Chlorine In Aqueous Solution Research Articles

Detection of chlorine species in water by chemiluminescence with electrochemical analyte modification

A flow system for the chemiluminescence reaction of Rhodamine 6G and free chlorine in aqueous solution is described. The system was optimized such that a detection limit (signal-to-noise ratio = 3) of 500 µg l–1 was obtained for free chlorine, and the system was then used to detect bound available chlorine in water by electrochemical conversion to free available chlorine at a platinum electrode followed by chemiluminescence. Principal component analysis allowed the identification of chlorine species from the chemiluminescence voltage curve.

Leaching behaviour of nickel in aqueous chlorine solutions and its application in the recovery of nickel from a spent catalyst

A preliminary study on the kinetics of leaching of pure nickel powder in aqueous chlorine solution is reported. The strong dependence of the rate of leaching on the stirring speed, and the low apparent activation energy of 12.5 kJ/mol for nickel dissolution, suggested diffusion of aqueous chlorine through the boundary layer as the rate-controlling step. The order of the reaction with respect to chlorine concentration was found to be 1.7. Based on this information, a process flow sheet incorporating chlorine leaching was developed for the recovery of pure nickel powder from a spent catalyst. The paper discusses the results of various operations involved in the process, namely: reduction, leaching, precipitation of nickel oxalate and its decomposition to nickel metal powder.

Response to comments on "Stoichiometry and kinetics of the reaction of nitrite with free chlorine in aqueous solutions"

Response to comments on "Stoichiometry and kinetics of the reaction of nitrite with free chlorine in aqueous solutions"

Comments on "Stoichiometry and kinetics of the reaction of nitrite with free chlorine in aqueous solutions"

Comments on "Stoichiometry and kinetics of the reaction of nitrite with free chlorine in aqueous solutions"

Platinum(IV) complexes of a tetraaza macrocycle with pendent dichloroamine or ammonium groups

Reaction of the platinum(II) complex of the pendent-arm macrocycle 6,13-diammonio-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane with chlorine in aqueous solution does not lead simply to oxidation of the platinum(II) complex to a trans-dichloroplatinum(IV) complex. Instead, complete chlorination of the pendent primary amines occurs also, producing the trans-dichloroplatinum(IV) complex of a bis(dichloroamino) macrocycle. The dichloroamino complex was characterized by a crystal structure analysis, the first X-ray crystal structure of a dichloroamine; the perchlorate salt of trans-[Pt(2)Cl2](ClO4)2 crystallized in the P2(1)/n space group, with Z = 2, a = 10.612 (5) angstrom, b = 10.280 (3) angstrom, c = 12.792 (4) angstrom, and beta = 110.56 (3)-degrees. Inequivalent N-Cl bond lengths (1.718 (12) and 1.779 (12) angstrom) were observed. In aqueous acid, slow dechlorination occurs to produce the trans-dichloroplatinum(IV) complex of the precursor macrocycle, also characterized by a crystal structure analysis. The complex of the precursor macrocycle, trans-[Pt(1)Cl2]Cl2(ClO4)2.4H2O, crystallized in the P1BAR space group, with Z = 1, a = 7.308 (2) angstrom, b = 10.448 (2) angstrom, c = 10.672 (2) angstrom, alpha = 103.89 (1)-degrees, beta = 104.50 (1)-degrees, and gamma = 103.90 (1)-degrees.

Etude du mecanisme et de la cinetique de l'action du chlore sur le bioxyde de chlore en solution aqueuse diluee

Abstract The aim of this work was to study the mechanism and the rate of the reaction between chlorine and chlorine dioxide in dilute aqueous solution at pH values near neutrality. The results showed that chlorination of aqueous solutions of chlorine dioxide leads to the production of chlorate (as an end by‐product) and to chlorite (as an intermediate). Secondary reactions between chlorite and chlorine yield chlorate. The overall stoichiometry for the reaction of chlorine with chlorine dioxide corresponds to the production of one mole of chlorate/mole of chlorine dioxide and to the consumption of 0.5 mole of chlorine/mole of chlorine dioxide. The data obtained from experiments carried out at different pH values (6.5 < pH < 10.8) and with different initial concentrations of reactants (chlorine and chlorine dioxide) showed that the rate of disappearance of chlorine dioxide can be described by a second‐order kinetic equation (d[ClO2]/dt = k[Chlorine][ClO2]) and that the second‐order rate constants increase w...

Mutagenic activity of diphenyl ether herbicides and their reactivity with chlorine in aqueous solution

Mutagenic activity of diphenyl ether herbicides and their reactivity with chlorine in aqueous solution

Stoichiometry and kinetics of the reaction of nitrite with free chlorine in aqueous solutions

The reaction of nitrite with free chlorine in dilute aqueous solution (3.4 < pH < 11.5) was studied under continuous-flow mixing conditions. Chlorine, chloride, nitrite, and nitrate were all measured analytically. Stoichiometric balances demonstrated that nitrate was oxidized to nitrate, and chlorine was reduced to chloride, without the significant production of any other chemical species. The kinetic studies demonstrated that the reaction is very fast at neutral or acidic pH with the rate decreasing with increasing pH. The reaction was strictly bimolecular in the pH range of 9.5-11.6, whereas it was sufficiently slow to be followed with time. The reaction appears to proceed between nitrous and hypochlorous acid molecules, or HNO{sub 2} + HOCl {yields} 2H{sup +} + NO{sub 3}{sup {minus}} + Cl{sup {minus}}.

Leaching of FeS in aqueous chlorine solution

FeS leaching was carried out in aqueous chlorine solution at low temperatures (12–40°C) and ambient pressure ( ⋍610 mm Hg in Erzurum). The effects of particle size, reaction time, solid to liquid ratio, gas flow rate, temperature, and speed of stirring were investigated. The sulfide ion in the FeS was oxidized to sulfate and elemental sulfur during the leaching. Most of the oxidized sulfide ion was found in the solution as sulfate. All of the elemental sulfur was oxidized to sulfate as the reaction progressed to completion. The dissolution rate increased with increase in stirring speed and temperature, and with decrease in particle size, but it was not affected by the flow rate of Cl 2 and the solid to liquid ratio under the conditions covered in this study. The data were well correlated by the shrinking core-diffusion (through the fluid film) control model. The activation energy was calculated as 18.9 kJ mol −1.

The Intehaction of Aqueous Solutions of Chlorine with Malic Acid, Tartaric Acid, and Various Fruit Juices: A Source of Mutagens

Abstract The interactions of aqueous solutions of chlorine with some fruit acids (citric acid, DL-malic acid, arid L-tartaric acid) at different pH values were studied. Diethyl ether extraction followed by GC/MS analysis indicated that a number of mutagens (certain chlorinated propanones and chloral hydrate) are present as major products in some of these samples. A number of fruit juices (orange, grape, apple, pineapple, and grapefruit) were also treated with aqueous solutions of chlorine at their pH values. The products were analyzed by GC/MS. The same mutagens that were formed by the pure acids (citric acid and DL-malic acid) were identified as major products in ether extracts of these samples. Another mutagen, dichloroacetonitrile, was also identified as a minor product in some of these juice samples. All of the major products observed in the chlorination of all five fruit juices are potentially derived from reactions of aqueous solutions of chlorine with citric or malic acid and with trace amounts of ...

Linear-sweep polarographic determination of active chlorine in aqueous solutions containing phenylthiourea

The linear-sweep polarographic determination of active chlorine is based on its reaction with phenylthiourea in acidic phosphate buffer (pH 2.5) containing potassium chloride. The product, C,C-diphenyldithiodiformamidine, is strongly adsorbed and then reduced at a mercury electrode with two peaks at about −0.35 V and −0.87 V (vs. SCE). In the presence of 0.05 M potassium chloride, the potential of the first peak shifts positively to −0.31 V. This peak provides high sensitivity and selectivity for the determination of traces of active chlorine. The linear range is 1×10 −7−2.5×10 −5 M and the detection limit is 5×10 −8 M (3.6 μg l −1). The method is used for the direct determination of active chlorine in tap water. The mechanism of the reaction was studied by cyclic voltammetry, electrolysis and potentiometric titration. The first peak (−0.35 V) is ascribed to the reduction of a mercury (II) sulfide film produced by reaction of the adsorbed dithio product with mercury. In the presence of 0.05 M chloride, the formation of a mixed HgS· xHg 2Cl 2 film shifts the peak to −0.31 V.

Methods for preparing aqueous solutions of chlorine and bromine for halogen displacement reactions

Alternatives to handling and storing cylinders of chlorine gas and containers of liquid bromine.

Novel anion exchange membranes having fluorocarbon backbone: Preparation and stability

AbstractAnion exchange membranes with excellent durability were prepared by chemical modification of Nafion. The modification was achieved by transformation of the sulfonic acid group into quaternary ammonium group. Namely, Nafion membrane was first converted into an amide‐type membrane. Reduction of the carbonxyl group to methylene followed by quaternarization with alkyl iodide resulted in the formation of an anion exchange membrane. The electric resistance of the resulting membranes depends on the equivalent weight of the starting membranes (4.4–6.0 Ω cm2 in 0.5N NaCl). The characteristics of the membranes are the excellent stability toward chemical substances such as organic solvents, oxidizing agents, acids, etc. For example, the membranes are stable in aqueous saturated chlorine solution at 60°C for 1000 hr.

Chlorimine formation and deamination of the model nucleobase 1‐methylcytosine

AbstractTreatment of the model nucleobase 1‐methylcytosine with chlorine in aqueous solution gives, depending on the reaction conditions, 5‐chloro‐1‐methylcytosine (3) or its hemiprotonated form 2, 5,5‐dichloro‐6‐hyd‐roxy‐5,6‐dihydro‐4‐chlorimino‐1‐methylpyrimidin‐2‐one (5), and 5,5‐dichloro‐6‐hydroxy‐5,6‐dihydro‐1‐methyl‐uracil (4). While substitution of H5 of 1‐methylcytosine by chlorine giving 2 and 3, and subsequent addition of hypochlorous acid to the 5,6‐double bond is not unexpected, chlorination of the exocyclic amino group 5 and deamination to give 4 is novel. The X‐ray structures of 4 and 5 are reported.

The Interactions of Aqueous Solutions of Chlorine with Citric Acid. A Source of Mutagens. (A Preliminary Report)

Abstract Citric acid, an additive to an important acrylamide based polymeric flocculant, was found to react with an aqueous solution of chlorine to give several chlorinated propanones, di- and trichloroacetic acid, chloroform, and a number of as yet unidentified chlorine containing compounds. Formation of these alledged carcinogens and mutagens also takes place by treating diluted aqueous solutions of frozen orange juice concentrate with such chlorine solutions. The formation and ratios of the detected chlorinated compounds is pH-dependent. A tentative scheme which could account for these findings is presented.

Henry constant of molecular chlorine in aqueous solution

Henry constant of molecular chlorine in aqueous solution

ChemInform Abstract: KINETICS AND MECHANISM FOR OXIDATION OF TETRACYANOPLATINATE(II) BY CHLORINE AND HYPOCHLOROUS ACID AND FOR HYDROLYSIS OF CHLORINE IN AQUEOUS SOLUTION

Oxidation of Pt(CN)42- in aqueous solutions of chlorine has been followed by stopped-flow spectrophotometry. For pH less than ca. 7, the reaction takes place by two parallel paths with Cl2 and HOCl as oxidants. Rate law determined. In unbuffered solutions of chlorine in aqueous NaClO4, the slow HOCl path is predominant, whereas in weakly acidic solutions buffered with HCl, oxidation takes place via the five orders of magnitude faster Cl2 path. For certain conditions, the displacement of the hydrolysis equilibrium of chlorine becomes rate-determining for the oxidation of Pt(CN)42- by chlorine, which then appears to be zero order in complex. Equilibrium and rate constants determined. Oxidation by HOCl gives primarily trans-Pt(CN)4(OH)22-, which rapidly reacts with a second molecule of HOCl to form a stable hypochlorite complex. Oxidations with HOCl and ClO- are inner-sphere two-electron transfers with the oxygen of the hypochlorite as bridging atom.

Kinetics and mechanism for oxidation of tetracyanoplatinate(II) by chlorine and hypochlorous acid and for hydrolysis of chlorine in aqueous solution

Oxidation of Pt(CN)42- in aqueous solutions of chlorine has been followed by stopped-flow spectrophotometry. For pH less than ca. 7, the reaction takes place by two parallel paths with Cl2 and HOCl as oxidants. Rate law determined. In unbuffered solutions of chlorine in aqueous NaClO4, the slow HOCl path is predominant, whereas in weakly acidic solutions buffered with HCl, oxidation takes place via the five orders of magnitude faster Cl2 path. For certain conditions, the displacement of the hydrolysis equilibrium of chlorine becomes rate-determining for the oxidation of Pt(CN)42- by chlorine, which then appears to be zero order in complex. Equilibrium and rate constants determined. Oxidation by HOCl gives primarily trans-Pt(CN)4(OH)22-, which rapidly reacts with a second molecule of HOCl to form a stable hypochlorite complex. Oxidations with HOCl and ClO- are inner-sphere two-electron transfers with the oxygen of the hypochlorite as bridging atom.

Isothermal diffusion in aqueous solutions of chlorine: a ternary process

Isothermal diffusion in aqueous solutions of chlorine: a ternary process

Absorption of chlorine in aqueous solutions of sodium hydroxide: Desorption of hypochlorous acid followed by its dissociation to chlorine monoxide

The absorption of chlorine in aqueous solutions of sodium hydroxide with concurrent desorption of hypochlorous acid (followed by its dissociation to chlorine monoxide) was studied at 55 and 75°C in a model stirred contactor with a flat gas-liquid interface. Theoretical and experimental aspects of this unique case of desorption (followed by dissociation) have been considered. A reasonably good agreement between the theoretical predictions and experimental observations has been found.