• Journal of Electrochemical Science and Technology
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• 제15권2호
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• pp.268-275
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• 2024

The study examined the electrogeneration of hypochlorite ions (ClO^-) via electrolysis of aqueous NaCl solutions using a dimensionally stable anode-type (DSA-type) electrode based on platinum and palladium oxides supported on titanium mesh (Ti/PtPd(10%)O_x). The electrogenerated ClO^- was quantified on the basis of the absorption band at 292 nm (A_λ = 292) of the UV-Vis spectrum. The effect of initial pH, concentration of NaCl, cell potential difference and electrolysis time were investigated in this study. The results showed that the electrolysis of aqueous NaCl solutions increases the solution pH up to high values (≥ 8.0) that favor the formation of ClO^- over chlorine or hypochlorous acid. The hypochlorite concentration increases significantly at pH values > 7.0 and shows a linear trend with increasing NaCl concentration and with increasing cell potential difference. When the cell potential and NaCl concentration are held constant, the maximum hypochlorite value during electrolysis depends on both the cell potential and NaCl concentration. The Ti/PtPd(10%)O_x anode favors the production of hypochlorite ions, making this anode a promising material for use in electrochemical oxidation of wastewater via an indirect mechanism.

• Environmental Analysis Health and Toxicology
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• 제16권2호
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• pp.67-74
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• 2001

In a previous study by Kim et al. (2000), sodium hypochlorite (NaOCl) has been demonstrated to be effective against algae that cause red tides. To secure the environmental safely of the chemical in practical use, effect of NaOCl, at concentrations required for algicidal activity, on the histology of rockfish and little neck clam was examined. When the animals were exposed to NaOCl at concentrations of 0.5 or 2ppm for 1 hr, there was no exposure-associated histological change in either animal. As the experimental exposure condition was set in consideration of the use, our results provide safety information necessary for practical application to marine fields.

• Korean Journal of Food Science and Technology
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• 제29권6호
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• pp.1094-1100
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• 1997

Effects of sodium hypochlorite (NaOCl) concentration, temperature and pH on oxidation mechanism of corn starch were investigated. The rate of oxidation was dependent on the concentration of hypochlorite, pH and temperature of oxidation. The reaction was either first or second order depending on the concentration of NaOCl. At oxidant concentration of $0.75{\sim}3.0%$ active Cl/g starch, the reaction was first-order and it was second-order at $3.75{\sim}4.5%$ active Cl/g starch. The first-order rate constants were increased with increasing oxidant concentration. The rate of oxidation of starch was highest at pH 7 and decreased with increasing acidity or alkalinity of the medium. As the reaction temperature increased, the rate of oxidation was increased.

• ALGAE
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• 제29권4호
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• pp.311-319
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• 2014

The biocide sodium hypochlorite (NaOCl) is widely used for controlling algal growth, and this application can be extended to marine environments as well. This study evaluates the biocidal efficiency and cellular toxicity of NaOCl on the harmful dinoflagellate Cochlodinium polykrikoides, with emphasis on pigment production and antioxidant enzyme activity. The test organism showed dose-dependent decrease in growth rate on exposure to NaOCl, and the 72 h $EC_{50}$ was measured to be $0.584mg\;L^{-1}$. NaOCl significantly decreased pigment levels and chlorophyll autofluorescence intensity, indicating possible detrimental effects on the photosystem of C. polykrikoides. Moreover, it significantly increased the activities of antioxidant enzymes, suggesting the production of reactive oxygen species in the cells. These data indicate that NaOCl exerted deleterious effects on the photosynthetic machinery and induced oxidative damage in the dinoflagellate and this biocide could be effectively used for the control of algal blooms.

• Mycobiology
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• 제34권2호
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• pp.92-98
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• 2006

A total of 34 species belonging to 21 genera of fungi were recorded on passion fruits of both pure and hybrid origin in Uganda, however, the pure type exhibited wider spectrum (28 species and 16 genera) than the hybrid type (21 & 15). Also, yeasts (unidentified and Rhodotorula mucilaginosa) were also encountered in high numbers. Moreover, the mean count of all mycobiota obtained from the pure type was higher than that of hybrid, despite the bigger size of the later. Members of yeasts and Cladosporium followed by Phoma, Penicillium, Fusarium and Alternaria species dominated on passion fruits of pure origin, while only C. cladosporioides, F. solani and yeasts dominated on the hybrid type. Treatment with Na-hypochlorite exhibited inhibitory effects on the total mycobiotic propagules as well as the dominant species from fruits of both types. The current results, therefore, suggest the use of Na-hypochlorite to control the post-harvest mycobiota associated with passion fruits. Regarding the mycobiota contaminating passion juice, yeasts were found to be the major contaminants with Candida parapsilosis being the most common. Moulds constituted only a minor proportion with Acremonium strictum followed by Fusarium chlamydosporum, F. moniliforme, F. acuminatum and F. solani as the most dominant species. In the heat-treated juice samples, the counts of the most commonly encountered mycobiota (both yeasts and molds) were significantly inhibited or completely eliminated. Some unidentified Bacillus species were also recovered from the juice, however, their counts in the heated samples were increased but insignificantly.

• Environmental Analysis Health and Toxicology
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• 제17권2호
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• pp.135-140
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• 2002

Sodium hypochlorite (NaOCl) has been demonstrated to be effective against algae that cause red tides. To secure the environmental safety of this chemical for practical use, toxic effects of NaOCl were evaluated in two important aquaculture fishes, flounder and rockfish. At concentrations above 2.5 and 5 ppm for 1 hr, mortality occurred in flounder and rockfish, respectively. Flounder, however, did not die at 2 ppm up to an 8 hr exposure, nor did lipid peroxide level change at the same concentration in 1 hr. Plasma glucose level significantly increased in 1 hr with more than 2 ppm exposure. The results indicate that NaOCl may not induce persistent severe toxicity in flounder and rockfish at the algicidal concentration, 0.5 ppm.

• Korean Journal of Environmental Agriculture
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• 제28권2호
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• pp.186-193
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• 2009

The removal efficiency of herbicide glyphosate in a drinking water treatment system was investigated. Four major processes of a drinking water treatment system were selected and experiments were performed separately including; treatments by sodium hypochlorite (NaOCl), a sedimentation process by PAC (polyaluminum chloride), ozonation and a GAC (granular activated carbon) treatment. In the sodium hypochlorite experiment, about 50% of the glyphosate was removed by 2 mg/L of hypochlorite and more than 90% was eliminated when 5 mg/L of NaOCl was applied. Also, AMPA, the main metabolite of glyphosate, was treated with hypochlorite. More than 30% of the AMPA was removed by 2 mg/L of hypochlorite and 50% by 5 mg/L. In the PAC experiment, it was determined that more than 60% could be removed. Further experiments were performed and the results indicated that the removed amount was dependent upon the amount of soil and upon the properties of the soil especially that of clay minerals. Ozonation could oxidize glyphosate to its byproducts at about a level of 50%. In contrast, when 1 mg/L of glyphosate was treated with GAC, the amount removed was negligible. The results of this experiment were conclusive. We confirmed that drinking water, which has been contaminated with water polluted with glyphosate can be effectively purified by the application of the drinking water treatment processes currently used.

• Journal of Environmental Health Sciences
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• 제35권1호
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• pp.58-63
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• 2009

This study investigated improvement to sludge dewaterability and coagulation for sewage treatment plant sludge by using sodium hypochlorite solution (NaOCl), ferric sulfate [$Fe_2(SO_4)_3$] and zeolite. The specific resistance to filtration(SRF), chloride, pH and turbidity were used to evaluate the sludge dewatering behaviors. The results of study were as follows: By varying the amount of NaOCl added the optimum result in terms of enhancement for pretreatment occurred when 34 mg/l of NaOCl was injected. When the total solids concentration of the sludge was 10,000 mg/l, the optimum ferric sulfate dosage for the sludge dewaterability was 150 mg/l and the corresponding SRF was $1.7{\times}10^7sec^2/g$. It was observed that injecting zeolite into sludge was effective in improving the dewaterability of sludge.

• The Journal of the Korean dental association
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• 제53권12호
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• pp.958-966
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• 2015

Objective: Sodium hypochlorite (NaOCl) decreases the bond strength of resin composite. The purpose of this study was to compare the effect of antioxidant and superficial dentin surface removal on the microtensile bond strength of NaOCl-treated dentin. Materials and Methods: Twenty non-carious human third molars were used in this study. The dentin surfaces were treated with 5.25% NaOCl for 10 min, followed either by treatment with 10% ascorbic acid or superficial dentin surface removal. Two-step self-etch adhesive and resin composite were used for restoration. The bonded specimens were subjected to the microtensile bond strength test. Statistical analysis was performed using one-way analysis of variance (ANOVA) and Tukey's test (p < 0.05). Results: The bond strength after removal of the superficial dentin surface following NaOCl irrigation was similar to that in the control group. The group treated with 10% ascorbic acid demonstrated significantly higher bond strength than the other groups. Conclusion: NaOCl irrigation-induced reduction in dentin bond strength could be recovered by either treatment with 10% ascorbic acid or simple removal of the superficial dentin surface.

• Korean Journal of Agricultural Science
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• 제20권1호
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• pp.18-24
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• 1993

This experiment was focused on determining the potential of sodium hypochlorite (NaOCl) as fungicide against seed-borne fungi. Effects of NaOCl to control seed-borne fungi were compared to the those of Benlate T in several crop seeds. 1. The effect of NaOCl on disinfection of sesame seeds without imparing germination was highest in the range of 1-2% solution for 10 min. Also, a 30 min immersion of rice seed in 1-2% solution reduced incedence of seed-borne fungi. 2. Alternaria spp. in seeds of radish and chinese cabbage and Colletoricum spp. in pepper were significantly reduced by a 10 min immersion of seeds in 1% NaOCl. 3. The effective control range of NaOCl for seed-borne fungi was much wider than that of Benlate T in sesame seeds. No clear difference between chemicals was found in rice seeds. However, germination of seeds were impaired at 1-2% NaOCl immersion for more than 1 hour.