Amount Of Chloroform Research Articles

UV-activated persulfate oxidation of sulfamethoxypyridazine: Kinetics, degradation pathways and impact on DBP formation during subsequent chlorination

The kinetics and mechanisms of the degradation of sulfamethoxypyridazine (SMP) by an ultraviolet-activated persulfate (UV/PS) advanced oxidation process (AOP) and the formation of disinfection byproducts (DBPs) during subsequent chlorination were investigated in this study. The UV/PS process can significantly remove SMP through pseudo-first-order reaction kinetics. In a competitive kinetic experiment, the second-order rate constant of SMP with sulfate radical was determined to be 2.73 × 1010 M−1 s−1, while that with hydroxyl radical was 2.22 × 1010 M−1 s−1. Six major transformation products in SMP degradation were recognized by LC/MS/MS analysis. It was assumed that the degradation pathway of SMP involves the hydroxylation of the aromatic ring, cleavage of the sulfonamide bond, oxidation of the aniline moiety and elimination of SO2. The impacts of persulfate dose, pH, anions (HCO3–, SO42−, and Br−) and humic acid (HA) concentration on SMP degradation efficiency and DBP formation during subsequent chlorination were also examined. SMP degradation was accelerated with increasing persulfate dose, HCO3– and Br- concentration as well as decreasing pH and HA concentration. However, the amount of chloroform (CF) formed was reduced under a higher persulfate dosage and lower pH. In contrast, the amount of dichloroacetonitrile (DCAN) formed was enhanced under a higher persulfate dose and lower pH. Adding HA also increased the formation of both CF and DCAN. While, both HCO3– and SO42– had little effects on the formation of CF and DCAN. The presence of Br– had no significant effects on the bromine incorporation factors (BIFs) of trihalomethanes (THMs) and dihaloacetonitriles (DHANs). Raw water experiments showed that the UV/PS process could destroy SMP in natural water as well as control the formation of DBPs.

Preconcentration of nickel in waters by vortex assisted dispersive liquid-liquid microextraction

AbstractThe present work describes the attempt for the preconcentration of nickel ions by using vortex assisted dispersive liquid-liquid microextraction from aqueous samples. In this method, a small amount of chloroform is rapidly injected by syringe into the water sample containing nickel ions complexed by diethyldithiocarbamate (DDTC).This forms a cloudy solution. The cloudy state is the result of chloroform fine droplets formation, which are dispersed in bulk aqueous sample. Therefore, Ni-DDTC complex is extracted into the fine chloroform droplets and vortex agitation takes place during six minutes. After optimization of experimental variables and determination of analytical characteristics, the method is evaluated for application in real samples. HPLC is used as separation and detection system.

Nanoporous solvate of N,N-phthaloyl-glycine

N,N-phthaloyl-glycine is synthesized under microwave activation without solvent. Its nanoporous solvate is obtained by recrystallization. The solvate is studied by single crystal and powder XRD, thermogravimetry, and mass spectrometry. The crystals are composed of dimers that form a framework structure with infinite channels of about 4 A in diameter, containing a non-stoichiometric amount of chloroform (the mole fraction is close to 0.35). The nature of the incorporated solvate molecules is determined by high-resolution mass spectrometry, and their quantity is found by thermogravimetry.

KINETIC STUDY OF THE SYNTHESIS OF DICHLOROCYCLOPROPANE BY TRIALKYLAMMONIUM PROPANSULTANS AS NEW PHASE-TRANSFER CATALYSTS

In this work, the synthesis of dichlorocyclopropane, from a phase-transfer catalyzed reaction of chloroform and olefins (1-octene or 1,7-octadiene), was carried out in an alkaline solution of NaOH/chloroform two-phase medium. Trialkylammonium propansultan, a zwitterionic compound, acts as a new phase-transfer catalyst of high reactivity to produce high yields of dichlorocyclopropane. Dichlorocarbene (:CCl2), which is an active species to react with olefins to produce dichlorocyclopropane in the organic phase, is generated from the reaction of chloroform, sodium hydroxide, and trialkylammonium propansultan as phase-transfer catalyst at the interface between two phases. The dichlorocyclopropanation is dramatically enhanced by adding a small quantity of trialkylammonium propansultan. An interfacial reaction mechanism was proposed to explain the reaction characteristics. A pseudo first-order rate law is used to describe the reaction rate at high alkaline concentration solution (>50 wt% NaOH). There is detailed investigation of the reaction kinetics, including the effect of the reaction conditions—the agitation speed, temperature, phase-transfer catalysts and their amounts, the amount of chloroform, the amount of 1-octene, inorganic salt (NaCl and Na2SO3), and alkali concentration—on the conversion of 1-octene.

Ultrasound assisted phase-transfer catalytic epoxidation of 1,7-octadiene – A kinetic study

An ultrasound assisted phase-transfer catalyzed epoxidation of 1,7-octadiene is greatly enhanced by using a cocatalyst of phosphotungstic acid in the presence of hydrogen peroxide in an organic solvent/aqueous solution two-phase medium. An active intermediate of the catalyst (Q 3PW 12(O) n O 40, where Q = R 4N +) produced from the reaction of phosphotungstic acid, hydrogen peroxide, and Aliquat 336. A rational mechanism of epoxidation is proposed to account for the reaction from the experimental evidence. The organic-phase reactions, including two series reactions, are the rate-controlling steps to produce two products, viz., 1,2-epoxy-7-octene and 1,2,7,8-diepoxyoctane. The kinetics of epoxidation, including the characteristics of the catalyst and the effect of the amount of cocatalyst, agitation speed, quaternary ammonium salts, amount of Aliquat 336, amount of hydrogen peroxide, amount of chloroform, pH value, organic solvents, and temperature on the conversion of 1,7-octadiene were investigated in detail. A kinetic model was built, from which a pseudo-first-order rate law is sufficient to describe the behavior of the reaction.

A Cyclic Hexamer of Silver Trifluoroacetate Supported by Four Triphenylphosphine Sulfide Template Molecules

Crystallization of silver trifluoroacetate from chloroform solutions containing triphenylphosphine sulfide affords a trigonal and a monoclinic form of a 6:4 complex {[CF3C(O)OAg]6(Ph3PS)4} of C2 symmetry with different amounts of chloroform in the crystals. With the Ph3PS components as template molecules, the CF3C(O)OAg units are assembled to form a 6-membered metallacycle codetermined by metallophilic bonding and enclosed by a 24-membered ring [AgOCO]6. A complex of the type [LAgOC(O)CF3]2, with L representing the isocyanide ligand pTolSO2CH2NC, has been shown to have a conventional bicyclic structure with three-coordinate silver atoms engaged in transannular metallophilic interactions.

Kinetic study of dichlorocyclopropanation of 1,7-octadiene under two-phase phase-transfer catalysis at low alkaline concentration

This work investigates the phase-transfer catalytic (PTC) reaction of dichlorocycloproanation of 1,7-octadiene in an alkaline solution/organic solvent two-phase medium. The reaction is dramatically enhanced in the presence of quaternary ammonium salt. The reaction mechanism proposed is that the active dichlorocarbene (:CCl2) is first generated from the interfacial reaction of chloroform, sodium hydroxide and quaternary ammonium salt to form an active complex (QCCl3) of the dichlorocarbene (:CCl2) precursor. Then, this active complex QCCl3 (or dichlorocarbene :CCl2), which transfers from the aqueous phase to the organic phase, further reacts with 1,7-octadiene to produce mono-dichlorocyclopropane and bi-dichlorocyclopropane in the organic phase. No other byproducts were detected during or after the reaction. The conversion of 1,7-octadiene is increased with the increase in the amount of NaOH in the aqueous phase. At lower alkaline concentration (30% NaOH or less), the reaction obeys a third-order rate law. However, a pseudo first-order rate law is sufficient to describe the kinetic behavior at higher alkaline concentration (>50% NaOH). Explanations are made for this discrepancy. The effects of the reaction conditions, such as quaternary ammonium salts, amount of catalyst, agitation, concentration of 1,7-octadiene, temperature, amount of chloroform, and amount of NaOH on the conversion were investigated in detail.

ATPase Activity of the MsbA Lipid Flippase of Escherichia coli

Escherichia coli MsbA, the proposed inner membrane lipid flippase, is an essential ATP-binding cassette transporter protein with homology to mammalian multidrug resistance proteins. Depletion or loss of function of MsbA results in the accumulation of lipopolysaccharide and phospholipids in the inner membrane of E. coli. MsbA modified with an N-terminal hexahistidine tag was overexpressed, solubilized with a nonionic detergent, and purified by nickel affinity chromatography to approximately 95% purity. The ATPase activity of the purified protein was stimulated by phospholipids. When reconstituted into liposomes prepared from E. coli phospholipids, MsbA displayed an apparent K(m) of 878 microm and a V(max) of 37 nmol/min/mg for ATP hydrolysis in the presence of 10 mm Mg(2+). Preincubation of MsbA-containing liposomes with 3-deoxy-d-mannooctulosonic acid (Kdo)(2)-lipid A increased the ATPase activity 4-5-fold, with half-maximal stimulation seen at 21 microm Kdo(2)-lipid A. Addition of Kdo(2)-lipid A increased the V(max) to 154 nmol/min/mg and decreased the K(m) to 379 microm. Stimulation was only seen with hexaacylated lipid A species and not with precursors, such as diacylated lipid X or tetraacylated lipid IV(A). MsbA containing the A270T substitution, which renders cells temperature-sensitive for growth and lipid export, displayed ATPase activity similar to that of the wild type protein at 30 degrees C but was significantly reduced at 42 degrees C. These results provide the first in vitro evidence that MsbA is a lipid-activated ATPase and that hexaacylated lipid A is an especially potent activator.

An unexplained death: Hannah Greener and chloroform.

An unexplained death: Hannah Greener and chloroform.

Monitoring of residues of ochratoxin A in blood and kidney of chicken using HPLC-FLD

Detoxification of ochratoxin A can be achieved by chemical or enzymatic hydrolyzation, the products of such reactions are ochratoxin α and phenylalanine. Ochratoxin α like ochratoxin A, is a fluorescing molecule, therefore sensitive analysis is possible at very low concentration levels. Methods have been established that make it possible to look for residues of ochratoxin A and its main metabolite ochratoxin α in blood and tissues at very low concentration levels. Plasma is extracted by the use of small amounts of chloroform; the extract is cleaned with water and afterwards evaporated to dryness]. The residue is re-dissolved and analysed by HPLC-FLD. Using this method a limit of detection of 0.5μg/l for both ochratoxin A and ochratoxin α can be reached.

Formation of trihalomethanes from dyes by ozone treatment

The amount of chloroform produced from dyes (orange II, methylene blue, and methylrosanilinium chloride) and humic acid by adding chlorine after the ozone treatments was investigated. Some dyes and humic acid were degraded by ozone and produced polar and acidic organic compounds. The amount of chloroform produced from orange II increased or decreased with the ozonization time, while that produced from methylene blue and humic acid decreased with ozonization time. Methylrosanilinium chloride did not produce the trihalomethane by chlorine disinfection. Thus, some but not all dyes produce trihalomethanes by ozone treatment and chlorine disinfection.

The influence of spreading solvent traces in the atmosphere on surface tension measurements by using a micro-film balance and the captive bubble method

Two different methods for investigating monolayer properties are presented, the micro-film balance and the captive bubble method. Both require the elimination of traces of the spreading solvent in the atmosphere, as in the micro-film balance experiment a drop is kept in a small hermetically closed chamber and in the captive bubble method the monolayer is spread inside a bubble. The influence of different organic spreading solvents on the surface tension at the air/water interface was checked for the two methods. The surface tension of water was measured by the micro-film balance when exchanging the air in the chamber after spreading. Using a small amount of methanol as solvent, similar results in the captive bubble experiments are obtained. In the presence of a monolayer, traces of solvents interact with the monolayer molecules and can be removed only immediately after spreading. In such cases, a good agreement with surface pressure isotherms determined by a Langmuir trough is achieved. When different amounts of chloroform, heptane and methanol are evaporated in the cell atmosphere, the π/A isotherms of 1-monoglycerid monolayers change dramatically up to atmosphere saturation by the hydrocarbons. These changes could not be removed by air exchange in the cell. Therefore, the micro-film balance is applicable in investigating interactions between monolayer and gas phase. Taking into account these results, dipalmitoyl phosphatidylcholine monolayers were investigated by both the captive bubble and the micro-film balance. The results of both methods are in good agreement when the methodological requirements stated above are met.

Pyrolysis of trichlorosilane in the presence of chloroform

The pyrolysis of trichlorosilane in the presence of different amounts of chloroform and the copyrolysis of HSiCl3 with buta-1,3-diene in the presence of 1 mol.% chloroform were studied. The enthalpies of formation of products resulting from the pyrolysis of HSiCl3 in the presence of chloroform were calculated by the quantum chemical method. Based on the thermochemical data as well as data from GLC and mass spectrometry, it was concluded from the condensate composition that introduction of chloroform into the zone of pyrolysis of HSiCl3 favors generation of silylenes.

Formation of trihalomethanes from humic acid by ozone and activated carbon fibers treatments

Humic acid, which is a trihalomethane precursor, was produced by the putrefaction of withered leaves. Trihalomethanes are produced by chlorine disinfection when tap water is treated with ozone and activated carbon in a purification plant. The amount of chloroform produced from humic acid by adding chlorine after the ozone and activated carbon fiber treatments was investigated. Humic acid was degraded by ozone to polar and acidic organic compounds by the addition of hypochlorite. The amount of chloroform produced increased with increasing treatment temperature, while it decreased with increasing ozonization time. It was also lowered by the addition of activated carbon fibers after the ozonization.

STUDIES ON REMOVAL EFFICIENCY OF CHLOROFORM FROM TAP WATER BY RICE BRAN

Removal efficiency of chloroform from tap water by rice bran was investigated. The adsorption rate by rice bran was similar to activated carbon. The amount of chloroform adsorbed was plotted against the equilibrium concentration of chloroform in solution on a logarithmic scale. A linear relationship was obtained, indicating that the adsorption reaction was a Freundlich type. The adsorption of chloroform by rice bran was observed in the range of pH 1-11. Chloroform was successfully removed from tap water with average removal efficiency of 70% after 60 min when rice bran was applied to tap water that contained 0.0064 mg/ L chloroform.

Mutagenicity and amount of chloroform after chlorination of bank filtered lake water

Chlorinated drinking waters produced from humus-rich waters often have a high content of halogenated organic by-products which increases the mutagenicity of drinking water. With in vitro chlorination experiments we studied the formation of chloroform (CHCl 3) and mutagenicity of artificially recharged ground water samples. The water samples where obtained from an artificial ground water plant which infiltrates humus-rich lake water through an esker island. The chlorination experiments showed that bank filtration reduced strongly the formation of chloroform and mutagenicity of chlorinated water. Reduction in the amount of chloroform and mutagenicity in chlorinated waters was strongly associated with the decrease in the total content of organic carbon and with the decrease in molecular weight of organic matter during bank filtration.

Adsorption removal of chloroform and bromoform by activated carbon fiber

Adsorption characteristics of chloroform and bromoform onto activated carbon fibers (ACFs) for the safety drinking water were investigated. The amounts of chloroform and bromoform adsorbed onto ACFs decreased with their grade number that is the surface area and pore volume. Bromoform was more easily adsorbed onto ACFs than chloroform due to the difference in water solubility. The dominant factor of chloroform and bromoform adsorption onto ACFs may be the surface hydrophobicity of adsorbent rather than the surface area or pore volume.

Chloroform removal by surface‐modified activated carbon

Chloroform as a carcinogen removal by surface‐modified activated carbon from an aqueous solution was investigated for the assurance of safe water. Surface hydrophobilized activated carbon by hydrogen gas adsorbed the largest amount of chloroform. To elucidate the dominant factor of adsorption removal of chloroform, correlations between the amount adsorbed and physicochemical properties of adsorbents. A significant inverse correlation was recognized between the amount of chloroform adsorbed and the base consumption. It was found that the existence of acidic groups on the surface of activated carbon inhibits the adsorption of chloroform. It was concluded that the suitable adsorbent for chloroform removal was an activated carbon with more hydrophobic surface.

Human Exposure and Body Burden for Chloroform and Other Trihalomethanes

ABSTRACTExisting information on human exposure to chloroform and other trihalomethanes (THMs) in air, water, and food is summarized. Three major surveys have collected data on chloroform levels in finished water at treatment plants. EPA's TEAM Studies have measured concentrations of THMs in residential drinking water and in personal, indoor, outdoor, and expired air from about 800 participants in eight cities. The Food and Drug Administration has surveyed chloroform levels in food and beverages. Recently, the Centers for Disease Control (CDC) have completed measuring blood levels of THMs in about 1000 participants in the National Health and Nutrition Examination Survey (NHANES).Exposure occurs through ingestion (drinking tap water and soft drinks and eating certain dairy foods), inhalation (breathing peak amounts of chloroform emitted during showers or baths, and lower levels in indoor air from other indoor sources), and dermal absorption (during showers, baths, and swimming). Each of these routes of exposure appear to be potentially substantial contributors to total exposure.The major source of exposure to chloroform is chlorination of water supplies. This results in exposure through ingestion of drinking water, but also through inhalation and skin absorption as a result of the myriad other uses of chlorinated water in the home: showers, baths, washing clothes and dishes, etc. Because chlorinated water supplies are used by bottling plants of soft drink manufacturers, even the chloroform found in beverages may be partially due to the chlorination of water supplies. Other sources of exposure, which can be important for specific groups of people, include chlorination of swimming pools, industrial production and use, and use of bleach during clothes washing.

Chloroform adsorption by activated carbon

Chloroform removal by activated carbon with a view to elucidating the dominant factor was investigated for the assurance of safe water. A significant correlation was recognized between the amount of chloroform adsorbed and the amount of water adsorbed as the indicator of surface hydrophobicity of adsorbent. No significant correlations were recognized between the amount of chloroform adsorbed and the surface area, pore volume or surface pH. It was concluded that a dominant factor of chloroform adsorption by activated carbon was the degree of surface hydrophobicity of adsorbent.