Addition Of Chlorine Research Articles

Decontamination of Escherichia coli O157:H7 on green onions using pulsed light (PL) and PL–surfactant–sanitizer combinations

Imported green onion has been associated with three large outbreaks in the USA. Contamination has been found on both domestic and imported green onions. The objective of our study was to investigate Escherichia coli O157:H7 inactivation efficacy of pulsed light (PL) as well as its combination with surfactant and/or sanitizers on green onions. Green onions were cut into two segments, stems and leaves, to represent two different matrixes. Stems were more difficult to be decontaminated. Spot and dip inoculation methods were compared and dipped inoculated green onions were found to be more difficult to be decontaminated. Results showed that 5s dry PL (samples were not immersed in water during PL treatment) and 60s wet PL (samples were immersed in water and stirred during PL treatment) treatments provided promising inactivation efficacy (>4log10CFU/g) for spot inoculated stems and leaves. For dip inoculated green onions, 60s wet PL treatment was comparable with 100ppm chlorine washing, demonstrating that PL could be used as an alternative to chlorine. To further increase the degree of microbial inactivation, combined treatments were applied. PL combined with surfactant (SDS) was found to be more effective than single treatments of PL, SDS, chlorine, citric acid, thymol, and hydrogen peroxide, and binary combined treatments of PL with one of those chemicals. Addition of chlorine or hydrogen peroxide to the PL–SDS combination did not further enhanced its microbial inactivation efficacy. The combination of PL and 1000ppm of SDS reduced the E. coli O157:H7 populations dip inoculated on the stems and leaves of green onions by 1.4 and 3.1log10CFU/g, respectively. Our findings suggest that PL could potentially be used for decontamination of E. coli O157:H7 on green onions, with wet PL added with SDS being the most effective PL treatment.

Post-treatment of secondary wastewater treatment plant effluent using a two-stage fluidized bed bioreactor system

The aim of this study was to investigate the performance of a two-stage fluidized bed reactor (FBR) system for the post-treatment of secondary wastewater treatment plant effluents (Shahrak Gharb, Tehran, Iran). The proposed treatment scheme was evaluated using pilot-scale reactors (106-L of capacity) filled with PVC as the fluidized bed (first stage) and gravel for the filtration purpose (second stage). Aluminum sulfate (30 mg/L) and chlorine (1 mg/L) were used for the coagulation and disinfection of the effluent, respectively. To monitor the performance of the FBR system, variation of several parameters (biochemical oxygen demand (BOD5), chemical oxygen demand (COD), turbidity, total phosphorous, total coliform and fecal coliform) were monitored in the effluent wastewater samples. The results showed that the proposed system could effectively reduce BOD5 and COD below 1.95 and 4.06 mg/L, respectively. Turbidity of the effluent could be achieved below 0.75 NTU, which was lower than those reported for the disinfection purpose. The total phosphorus was reduced to 0.52 mg/L, which was near the present phosphorous standard for the prevention of eutrophication process. Depending on both microorganism concentration and applied surface loading rates (5–10 m/h), about 35 to 75% and 67 to 97% of coliform were removed without and with the chlorine addition, respectively. Findings of this study clearly confirmed the efficiency of the FBR system for the post-treatment of the secondary wastewater treatment plant effluents without any solid problem during the chlorination.

PCDD/F Formation in an Iron/Potassium-Catalyzed Diesel Particle Filter

Catalytic diesel particle filters (DPFs) have evolved to a powerful environmental technology. Several metal-based, fuel soluble catalysts, so-called fuel-borne catalysts (FBCs), were developed to catalyze soot combustion and support filter regeneration. Mainly iron- and cerium-based FBCs have been commercialized for passenger cars and heavy-duty vehicle applications. We investigated a new iron/potassium-based FBC used in combination with an uncoated silicon carbide filter and report effects on emissions of polychlorinated dibenzodioxins/furans (PCDD/Fs). The PCDD/F formation potential was assessed under best and worst case conditions, as required for filter approval under the VERT protocol. TEQ-weighted PCDD/F emissions remained low when using the Fe/K catalyst (37/7.5 μg/g) with the filter and commercial, low-sulfur fuel. The addition of chlorine (10 μg/g) immediately led to an intense PCDD/F formation in the Fe/K-DPF. TEQ-based emissions increased 51-fold from engine-out levels of 95 to 4800 pg I-TEQ/L after the DPF. Emissions of 2,3,7,8-TCDD, the most toxic congener (TEF = 1.0), increased 320-fold, those of 2,3,7,8-TCDF (TEF = 0.1) even 540-fold. Remarkable pattern changes were noticed, indicating a preferential formation of tetrachlorinated dibenzofurans. It has been shown that potassium acts as a structural promoter inducing the formation of magnetite (Fe3O4) rather than hematite (Fe2O3). This may alter the catalytic properties of iron. But the chemical nature of this new catalyst is yet unknown, and we are far from an established mechanism for this new pathway to PCDD/Fs. In conclusion, the iron/potassium-catalyzed DPF has a high PCDD/F formation potential, similar to the ones of copper-catalyzed filters, the latter are prohibited by Swiss legislation.

Chlorine treatment effectiveness and physico-chemical and bacteriological characteristics of treated water supplies in distribution networks of Accra-Tema Metropolis, Ghana

Drinking water quality from two major treatment plants in Ghana; Kpong and Weija Plants, and distribution networks in the Accra-Tema Metropolis were monitored monthly for a year at fifteen different locations. The study determined the relationship between chlorine residual, other physico-chemical qualities of the treated water, and, bacteria regrowth. Results indicated that the treated water at the Kpong and Weija Treatment Plants conformed to WHO guidelines for potable water. However, the water quality deteriorated bacteriologically, from the plants to the delivery points with high numbers of indicator and opportunistic pathogens. This could be due to inadequate disinfection residual, biofilms or accidental point source contamination by broken pipes, installation and repair works. The mean turbidity ranged from 1.6 to 2.4 NTU; pH varied from 6.8 to 7.4; conductivity fluctuated from 71.1 to 293 μS/cm. Chlorine residual ranged from 0.13 to 1.35 mg/l. High residual chlorine was observed at the treatment plants, which decreased further from the plants. Results showed that additional chlorination does not take place at the booster stations. Chlorine showed inverse relationship with microbial counts. Total coliform bacteria ranged from 0 to 248 cfu/100 ml, and faecal coliform values varied from 0 to 128 cfu/100 ml. Other microorganisms observed in the treated water included Aeromonas spp., Clostridium spp. and Pseudomonas spp. Boiling water in the household before consumption will reduce water-related health risks.

Halogen-induced organic aerosol (XOA): a study on ultra-fine particle formation and time-resolved chemical characterization

The concurrent presence of high values of organic SOA precursors and reactive halogen species (RHS) at very low ozone concentrations allows the formation of halogen-induced organic aerosol, so-called XOA, in maritime areas where high concentrations of RHS are present, especially at sunrise. The present study combines aerosol smog-chamber and aerosol flow-reactor experiments for the characterization of XOA. XOA formation yields from alpha-pinene at low and high concentrations of chlorine as reactive halogen species (RHS) were determined using a 700 L aerosol smog-chamber with a solar simulator. The chemical transformation of the organic precursor during the aerosol formation process and chemical aging was studied using an aerosol flow-reactor coupled to an FTIR spectrometer. The FTIR dataset was analysed using 2D correlation spectroscopy. Chlorine induced homogeneous XOA formation takes place at even 2.5 ppb of molecular chlorine, which was photolysed by the solar simulator. The chemical pathway of XOA formation is characterized by the addition of chlorine and abstraction of hydrogen atoms, causing simultaneous carbon-chlorine bond formation. During further steps of the formation process, carboxylic acids are formed, which cause a SOA-like appearance of XOA. During the ozone-free formation of secondary organic aerosol with RHS a special kind of particulate matter (XOA) is formed, which is afterwards transformed to SOA by atmospheric aging or degradation pathways.

Synthesis and Characterization of LiNi1/3Co1/3Mn1/3O2−xClx as Cathode Materials for Lithium Ion Batteries at 55°C

A series of materials based on the LiNi<sub >1/3</sub>Co<sub >1/3</sub>Mn<sub >1/3</sub><svg style="vertical-align:-3.39066pt;width:55.762501px;" id="M1" height="16.450001" version="1.1" viewBox="0 0 55.762501 16.450001" width="55.762501" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,12.162)"><path id="x4F" d="M381 665q131 0 226.5 -93t95.5 -239q0 -158 -96 -253t-238 -95q-137 0 -231 95t-94 238q0 142 92.5 244.5t244.5 102.5zM359 629q-89 0 -151 -74.5t-62 -208.5q0 -141 69 -233t175 -92q90 0 150.5 74t60.5 211q0 152 -69 237.5t-173 85.5z" /></g> <g transform="matrix(.012,-0,0,-.012,12.763,16.25)"><path id="x32" d="M412 140l28 -9q0 -2 -35 -131h-373v23q112 112 161 170q59 70 92 127t33 115q0 63 -31 98t-86 35q-75 0 -137 -93l-22 20l57 81q55 59 135 59q69 0 118.5 -46.5t49.5 -122.5q0 -62 -29.5 -114t-102.5 -130l-141 -149h186q42 0 58.5 10.5t38.5 56.5z" /></g><g transform="matrix(.012,-0,0,-.012,18.474,16.25)"><path id="x2212" d="M535 230h-483v50h483v-50z" /></g><g transform="matrix(.012,-0,0,-.012,25.458,16.25)"><path id="x1D465" d="M536 404q0 -17 -13.5 -31.5t-26.5 -14.5q-8 0 -15 10q-11 14 -25 14q-22 0 -67 -50q-47 -52 -68 -82l37 -102q31 -88 55 -88t78 59l16 -23q-32 -48 -68.5 -78t-65.5 -30q-19 0 -37.5 20t-29.5 53l-41 116q-72 -106 -114.5 -147.5t-79.5 -41.5q-21 0 -34.5 14t-13.5 37&#xA;q0 16 13.5 31.5t28.5 15.5q12 0 17 -11q5 -10 25 -10q22 0 57.5 36t89.5 111l-40 108q-22 58 -36 58q-21 0 -67 -57l-19 20q81 107 125 107q17 0 30 -22t39 -88l22 -55q68 92 108.5 128.5t74.5 36.5q20 0 32.5 -14t12.5 -30z" /></g> <g transform="matrix(.017,-0,0,-.017,32.725,12.162)"><path id="x43" d="M614 175l29 -10q-33 -109 -57 -154q-121 -26 -184 -26q-90 0 -160.5 29t-112.5 77t-63.5 105.5t-21.5 119.5q0 157 108 253t277 96q36 0 71.5 -5t69 -13.5t36.5 -8.5q15 -102 20 -150l-29 -8q-20 79 -66.5 114t-128.5 35q-119 0 -187.5 -86t-68.5 -207&#xA;q0 -140 73.5 -227.5t188.5 -87.5q73 0 119.5 37.5t86.5 116.5z" /></g><g transform="matrix(.017,-0,0,-.017,44.114,12.162)"><path id="x6C" d="M238 0h-223v26q48 5 60 17t12 61v473q0 50 -10.5 60.5t-58.5 15.5v24q73 8 148 35v-608q0 -49 11.5 -61t60.5 -17v-26z" /></g> <g transform="matrix(.012,-0,0,-.012,48.425,16.25)"><use xlink:href="#x1D465"/></g> </svg> system were prepared by a sol-gel method, and their phase formation processes, crystal structures, and electrochemical performances were studied by thermogravimetric analyses (TG/DTG), X-ray diffraction (XRD), charge-discharge tests, and cyclic voltammetry (CV). The XRD patterns indicate that the LiNi<sub >1/3</sub>Co<sub >1/3</sub>Mn<sub >1/3</sub><svg style="vertical-align:-3.39066pt;width:55.762501px;" id="M2" height="16.450001" version="1.1" viewBox="0 0 55.762501 16.450001" width="55.762501" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,12.162)"><use xlink:href="#x4F"/></g> <g transform="matrix(.012,-0,0,-.012,12.763,16.25)"><use xlink:href="#x32"/></g><g transform="matrix(.012,-0,0,-.012,18.474,16.25)"><use xlink:href="#x2212"/></g><g transform="matrix(.012,-0,0,-.012,25.458,16.25)"><use xlink:href="#x1D465"/></g> <g transform="matrix(.017,-0,0,-.017,32.725,12.162)"><use xlink:href="#x43"/></g><g transform="matrix(.017,-0,0,-.017,44.114,12.162)"><use xlink:href="#x6C"/></g> <g transform="matrix(.012,-0,0,-.012,48.425,16.25)"><use xlink:href="#x1D465"/></g> </svg> powders with better crystalline structure could be obtained at calcining temperature 850&#xb0;C for 20&#x2009;h under air atmosphere and show that the chlorine addition may induce the change of lattice parameters. The charge-discharge tests show that both the specific capacities and capacity retentions of Cl-doped materials increase compared to the undoped material, especially for the capacity retention at the high-voltage region. At 55&#xb0;C, the LiNi<sub >1/3</sub>Co<sub >1/3</sub>Mn<sub >1/3</sub>O<sub >2-0.10</sub>Cl<sub >0.10</sub> cathode material shows the highest initial discharge capacity of 180.1&#x2009;mAh&#x000B7;g<sup >&#x2212;1</sup> and the best capacity retention with the value of 91.9&#x25; after 100 cycles in the region of 2.0&#x2013;4.4&#x2009;V at 0.1&#x2009;C, while the initial discharge capacity is 208.2&#x2009;mAh&#x000B7;g<sup >&#x2212;1</sup> when the charge cutoff voltage is up to 4.6&#x2009;V.

Factors associated with the isolation of Nontuberculous mycobacteria (NTM) from a large municipal water system in Brisbane, Australia

BackgroundNontuberculous mycobacteria (NTM) are normal inhabitants of a variety of environmental reservoirs including natural and municipal water. The aim of this study was to document the variety of species of NTM in potable water in Brisbane, QLD, with a specific interest in the main pathogens responsible for disease in this region and to explore factors associated with the isolation of NTM. One-litre water samples were collected from 189 routine collection sites in summer and 195 sites in winter. Samples were split, with half decontaminated with CPC 0.005%, then concentrated by filtration and cultured on 7H11 plates in MGIT tubes (winter only).ResultsMycobacteria were grown from 40.21% sites in Summer (76/189) and 82.05% sites in winter (160/195). The winter samples yielded the greatest number and variety of mycobacteria as there was a high degree of subculture overgrowth and contamination in summer. Of those samples that did yield mycobacteria in summer, the variety of species differed from those isolated in winter. The inclusion of liquid media increased the yield for some species of NTM. Species that have been documented to cause disease in humans residing in Brisbane that were also found in water include M. gordonae, M. kansasii, M. abscessus, M. chelonae, M. fortuitum complex, M. intracellulare, M. avium complex, M. flavescens, M. interjectum, M. lentiflavum, M. mucogenicum, M. simiae, M. szulgai, M. terrae. M. kansasii was frequently isolated, but M. avium and M. intracellulare (the main pathogens responsible for disease is QLD) were isolated infrequently. Distance of sampling site from treatment plant in summer was associated with isolation of NTM. Pathogenic NTM (defined as those known to cause disease in QLD) were more likely to be identified from sites with narrower diameter pipes, predominantly distribution sample points, and from sites with asbestos cement or modified PVC pipes.ConclusionsNTM responsible for human disease can be found in large urban water distribution systems in Australia. Based on our findings, additional point chlorination, maintenance of more constant pressure gradients in the system, and the utilisation of particular pipe materials should be considered.

The encapsulated lithium effect of Li@C60Cl8 remarkably enhances the static first hyperpolarizability

Recently, C60Cl8 (C2v) has been experimentally synthesized (Y.-Z. Tan, et al., Nat. Mater., 2008, 7, 790) by the addition of eight chlorine atoms to C60 (C2v), which is associated with a Stone–Wales transformation of C60 (Ih). In this work, the first hyperpolarizabilities (βtot) of C60 (C2v) and C60Cl8 (C2v) are investigated. After the Stone–Wales transformation and chlorine addition reaction, the βtot values slightly increase from 0 for C60 (Ih) to 60 au for C60 (C2v) and 502 au for C60Cl8 (C2v), respectively. To further enhance the first hyperpolarizability, the endohedral fullerene derivative, Li@C60Cl8, formed by encapsulating a lithium (Li) atom inside the C60Cl8, has been designed. Interestingly, the electron transfer between Li and C60Cl8 leads to an extremely large βtot value of 25 569 au, which is considerably larger (51 times) than the 502 au of C60Cl8. It shows that the encapsulated Li effect plays an important role in enhancing the first hyperpolarizability, so the Li@C60Cl8 can be considered as a candidate for high-performance nonlinear optical materials.

Heterogeneous chlorine activation on stratospheric aerosols and clouds in the Arctic polar vortex

Abstract. Chlorine activation in the Arctic is investigated by examining different parameterizations for uptake coefficients on stratospheric aerosols, high-resolution in-situ measurements and vortex-wide satellite observations. The parameterizations for heterogeneous chemistry on liquid aerosols are most sensitive to temperature with the reaction rates doubling for every 1 K increase in temperature. However, differences between the currently available parameterizations are negligible. For Nitric Acid Trihydrate particles (NAT) the major factors of uncertainty are the number density of nucleated particles and different parameterizations for heterogeneous chemistry. These two factors induce an uncertainty that covers several orders of magnitude on the reaction rate. Nonetheless, since predicted reaction rates on liquid aerosols always exceed those on NAT, the overall uncertainty for chlorine activation is small. In-situ observations of ClOx from Arctic winters in 2005 and 2010 are used to evaluate the heterogeneous chemistry parameterizations. The conditions for these measurements proved to be very different between those two winters with HCl being the limiting reacting partner for the 2005 measurements and ClONO2 for the 2010 measurements. Modeled levels of chlorine activation are in very good agreement with the in-situ observations and the surface area provided by Polar Stratospheric Clouds (PSCs) has only a limited impact on modeled chlorine activation. This indicates that the parameterizations give a good representation of the processes in the atmosphere. Back-trajectories started on the location of the observations in 2005 indicate temperatures on the threshold for PSC formation, hence the surface area is mainly provided by the background aerosol. Still, the model shows additional chlorine activation during this time-frame, providing cautionary evidence for chlorine activation even in the absence of PSCs. Vortex-averaged satellite observations by the MLS instrument also show no definite connection between chlorine activation and PSC formation. The inter -and intra-annual variability of vortex-average HCl and HNO3 based on MLS observations is examined for the Arctic winters 2004/2005 to 2010/2011. These observations show that removal of HCl and HNO3 from the gas-phase are not correlated. HNO3 loss exhibits great inter-annual variability depending on prevailing temperatures while HCl loss is continuous through December without considerable inter- or intra-annual variability. Only the recovery of HCl in late winter depends on the level of denitrification. Hence, the occurrence of HNO3 containing PSC particles does not seem to have a significant effect on the speed of initial chlorine activation on a vortex-wide scale.

Oxidative Difunctionalization of 2-Amino-4H-pyrans in Iodobenzene Diacetate and N-Chlorosuccinimide: Reactivity, Mechanistic Insights, and DFT Calculations

Oxidative difunctionalization of 2-amino-4H-pyrans was accomplished with iodobenzene diacetate (IBD) and N-chlorosuccinimide (NCS) reagents in alcoholic medium. 2-Amino-4H-pyrans undergo geminal dialkoxylation with the migration of an amino group (1a,b, 2a-i, 3a,b, and 4) in IBD, whereas with NCS addition of both chlorine and alkoxy groups takes place across the chromene double bond (6a-i).

Influence of chlorine added to drinking water during the preslaughter feed withdrawal on microbiology and morphology of the broiler gastrointestinal tract

The objective of this experiment was to test the effects of the addition of chlorine to broiler drinking water during a 12-h preslaughter feed withdrawal period on reduction of the quantities of microorganisms, such as Escherichia coli and enterococci, in broiler crops and ceca. Reduction of these microorganisms would likely also reduce contamination of broiler meat by pathogenic bacteria during processing. It was also investigated if the chlorine caused some intestinal damage that could disseminate the microorganisms to the carcass. A total of 40 Cobb male broilers were used. Samples of crop and cecal content were collected for microbiological analysis, and duodenum and jejunum were used for morphological analysis from 10 birds in each treatment. The most probable number (MPN) of E. coli and enterococci in the collected samples of crop and ceca and the measure of the free residual chlorine in water were determined. The scanning electron microscopy from duodenum and jejunum was used to illustrate the mucosa integrity. The chlorine added to water was efficient in reducing the quantities of microorganisms in broiler crops and improved the integrity of the mucosa. Therefore, preslaughter feed withdrawal should be coupled with crop disinfection, because preslaughter feed withdrawal increases the MPN of enterococci and E. coli in broiler crops. So, it presents a higher risk for carcass contamination during slaughterhouse processing and, consequently, a higher risk for public health.

Surface Reactivity for Chlorination on Chlorinated (5,5) Armchair SWCNT: A Computational Approach

In the present work, we first attached one chlorine radical and then examined the site selectivity for the addition of a second chlorine radical on the external surface of (5,5) armchair single-walled carbon nanotubes (SWCNTs) of 9 and 15 carbon layers. Optimized geometries and energetics were determined using density functional theory (DFT), at the M06-2X/6-31G(d,p) level. Computed reaction energy values for second chlorination have been used to corroborate the prediction of the reactivities of different sites based on the electron density distribution in the singly occupied molecular orbital (SOMO), total spin density, the DFT based local reactivity descriptors (viz., Fukui function, local softness), and the average local ionization energy. Natural bond orbital (NBO) analysis was performed to confirm the covalent bonding between the chlorine and carbon of the SWCNT. The present study reveals that the first chlorine attached to the SWCNT behaves like an ortho- and para-director. The addition of a second chlorine on an already chlorinated SWCNT exhibits positional preference.

Compositional dependence of the rheology of halogen (F, Cl) bearing aluminosilicate melts

The rheology of three melt compositions containing different amounts of fluorine (F) and chlorine (Cl) or both was investigated with micropenetration and parallel-plate techniques. The heat capacity and configurational entropy of the melts were also determined. The observed viscosity range is between 105.5 and 1013Pas. The melts were produced in a 1atm furnace at temperatures between 1523 and 1923K using oxide and carbonate compounds. The halogens were incorporated using halides and halogen-bearing ammonium compounds. The first composition is a peraluminous Na2O–CaO–Al2O3–SiO2 melt (ANCS) with an apparent NBO/T of ~−0.08, the second composition is a peralkaline Na2O–CaO–Al2O3–SiO2 melt (NACS) (NBO/T=~0.24), which is an analogue for phonolites, and the third is an aluminium-free Na2O–CaO–SiO2 melt (NCS) (NBO/T of ~0.68). Five halogen-bearing ANCS melts with up to 1.10mol% Cl and 18.25mol% F, 6 halogen-bearing NACS melts with up to 1.38mol% Cl and 2.58mol% F and 3 halogen-bearing NCS melts with up to 2.15mol% Cl and 2.04mol% F were investigated in this study.Fluorine was found to decrease the viscosity for all compositions, but not with equal strength. Interpolated to 1mol%, F decreases the viscosity by 0.31±0.08 log units in the peraluminous melt (ANCS), 0.57±0.11 log units in the peralkaline melt (NACS) and 0.47±0.14 log units in the NCS melt.The effect of Cl on rheology depends on the melt composition. Interpolated to 1mol%, Cl decreases the viscosity by 0.57±0.13 log units in the peraluminous melt, but increases viscosity by 0.87±0.10 log units in the peralkaline melt. There is no measurable effect on viscosity due to the addition of chlorine to the aluminium-free melt.In the peraluminous melts the effects of F and Cl add almost linearly to decrease viscosity. In the peralkaline melts, Cl increases the viscosity while F decreases it, if both are present, the effects appear to balance each other; resulting in no change in viscosity for the addition of equal amounts (in mol%) of fluorine and chlorine. The results were obtained from samples with higher and more varied halogen contents than in the most previous studies, therefore they hold true for a wide range of concentrations of both elements and should be taken into account for modelling magmatic processes.

Control of assimilable organic carbon (AOC) concentrations in a water distribution system

The aim of this study is to measure the bioavailable organic matter content in water. This study examines the changes in assimilable organic carbon (AOC) concentrations in a traditional water treatment plant in southern Taiwan and its associate water distribution system. The addition of chlorine to raw water is shown to produce an increase in AOC, resulting in waterborne AOC concentrations in excess of 50 μg acetate-C/L in some circumstances. Examination of water distribution networks indicate that AOC values decrease as the distance from the treatment facility increases. The residual chlorine concentrations in the distribution system must be in the range from 0.52 to 0.73 mg/L.

Occurrences of nitrosamines in chlorinated and chloraminated drinking water in three representative cities, China

An investigation of the occurrence of nine nitrosamines in drinking water following different water treatment processes was conducted using samples from seven drinking water treatment plants in three cities and tap waters in one city in China. The total nitrosamine levels ranged from not detected (n.d.) to 43.45ng/L. The species and concentrations of the nine nitrosamines varied with disinfection methods and source waters. N-nitrosodimethylamine (NDMA), which is the nitrosamines of greatest concern, was identified in raw water, disinfecting water, finished water and tap water samples, ranging from 0.8 to 21.6, 0.12 to 24.2, n.d. to 8.8, and n.d. to 13.3ng/L, respectively. Chloramination alone produced the most significant amounts of NDMA, while ozonation followed by chloramination led to moderately reduced levels. Additionally, chlorination produced relatively less NDMA, while low pressure ultraviolet radiation followed by chlorination could also significantly reduce them. Total organic carbon is one of the most important factors influencing nitrosamines formation in disinfecting water. In contrast, the addition of chlorine following any other disinfection was found to increase the formation of the other eight species of nitrosamines. The three nitrosamines recommended for monitoring by the US EPA were detected in the tap water samples, but most were present at levels below those that pose a risk to human health. Nevertheless, the occurrence and concentration of nitrosamines regulated in the Drinking Water Contaminant Candidate List could cause some potential human effects and therefore warrant attention.

Coronenediimides Synthesized via ICl-Induced Cyclization of Diethynyl Perylenediimides

Treating diethynyl-substituted perylenediimides with ICl successfully induced an annulation reaction and generated a series of coronenediimide derivatives. Instead of the expected iodine-substituted cyclization product, chlorine-substituted analogues were produced. The mechanism of this annulation reaction thus necessarily involved a chlorine addition step prior to the aromatic substitution reaction. With facile subsequent transformations, various tetraaryl coronenediimides could be obtained via the annulated chloro-substituted coronenediimide.

Capturing the Antiaromatic #6094C68 Carbon Cage in the Radio‐Frequency Furnace

Although all fullerenes do not satisfy the classical aromaticity condition, as a result of their nonplanar nature, they experience effective stabilization due to extensive cyclic π-electron delocalization and exhibit pronounced "spherical aromaticity". This feature has raised the question of the opposite phenomenon, that is, the existence of antiaromatic carbon cages. Here the first experimental evidence of the existence of antiaromatic fullerenes is reported. The elusive (#6094)C(68) was effectively captured as C(68)Cl(8) by in situ chlorination in the gas phase during radio-frequency synthesis. The chlorinated cage was separated by means of multistage HPLC, and its connectivity unambiguously determined by single-crystal X-ray analysis. Halogen-stripped pristine (#6094)C(68) was monitored by mass spectrometry of the chlorinated C(68)Cl(8) cage. Quantum chemical calculations reveal the highly antiaromatic character of (#6094)C(68), in accordance with all geometric, energetic, and magnetic criteria of aromaticity. Chlorine addition leads to substantial stabilization of the cage owing to aromatization in the resulting C(68)Cl(8), which explains its high abundance in the primary fullerene soot. This work provides new insights into the process of fullerene formation and better understanding of aromaticity phenomena in general.

Evaluation of trichloromethane formation from chlorine‐based cleaning and disinfection agents in cow’s milk

The development of trichloromethane (TCM) in milk can result from the use of chlorine‐based detergent solutions during the milk production process. Different factors affecting the development of TCM in milk were investigated. Gas chromatography with electron capture detector was the method of analysis. Combining milks of different TCM levels resulted in milk TCM levels similar to that calculated mathematically. Increased chlorine concentration in the detergent and reduced rinse water volume resulted in increased TCM concentrations (P &lt; 0.05) in milk, while the addition of chlorine to the rinse water also increased (P &lt; 0.001) milk TCM.

Chlorine atom substitution influences radical scavenging activity of 6-chromanol

Synthetic 6-chromanol derivatives were prepared with several chlorine substitutions, which conferred both electron-withdrawing inductive effects and electron-donating resonance effects. A trichlorinated compound (2), a dichlorinated compound (3), and three monochlorinated compounds (4, 5, and 6) were synthesized; compounds 2, 3, and 6 were novel. The antioxidant activities of the compounds, evaluated in terms of their capacities to scavenge galvinoxyl radical, were associated with the number and positioning of chlorine atoms in the aromatic ring of 6-chromanol. The activity of compound 1 (2,2-dimethyl-6-chromanol) was slightly higher than the activities of compounds 2 (2,2-dimethyl-5,7-dichloro-6-chromanol) or 3 (2,2-dimethyl-5,7,8-trichloro-6-chromanol), in which the chlorine atoms were ortho to the phenolic hydroxyl group of 6-chromanol. The scavenging activity of compound 3 was slightly higher than that of 2, which contained an additional chlorine substituted in the 8 position. The activities of polychlorinated compounds 2 and 3 were higher than the activities of any of the monochlorinated compounds (4–6). Compound 6, in which a chlorine was substituted in the 8 position, exhibited the lowest activity. Substitution of a chlorine atom meta to the hydroxyl group of 6-chromanol (compounds 2 and 6) decreased galvinoxyl radical scavenging activity, owing to the electron-withdrawing inductive effect of chlorine. Positioning the chloro group ortho to the hydroxyl group (compounds 4 and 5) retained antioxidant activity because the intermediate radical was stabilized by the electron-donating resonance effect of chlorine in spite of the electron-withdrawing inductive effect of chlorine. Antioxidant activities of the synthesized compounds were evaluated for correlations with the O–H bond dissociation energies (BDEs) and the ionization potentials. The BDEs correlated with the second-order rate constants (k) in the reaction between galvinoxyl radical and the chlorinated 6-chromanol derivatives in acetonitrile. This indicated that the antioxidant mechanism of the synthesized compounds consisted of a one-step hydrogen atom transfer from the phenolic OH group rather than an electron transfer followed by a proton transfer. The synthesized compounds also exhibited hydroxyl radical scavenging capacities in aqueous solution.

Chemical fate and genotoxic risk associated with hypochlorite treatment of nicotine

Nicotine, the main alkaloid of tobacco, is a non- prescription drug to which all members of a tobacco-smoking society are exposed either through direct smoke inhalation or through second-hand passive ‘smoking’. Nicotine is also commercially available in some pharmaceutical products and is used worldwide as a botanical insecticide in agriculture. Nicotine dynamics in indoor and outdoor environments as well as the human excretions and the manufacturing process are responsible for its entry in the environment through municipal and industrial wastewater discharges. The presence of nicotine in surface and ground waters points out that it survives a conventional treatment process and persists in potable-water supplies. Complete removal of nicotine is instead reported when additional chlorination steps are used.In this paper a simulation of STP chlorination of nicotine and a genotoxic evaluation of its main degradation products are reported. Under laboratory conditions removal of nicotine seems not to be due to mineralization but to transformation in oxidized and chlorinated products. The by-products have been isolated after fractionation by diverse chromatographic procedures and their structures determined using mass spectrometry and 1H and 13C NMR spectroscopy. Preliminary genotoxic SOS Chromotests with Escherichia coli PQ37 evidence no toxicity of the products.