的测量,且在该质量浓度以上的测定精度更高,因此适合于饮用水中二氧化氯含量的测定。

  5. Kinetics of Inactivation of Bacillus subtilis subsp. niger Spores and Staphylococcus albus on Paper by Chlorine Dioxide Gas in an Enclosed Space.

    Science.gov (United States)

    Wang, Tao; Wu, Jinhui; Qi, Jiancheng; Hao, Limei; Yi, Ying; Zhang, Zongxing

    2016-05-15

    Bacillus subtilis subsp. niger spore and Staphylococcus albus are typical biological indicators for the inactivation of airborne pathogens. The present study characterized and compared the behaviors of B. subtilis subsp. niger spores and S. albus in regard to inactivation by chlorine dioxide (ClO2) gas under different gas concentrations and relative humidity (RH) conditions. The inactivation kinetics under different ClO2 gas concentrations (1 to 5 mg/liter) were determined by first-order and Weibull models. A new model (the Weibull-H model) was established to reveal the inactivation tendency and kinetics for ClO2 gas under different RH conditions (30 to 90%). The results showed that both the gas concentration and RH were significantly (P 70%). Compared with the first-order model, the Weibull and Weibull-H models demonstrated a better fit for the experimental data, indicating nonlinear inactivation behaviors of the vegetative bacteria and spores following exposure to ClO2 gas. The times to achieve a six-log reduction of B. subtilis subsp. niger spore and S. albus were calculated based on the established models. Clarifying the kinetics of inactivation of B. subtilis subsp. niger spores and S. albus by ClO2 gas will allow the development of ClO2 gas treatments that provide an effective disinfection method. Chlorine dioxide (ClO2) gas is a novel and effective fumigation agent with strong oxidization ability and a broad biocidal spectrum. The antimicrobial efficacy of ClO2 gas has been evaluated in many previous studies. However, there are presently no published models that can be used to describe the kinetics of inactivation of airborne pathogens by ClO2 gas under different gas concentrations and RH conditions. The first-order and Weibull (Weibull-H) models established in this study can characterize and compare the behaviors of Bacillus subtilis subsp. niger spores and Staphylococcus albus in regard to inactivation by ClO2 gas, determine the kinetics of inactivation of

  6. 氯酸钠法制备二氧化氯还原剂研究进展%Research progress in reducing agent for preparation of chlorine dioxide by sodium chlorate process

    Institute of Scientific and Technical Information of China (English)

    李建生; 刘炳光; 孙宝丰; 董广前; 王芳

    2012-01-01

    对比介绍了氯酸钠法生产二氧化氯常用还原剂的特点;综述了氯酸钠法制备二氧化氯新还原剂(硫化合物、多元醇、有机酸、碳水化合物、尿素和乙二醛)的研究进展;讨论了氯酸钠法制备二氧化氯有机还原剂甲醇和乙二醛的作用机理;指出采用复合还原剂降低生产成本和采用有机还原剂同时制备两种有用产品是氯酸钠法制备二氧化氯还原剂发展趋势.%Characteristics of reducing agents commonly used in industrially producing chlorine dioxide were introduced with comparison.Research progress in new reducing agents,such as sulfur compound, poly alcohol, organic acid, carbohydrate, urea, and glyoxal for the preparation of chlorine dioxide by sodium chlorate process was summarized.Reaction mechanism of organic reducing agents, methanol and glyoxal, in preparation of chlorine dioxide was discussed.lt was pointed that decreasing production cost by using combined reducing agent as well as preparing two useful products simultaneously by using organic reducing agenl is the tendency of reducing agent development.

  7. Selective reactivity of monochloramine with extracellular matrix components affects the disinfection of biofilm and detached clusters.

    Science.gov (United States)

    Xue, Zheng; Lee, Woo Hyoung; Coburn, Kimberly M; Seo, Youngwoo

    2014-04-01

    The efficiency of monochloramine disinfection was dependent on the quantity and composition of extracellular polymeric substances (EPS) in biofilms, as monochloramine has a selective reactivity with proteins over polysaccharides. Biofilms with protein-based (Pseudomonas putida) and polysaccharide based EPS (Pseudomonas aeruginosa), as well as biofilms with varied amount of polysaccharide EPS (wild-type and mutant P. aeruginosa), were compared. The different reactivity of EPS components with monochloramine influenced disinfectant penetration, biofilm inactivation, as well as the viability of detached clusters. Monochloramine transport profiling measured by a chloramine-sensitive microelectrode revealed a broader diffusion boundary layer between bulk and biofilm surface in the P. putida biofilm compared to those of P. aeruginosa biofilms. The reaction with proteins in P. putida EPS multiplied both the time and the monochloramine mass required to achieve a full biofilm penetration. Cell viability in biofilms was also spatially influenced by monochloramine diffusion and reaction within biofilms, showing a lower survival in the surface section and a higher persistence in the middle section of the P. putida biofilm compared to the P. aeruginosa biofilms. While polysaccharide EPS promoted biofilm cell viability by obstructing monochloramine reactive sites on bacterial cells, protein EPS hindered monochloramine penetration by reacting with monochloramine and reduced its concentration within biofilms. Furthermore, the persistence of bacterial cells detached from biofilm (over 70% for P. putida and ∼40% for polysaccharide producing P. aeruginosa) suggested that currently recommended monochloramine residual levels may underestimate the risk of water quality deterioration caused by biofilm detachment.

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

    Science.gov (United States)

    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.

  9. Sludge reduction by direct addition of chlorine dioxide into a sequencing batch reactor under operational mode of repeatedly alternating aeration/non-aeration.

    Science.gov (United States)

    Peng, Hong; Liu, Weiyi; Li, Yuanmei; Xiao, Hong

    2015-01-01

    The effect of direct addition of chlorine dioxide (ClO2) into a repeatedly alternating aeration/non-aeration sequencing batch reactor (SBR) on its sludge reduction and process performance was investigated. The experimental results showed that the sludge reduction efficiency was 32.9% and the observed growth yield (Yobs) of SBR was 0.11 kg VSS (volatile suspended solids) /kg COD (chemical oxygen demand) for 80 days' operation at the optimum ClO2 dosage of 2.0 mg/g TSS (total suspended solids). It was speculated that cell lysis and cryptic growth, uncoupled metabolism and endogenous metabolism were jointly responsible for the sludge reduction in this study. COD, NH3-N, total nitrogen (TN) and total phosphorus (TP) in the effluent increased on average 29.47, 4.44, 1.97 and 0.05 mg/L, respectively. However, the effluent quality still satisfied the first-class B discharge standards for municipal wastewater treatment plants in China. In that case, the sludge maintained fine viability with the specific oxygen uptake rate (SOUR) being 14.47 mg O2/(g VSS·h) and demonstrated good settleability with the sludge volume index (SVI) being 116 mL/g. The extra cost of sludge reduction at the optimum ClO2 dosage was estimated to be 2.24 CNY (or 0.36 dollar)/kg dry sludge.

  10. Distribution, Identification, and Quantification of Residues after Treatment of Ready-To-Eat Salami with (36)Cl-Labeled or Nonlabeled Chlorine Dioxide Gas.

    Science.gov (United States)

    Smith, David J; Giddings, J Michael; Herges, Grant R; Ernst, William

    2016-11-09

    When ready-to-eat salami was treated in a closed system with (36)Cl-labeled ClO2 (5.5 mg/100 g of salami), essentially all radioactivity was deposited onto the salami. Administered (36)ClO2 was converted to (36)Cl-chloride ion (>97%), trace levels of chlorate (<2%), and detectable levels of chlorite. In residue studies conducted with nonlabeled ClO2, sodium perchlorate residues (LOQ, 4 ng/g) were not formed when reactions were protected from light. Sodium chlorate residues were present in control (39.2 ± 4.8 ng/g) and chlorine dioxide treated (128 ± 31.2 ng/g) salami. If sanitation occurred under conditions of illumination, detectable levels (3.7 ± 1.5 ng/g) of perchlorate were formed along with greater quantities of sodium chlorate (183.6 ± 75.4 ng/g). Collectively, these data suggest that ClO2 is chemically reduced by salami and that slow-release formulations might be appropriate for applications involving the sanitation of ready-to-eat meat products.

  11. Combined treatment with low concentrations of aqueous and gaseous chlorine dioxide inactivates Escherichia coli O157:H7 and Salmonella Typhimurium inoculated on paprika.

    Science.gov (United States)

    Kim, Hyun-Gyu; Song, Kyung Bin

    2016-12-30

    Combined treatment with gaseous and aqueous chlorine dioxide (ClO₂) was performed to improve the microbiological safety and quality of paprika. A single treatment of 50 ppmv ClO₂ gas for 30 min decreased the populations of Escherichia coli O157:H7 and Salmonella Typhimurium by 2.33 and 2.91 log CFU/g, respectively. In addition, a single treatment of aqueous ClO₂ (50 ppm) for 5 min decreased these populations by 1.86 and 1.37, respectively. The most dramatic effects were achieved by combined treatment of 50 ppm aqueous and gaseous ClO₂ for 30 min, which decreased populations of E. coli O157:H7 and S. Typhimurium by 4.11 and 3.61 log CFU/g, respectively. With regard to the qualities of paprika, no adverse effects were elicited by the combined treatment. Thus, combined treatment with aqueous and gaseous ClO₂ is a suitable approach that can be used to improve the microbial safety and quality of paprika.

  12. Chlorine Dioxide is a Better Disinfectant than Sodium Hypochlorite against Multi-Drug Resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii.

    Science.gov (United States)

    Hinenoya, Atsushi; Awasthi, Sharda Prasad; Yasuda, Noritomo; Shima, Ayaka; Morino, Hirofumi; Koizumi, Tomoko; Fukuda, Toshiaki; Miura, Takanori; Shibata, Takashi; Yamasaki, Shinji

    2015-01-01

    In this study, we evaluated and compared the antibacterial activity of chlorine dioxide (ClO2) and sodium hypochlorite (NaClO) on various multidrug-resistant strains in the presence of bovine serum albumin and sheep erythrocytes to mimic the blood contamination that frequently occurs in the clinical setting. The 3 most important species that cause nosocomial infections, i.e., methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant Pseudomonas aeruginosa (MDRP), and multidrug-resistant Acinetobacter baumannii (MDRA), were evaluated, with three representative strains of each. At a 10-ppm concentration, ClO2 drastically reduced the number of bacteria of all MDRP and MDRA strains, and 2 out of 3 MRSA strains. However, 10 ppm of NaClO did not significantly kill any of the 9 strains tested in 60 seconds (s). In addition, 100 ppm of ClO2 completely killed all MRSA strains, whereas 100 ppm of NaClO failed to significantly lower the number of 2 MRSA strains and 1 MDRA strain. A time-course experiment demonstrated that, within 15 s, 100 ppm of ClO2, but not 100 ppm of NaClO, completely killed all tested strains. Taken together, these data suggest that ClO2 is more effective than NaClO against MRSA, MDRP, and MDRA, and 100 ppm is an effective concentration against these multidrug-resistant strains, which cause fatal nosocomial infections.

  13. ANTI-MICROORGANISM ACTIVITIES AND APPLICATIONS OF CHLORINE DIOXIDE%化学消毒剂二氧化氯抗微生物作用及应用

    Institute of Scientific and Technical Information of China (English)

    熊中奎; 郎娟; 夏国园

    2011-01-01

    二氧化氯(C102)作为一种高效化学消毒剂,能有效地杀灭或抑制病毒、细菌、真菌和寄生虫等各种病原体,在饮用水处理、食品保鲜防腐、废水处理、室内环境消毒、医疗设备和口腔科消毒等领域都具有广阔的应用前景.但是由于存在一些安全性问题,在一定程度上限制了C102推广应用.%Chlorine dioxide, as a chemical sanitizer, is highly effective for sterilizing or inhibiting many pathogens, such as viruses, bacteria, fungi and parasites, so it illustrates a good prospect of application in drinking water treatment, food preservation, effluent disposal, disinfections of interior space and medical equipments, and antisepsis of medical activities in department of stomatology. To some degrees, it is restricted in application and extension for its security fla13:34 2012-7-25ws.

  14. Generation and Measurement of Chlorine Dioxide Gas at Extremely Low Concentrations in a Living Room: Implications for Preventing Airborne Microbial Infectious Diseases.

    Science.gov (United States)

    Ogata, Norio; Sogawa, Koushirou; Takigawa, Yasuhiro; Shibata, Takashi

    2017-01-01

    Preventing respiratory diseases caused by airborne microbes in enclosed spaces is still not satisfactorily controlled. At extremely low concentrations (about 30 parts per billion), chlorine dioxide (ClO2) gas can inactivate airborne microbes and prevent respiratory disease. It has no toxic effect on animals at this level. However, controversies still remain regarding how to measure concentrations of ClO2 gas at such low levels. It is therefore necessary to prove that measured gas concentrations are accurate and reproducible. ClO2 gas was released from a gas generator and its concentration was measured by a novel highly sensitive gas analyzer. We compared its data with those from ion chromatography. We demonstrate that the gas concentrations measured in a room using the gas analyzer are accurate and reproducible after comparing the results with those from ion chromatography. However, the temperature dependence of the gas analyzer was found. Therefore, data correction is required for each temperature at which gas concentration is measured. A theoretical analysis of the gas concentrations predicted by the rate of ClO2 gas released from the ClO2 generator was also performed. Our results advance progress toward using low concentration ClO2 gas to prevent airborne infectious diseases such as influenza. © 2016 S. Karger AG, Basel.

  15. Application of Chlorine Dioxide in the Disinfection of Drinking Water%二氧化氯在饮用水消毒应用的探讨

    Institute of Scientific and Technical Information of China (English)

    王欣玮

    2012-01-01

    It is well known that chlorine dioxide, with high quality, is one kind of disinfectant for drinking water. In this paper, the author introduced ClO2 characteristic function, disinfection principle and the advantages of disinfection. Then, the author emphasized on preparation methods of ClO2, inhibition of detrimental by-products generation, as well as elimination of detrimental byproducts above-mentioned. In addition, the author also analyzed the automation control issue of water application.%二氧化氯(ClO2)是一种性能优越的饮用水消毒剂.本文对二氧化氯的特性、消毒原理和消毒的优点进行了介绍,着重阐述二氧化氯的制备方法,二氧化氯有害副产物的生成抑制和消除,分析了二氧化氯在水厂应用中自动化控制的问题.

  16. 气体二氧化氯浓度检测研究进展%Advances in Determination of Gaseous Chlorine Dioxide

    Institute of Scientific and Technical Information of China (English)

    崔超; 胡双启; 晋日亚

    2011-01-01

    This paper reviewed the research works on the determination of chlorine dioxide (ClO2) in recent two decades,and spectrophotometry, fluorimetry, electroanalysis, chromatography, chemiluminescence, resonance scattering and differential optical absorption spectroscopy (DOAS) were discussed also. Base on the request of determination of ClO2 in the future, it is pointed out the DOAS is a promising method compared with other methods at the end of the paper.%通过回顾近二十年来关于气体二氧化氯(ClO2)检测方法的发展和应用,介绍了分光光度法、荧光光度法、电化学分析法、色谱法、化学发光法、共振散射光谱法以及差分吸收光谱法,比较了各类方法的优缺点和适用范围,并提出了对空气中ClO2浓度检测要求,指出差分吸收光谱法在未来气体二氧化氯检测方面有着广阔的应用前景.

  17. Inactivation of Bacillus cereus Spores on Red Chili Peppers Using a Combined Treatment of Aqueous Chlorine Dioxide and Hot-Air Drying.

    Science.gov (United States)

    Kim, Songyi; Lee, Huyong; Ryu, Jee-Hoon; Kim, Hoikyung

    2017-08-01

    The effect of a combined treatment using aqueous chlorine dioxide (ClO2 ) and hot-air drying to inactivate Bacillus cereus spores on red chili peppers was evaluated. Ten washed and dried pepper samples, each comprising half of a single pepper (Capsicum annuum L.), were inoculated with B. cereus spore suspension. The inoculated samples were washed with sodium hypochlorite (NaOCl; 50, 100, or 200 μg/mL) or ClO2 (50, 100, or 200 μg/mL) solution for 1 min and then air-dried (25 ± 1 °C, 47 ± 1% relative humidity), which was followed by drying with hot air at 55 °C for up to 48 h. The spore populations on the samples were enumerated and their aw and chromaticity values were measured. The spore numbers immediately after treatment with NaOCl and ClO2 were not significantly different. A more rapid reduction in spore numbers was observed in the samples treated with ClO2 than those treated with NaOCl during drying. A combined treatment of ClO2 and hot-air drying significantly reduced the spore populations to below the detection limit (1.7 log CFU/sample). B. cereus spores on chili peppers were successfully inactivated by washing with ClO2 solution followed by hot-air drying whereas the pepper color was maintained. © 2017 Institute of Food Technologists®.

  18. Research on Bacteriostatic and Bactericidal Effect of Chlorine Dioxide on Aeromonas%二氧化氯对气单胞菌的抑菌和杀菌效果研究

    Institute of Scientific and Technical Information of China (English)

    谭凤霞; 吴全超

    2012-01-01

    Aeromonas bacteria strains, including the standard bacteria Aeromonas hydrophila and the Aeromonas bacteria strains which isolated from the culture water or diseased fish, were used to investigate the bacteriostatic and bactericidal efficacy of chlorine dioxide to Aeromonas bacterium by double broth dilution method. The results showed that the chlorine dioxide could inhibit the growth of bacterium at the lower concentration, and killed the bacterium at the higher concentration. The minimal inhibitory concentration (MIC) of chlorine dioxide to seven Aeromonas bacterium are 12 mg/L to strians ATCC7966, Ti, T3, T4, T5; and T6, and 24 mg/L to strain T2; The minimal bactericidal concentration (MBC) of chlorine dioxide to Aeromonas are 96 mg/L to strians ATCC7966, T1, T3 and T4, and 384 mg/L to strains T2, T5 and T6. These results provided the scientific basis for reasonable application of chlorine dioxide.%以嗜水气单胞菌(Aeromonas hydrophila)标准菌株ATCC7966和分离自养殖水环境及患病鲫鱼的气单胞菌(Aeromonas)为试验菌株,通过肉汤二倍稀释法研究二氧化氯的抑菌及杀菌效果.结果表明,二氧化氯在低浓度时能抑制气单胞菌的生长增殖,高浓度时能杀灭细菌,其对ATCC7966、T1、T3、T4、T5、T6菌株的最小抑菌浓度(MIC)为12 mg/L,对T2菌株的最小抑菌浓度为24 mg/L;二氧化氯对ATCC7966、T1、T3、T4菌株的最小杀菌浓度(MBC)为96 mg/L,对T2、T5、T6菌株的最小杀菌浓度为384 mg/L.研究结果能为二氧化氯在水产养殖上的合理使用提供一定的依据.

  19. In Situ Identification and Stratification of Monochloramine Inhibition Effects on Nitrifying Biofilms as Determined by the Use of Microelectrodes

    Science.gov (United States)

    The nitrifying biofilm grown in an annular biofilm reactor and the microbial deactivation achieved after monochloramine treatment were investigated using microelectrodes. The nitrifying biofilm ammonium microprofile was measured and the effect of monochloramine on nitrifying bio...

  20. Inactivation of Salmonella enterica in chicken feces on the surface of eggshells by simultaneous treatments with gaseous chlorine dioxide and mild wet heat.

    Science.gov (United States)

    Park, Sunhyung; Beuchat, Larry R; Kim, Hoikyung; Ryu, Jee-Hoon

    2017-04-01

    The aim of this study was to investigate the lethal effects of simultaneous treatments with gaseous chlorine dioxide (ClO2) and mild wet heat (55 °C at 100% relative humidity [RH]) on Salmonella enterica in chicken feces on the surface of eggshells. Gaseous ClO2 production decreased significantly (P ≤ 0.05) as the RH (23, 43, 68, 85, and 100%) at 25 °C was increased. The lethality of gaseous ClO2 against S. enterica in feces on eggshells increased significantly (P ≤ 0.05) as RH increased. For example, when treated with gaseous ClO2 at 85 and 100% RH at 25 °C, S. enterica (5.9 log CFU/egg) was inactivated within 4 h. In contrast, at 23, 43, and 68% RH, the pathogen remained at 5.1, 5.0, and 2.8 log CFU/egg, respectively, after 6 h. Finally, when eggshells surface-contaminated with S. enterica (5.8 log CFU/egg) were treated with gaseous ClO2 (peak concentration of ClO2: 185.6 ppm) at 100% RH and 55 °C, inactivation occurred within 1 h. These results indicate that treatment of surface-contaminated shell eggs with gaseous ClO2 at elevated RH and temperature is effective in inactivating S. enterica. These observations will be useful when developing an effective sanitation program to enhance the microbiological safety of shell eggs.

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

    Science.gov (United States)

    Aggarwal, R. L.; Farrar, L. W.; Di Cecca, S.; Jeys, T. H.

    2016-02-01

    Raman spectra of ammonia (NH3), chlorine (Cl2), hydrogen sulfide (H2S), phosgene (COCl2), and sulfur dioxide (SO2) toxic gases have been measured in the fingerprint region 400-1400 cm-1. A relatively compact (Cl2 at 554, 547, and 539 cm-1, which are due to the 35/35 35/37, and 37/37 Cl isotopes, respectively. Raman modes are observed at 870, 570, and 1151 cm-1 in H2S, COCl2, and SO2, respectively. Values of 3.68 ± 0.26x10-32 cm2/sr (3.68 ± 0.26x10-36 m2/sr), 1.37 ± 0.10x10-30 cm2/sr (1.37 ± 0.10x10-34 m2/sr), 3.25 ± 0.23x10-31 cm2/sr (3.25 ± 0.23x10-35 m2/sr), 1.63 ± 0.14x10-30 cm2/sr (1.63 ± 0.14x10-34 m2/sr), and 3.08 ± 0.22x10-30 cm2/sr (and 3.08 ± 0.22x10-34 m2/sr) were determined for the differential Raman cross section of the 967 cm-1 mode of NH3, sum of the 554, 547, and 539 cm-1 modes of Cl2, 870 cm-1 mode of H2S, 570 cm-1 mode of COCl2, and 1151 cm-1 mode of SO2, respectively, using the differential Raman cross section of 3.56 ± 0.14x10-31 cm2/sr (3.56 ± 0.14x10-35 m2/sr) for the 1285 cm-1 mode of CO2 as the reference.

  2. Absorption coefficients of chlorine-dioxide at /sup 12/C/sup 16/O/sub 2/ and /sup 12/C/sup 18/O/sub 2/ laser wavelengths: applications to remote monitoring in the working environment

    Energy Technology Data Exchange (ETDEWEB)

    Ahlberg, H.; Lundqvist, S.; Eng, S.T.

    1984-09-01

    Absorption coefficients of chlorine-dioxide at /sup 12/C/sup 16/O/sub 2/ and /sup 12/C/sup 18/O/sub 2/ laser wavelengths have been measured using a computerized CO/sub 2/ laser spectrometer. The results show that there is a large differential absorption in the 9-..mu..m band due to the ..nu../sub 3/ vibrational mode in the ClO/sub 2/ molecule and that remote sensing of ClO/sub 2/ with a sensitivity of 12 ppm x m can be performed using a long-path differential absorption technique.

  3. REACTION MECHANISM AND DYNAMICS OF H2O2-BASED CHLORINE DIOXIDE PRODUCTION%过氧化氢法制备二氧化氯的反应机理及动力学

    Institute of Scientific and Technical Information of China (English)

    钱宇; 陈赟; 江燕斌; 纪红兵

    2004-01-01

    To develop a cleaner production process of H2O2-based chlorine dioxide, this paper presents a study on reaction mechanism and dynamics of the process. It is shown that a complex H2ClO2-ClO3 exists as an intermediate in the process. A rational reaction process is proposed, which unifies several reaction mechanisms reported by different researchers in a wider range of reaction temperature. A theoretical model of the dynamics is presented, and parameters of the model are experimentally estimated and verified.

  4. 二氧化氯杀菌剂配伍羧酸水处理剂的缓蚀性能%Corrosion Inhibition of Chlorine Dioxide with Carboxylic Acid Water Treatment Agents

    Institute of Scientific and Technical Information of China (English)

    朱小梅; 朱明新; 周桃玉; 徐炎华

    2012-01-01

    投加二氧化氯可以有效地控制冷却水中的微生物。采用旋转挂片腐蚀试验和电化学试验研究了二氧化氯对金属的腐蚀问题,并研究了二氧化氯溶液中配伍羧酸类水处理剂PBTCA(2-膦酸基丁烷-1,2,4-三羧酸)、PESA(聚环氧琥珀酸)、TH-628(有机羧酸复合药剂)的缓蚀性能。结果表明,二氧化氯浓度为0.8mg/L时,碳钢的腐蚀率最低。三种药剂在二氧化氯的体系中均有一定的缓蚀作用,PESA的缓蚀效果最好。在碳钢的腐蚀过程中,复合药剂TH-628对电极的阳极和阴极过程均具有抑制作用,属于混合型缓蚀剂。%Microorganisms in circulating cooling water can be effectively controlled by injecting chlorine dioxide. The metal corrosion due to chlorine dioxide and the corrosion inhibition property of PBTCA (2-phosphonobutane-1, 2, 4- tricarboxylic acid), PESA (polyepoxysuccinic acid) and TH-628(organic carboxylic acid complex reagent) in chlorine dioxide solution were investigated by rotary weight-loss measurement and electrochemical testing. The results indicated that the concentration of 0. 8 mg/L chlorine dioxide resulted in the lowest corrosive rate of carbon steel. Complex drugs TH-628, PBTCA and PESA had good inhibition effects. In the process of corrosion of carbon steel, complex reagent TH-628 has inhibition effect on the reactions of both anode and cathode. So it is a mixed inhibitor.

  5. Observation of disinfectant effect of chlorine dioxide reactor on drinking water%一种二氧化氯发生器对饮用水的消毒实验观察

    Institute of Scientific and Technical Information of China (English)

    王晓; 杨宁; 赖发伟

    2012-01-01

    OBJECTIVE To observe the disinfectant effect of chlorine dioxide reactor in drinking water and its influencing factors. METHODS The quantitative suspension method, the membrane filter method were used to detect disinfectant effect a-gainst e. Coli in 30 min by the chlorine dioxide reactor. RESULTS When chlorine dioxide content was 0.3 mg/L, e. Coli decreased to 0 cfu/100 ml in 30min in artificial water; For natural water in 30m in, it also decreased to 0 cfu/100 ml, and the bacterial colony, coli groups and fecal coli groups were in line with (GB/T5750.12-2006) "Standard Microbiology Indicators of Living and Drinking Water"; pH of 5.0-9.0, and temperature of 10℃-30℃ had no influence on the results. CONCLUSION Low concentrations of chlorine dioxide in the water have good disinfectant effect against e.coli and are not influenced by pH and temperature.%目的 观察二氧化氯发生器产生的二氧化氯对饮用水中大肠杆菌的杀灭效果及影响因素.方法 悬液定量法、滤膜抽滤法,对二氧化氯发生器运行30 min后产生的二氧化氯消毒液杀灭水中大肠杆菌的效果及影响因素进行了实验室观察.结果 二氧化氯含量为0.3 mg/L时,对人工染菌水样作用30 min,其中大肠杆菌下降至0 cfu/100 ml;对天然水样作用30 min,大肠菌群下降0 cfu/100 ml,且作用后天然水样的菌落总数、大肠菌群和粪大肠菌群均符合《生活饮用水标准检验方法微生物指标》(GB/T5750.12-2006);pH值在5.0~9.0时,温度10℃~30℃对其杀菌结果无影响.结论 水体中二氧化氯在低浓度下,具有良好的杀灭大肠杆菌效果,不受pH、温度值影响.

  6. Establishment and Early Succession of Bacterial Communities in Monochloramine-Treated Drinking Water Biofilms

    Science.gov (United States)

    Monochloramine is increasingly used as a drinking water disinfectant because it forms lower levels of regulated disinfection by-products. While its use has been shown to increase nitrifying bacteria, little is known about the bacterial succession within biofilms in monochloramin...

  7. Effects of a mouthwash with chlorine dioxide on oral malodor and salivary bacteria: a randomized placebo-controlled 7-day trial

    Science.gov (United States)

    2010-01-01

    Background Previous research has shown the oxidizing properties and microbiological efficacies of chlorine dioxide (ClO2). Its clinical efficacies on oral malodor have been evaluated and reported only in short duration trials, moreover, no clinical studies have investigated its microbiological efficacies on periodontal and malodorous bacteria. Thus, the aim of this study was to assess the inhibitory effects of a mouthwash containing ClO2 used for 7 days on morning oral malodor and on salivary periodontal and malodorous bacteria. Methods/Design A randomized, double blind, crossover, placebo-controlled trial was conducted among 15 healthy male volunteers, who were divided into 2 groups. Subjects were instructed to rinse with the experimental mouthwash containing ClO2 or the placebo mouthwash, without ClO2, twice per day for 7 days. After a one week washout period, each group then used the opposite mouthwash for 7 days. At baseline and after 7 days, oral malodor was evaluated with Organoleptic measurement (OM), and analyzed the concentrations of hydrogen sulfide (H2S), methyl mercaptan (CH3SH) and dimethyl sulfide ((CH3)2S), the main VSCs of human oral malodor, were assessed by gas chromatography (GC). Clinical outcome variables included plaque and gingival indices, and tongue coating index. The samples of saliva were microbiologically investigated. Quantitative and qualitative analyses were performed using the polymerase chain reaction-Invader method. Results and Discussion The baseline oral condition in healthy subjects in the 2 groups did not differ significantly. After rinsing with the mouthwash containing ClO2 for 7 days, morning bad breath decreased as measured by the OM and reduced the concentrations of H2S, CH3SH and (CH3)2S measured by GC, were found. Moreover ClO2 mouthwash used over a 7-day period appeared effective in reducing plaque, tongue coating accumulation and the counts of Fusobacterium nucleatum in saliva. Future research is needed to examine long

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

    Directory of Open Access Journals (Sweden)

    R. L. Aggarwal

    2016-02-01

    Full Text Available Raman spectra of ammonia (NH3, chlorine (Cl2, hydrogen sulfide (H2S, phosgene (COCl2, and sulfur dioxide (SO2 toxic gases have been measured in the fingerprint region 400-1400 cm−1. A relatively compact (<2′x2′x2′, sensitive, 532 nm 10 W CW Raman system with double-pass laser and double-sided collection was used for these measurements. Two Raman modes are observed at 934 and 967 cm−1 in NH3. Three Raman modes are observed in Cl2 at 554, 547, and 539 cm−1, which are due to the 35/35 35/37, and 37/37 Cl isotopes, respectively. Raman modes are observed at 870, 570, and 1151 cm−1 in H2S, COCl2, and SO2, respectively. Values of 3.68 ± 0.26x10−32 cm2/sr (3.68 ± 0.26x10−36 m2/sr, 1.37 ± 0.10x10−30 cm2/sr (1.37 ± 0.10x10−34 m2/sr, 3.25 ± 0.23x10−31 cm2/sr (3.25 ± 0.23x10−35 m2/sr, 1.63 ± 0.14x10−30 cm2/sr (1.63 ± 0.14x10−34 m2/sr, and 3.08 ± 0.22x10−30 cm2/sr (and 3.08 ± 0.22x10−34 m2/sr were determined for the differential Raman cross section of the 967 cm−1 mode of NH3, sum of the 554, 547, and 539 cm−1 modes of Cl2, 870 cm−1 mode of H2S, 570 cm−1 mode of COCl2, and 1151 cm-1 mode of SO2, respectively, using the differential Raman cross section of 3.56 ± 0.14x10−31 cm2/sr (3.56 ± 0.14x10−35 m2/sr for the 1285 cm−1 mode of CO2 as the reference.

  9. A randomized double blind crossover placebo-controlled clinical trial to assess the effects of a mouthwash containing chlorine dioxide on oral malodor

    Directory of Open Access Journals (Sweden)

    Yokoyama Sayaka

    2008-12-01

    Full Text Available Abstract Background Previous research has shown the oxidizing properties and microbiological efficacies of chlorine dioxide (ClO2, however, its clinical efficacies on oral malodor have been evaluated only with organoleptic measurements (OM or sulphide monitors. No clinical studies have investigated the inhibitory effects of ClO2 on volatile sulfur compounds (VSCs using gas chromatography (GC. The aim of this study was to assess the inhibitory effects of a mouthwash containing ClO2 on morning oral malodor using OM and GC. Methods A randomized, double blind, crossover, placebo-controlled clinical trial was conducted among 15 healthy male volunteers, who were divided into 2 groups. In the first test phase, the group 1 subjects (N = 8 were instructed to rinse with the experimental mouthwash containing ClO2, and those in group 2 (N = 7 to rinse with the placebo mouthwash without ClO2. In the second test, phase after a one week washout period, each group used the opposite mouthwash. Oral malodor was evaluated before rinsing, right after rinsing and every 30 minutes up to 4 hours with OM, and concentrations of hydrogen sulfide (H2S, methyl mercaptan (CH3SH and dimethyl sulfide ((CH32S, the main VSCs of human oral malodor, were evaluated with GC. Results The baseline oral condition in the subjects in the 2 groups did not differ significantly. The mouthwash containing ClO2 improved morning bad breath according to OM and reduced concentrations of H2S, CH3SH and (CH32S according to GC up to 4 hours after rinsing. OM scores with ClO2 were significantly lower than those without ClO2 at all examination times. Significant reductions in the concentrations of the three kinds of VSCs measured by GC were also evident at all examination times. The concentrations of the three gases with ClO2 were significantly lower than those without ClO2 at most examination times. Conclusion In this explorative study, ClO2 mouthwash was effective at reducing morning malodor for 4

  10. A randomized double blind crossover placebo-controlled clinical trial to assess the effects of a mouthwash containing chlorine dioxide on oral malodor

    Science.gov (United States)

    Shinada, Kayoko; Ueno, Masayuki; Konishi, Chisato; Takehara, Sachiko; Yokoyama, Sayaka; Kawaguchi, Yoko

    2008-01-01

    Background Previous research has shown the oxidizing properties and microbiological efficacies of chlorine dioxide (ClO2), however, its clinical efficacies on oral malodor have been evaluated only with organoleptic measurements (OM) or sulphide monitors. No clinical studies have investigated the inhibitory effects of ClO2 on volatile sulfur compounds (VSCs) using gas chromatography (GC). The aim of this study was to assess the inhibitory effects of a mouthwash containing ClO2 on morning oral malodor using OM and GC. Methods A randomized, double blind, crossover, placebo-controlled clinical trial was conducted among 15 healthy male volunteers, who were divided into 2 groups. In the first test phase, the group 1 subjects (N = 8) were instructed to rinse with the experimental mouthwash containing ClO2, and those in group 2 (N = 7) to rinse with the placebo mouthwash without ClO2. In the second test, phase after a one week washout period, each group used the opposite mouthwash. Oral malodor was evaluated before rinsing, right after rinsing and every 30 minutes up to 4 hours with OM, and concentrations of hydrogen sulfide (H2S), methyl mercaptan (CH3SH) and dimethyl sulfide ((CH3)2S), the main VSCs of human oral malodor, were evaluated with GC. Results The baseline oral condition in the subjects in the 2 groups did not differ significantly. The mouthwash containing ClO2 improved morning bad breath according to OM and reduced concentrations of H2S, CH3SH and (CH3)2S according to GC up to 4 hours after rinsing. OM scores with ClO2 were significantly lower than those without ClO2 at all examination times. Significant reductions in the concentrations of the three kinds of VSCs measured by GC were also evident at all examination times. The concentrations of the three gases with ClO2 were significantly lower than those without ClO2 at most examination times. Conclusion In this explorative study, ClO2 mouthwash was effective at reducing morning malodor for 4 hours when used by

  11. Effect of One-methylcyclopropene (1-MCP) and chlorine dioxide (ClO2) on preservation of green walnut fruit and kernel traits.

    Science.gov (United States)

    Jiang, Liuqing; Feng, Wenyu; Li, Fang; Xu, Jingying; Ma, Yanping; Ma, Huiling

    2015-01-01

    The effect of the ethylene receptor competitor 1-methylcyclopropene (1-MCP) and the legally approved disinfectant chlorine dioxide (ClO2) on preservation of the green walnut fruit during storage was investigated. Green Chinese walnut fruit cv. Xilin No.2 was harvested on commercial maturity and stored at 0-1 °C after the fruit was treated by water (control), 80 mg L(-1)ClO2 (ClO2), 0.5 μL L(-1)1-MCP (1-MCP), or combination treatment of 80 mg L(-1) ClO2 with either 0.1 μL L(-1) 1-MCP (0.1 1-MCP+ ClO2) or 0.5 μL L(-1) 1-MCP (0.5 1-MCP+ ClO2). During storage, respiration, ethylene production, phenolics content, antioxidative activity, weight changes, decay of the fruit and kernel traits of acid value, peroxide value,free fatty were measured. All treatments decreased postharvest respiration intensity in different degrees and inhibited ethylene production peak. ClO2 increased the total phenol and flavonoid content of the green fruit compared with other treatments and the control (P < 0.05), but not did the total antioxidant activity for this treatment. After 42-day storage, ClO2 remained higher fresh weight and lower decay index than control, while 1-MCP increased the fruit decay index. Final acid values of kernel from ClO2, control and 0.1 1-MCP+ ClO2 were not different from their initial values, which from 0.5 1-MCP increased. Final peroxide value for kernel from ClO2 showed no change during storage but increased at least 1.0-fold for other treatments. ClO2 preserved 99.9 % of initial free fatty acid, similar to that for the control (99.8 %), whereas 0.5 1-MCP preserved only 95.7 %. ClO2 is of potential in decay retardation and kernel traits maintenance of green walnut fruit, whereas the 1-MCP has a negative effect for decay control on walnut.

  12. Effects of a mouthwash with chlorine dioxide on oral malodor and salivary bacteria: a randomized placebo-controlled 7-day trial

    Directory of Open Access Journals (Sweden)

    Ohnuki Mari

    2010-02-01

    Full Text Available Abstract Background Previous research has shown the oxidizing properties and microbiological efficacies of chlorine dioxide (ClO2. Its clinical efficacies on oral malodor have been evaluated and reported only in short duration trials, moreover, no clinical studies have investigated its microbiological efficacies on periodontal and malodorous bacteria. Thus, the aim of this study was to assess the inhibitory effects of a mouthwash containing ClO2 used for 7 days on morning oral malodor and on salivary periodontal and malodorous bacteria. Methods/Design A randomized, double blind, crossover, placebo-controlled trial was conducted among 15 healthy male volunteers, who were divided into 2 groups. Subjects were instructed to rinse with the experimental mouthwash containing ClO2 or the placebo mouthwash, without ClO2, twice per day for 7 days. After a one week washout period, each group then used the opposite mouthwash for 7 days. At baseline and after 7 days, oral malodor was evaluated with Organoleptic measurement (OM, and analyzed the concentrations of hydrogen sulfide (H2S, methyl mercaptan (CH3SH and dimethyl sulfide ((CH32S, the main VSCs of human oral malodor, were assessed by gas chromatography (GC. Clinical outcome variables included plaque and gingival indices, and tongue coating index. The samples of saliva were microbiologically investigated. Quantitative and qualitative analyses were performed using the polymerase chain reaction-Invader method. Results and Discussion The baseline oral condition in healthy subjects in the 2 groups did not differ significantly. After rinsing with the mouthwash containing ClO2 for 7 days, morning bad breath decreased as measured by the OM and reduced the concentrations of H2S, CH3SH and (CH32S measured by GC, were found. Moreover ClO2 mouthwash used over a 7-day period appeared effective in reducing plaque, tongue coating accumulation and the counts of Fusobacterium nucleatum in saliva. Future research is

  13. 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(-)).

    Science.gov (United States)

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

    2016-12-01

    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 (ClO2) as well as two by-products of their use: hydrogen peroxide (H2O2) and chlorite. All of the five chemicals investigated showed clear toxicity to the algae with well-defined dose response curves. The EC50 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 ClO2 has the highest environmental hazard potential, it may still be suitable as an alternative disinfectant due to its rapid degradation in water.

  14. Chlorine decay under steady and unsteady-state hydraulic conditions

    DEFF Research Database (Denmark)

    Stoianov, Ivan; Aisopou, Angeliki

    2014-01-01

    This paper describes a simulation framework for the scale-adaptive hydraulic and chlorine decay modelling under steady and unsteady-state flows. Bulk flow and pipe wall reaction coefficients are replaced with steady and unsteady-state reaction coefficients. An unsteady decay coefficient is defined...... which depends upon the absolute value of shear stress and the rate of change of shear stress for quasi-unsteady and unsteady-state flows. A preliminary experimental and analytical investigation was carried out in a water transmission main. The results were used to model monochloramine decay...

  15. Simultaneous Control of Microorganisms and Disinfection By-products by Sequential Chlorination

    Institute of Scientific and Technical Information of China (English)

    CHAO CHEN; XIAO-JIAN ZHANG; WEN-JIE HE; HONG-DA HAN

    2007-01-01

    Objective To introduce a new sequential chlorination disinfection process in which short-term free chlorine and chloramine are sequentially added. Methods Pilot tests of this sequential chlorination were carried out in a drinking water plant. Results The sequential chlorination disinfection process had the same or better efficiency on microbe (including virus)inactivation compared with the free chlorine disinfection process. There seemed to be some synergetic disinfection effect between free chlorine and monochloramine because they attacked different targets. The sequential chlorination disinfection process resulted in 35.7%-77.0% TTHM formation and 36.6%-54.8% THAA5 formation less than the free chlorination process.The poorer the water quality was, the more advantage the sequential chlorination disinfection had over the free chlorination.Conclusion This process takes advantages of free chlorine's quick inactivation of microorganisms and chloramine's low disinfection by-product (DBP) yield and long-term residual effect, allowing simultaneous control of microbes and DBPs in an effective and economic way.

  16. Comparison of chlorine and chloramine in the release of mercury from dental amalgam.

    Science.gov (United States)

    Stone, Mark E; Scott, John W; Schultz, Stephen T; Berry, Denise L; Wilcoxon, Monte; Piwoni, Marv; Panno, Brent; Bordson, Gary

    2009-01-01

    The purpose of this project was to compare the ability of chlorine (HOCl/OCl(-)) and monochloramine (NH(2)Cl) to mobilize mercury from dental amalgam. Two types of amalgam were used in this investigation: laboratory-prepared amalgam and samples obtained from dental-unit wastewater. For disinfectant exposure simulations, 0.5 g of either the laboratory-generated or clinically obtained amalgam waste was added to 250 mL amber bottles. The amalgam samples were agitated by end-over-end rotation at 30 rpm in the presence of 1 mg/L chlorine, 10 mg/L chlorine, 1 mg/L monochloramine, 10 mg/L monochloramine, or deionized water for intervals of 0 h, 2 h, 4 h, 8 h, and 24 h for the clinically obtained amalgam waste samples and 4 h and 24 h for the laboratory-prepared samples. Chlorine and monochloramine concentrations were measured with a spectrophotometer. Samples were filtered through a 0.45 microm membrane filter and analyzed for mercury with USEPA standard method 245.7. When the two sample types were combined, the mean mercury level in the 1 mg/L chlorine group was 0.020 mg/L (n=25, SD=0.008). The 10 mg/L chlorine group had a mean mercury concentration of 0.59 mg/L (n=25, SD=1.06). The 1 mg/L chloramine group had a mean mercury level of 0.023 mg/L (n=25, SD=0.010). The 10 mg/L chloramine group had a mean mercury level of 0.024 mg/L (n=25, SD=0.011). Independent samples t-tests showed that there was a significant difference between the natural log mercury measurements of 10 mg/L chlorine compared to those of 1 mg/L and 10 mg/L chloramine. Changing from chlorine to chloramine disinfection at water treatment plants would not be expected to produce substantial increases in dissolved mercury levels in dental-unit wastewater.

  17. 气体二氧化氯用于空间消毒的评价%Evaluation of gaseous chlorine dioxide fumigation for enclosed space decontamination

    Institute of Scientific and Technical Information of China (English)

    贾海泉; 张宗兴; 祁建城; 吴金辉; 衣颖; 张恩雷; 张金明; 李艳菊; 赵明; 郝丽梅; 林松

    2013-01-01

    Objective To determine the fumigation parameters required for gaseous chlorine dioxide( CD ) to sterilize space using commercially available bioindicators and to investigate the effect environmental humidity, organic burden and material types of contents surface on the results of gaseous chlorine CD for enclosed space biodecontamination. Methods Self-made or commercially available coupons inoculated with spores of Bacillus subtilis var nigery ATCC9372 ) were used as bioindicators to qualitatively evaluate the biodecontamination consequence of microenvironmental laboratories by gaseous CD with various fumigation parameters and under various experimental conditions. Results The ability of gaseous CD to inactivate spores was enhanced with environmental humidity. However, too high concentration vapor was liable to condense on the slick surface and there was a slight corrosion mark on the metal surface. According to the results indicated by commercially available bioindicators, enclosed space could be sterilized by 3 hours of fumigation of 300 parts per million volume ( ppmv ) gaseous CD. Albumin could well protect spores from gasous CD killing. 300 ppm gaseous CD fumigation for 4 hours could sterilize filter paper coupons, while 1000 ppm gaseous CD for 4 hours still failed to biodecontaminate steel coupons or cloth coupons completely. Conclusion The relative humidity of enclosed space should be maintained at about 75% for enclosed space fumigation with gaseous CD. Commercially available bioindicators fail to indicate accurately the decontamination of enclosed space with gaseous CD. CD concentration or docontamination time should be increased according to surface material types and the absence or presence of organic burdens in disinfection objects in enclosed space.%目的 用商品化的生物指示剂确定气体二氧化氯达到空间灭菌水平所需消毒参数,同时评价环境湿度、有机干扰物、物体表面材料对气体二氧化

  18. Monochloramine Cometabolism by Mixed-Culture Nitrifiers under Drinking Water Conditions

    Data.gov (United States)

    U.S. Environmental Protection Agency — Data for Figures in manuscript. This dataset is associated with the following publication: Maestre, J., D. Wahman , and G. Speitel. Monochloramine Cometabolism by...

  19. Thiol-oxidant monochloramine mobilizes intracellular Ca2+ in parietal cells of rabbit gastric glands.

    Science.gov (United States)

    Walsh, Breda M; Naik, Haley B; Dubach, J Matthew; Beshire, Melissa; Wieland, Aaron M; Soybel, David I

    2007-11-01

    In Helicobacter pylori-induced gastritis, oxidants are generated through the interactions of bacteria in the lumen, activated granulocytes, and cells of the gastric mucosa. In this study we explored the ability of one such class of oxidants, represented by monochloramine (NH(2)Cl), to serve as agonists of Ca(2+) accumulation within the parietal cell of the gastric gland. Individual gastric glands isolated from rabbit mucosa were loaded with fluorescent reporters for Ca(2+) in the cytoplasm (fura-2 AM) or intracellular stores (mag-fura-2 AM). Conditions were adjusted to screen out contributions from metal cations such as Zn(2+), for which these reporters have affinity. Exposure to NH(2)Cl (up to 200 microM) led to dose-dependent increases in intracellular Ca(2+) concentration ([Ca(2+)](i)), in the range of 200-400 nM above baseline levels. These alterations were prevented by pretreatment with the oxidant scavenger vitamin C or a thiol-reducing agent, dithiothreitol (DTT), which shields intracellular thiol groups from oxidation by chlorinated oxidants. Introduction of vitamin C during ongoing exposure to NH(2)Cl arrested but did not reverse accumulation of Ca(2+) in the cytoplasm. In contrast, introduction of DTT or N-acetylcysteine permitted arrest and partial reversal of the effects of NH(2)Cl. Accumulation of Ca(2+) in the cytoplasm induced by NH(2)Cl is due to release from intracellular stores, entry from the extracellular fluid, and impaired extrusion. Ca(2+)-handling proteins are susceptible to oxidation by chloramines, leading to sustained increases in [Ca(2+)](i). Under certain conditions, NH(2)Cl may act not as an irritant but as an agent that activates intracellular signaling pathways. Anti-NH(2)Cl strategies should take into account different effects of oxidant scavengers and thiol-reducing agents.

  20. The application of high-concentration short-time chlorine dioxide treatment for selected specialty crops including Roma tomatoes (Lycopersicon esculentum), cantaloupes (Cucumis melo ssp. melo var. cantaloupensis) and strawberries (Fragaria×ananassa).

    Science.gov (United States)

    Trinetta, V; Linton, R H; Morgan, M T

    2013-06-01

    The effects of high-concentration short-time chlorine dioxide (ClO2) gas treatment on food-borne pathogens inoculated onto the surface of tomatoes, cantaloupes, and strawberries were studied. Produce were spot-inoculated with a mixture of Salmonella enterica (serotypes Montevideo, Javiana and Baildon), Escherichia coli O157:H7 (serotypes 204 P, EDL 933 and C792) or Listeria monocytogenes (serotypes Scott A, F 5069 and LCDC 81-861), and treated with ClO2 gas at 10 mg/l for 180 s. After ClO2 gas treatment, surviving populations were determined and shelf-life studies were conducted (microbial spoilage population, change in color and overall appearance). Significant microbial reduction (p 0.05). Results obtained suggest the potential use of high-concentration short-time ClO2 gas treatment as an effective online pathogen inactivation technology for specialty crops in large-scale produce packing operations.

  1. Investigation of an Oscillation System in the Reaction of Chlorine Dioxide-Iodine-Malonic Acid-Sulfuric Acid%二氧化氯-碘-丙二酸-硫酸化学振荡体系的探讨

    Institute of Scientific and Technical Information of China (English)

    王芳; 施来顺

    2011-01-01

    The initial concentration of every reagent was changed in the chlorine dioxide-iodine-malonic acid-sulfuric acid oscillator in a closed system,and the system was investigated by determining the absorbance of I-3 with reaction time at 350 nm.As a result,the higher was the initial concentration of malonic acid,iodine or sulfuric acid,the bigger was the amplitude.Also,the number of oscillations became small.An opposite influence existed for chlorine dioxide.The oscillation occurred as long as the reactants mixed when the concentrations of components were comparatively high.However,the oscillation was preceded by a pre-oscillatory or induction period when the concentrations of components were relatively low.%对ClO2-I2-CH2(COOH)2-H2SO4化学振荡封闭体系,改变体系中各反应物的初始浓度,在350 nm处检测I3-的吸光度随反应时间的变化,结果发现丙二酸、碘及硫酸的初始浓度越高,二氧化氯的浓度越低,振荡的振幅越大,波数越少;当反应组分浓度较高时反应物一经混合振荡立即出现,没有诱导期,但当反应组分浓度较低时存在诱导期。

  2. 居家桥水厂自动加氯工艺优化%Optimization of Technological Process of Automatic Chlorination Dosing System in Jujiaqiao Water Treatment Plant

    Institute of Scientific and Technical Information of China (English)

    陈志平; 胡介明

    2013-01-01

    自动加氯数学模型与加氯消毒理论相结合,对原有自动加氯工艺进行优化设计,改进国内加氯消毒控制模式,以出厂水余氯(一氯胺)目标值来自动控制整个工艺过程的加氯、加氨量;以滤后一氯胺和游离氨作为工艺控制参数,来监控出厂水的总氯和总氨值,使加氯和加氨量达到最小化,降低药耗,减少消毒副产物.%Optimization of the original automatic chlorination disinfection process was earned out by combining the mathematical model of the automatic chlorination with chlorination theory. The entire disinfection process of chlorine and ammonia dosing was automatically controlled by the target value of finished water residual chlorine (monochloramine). The total chlorine and total ammonia of the finished water were monitored by the filtered water monochloramine and free ammonia as process control parameter. As a result, chlorine and ammonia dosage were minimized, the chemical consumption and the disinfection by-products were reduced.

  3. Desinfecção de efluentes sanitários através de dióxido de cloro Disinfection of domestic wastewater using chlorine dioxide

    Directory of Open Access Journals (Sweden)

    Flávio Rubens Lapolli

    2005-09-01

    Full Text Available A desinfecção dos esgotos deve ser considerada quando se pretende reduzir os riscos de transmissão de doenças infecto-contagiosas. Nesse sentido, os requisitos de qualidade de uma água devem ser avaliados em função dos usos previstos para a mesma. O dióxido de cloro (ClO2 possui excelentes propriedades bactericidas, virucidas, esporocidas e algicidas e, devido a isso, é usado como desinfetante de água de abastecimento e efluente doméstico, bem como inibidor de crescimento de algas. O objetivo do trabalho foi estudar a melhor dosagem para uma boa desinfecção de efluentes sanitários previamente tratados mediante lodos ativados por aeração prolongada, avaliar a inativação de coliformes e o residual de dióxido de cloro remanescente. Foram realizados ensaios para diferentes dosagens de dióxido de cloro e diferentes tempos de contato. Os resultados obtidos mostraram que a dosagem mais indicada para desinfecção do efluente estudado foi 2,0 mg ClO2/L com um tempo de contato de 20 minutos, condições sob as quais é atingido 100% de remoção de coliformes fecais e oxidada parcialmente a matéria orgânica remanescente, em tanto que os valores de pH e residual de ClO2 do efluente mantêm-se dentro dos admitidos pelas normativas brasileira e estadunidense em vigor. O estudo econômico levado a cabo permitiu concluir que a desinfecção de efluente doméstico mediante dióxido de cloro pode ser economicamente viável.Disinfection of sewage must be considered when reduction of infect-contagious disease transmission risks is intended. Thus, water quality requirements have to be evaluated in function of its predetermined uses. Chlorine dioxide (ClO2 has excellent bactericide, viruscide, sporicide and algaecide properties and, by these reasons, it is used as a disinfectant for drinking water and municipal sewage and as an algal growing inhibitor. The objective of this work was to investigate the most adequate ClO2 doses for an adequate

  4. APPLICATION OF CHLORINE DIOXIDE FOR PRE-MILKING TREATMENT OF COW UDDER AND DEVELOPMENT OF MEDICATION FOR POST-MILKING TREATMENT OF DUGS OF COW UDDER

    Directory of Open Access Journals (Sweden)

    Komarov V. Y.

    2015-09-01

    Full Text Available In the present article the main research results of investigation of the means of pre-milking and postmilking treatment of cow udder and dugs are presented. The treatment of cow udder dugs produces great effect on the milk quality, the incidence level of mastitis of cows in the herd, extension and pathogenic agents transmission from sick to healthy animals; and also udder treatment provides hygienic protection of udder dugs. Tree concentrations of detergent of chloride dioxide were tested. Whereof, dilution of detergent with concentration of 90 mg/l chloride dioxide proved effective disinfective effect in pre-milking treatment of udder dugs. The developed medication for post-milking treatment of cow udder dugs presented high preventive efficiency against mastitis and provided longer hygienic protection of cow udder dugs after milking

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

    Science.gov (United States)

    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...

  6. Chlorine dioxide against bacteria and yeasts from the alcoholic fermentation Dióxido de cloro contra bactérias e leveduras da fermentação alcoólica

    Directory of Open Access Journals (Sweden)

    Silvana Perissatto Meneghin

    2008-06-01

    Full Text Available 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.A produção de etanol no Brasil é atualmente realizada pelo processo de fermentação em batelada alimentada ou contínuo, com reciclo de células de leveduras, de forma que contaminantes bacterianos são também reciclados e podem causar problemas devido à competição pelo

  7. Absorption and resonance Raman study of the {sup 2}B{sub 1}(X)-{sup 2}A{sub 2}(A) transition of chlorine dioxide in the gas phase

    Energy Technology Data Exchange (ETDEWEB)

    Esposito, A.P.; Stedl, T.; Jonsson, H.; Reid, P.J. [Univ. of Washington, Seattle, WA (United States). Dept. of Chemistry; Peterson, K.A. [Washington State Univ., Pullman, WA (United States). Dept. of Chemistry

    1999-03-25

    The photochemical reaction dynamics of chlorine dioxide (OClO) are investigated using absorption and resonance Raman spectroscopy. The first Raman spectra of gaseous OClO obtained directly on resonance with the {sup 2}B{sub 1}-{sup 2}A{sub 2} electronic transition are reported. Significant scattering intensity is observed for all vibrational degrees of freedom (the symmetric stretch, bend, and asymmetric stretch), demonstrating that structural evolution occurs along all three normal coordinates following photoexcitation. The experimentally measured absorption and resonance Raman intensities are compared to the intensities predicted using both empirical and ab initio models for the optically active {sup 2}A{sub 2} surface. Comparison of the experimental and theoretical absorption spectra demonstrates that the frequencies and intensities of transitions involving the asymmetric stretch are well reproduced by the empirical model characterized by a double-minimum along the asymmetric stretch. However, the ab initio model is also found to reproduce a subset of the experimental intensities. In addition, the extremely large resonance Raman intensity of the asymmetric stretch overtone transition is predicted by both models. The results presented here taken in combination with the model for the {sup 2}A{sub 2} surface in condensed environments suggest that the phase-dependent photochemical reactivity of OClO is due to environment-dependent excited-state structural evolution along the asymmetric stretch coordinate.

  8. 分散蓝2BLN染料的二氧化氯氧化脱色研究%STUDY ON DECOLORIZATION OF DISPOSAL BLUE 2BLN BY CHLORINE DIOXIDE

    Institute of Scientific and Technical Information of China (English)

    谢家理; 向芹; 冯易君; 付嘉媛; 杨庆良; 刘俊

    2001-01-01

    We have treated Disposal Blue 2BLN with chlorine dioxide for decolorization.Under the optimum reaction condition,study of the dynamical mechanics of reaction with SF stop-flowing spectrophotometer has been carried out.Utilizing the PM3 semi-experience method to calculate the configuration of molecular of 2BLN,we have found out a theoretical reaction route,showing that the decolorization reaction order of 2BLN is 1,while that of ClO2 is 0.5.This kind of reaction is considered as fast one,being a Sn2 path way.%我们用ClO2氧化分散蓝2BLN,对其进行脱色,在1分钟内脱色率为90%以上。在最佳条件下,研究了反应的动力学。用PMS半经验方法计算了2BLN分子的键级。结果表明,脱色反应的级数,对2BLN为1级,对ClO2为0.5级,这个反应是十分快的,开始于一个Sn2亲核历程。

  9. CHLORINATION OF AMINO ACIDS: REACTION PATHWAYS AND REACTION RATES.

    Science.gov (United States)

    How, Zuo Tong; Linge, Kathryn; Busetti, Francesco; Joll, Cynthia A

    2017-03-15

    Chlorination of amino acids can result in the formation of organic monochloramines or organic dichloramines, depending on the chlorine to amino acid ratio (Cl:AA). After formation, organic chloramines degrade into aldehydes, nitriles and N-chloraldimines. In this paper, the formation of organic chloramines from chlorination of lysine, tyrosine and valine were investigated. Chlorination of tyrosine and lysine demonstrated that the presence of a reactive secondary group can increase the Cl:AA ratio required for the formation of N,N-dichloramines, and potentially alter the reaction pathways between chlorine and amino acids, resulting in the formation of unexpected by-products. In a detailed investigation, we report rate constants for all reactions in the chlorination of valine, for the first time, using experimental results and modelling. At Cl:AA = 2.8, the chlorine was found to first react quickly with valine (5.4x104 M-1 s-1) to form N-monochlorovaline, with a slower subsequent reaction with N-monochlorovaline to form N,N-dichlorovaline (4.9x102 M-1 s-1), although some N-monochlorovaline degraded into isobutyraldehyde (1.0x10-4 s-1). The N,N-dichlorovaline then competitively degraded into isobutyronitrile (1.3x10-4 s-1) and N-chloroisobutyraldimine (1.2x10-4 s-1). In conventional drinking water disinfection, N-chloroisobutyraldimine can potentially be formed in concentrations higher than its odour threshold concentration, resulting in aesthetic challenges and an unknown health risk.

  10. Quality assessment of ground-based microwave measurements of chlorine monoxide, ozone, and nitrogen dioxide from the NDSC radiometer at the plateau de bure

    Energy Technology Data Exchange (ETDEWEB)

    Ricaud, P.; Noe, J. de la [Observatoire Aquitain des Sciences de l' Univers (OASU), Lab. d' Astrodynamique, d' Astrophysique et d' Aeronomie de Bordeaux, Floirac (France); Baron, P. [Noveltis, Toulouse (France)

    2004-07-01

    A ground-based microwave radiometer dedicated to chlorine monoxide (ClO) measurements around 278 GHz has been in operation from December 1993-June 1996 at the Plateau de Bure, France (45 N, 5.9 E, 2500 m altitude). It belongs to the international network for the detection of stratospheric change. A detailed study of both measurements and retrieval schemes has been undertaken. Although dedicated to the measurements of ClO, simultaneous profiles of O{sub 3}, ClO and NO{sub 2}, together with information about the instrumental baseline, have been retrieved using the optimal estimation method. The vertical profiles have been compared with other ground-based microwave data, satellite-borne data and model results. Data quality shows: 1) the weak sensitivity of the instrument that obliges to make time averages over several hours; 2) the site location where measurements of good opacities are possible for only a few days per year; 3) the baseline undulation affecting all the spectra, an issue common to all the microwave instruments; 4) the slow drift of some components affecting frequencies by 3-4 MHz within a couple of months. Nevertheless, when temporally averaging data over a few days, ClO temporal variations (diurnal and over several weeks in winter 1995) from 35-50 km are consistent with model results and satellite data, particularly at the peak altitude around 40 km, although temporal coincidences are infrequent in winter 1995. In addition to ClO, it is possible to obtain O{sub 3} information from 30-60 km whilst the instrument is not optimized at all for this molecule. Retrievals of O{sub 3} are reasonable when compared with model and another ground-based data set, although the lowermost layers are affected by the contamination of baseline remnants. Monthly-averaged diurnal variations of NO{sub 2} are detected at 40 km and appear in agreement with photochemical model results and satellite zonally-averaged data, although the amplitude is weaker than the other data sets

  11. Efficacy of chlorine dioxide disinfection to non-fermentative Gram-negative bacilli and non-tuberculous mycobacteria in a hospital water system.

    Science.gov (United States)

    Hsu, M-S; Wu, M-Y; Huang, Y-T; Liao, C-H

    2016-05-01

    Chlorinated tap water in hospitals often contains low levels of non-fermentative Gram-negative bacilli (NFGNB) and non-tuberculous mycobacteria (NTM). Measures are needed to ensure a safe water supply in hospitals to prevent nosocomial infections from these waterborne pathogens. To evaluate the efficacy of ClO2 treatment of a hospital water system on the levels of NFGNB and NTM in the water. Our institution is a 1000-bed medical centre with two main buildings (B1 and B2). B1 has three intensive care units (ICUs) and transplant wards and polyethylene water pipes. B2 (control) has no ICUs and galvanized water pipes. A ClO2 generating unit was installed in the water system of B1 in April 2012 and water samples were collected in B1 and B2 before and eight times after installation. All samples were cultured for NFGNB and NTM. The ClO2 concentration was significantly lower in the hot water than in the cold water (P<0.001). After 40 weeks of ClO2 use, the overall NFGNB colonies decreased significantly (hot water: 160±143 vs 2±4cfu/mL, P<0.001; cold water: 108±138 vs 3±7cfu/mL, P<0.001). Highly prevalent nosocomial NFGNB, such as Pseudomonas spp. and Stenotrophomonas spp., were undetected three months after ClO2 disinfection; Sphingomonas spp. persisted but had lower colony counts. NTM was present in 25% (three out of 12) of sampling locations initially, but was not detected at two weeks after ClO2 disinfection. The ICUs had no overall change in the number of NFGNB nosocomial infections after the intervention. Addition of a ClO2 disinfection unit to our hospital water system reduced the numbers of NTM and NFGNB in the hot and cold water systems. Copyright © 2016 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  12. Quality assessment of ground-based microwave measurements of chlorine monoxide, ozone, and nitrogen dioxide from the NDSC radiometer at the Plateau de Bure

    Directory of Open Access Journals (Sweden)

    P. Ricaud

    2004-06-01

    Full Text Available A ground-based microwave radiometer dedicated to chlorine monoxide (ClO measurements around 278GHz has been in operation from December 1993-June 1996 at the Plateau de Bure, France (45° N, 5.9° E, 2500m altitude. It belongs to the international Network for the Detection of Stratospheric Change. A detailed study of both measurements and retrieval schemes has been undertaken. Although dedicated to the measurements of ClO, simultaneous profiles of O3, ClO and NO2, together with information about the instrumental baseline, have been retrieved using the optimal estimation method. The vertical profiles have been compared with other ground-based microwave data, satellite-borne data and model results. Data quality shows: 1 the weak sensitivity of the instrument that obliges to make time averages over several hours; 2 the site location where measurements of good opacities are possible for only a few days per year; 3 the baseline undulation affecting all the spectra, an issue common to all the microwave instruments; 4 the slow drift of some components affecting frequencies by 3-4MHz within a couple of months. Nevertheless, when temporally averaging data over a few days, ClO temporal variations (diurnal and over several weeks in winter 1995 from 35-50km are consistent with model results and satellite data, particularly at the peak altitude around 40km, although temporal coincidences are infrequent in winter 1995. In addition to ClO, it is possible to obtain O3 information from 30-60km whilst the instrument is not optimized at all for this molecule. Retrievals of O3 are reasonable when compared with model and another ground-based data set, although the lowermost layers are affected by the contamination of baseline remnants. Monthly-averaged diurnal variations of NO2 are detected at 40km and appear in agreement with photochemical model results and satellite zonally-averaged data, although the amplitude

  13. The role of bound chlorine in the brightness reversion of bleached hardwood kraft pulp

    Directory of Open Access Journals (Sweden)

    Kátia Maria Morais Eiras

    2009-01-01

    Full Text Available Our previous paper showed fragmentary evidence that pulp brightness reversion may be negatively affected by its organically bound chlorine (OX content. A thorough investigation on eucalyptus kraft pulp led to the conclusion that OX increases reversion of certain pulps but this trend is not universal. Alkaline bleaching stages decrease reversion regardless of pulp OX content. Pulps bleached with high temperature chlorine dioxide revert less than those bleached with conventional chlorine dioxide in sequences ending with a chlorine dioxide stage but similarly in sequences ending with a final peroxide stage. The use of secondary condensate for pulp washing decreases reversion.

  14. Efficacy of preprocedural mouth rinse containing chlorine dioxide in reduction of viable bacterial count in dental aerosols during ultrasonic scaling: A double-blind, placebo-controlled clinical trial

    Directory of Open Access Journals (Sweden)

    Rajiv Saini

    2015-01-01

    Full Text Available Background: The risk to dentists, dental assistants, and patients of infectious diseases through aerosols has long been recognized. The aim of this study was to evaluate and compare the efficacy of commercially available preprocedural mouthrinses containing 0.2% chlorhexidine (CHX gluconate, chlorine dioxide (ClO 2 mouthwash, and water in reducing the levels of viable bacteria in aerosols. Materials and Methods: This single-center, double-blind, placebo-controlled, three-group parallel-designed study was conducted over a period of 4 months. One hundred twenty patients with chronic periodontitis were divided randomly into three groups (A, B, and C of 40 patients each to receive the ClO 2 mouthwash, water, and 0.2% CHX gluconate respectively as preprocedural rinse. The aerosol produced by the ultrasonic unit was collected at five standardized locations with respect to the reference point, i.e., the mouth of the patient. The blood agar plates were incubated at 37°C for 48 h, and the total number of colony-forming units (CFUs was counted and statistically analyzed. Results: The results showed that CFUs in groups A and C were significantly reduced compared to group B, and P 0.05. The numbers of CFUs were the highest at the patient′s chest area and lowest at the patient′s front i.e., the 6 o′clock position. Conclusion: This study proves that a regular preprocedural mouthrinse could significantly eliminate the majority of aerosols generated by the use of an ultrasonic unit, and that ClO 2 mouthrinse was found to be statistically equally effective in reducing the aerosol contamination to 0.2% CHX gluconate.

  15. Production and stability of chlorine dioxide in organic acid solutions as affected by pH, type of acid, and concentration of sodium chlorite, and its effectiveness in inactivating Bacillus cereus spores.

    Science.gov (United States)

    Kim, Hoikyung; Kang, Youngjee; Beuchat, Larry R; Ryu, Jee-Hoon

    2008-12-01

    We studied the production and stability of chlorine dioxide (ClO(2)) in organic acid solutions and its effectiveness in killing Bacillus cereus spores. Sodium chlorite (5000, 10,000, or 50,000 microg/ml) was added to 5% acetic, citric, or lactic acid solution, adjusted to pH 3.0, 4.0, 5.0, or 6.0, and held at 21 degrees C for up to 14 days. The amount of ClO(2) produced was higher as the concentration of sodium chlorite was increased and as the pH of the acid solutions was decreased. However, the stability in production of ClO(2) was enhanced by increasing the pH of the organic acid solutions. To evaluate the lethal activity of ClO(2) produced in various acid solutions as affected by acidulant and pH, suspensions of B. cereus spores were treated at 21 degrees C for 1, 3, 5, or 10 min in hydrochloric acid or organic acid solutions (pH 3.0, 4.0, 5.0, or 6.0) containing ClO(2) at concentrations of 100, 50, or 25 microg/ml. Populations of viable spores treated with ClO(2) at concentrations of 100 or 50 microg/ml in organic acid solutions decreased more rapidly than populations treated with the same concentrations of ClO(2) in HCl. Rates of inactivation tended to increase with higher pH of ClO(2) solutions. Results show that ClO(2) formed in organic acid solutions has higher stability and is more lethal to B. cereus spores than ClO(2) formed at the same concentration in HCl solution. This finding emphasizes the benefits of using organic acid solutions to prepare ClO(2) intended for use as an antimicrobial.

  16. 微波/CIO《,2》体系降解水中苯胺的研究%Study on Decomposition of Aniline in Water by Microwave/Chlorine Dioxide

    Institute of Scientific and Technical Information of China (English)

    曹福; 顾海英

    2011-01-01

    以苯胺为研究对象,对微波/CIO体系降解苯胺的过程进行了研究,分别考察了微波功率、微波辐照时间、CIO投加量、初始pH和CIO反应时间对苯胺降解的影响规律.结果表明,微波/CIO体系适宜处理苯胺浓度较低的废水,在微波功率500 W、辐照时间10min、CIO:投加量180 mg/L,初始pH 5时效果较优.微波/CIO体系降解水中苯胺具有协同作用,出水满足(GB8978-1996)中3级标准.%Taking aniline as study object,degradation of aniline in water by microwave/chlorine dioxide system was explored. The effect of microwave power, irradiation time of microwave, CIO2 dose, initial pH value and reaction time of CIO2 on the degradation efficiency were studied.The results indicated that degradation efficiency was found to be the largest when microwave power was 500 W, irradiation time of microwave was 10min,CIO2 was 180 mg/L and initial pH value was 5. The synergistic effects existed between microwave and CIO2. The effluent quality met the third grade criteria of integrated wastewater discharge standard (GB8978 - 1996).

  17. Chlorinated drinking water for lightweight laying hens

    Directory of Open Access Journals (Sweden)

    A.F. Schneider

    Full Text Available ABSTRACT The study aimed to evaluate the effect of different levels of chlorine in drinking water of laying hens on zootechnical performance, eggs shell quality, hemogasometry levels and calcium content in tibia. 144 Hy-Line laying hens, 61 weeks old, were used distributed in 24 metabolism cages. They were subjected to water diets, for a period of 28 days, using sodium hypochlorite as a chlorine source in order to obtain the following concentrations: 5ppm (control, 20ppm, 50ppm, and 100ppm. Their performance was evaluated through water consumption, feed intake, egg production and weight, egg mass, feed conversion. Shell quality was measured by specific gravity. At the end of the experiment, arterial blood was collected for blood gas level assessment and a poultry of each replicate was sacrificed to obtain tibia and calcium content measurement. There was a water consumption reduction from 20ppm of chlorine and feed intake reduction in poultry receiving water with 100ppm of chlorine. The regression analysis showed that the higher the level of chlorine in water, the higher the reduction in consumption. There were no differences in egg production and weight, egg mass, feed conversion, specific gravity, tibia calcium content, and hemogasometry levels (hydrogenionic potential, carbon dioxide partial pressure, oxygen partial pressure, sodium, potassium, chloride, bicarbonate, carbon dioxide total concentration, anion gap and oxygen saturation. The use of levels above 5ppm of chlorine is not recommended in the water of lightweight laying hens.

  18. 顺序投加联合消毒剂二氧化氯氯胺对饮用水中消毒副产物的控制%Control of Disinfection Byproducts (DBPs)in Drinking Water by Sequential Dosing of Joint Disinfection with Chlorine Dioxide and Chloramine

    Institute of Scientific and Technical Information of China (English)

    易芳; 吴立波; 杨林锋; 叶竹兰; 万芬

    2015-01-01

    Traditional chlorine disinfection process has attracted wide attention because of its harmful disinfection byproducts. The control of disinfection byproducts in drinking water by sequential dosing of joint disinfectants with dioxide and chloramine was investigated in this study. The raw water was taken from filtration water in a waterworks in Tianjin,which was disinfected by the different doses combination of chlorine dioxide and chloramine. The results show that when dosage of chlorine dioxide is 0. 10 ~0. 50 mg / L and chloramine is 0. 50 ~ 1. 50 mg / L,the generation of disinfection byproducts can be effectively controlled,which meets the requirements of relevant standards.%传统氯消毒工艺因易生成对人体有害的消毒副产物被广泛关注,采用替代氯消毒工艺控制消毒副产物是目前的研究重点。该文以天津市某自来水厂滤后水为试验对象,采用二氧化氯氯胺顺序投加联合消毒工艺,分析了不同投加量组合对消毒副产物( THMs,HAAs和亚氯酸盐)产量的控制情况。结果表明当二氧化氯投加量为0.10~0.50 mg / L、氯胺投加量为0.50~1.50 mg / L时,消毒副产物的生成量均能得到有效控制,符合相关标准的要求。

  19. Formation of emerging DBPs from the chlorination and chloramination of seawater algal organic matter and related model compounds

    KAUST Repository

    Nihemaiti, Maolida

    2014-05-01

    Limited studies focused on reactions occurring during disinfection and oxidation processes of seawater. The aim of this work was to investigate disinfection by-products (DBPs) formation from the chlorination and chloramination of seawater algal organic matter and related model compounds. Simulated algal blooms directly growing in Red Sea, red tide samples collected during an algal bloom event and Hymenomonas sp. monoculture were studied as algal organic matter sources. Experiments were conducted in synthetic seawater containing bromide ion. A variety of DBPs was formed from the chlorination and chloramination of algal organic matter. Brominated DBPs (bromoform, DBAA, DBAN and DBAcAm) were the dominant species. Iodinated DBPs (CIAcAm and iodinated THMs) were detected, which are known to be highly toxic compared to their chlorinated or brominated analogues. Algal organic matter was found to incorporate important precursors of nitrogenous DBPs (N-DBPs), which have been reported to be more toxic than regulated THMs and HAAs. Isotopically-labeled monochloramine (15N- NH2Cl) was used in order to investigate the nitrogen source in N-DBPs. High formation of N-DBPs was found from Hymenomonas sp. sample in exponential growth phase, which was enriched in nitrogen-containing organic compounds. High inorganic nitrogen incorporation was found from the algal samples enriched in humic-like compounds. HAcAms formation was studied from chlorination and chloramination of amino acids. Asparagine, aspartic acid and other amino acids with an aromatic structure were found to be important precursors of HAcAms and DCAN. Factors affecting HAcAms formation (Cl2/ amino acid molar ratio and pH) were evaluated. Studies on the formation kinetics of DCAcAm and DCAN from asparagine suggested a rapid formation of DCAcAm from organic nitrogen (amide group) and a slower incorporation of inorganic nitrogen coming from monochloramine to form DCAN. High amounts of DCAN and DCAcAm were detected from the

  20. Bayesian belief network modelling of chlorine disinfection for human pathogenic viruses in municipal wastewater.

    Science.gov (United States)

    Carvajal, Guido; Roser, David J; Sisson, Scott A; Keegan, Alexandra; Khan, Stuart J

    2017-02-01

    Chlorine disinfection of biologically treated wastewater is practiced in many locations prior to environmental discharge or beneficial reuse. The effectiveness of chlorine disinfection processes may be influenced by several factors, such as pH, temperature, ionic strength, organic carbon concentration, and suspended solids. We investigated the use of Bayesian multilayer perceptron (BMLP) models as efficient and practical tools for compiling and analysing free chlorine and monochloramine virus disinfection performance as a multivariate problem. Corresponding to their relative susceptibility, Adenovirus 2 was used to assess disinfection by monochloramine and Coxsackievirus B5 was used for free chlorine. A BMLP model was constructed to relate key disinfection conditions (CT, pH, turbidity) to observed Log Reduction Values (LRVs) for these viruses at constant temperature. The models proved to be valuable for incorporating uncertainty in the chlor(am)ination performance estimation and interpolating between operating conditions. Various types of queries could be performed with this model including the identification of target CT for a particular combination of LRV, pH and turbidity. Similarly, it was possible to derive achievable LRVs for combinations of CT, pH and turbidity. These queries yielded probability density functions for the target variable reflecting the uncertainty in the model parameters and variability of the input variables. The disinfection efficacy was greatly impacted by pH and to a lesser extent by turbidity for both types of disinfections. Non-linear relationships were observed between pH and target CT, and turbidity and target CT, with compound effects on target CT also evidenced. This work demonstrated that the use of BMLP models had considerable ability to improve the resolution and understanding of the multivariate relationships between operational parameters and disinfection outcomes for wastewater treatment. Copyright © 2016 Elsevier Ltd. All

  1. Modeling chlorine dioxide bleaching of chemical pulp

    OpenAIRE

    Tarvo, Ville

    2010-01-01

    This doctoral thesis deals with the phenomenon-based modeling of pulp bleaching. Previous bleaching models typically utilize one or two empirical correlations to predict the kinetics in kappa number development. Empirical correlations are simple to develop, but their parameters are often tied to the validation system. A major benefit of