Hypochlorite Oxidation Research Articles

Photo-promoted Hypochlorite Oxidation of α-Amino Acids. Kinetics and Irradiation Effect for the Strecker Degradation

Abstract Hypochlorite oxidation of simple α-amino acids (the Strecker degradation) in aqueous solutions has been studied in the dark and under UV-irradiation. UV-spectra, iodometry, and amino acid determination (2,4-dinitrofluorobenzene method) suggest that the intermediate N-chloro amino acid is formed quickly at an initial stage, then its slow oxidative decomposition takes place to give aldehyde, carbon dioxide, and ammonia. The mechanism is also supported by the fact that the oxidation follows the first-order rate expression; −d[RCH(NH2)CO2H]⁄dt=k[1[RCH(NHCl)CO2H]. UV-irradiation was found to promote remarkably the degradation of N-chloro amino acid. When equimolar amounts of amino acid and hypochlorite were used, the products such as unreacted amino acid, ammonia, and aldehyde were analogous to those of the dark reaction. The use of a large excess of hypochlorite under irradiation enables complete oxidative degradation of amino acid to carbon dioxide,, water, and nitrogen. Its application to waste water treatment is discussed.

ChemInform Abstract: HYPOCHLORITE OXIDATION OF AMMONIA. EFFECTIVE REMOVAL OF AMMONIA FROM WASTE WATER BY UV IRRADIATION

AbstractDie Oxidation von NH3 mit Hypochlorit zu N2 (Reaktion A) wird im Dunkeln und unter Bestrahlung durchgeführt, um den Reaktionsmechanismus zu untersuchen und die Anwendbarkeit des Prozesses zur Abwasserreinigung.

Hypochlorite Oxidation of Ammonia. Effective Removal of Ammonia from Waste Water by UV-irradiation

Abstract The hypochlorite oxidation of ammonia giving rise to nitrogen evolution was carried out in the dark or under irradiation in order to study the reaction mechanism and application to waste water treatment. UV-irradiation accelerates remarkably the rate of decomposition of unfavorable chloramines. The acceleration covers the pH region 2–12, where corresponding dark reactions are slow. The irradiation also affects the formation of byproducts such as NO2− and NO3−, the effect being a slight increase in NO2− formation in the pH range 2–12. These results suggest an effective industrial application to avoid eutrophication in seas and lakes. The irradiation effect is discussed in relation to reaction mechanism, in which the irradiation possibly facilitates the N–N bond formation after chloramine formation.

Cyano-sugars. Part 4. Hypochlorite oxidation of branched-chain nitro-sugars and conversion of the products into branched-chain cyano-sugars

Carbohydrate derivatives containing a primary nitro-group react with hypochlorite to give αα-dichloronitrocompounds which afford branched-chain cyano-sugars on treatment with triphenylphosphine. The preparation of 3,3-C-bis(nitromethyl) doubly-branched carbohydrate derivatives is also described.

Studies in chemically modified celluloses. XI. Hypochlorite oxidation of cellulose in the presence of chromium oxide

AbstractIn the dyeing of mineral Khaki on cotton fabrics, which are mainly used for military uniforms in India, a mixture of Fe2O3 and Cr2O3 is deposited in the fabric. When these garments are laundered using bleaching powder solution, the chromium oxide is likely to accelerate the oxidation of cotton cellulose. This aspect has been studied by oxidizing cotton yarn with sodium hypochlorite solution in the presence of chromium oxide, varying the chromium content, the pH of the oxidizing medium, and the concentration of the oxidizing agent. The properties of these chemically modified celluloses indicate that chromium oxide does accelerate the hypochlorite oxidation of cellulose and that the maximum extent of acceleration takes place when the oxidation is carried out at pH 7. The oxidized products were further modified separately by treatment with chlorous acid and sodium borohydride, and the effects of these agents on the properties of the oxidized products were studied.

Molecular Weight Distribution in Starch Solutions when Hydrolised with alpha‐Amylase and when Oxidised with Sodium Hypochlorite

AbstractThe time course for hydrolysis of starch with α‐amylase and oxidation of starch with Na‐hypochlorite was studied with the aid of gel chromatography. It was found that the initial steps in the hydrolysis can be described as a consecutive reaction in which the fractions Mw > 5 · 105, 5 · 105 > Mw > 1 · 105 and Mw < 1 · 105 are contained. The reaction in the course of decomposition with α‐amylase is one of the first order, while decomposition by means of hypochlorite is a second order reaction. There are considerable differences in the changes in molecular weight distribution between the two methods. Hydrolysis with α‐amylase gives a solution with a symmetrical molecular weight distribution whereas hypochlorite oxidation obviously causes splitting of some of the starch molecules, which results in solutions with two molecular weight maxima.

Studies in chemically modified celluloses. VIII. Hypochlorite oxidation of cellulose in the presence of cuprous hydroxide

Cotton cellulose has been oxidized with aqueous sodium hypochlorite solution in the presence of cuprous hydroxide for a short time (10 min). The copper hydroxide content, the pH of the oxidizing medium, and the concentration of the oxidant were varied and their effect on the chemical and physical properties of cellulose has been studied. Cuprous hydroxide has been shown to possess intense catalytic activity in this oxidation. The oxidized products are further modified by chlorous acid and sodium borohydride treatments and their effects on the properties of the oxidized products studied.

The influence of carbon-nitrogen ratio on the chlorination of microbial aggregates

Experiments were conducted with attached microbial films in a continuous flow reactor to determine the response of the film to hypochlorite treatment as a function of influent substrate concentration, influent carbon-nitrogen ratio (C/N) and shear force at the slime-water interface. Experiments were also conducted in batch systems with suspended organisms grown at varying C/N. Results were obtained regarding the relationship of bactericidal action to slime destruction. Comparison of experiments with HOCl and Hg 2+ indicate that bactericidal efficiency does not influence slime destruction. Destructive effects of hypochlorite oxidation were noted by measuring decrease in solids concentration of bacterial cultures.

Application of sodium hypochlorite oxidations to the structure of coal

Investigations of the reactions of sodium hypochlorite with 2-naphthol, 2-naphthoic acid, and benzoic acid show that the naphthalene derivatives react vigorously with the reagent at 65 °C to give phthalic acid and that benzoic acid accelerates the disproportionation of hypochlorite into chloride and chlorate. Some previous conclusions about the aliphatic structure of coal appear to be unjustified.

The Oxidation and Alkaline Degradation of Mercerized Cotton: A Morphological Study

The morphological changes introduced during slack mercerization of cotton fibers, as detected after oxidation with sodium hypochlorite at pH 7 and after subsequent hot alkaline degradation with sodium bicarbonate, are described. X-ray diffraction and electron microscopy techniques were used. Slack mercerization produces, besides the recognized phase transition from Cell. I to Cell. II, a decrease in order inside the crystallites themselves rather than in the low- ordered regions (LOR). The hypochlorite oxidation of the mercerized cotton induces morphological changes which can be understood as the result of a duality in behavior, i.e., as an oxidant, and as a poor intracrystalline swelling agent. The alkaline degradation results in an extraction of the anhydrous glucose units and an increase in crystallinity and morphologi cal order. However, crystallite lateral size is clearly reduced from that of the original Deltapine cotton but increased from that of the mercerized-oxidized sample. A model for the peeling off mechanism is visualized which involves not only those LOR regions associated in series with the crystalline regions, but those associated laterally to their fringes and also those limiting the macrofibrils. Advantage of extraction with a particular alkaline medium over others is explained by the critical swelling effect neces sary for transporting the anhydrous glucose units outside the remaining fibril morphology.

55—THE ESTIMATION OF DAMAGE IN JUTE MATERIALS

The application of microscopical and chemical methods of estimating the type and degree of damage in jute materials is described. These include the iodine-sulphuric acid microscopical test and the determination of fluidity, matter insoluble in cuprammonium hydroxide, copper number, alkali solubility, and carboxylic acid content, and it is shown that by these means it is possible to distinguish between the effects of damage by heat, and weathering, acid, hypochlorite oxidation, and fungal attack.

Studies in Accelerated Oxidation of Cellulose

Sodium hypochlorite oxidation of cotton cellulose in the presence of traces of cobaltous hydroxide has been studied. The oxycellulose thus formed has been further chemically modified by subjecting it separately to aqueous solutions of chlorous acid and sodium borohydride. Cobaltous hydroxide has been shown to possess more intense catalytic activity in the hypochlorite oxidation of cellulose than nickel hydroxide, ferrous hydroxide, and manganous hydroxide reported earlier.

Kinetics and mechanism of oxidation of starch with sodium hypochlorite

Kinetics of heterogeneous oxidation of starch with hypochlorite were studied under varying conditions of temperature, pH, buffer components, buffer concentration, and concentration of substrate and oxidant. The kinetic data show that the reaction is first order with respect to hypochlorite. A plot of first-order rate constant for varying starch concentrations versus starch concentration is linear. The rate of oxidation of starch is highest at pH 7.0 and decreases with increasing acidity or alkalinity of the medium. In unbuffered system, pH of the medium decreases from 10 to 3.4 during the reaction. Based on observed trends of reaction rate, energy, and entropy of activation, a mechanism for hypochlorite oxidation of starch is proposed.

Anodic chlorate formation on platinized titanium

The mechanism of anodic chlorate formation on platinized titanium was studied under well-controlled forced-convection conditions identical to those of previous experiments with graphite. Experimental results obtained in 4m NaCl and in 0·05m NaCl were compared to those predicted by mass transfer models describing anodic chlorate formation on graphite. In concentrated NaCl solution anodic chlorate formation rates for both electrode materials are smaller than expected for a diffusion controlled process. In dilute NaCl the ratio between measured rates and those predicted for diffusion control is shifted to higher values in qualitative agreement with predictions. Quantitative differences observed between the two electrode materials were attributed to the fact that hypochlorite oxidation on platinized titanium did not proceed at limiting current because of the slowness of the heterogeneous oxidation reaction.

Acid‐Modified Wheat Flours. Pasting and Dispersion Properties

AbstractAcid‐modified (AM) and hydroxyethylated acid‐modified (HEAM) wheat flours were prepared with viscosities suitable for use as tub‐sizing agents and as coating adhesives for paper. The pasting characteristics and dispersion properties of both these flours were compared with those of commercial products now used in such applications. Effects were determined of time, temperature and solids concentration on pasting characteristics, paste viscosity and dispersion properties. Paste viscosity behavior of the modified flours, prepared under dry‐state reaction conditions, was more like that of hypochlorite‐oxidized (HO) starch than either AM or HEAM starches. Dispersibility of the modified flours was comparable to that of AM starch, but it was somewhat lower than dispersibility of HEAM and HO starches. Pastes of modified flours and starches, stored and periodically tested, varied little in dispersibility values for flour dispersions, whereas progressively less dispersible material was found in starch pastes.

Studies in Accelerated Oxidation of Cellulose. I—Hypochlorite Oxidation of Cellulose in Presence of Manganous Hydroxide

The oxidation of cellulose by treatment with sodium hypochlorite in the presence of different amounts of manganous hydroxide at different pH values (4·5–9·0) for a short time (10 min) has been investigated. Treatments with chlorous acid and sodium borohydride have been utilised to determine the different types of reducing and acidic groups formed in cellulose during accelerated oxidation. Manganous hydroxide has been shown to be a milder accelerant of the hypochlorite oxidation of cellulose than either leuco vat dyes or ferrous hydroxide under similar conditions.

Oxidation of substituted carbodiimides and ureas

Pertrifluoroacetic acid oxidation of N,N′-dicyclohexylcarbodiimide and N,N′-diphenyl- sulfurdiimide yielded N-trifluoroacetyl-N,N′-dicyclohexyl urea and 2,2,2-trifluoroacetanilide as the major products. Sodium hypochlorite oxidation of N-hydroxy-N,N′-diphenyl thiourea and N-hydroxy-N,N′- diphenyl urea afforded 1,3,4,6-tetraphenyl-2,5-dithio-biurea and 1,2,4-triphenylsemicarbazide, respectively. The dimeric nature of these latter compounds implies the involvement of radical oxidation schemes.

Comparison of Organic Matter Destruction by Hydrogen Peroxide and Sodium Hypochlorite and Its Effects on Selected Mineral Constituents

AbstractThe destruction of organic matter from widely different soils was evaluated by using hydrogen peroxide and sodium hypochlorite oxidation procedures. The amounts of extractable Si, Mn, Al, and Fe were determined on the residues following treatment with the oxidizing agents by using acid ammonium oxalate and 0.5N NaOH extraction procedures. In addition, the amount of Si, Mn, Fe, and Al in the extracting solutions was determined. It was found that NaOCl extracted more organic matter with less destruction of the oxides than procedures employing H2O2. This was substantiated statistically using the t‐test as applied to paired values. Three treatments with NaOCl were concluded to be satisfactory for destruction of organic matter with minimum removal of Si, Mn, Fe, and Al.

Ruthenium trichloride-catalysed hypochlorite oxidation of organic compounds

Household bleach (sodium hypochlorite) generates ruthenium tetroxide from its lower valence states.

Alkaline hypochlorite oxidation of methyl β-cellobioside

Methyl β-cellobioside was oxidized with 20 molar equivalents of sodium hypochlorite per mole of glycoside at pH 9 and 50°. D-Erythronic, glyoxylic, D-glyceric, and formic acids were the major products isolated from the hydrolyzate of the oxidized mixture. This indicates preferential attack on C-2 and C-3 of one of the rings and C-2′, C-3′, and C-4′ of the other, with removal of C-3′ as formic acid. Oxalic acid, a minor product of the oxidation, was isolated as the calcium salt before hydrolysis. Glucose and arabinose were detected in the oxidation mixture, before hydrolysis, indicating oxidative cleavage of the acetal linkage. The proportions present were small. Very small proportions of formaldehyde were also present and were shown to arise probably from methanol. Some glucose was found in the hydrolysis mixture, indicating incomplete oxidation, even with the large excess of oxidant used. All of these components were determined quantitatively (Table I). A specific micromethod for the determination of glyoxylic acid is described. A postulated intermediate tetrabasic acid was synthesized. Another acid, probably of related structure, was isolated in small amount.