Low Chlorine Concentrations Research Articles

Formation of Chlorinated Derivatives of Bisphenol. A in Waste Paper Recycling Plants and Their Estrogenic Activities.

High concentrations of bisphenol A were detected in the effluent from several pulping processes for waste paper containing thermal paper and/or other printed paper. Chlorinated derivatives of bisphenol A were found to be formed by its reaction with a low concentration of chlorine in the effluent from the bleaching process using sodium hypochlorite. Poly-chlorinated derivatives were mainly detected in the final effluents from two plants because they were not biodegraded in the water recycling process by treatment with activated sludge. The estrogenic activities of bisphenol A and its chlorinated derivatives were evaluated by an agonist assay using the yeast two-hybrid system with and without a metabolic activation test using rat liver S9. All of the chlorinated derivatives tested showed more potent activity than bisphenol A without S9. The activity of 3,3′-dichlorinated BPA was 38-fold stronger than that of bisphenol A. The activities of these compounds were almost eliminated upon treatment with S9.

TiN Films Prepared by Flow Modulation Chemical Vapor Deposition using TiCl4 and NH3

We propose a new chemical vapor deposition (CVD) process, the flow modulation chemical vapor deposition (FMCVD) process, to obtain high quality titanium nitride (TiN) films at low deposition temperature in a single CVD chamber. FMCVD uses sequential deposition and reduction processes, such as the deposition of TiN films followed by chlorine reduction. This cycle was repeated to achieve sufficient film thickness. By decreasing the thickness in one cycle, the residual chlorine concentration and the resistivity of the films decreased. Using FMCVD process, we could achieve low resistivity (250 µΩcm), low residual chlorine concentration (2 at.%) with uniform step coverage at low deposition temperature (380°C).

Deactivation of copper-based catalysts for fuel cell applications

The activity of copper catalysts for the steam reforming of methanol was investigated under deactivating conditions. The effects of adding poisonous substances which can occur in the fuel, such as sulphur and chlorine, were studied. Thermal ageing by sintering was observed while exposing the catalyst to high temperatures. The catalyst activity for steam reforming was greatly affected by the addition of low concentrations of sulphur and chlorine. Sulphur was more detrimental to the catalyst than chlorine.

A comparison of the bactericidal effects and cytotoxic activity of three types of oxidizing water, prepared by electrolysis, as chemical dental plaque control agents

Acid oxidizing water (AOW), neutral oxidizing water (NtOW) and acid oxidizing water with a low available chlorine concentration (AOW-LC) may be obtained by electrolyzing a solution of tap water containing various quantities of NaCl and HCl. This study compared the bactericidal effects of these waters on cariogenic and periodontopathogenic bacteria and their cytotoxicities against epithelial cells. AOW, NtOW and AOW-LC showed considerable bactericidal effects. The cytotoxicity of AOW-LC was significantly lower than the other solutions tested ( P<0.0001). The results indicated that the three types of oxidizing water had similar activity in inhibiting bacterial plaque formation as conventional chemical plaque-control agents.

Towards the development of a chemical kinetic model for the homogeneous oxidation of mercury by chlorine species

The potential for regulation of mercury emissions from coal-fired boilers is a concern for the electric utility industry. Field data show a wide variation in the fraction of mercury that is emitted as a vapor vs. that retained in the solid products. The reason for this variation is not well-understood. Near the end of the flue gas path, mercury exists as a combination of elemental vapor and HgCl 2 vapor. The data show that HgCl 2 is more likely to be removed from the flue gas. Thus, the degree of oxidation is considered to be a critical factor that tends to reduce emission. Mercury is certain to exist as elemental vapor in the flame, with the oxidation occurring at some point in the post-flame environment. At present, the mechanism promoting this oxidation is not quantitatively known, particularly under the low chlorine concentrations afforded by many coals. In the present work, we measure mercury oxidation from a furnace operating between 860°C and 1171°C. These data are compared with similar results from the literature. The possible elementary reactions that may lead to oxidation are reviewed and a chemical kinetic model is proposed. This model yields good qualitative agreement with the data and indicates that mercury oxidation occurs during the thermal quench of the combustion gases. The model also suggests that atomic chlorine is the key oxidizing species. The oxidation is limited to a temperature window between 700°C and 400°C that is defined by the overlap of (1) a region of significant superequilibrium Cl concentration, and (2) a region where oxidized mercury is favored by equilibrium. Above 700°C, reverse reactions effectively limit oxidized mercury concentrations. Below 400°C, atomic chlorine concentrations are too low to support further oxidation. The implication of these results are that homogeneous oxidation is governed primarily by (1) HCl concentration, (2) quench rate, and (3) background gas composition.

Use of UV Spectroscopy To Characterize the Reaction between NOM and Free Chlorine

Simple and reliable relationships exist between the change in UV absorbance (ΔA) of NOM when it is chlorinated and the formation of chlorinated byproducts. These relationships provide an approach for obtaining large amounts of data that can be used to interpret the kinetics, stoichiometry, and mechanism of the reactions. Analysis of these relationships suggests that the functional groups that are the major precursors for DBPs might be highly activated aromatic rings, as has been suggested previously, but that these groups have some fundamental differences from highly activated rings in pure compounds. The key evidence for this difference is that the UV absorbance of NOM decreases when dosed with even very low concentrations of chlorine, whereas the absorbance of pure compounds such as 3,5-DHBA and resorcinol increases. When hypochlorite species (HOCl and OCl-) are added to a solution containing NOM, between 1.6 and 4.1 Cl atoms become incorporated into NOM for each activated aromatic ring that is destroye...

Time-Resolved Laser-Induced Breakdown Spectroscopy: Application for Qualitative and Quantitative Detection of Fluorine, Chlorine, Sulfur, and Carbon in Air

Detection limits for the main heteroatoms in pollutants and chemical agents have been determined in atmospheric conditions with the use of the time-resolved laser-induced breakdown spectroscopy (TRELIBS) method. This method presents many advantages for detection in hazardous or corrosive gas mixtures where sampling systems are not usable. Moreover, low concentrations of fluorine, chlorine, sulfur, and carbon can be measured with short analysis times. Currently, concentration limits are close to 10–50 ppm (w/w) for F, Cl, and C atoms, while presently only 1500 ppm (w/w) limits are reached for S. These measurements are obtained with an analysis time of under 20 s.

Analyte volatilization procedure for the determination of low concentrations of chlorine by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry

A simple method is described for the generation of a continuous flow of volatile chlorine by the oxidation of aqueous chloride for the determination of low concentrations of chlorine by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry (He MIP-AES). The chlorine atom emission line at 438.976 nm and ion emission lines at 479.454 and 481.006 nm were selected as the analytical lines of interest. Of the various oxidation reactions investigated, two analyte volatilization reactions with potassium permanganate and perbromate in combination with sulfuric acid were found to be the most appropriate for the generation of elemental chlorine. The gaseous chlorine is separated from the solution in a simple gas–liquid separator, dried with concentrated sulfuric acid and swept into the MIP with helium carrier gas for analysis. The best attainable detection limits (3 σ criterion) for chlorine at 438.976, 479.454 and 481.006 nm with the use of potassium permanganate as an oxidant were found to be 29.9, 6.8 and 12.3 ng ml −1, respectively. Typical calibration graphs obtained under the optimized experimental conditions are rectilinear over approximately three orders of magnitude of concentration. The present method has successfully been applied to the determination of chlorine as chloride in several water samples.

Stability and bactericidal activity of chlorine solutions.

To determine the stability of sodium hypochlorite (diluted household bleach) when stored for 30 days in various types of containers and to determine the efficacy of low concentrations of free available chlorine to inactivate test bacteria. Laboratory-based study. Solutions of standard household bleach were prepared using tap water or sterile distilled water at dilutions of 1:100, 1:50, and 1:5. Chlorine concentrations were measured, and then the solutions were placed into five polyethylene containers and left at room temperature (20 degrees C) under various conditions (translucent containers with light exposure and with or without air; brown opaque container without light or air exposure). Samples for chlorine and pH determinations were taken at time 0 and on days 7, 14, 21, 30, and 40. Bactericidal activity of chlorine solutions was assessed using the Association of Official Analytical Chemists Use-Dilution Method. Test bacteria included Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella choleraesuis. Chlorine concentrations at 30 days varied from the 40% to 50% range for 1:50 or 1:100 dilutions stored in containers other than closed brown containers to 83% to 85% for the 1:5 dilution stored in closed but non-opaque containers to 97% to 100% for 1:50 or 1:5 solutions stored in closed brown containers. The lowest concentration of sodium hypochlorite solution that reliably inactivated all the test organisms was 100 ppm. These data suggest that chlorine solutions do not need to be prepared fresh daily, as is recommended currently, and the lowest concentration of chlorine that reliably inactivates S aureus, S choleraesuis, and P aeruginosa is 100 ppm.

Stability and Bactericidal Activity of Chlorine Solutions

To determine the stability of sodium hypochlorite (diluted household bleach) when stored for 30 days in various types of containers and to determine the efficacy of low concentrations of free available chlorine to inactivate test bacteria.Laboratory-based study. Solutions of standard household bleach were prepared using tap water or sterile distilled water at dilutions of 1:100, 1:50, and 1:5. Chlorine concentrations were measured, and then the solutions were placed into five polyethylene containers and left at room temperature (20 degrees C) under various conditions (translucent containers with light exposure and with or without air; brown opaque container without light or air exposure). Samples for chlorine and pH determinations were taken at time 0 and on days 7, 14, 21, 30, and 40. Bactericidal activity of chlorine solutions was assessed using the Association of Official Analytical Chemists Use-Dilution Method. Test bacteria included Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella choleraesuis.Chlorine concentrations at 30 days varied from the 40% to 50% range for 1:50 or 1:100 dilutions stored in containers other than closed brown containers to 83% to 85% for the 1:5 dilution stored in closed but non-opaque containers to 97% to 100% for 1:50 or 1:5 solutions stored in closed brown containers. The lowest concentration of sodium hypochlorite solution that reliably inactivated all the test organisms was 100 ppm.These data suggest that chlorine solutions do not need to be prepared fresh daily, as is recommended currently, and the lowest concentration of chlorine that reliably inactivates S aureus, S choleraesuis, and P aeruginosa is 100 ppm.

Evaluation of the disinfection potential of low chlorine concentrations in tap water using immobilised enterococcus faecium in a continuous flow device

A simple continuous flow device in which bacteria were immobilised on membrane filters and flushed with tap water with free chlorine residuals of 0.05, 0.1, 0.2 and 0.4mg/L at pH 7.7 and 10°C, has been used for disinfection experiments with faecal streptococci. A 99.99% reduction of Enterococcus faecium was observed between 3.4–5.2min (0.05mg/L), between 2.8–4.1min (0.1mg/L), between 1.7–3.1min (0.2mg/L) and between 0.8–2.1min (0.4mg/L). CT-products covered a range of 0.17 (0.05mg/L, lower limit) up to 0.85mg/L/min (0.4mg/L, upper limit). The test system is suggested as a more reliable alternative to batch experiments when the disinfection potential of low chlorine concentrations acting for several minutes has to be evaluated. The system cannot be used to demonstrate exact reduction kinetics but it allows the calculation of CT values and the evaluation of the disinfection potential of chlorinated water at any point of a distribution system where initial chlorine concentrations may have already remarkably declined.

Influence of Chlorine on the Decomposition of Ethylene over Iron and Cobalt Particles

The interaction of cobalt and iron powders with ethylene and ethylene/hydrogen mixtures containing trace concentrations of chlorine has been studied using a combination of flow reactor and transmission electron microscopy techniques. Detailed analysis of both the gaseous products and the amount of solid carbon (a filamentous form) deposited on the metal surfaces has permitted us to gain an insight into some of the factors surrounding the promotional effect of low concentrations of chlorine on the catalytic action of both cobalt and iron. The optimum carbon deposition activity was achieved when either of these metals was treated at 400 °C in an ethylene/hydrogen environment containing 75−100 ppm chlorine. If the halogen was removed from the reactant, then the high activity for carbon filament growth could not be sustained. Reintroduction of chlorine after a suitable period of time resulted in restoration of the carbon deposition activity to its original level, demonstrating the reversible nature of the “activation−deactivation” processes. The results of this study are rationalized according to the notion that the presence of adsorbed chlorine species is responsible for causing reconstruction of the metal surface; however, the possibility that the halogen is capable of inducing a perturbation in the electronic properties of the particles is also considered. It is possible that the charge transfer between adsorbed chlorine species and the metal surface atoms leads to a strengthening of the metal−ethylene bond and a concomitant weakening of the C−C bond in the olefin, making the latter more susceptible to decomposition and enhancing the formation of the solid carbon product.

Evaluation of the disinfection potential of low chlorine concentrations in tap water using immobilised Enterococcus Faecium in a continuous flow device

A simple continuous flow device in which bacteria were immobilised on membrane filters and flushed with tap water with free chlorine residuals of 0.05, 0.1, 0.2 and 0.4mg/L at pH 7.7 and 10°C, has been used for disinfection experiments with faecal streptococci. A 99.99% reduction of Enterococcus faeciam was observed between 3.4–5.2mm (0.05mg/L), between 2.8–4.1mm (0.1mg/L), between 1.7–3.1mm (0.2mg/L) and between 0.8–2.1mm (0.4mg/L). CT-products covered a range of 0.17 (0.05mg/L, lower limit) up to 0.85mg/L/min (0.4mg/L, upper limit). The test system is suggested as a more reliable alternative to batch experiments when the disinfection potential of low chlorine concentrations acting for several minutes has to be evaluated. The system cannot be used to demonstrate exact reduction kinetics but it allows the calculation of CT values and the evaluation of the disinfection potential of chlorinated water at any point of a distribution system where initial chlorine concentrations may have already remarkably declined.

Risk factors for domestic acquisition of legionnaires disease. Ohio legionnaires Disease Group

Legionnaires disease is a common cause of adult pneumonia. Outbreaks of legionnaires disease have been well described, but little is known about sporadically occurring legionnaires disease, which accounts for most infections. Exposure to contaminated residential water sources is I plausible means of disease acquisition. Employing a matched case-control study design in 15 hospitals in 2 Ohio counties, we prospectively enrolled 146 adults diagnosed as having nonepidemic, community-acquired legionnaires disease and compared each with 2 hospital-based control patients, matched for age, sex, and underlying illness category. An interview regarding potential exposures was followed by a home survey that included sampling residential sources for Legionella. Interview and home survey data were analyzed to estimate the risk of acquiring legionnaires disease associated with various exposures. Multivariate analysis showed that a nonmunicipal water supply (odds ratio [OR], 2.26; 95% confidence interval [CI], 1.17-4.37), recent residential plumbing repair (OR, 2.39; 95% CI, 1.10-5.18), and smoking (OR, 3.48; 95% CI, 2.09-5.79) were independent risk factors for legionnaires disease. Univariate analysis suggested that electric (vs gas) water heaters (OR, 1.97; 95% CI, 1.10-3.52), working more than 40 hours weekly (OR, 2.13; 95% CI, 1.12-4.07), and spending nights away from home before illness (OR, 1.68; 95% CI, 1.03-2.74) were additional possible risk factors. Lower chlorine concentrations in potable water and lower water heater temperatures were associated with residential Legionella colonization. A proportion of sporadic cases of legionnaires disease may be residentially acquired and are associated with domestic potable water and disruptions in residential plumbing systems. Potential strategies to reduce legionnaires disease risk include consistent chlorination of potable water, increasing water heater temperatures, and limiting exposure to aerosols after domestic plumbing repairs.

Risk Factors for Domestic Acquisition of Legionnaires Disease

Background: Legionnaires disease is a common cause of adult pneumonia. Outbreaks of legionnaires disease have been well described, but little is known about sporadically occurring legionnaires disease, which accounts for most infections. Exposure to contaminated residential water sources is 1 plausible means of disease acquisition. Methods: Employing a matched case-control study design in 15 hospitals in 2 Ohio counties, we prospectively enrolled 146 adults diagnosed as having nonepidemic, community-acquired legionnaires disease and compared each with 2 hospital-based control patients, matched for age, sex, and underlying illness category. An interview regarding potential exposures was followed by a home survey that included sampling residential sources for Legionella . Interview and home survey data were analyzed to estimate the risk of acquiring legionnaires disease associated with various exposures. Results: Multivariate analysis showed that a nonmunicipal water supply (odds ratio [OR], 2.26; 95% confidence interval [CI], 1.17-4.37), recent residential plumbing repair (OR, 2.39; 95% CI, 1.10-5.18), and smoking (OR, 3.48; 95% CI, 2.09-5.79) were independent risk factors for legionnaires disease. Univariate analysis suggested that electric (vs gas) water heaters (OR, 1.97; 95% CI, 1.10-3.52), working more than 40 hours weekly (OR, 2.13; 95% CI, 1.12-4.07), and spending nights away from home before illness (OR, 1.68; 95% CI, 1.03-2.74) were additional possible risk factors. Lower chlorine concentrations in potable water and lower water heater temperatures were associated with residential Legionella colonization. Conclusions: A proportion of sporadic cases of legionnaires disease may be residentially acquired and are associated with domestic potable water and disruptions in residential plumbing systems. Potential strategies to reduce legionnaires disease risk include consistent chlorination of potable water, increasing water heater temperatures, and limiting exposure to aerosols after domestic plumbing repairs. Arch Intern Med. 1996;156:1685-1692

Controls on halogen concentrations in sedimentary formation waters

AbstractChlorine is the most abundant halogen in sedimentary formation waters with concentrations from &lt;100 to &gt;250000 mg/l. Bromine is the second most abundant halogen at &lt;1 mg/l to &gt;6000 mg/l with iodine from &lt;0.1 mg/l to &gt;100 mg/l and fluorine from &lt;0.1 mg/l to 30 mg/l. Chlorine and bromine show a strong systematic covariation suggesting that they are subject to the same controlling mechanisms. Fluorine only shows relatively high concentrations at elevated chlorine and bromine concentrations showing that fluorine, chlorine and bromine are possibly controlled by the same processes. Iodine does not correlate with any of the other halogens indicating that unique processes control iodine.Key geological parameters that influence chlorine and bromine (and possibly fluorine) concentrations are the presence of salt in a basin, the age of the reservoir unit and the kerogen-type within the main hydrocarbon source rock in a basin. The presence of salt in a basin shows that sea water was evaporated to halite saturation producing connate waters with high concentrations of chlorine and bromine. The presence of salt also leads to high salinity waters through water-salt interaction during burial and diagenesis. Tertiary reservoirs typically have much lower chlorine and bromine concentrations than Mesozoic or Palaeozoic reservoirs. The age of the reservoir unit may simply reflect the different amounts of time available for formation water to interact with salt. The dominance of type II marine kerogen in a basin leads to higher bromine concentrations. This may reflect the dominance of a marine influence in a basin which is more likely to lead to salt deposition than terrestrial depositional environments. Iodine concentrations are independent of all these parameters. Other geological parameters such as depth of burial, temperature, basin forming mechanism and reservoir lithology have no influence upon halogen concentrations.Key processes that affect halogen concentrations are sea water evaporation and dilution, water—salt interaction and input from organic sources. Chlorine and bromine data lie close to the experimentally-derived sea water evaporation trend showing that sea water evaporation may be an important general control on halogens. Sea water dilution is probably responsible for most low salinity formation water chlorine and bromine concentrations for the same reason. Sea water dilution can occur either by meteoric invasion during burial, or following uplift and erosion, or by diagenetic dehydration reactions. Water can interact with salt in a variety of ways: halite dissolution by congruent processes, halite recrystallization by incongruent processes, sylvite dissolution or recrystallization and halite fluid inclusion rupture. Halite dissolution will lead to high chlorine and relatively low bromine waters because halite contains little bromine. In contrast, halite recrystallization will lead to bromine-enhanced waters because NaBr dissolves preferentially to NaCl. The occurrence of dissolution or recrystallization will depend on the water rock ratio, greater volumes of water will lead to more dissolution and waters with higher Cl/Br ratios. Sylvite is usually rich in bromine so dissolution will lead to bromine-enhanced waters. Primary aqueous inclusions in halite contain high bromine concentrations so that rupture, during deformation or recrystallization, will lead to bromine-enhanced formation water. A combination of these processes are responsible for the very limited range of Cl/Br ratios although congruent halite dissolution must have a limited role due to the absence of waters with high Cl/Br ratios.Iodine is strongly concentrated in organic materials in the marine environment; oils and organic rich-source rocks have high I/Cl and I/Br ratios relative to sea water or evaporated sea water. All formation waters are enriched in iodine relative to sea water implying that there has been input from organic matter or interaction with oil. However, hydrocarbon source rock type in a basin has no discernible effect upon iodine concentrations.

The search for a chlorine-resistant reverse osmosis membrane

Reverse osmosis membranes processing natural and waste waters are often exposed to low concentrations of chlorine in feed water. This biocide is chemically aggressive toward most commercial high performance membrane polymers. Chemical attack by chlorine ultimately results in membrane failure as measured by enhanced passage of both salt and water. Membrane failure is due to certain structural changes within the polymer in response to chlorine exposure. These changes in polyamide type membranes result from chlorine attack on amide nitrogen and aromatic rings. The resulting substitution products may cause deformation in the polymer chain or cleavage at amide linkages. The exact chemical mechanism of chlorine-polymer interaction and subsequent membrane failure is not, as yet, clearly understood. A review of published work on membrane-chlorine interaction will be presented here. Experimental evidence supporting various models for membrane failure will also be documented. In addition, certain common structural features known to enhance chlorine resistance of polymeric membranes are identified. It is anticipated that this paper will stimulate research efforts toward development of polymeric reverse osmosis membranes with high levels of chlorine resistance.

Efficacy of Chemical Disinfectants against Turbot Aquareovirus

The susceptibility of turbot aquareovirus to five chemical agents was examined. Treatment with 5 mg of malachite green per liter or 500 mg of iodine per liter resulted in a 90% reduction in virus titer within 1 h. Complete inactivation within 5 min was obtained with 2% formalin, 42.5% isopropanol, or 15 mg of free available chlorine per liter. Lower concentrations of chlorine were ineffective.

Effect of amplicon size on PCR detection of bacteria exposed to chlorine.

The effect of amplicon size on the PCR detection of Legionella pneumophila after chlorine inactivation was investigated. Two amplicons specific to the L. pneumophila mip gene were used for the PCR analyses: a 650-bp amplicon and smaller 168-bp amplicon within the 650-bp amplicon; a 108-bp amplicon specific to species rRNA coding sequence also was used. After exposure to chlorine, viable agar grown cells were not detected by plate counts or direct counts with p-iodonitrotetrazolium (INT) after 1 min for treatment at 10 mg/l, after 2 min for treatment at 5 mg/l, and after 4 min for treatment at 2.5 mg/l; viable water grown cells were present at least 4 min after biocide addition even with a chlorine dose of 5 mg/l. At the 10-mg/l dosage, PCR products from the 168-bp amplicon were detected on agarose gels up to 16 min after chlorination; even after 24 hr of PCR the 168-bp products were detectable using a capture probe hybridization assay. However, the 650-bp target was not detected after 4 min chlorine contact time at the same biocide dosage using agarose gels, and PCR products could not be detected by hybridization after 32 min. At lower chlorine concentrations, a similar pattern was seen with the 168-bp amplicon detectable longer after biocide addition than the 650-bp mip amplification target. On the basis of these data, larger amplicons appear to correlate better with viability of L. pneumophila in water samples.

Biofouling control with low levels of copper and chlorine

This paper describes a new technique which used low levels of copper and chlorine to minimise biofouling of pipes and heat exchangers in ships, offshore structures and power stations. Very low concentrations of copper (5 μg · 1−1) and chlorine 20 μg · 1−1) act synergistically to prevent the growth of micro‐ and macrofouling organisms.