Ozonation Kinetics Of Glucosamine And N-Acetyl Glucosamine In Aqueous Medium

Glucosamine and N-acetyl glucosamine show different behaviors towards ozone in aqueous medium: while glucosamine reacts relatively fast through ozone attack on the amino group, N-acetyl glucosamine is much more resistant, resembling the reactivity of glucose. Results obtained indicate that a mechanism of viral inactivation via ozone attack on the N-acetyl glucosamine of the viral capsid is not kinetically favored.     

Ozonation of an Extracted Aquatic Fulvic Acid : Theoretical and Practical Aspects

A laboratory study was conducted on the ozonation of an aquatic fulvic acid extracted from a forest pond near Poitiers in France. The rate of molecular ozone consumption was fast during the first minutes, and ozonation led to a slight increase of the lower apparent molecular 'weight, an enhancement of carboxyl content, and aldehyde formation. By ozonation of a bromide-containing solution of fulvic acid, some brominated organics were formed, while ozonation without bromide led to a reduction of the organic halide formation potential of a fulvic acid, especially in the presence of bicarbonate ions. The increase of GAC-filtration efficiency following ozonation was found to be the result of a biodegradability enhancement of fulvic acid by ozone. Manganese oxidation by ozone was partially inhibited by fulvic acid, particularly in the absence of bicarbonate ions.     

Ozone: A Means of Stimulating Biological Activated Carbon Reactors

To reduce the formation of chlorination byproducts in drinking water, the European strategy consists in developing techniques for the removal of organic matter. No chlorine is added to the water until the end of the treatment line, allowing a great reduction of the chlorine dose applied. Delaying the chlorination also improves the biological assimilation of organics within the filters. Identification of the basic properties (i.e., molecular weight, biodegradability) of the molecules which react with chlorine shows that the combination of ozone and biological activated carbon (BAC) filtration is an efficient and economical technique for the removal of these undesirable byproducts. More and more, drinking water suppliers are faced with the worrisome problem of chlorinated byproducts. This concern was prompted largely by the degradation of raw waters. Chlorinated byproducts are caused by the effect of chlorine on organic matter dissolved in water.     

Catalytic Ozonation of Citric Acid by Metallic Ions in Aqueous Solution

Ozonation of citric acid in water catalyzed by different ions from the first row of transition metals (Mn²⁺, Co²⁺, Ti⁴⁺, Fe²⁺, Cu²⁺, Ni²⁺ and Zn²⁺) was investigated at room temperature. The results showed that at pH=2, where the decomposition of citric acid is negligible by only ozone, the following order of efficiency of metallic ions for the decomposition of citric acid by ozone, and also for the TOC removal, was obtained: Mn²⁺ > Co²⁺ > Ti⁴⁺ > Fe²⁺. Cu²⁺, Ni²⁺ and Zn²⁺ showed negligible efficiency under the same experimental conditions. At pH=5.5, Mn²⁺ and Co²⁺ showed slightly higher efficiency than at pH=2 while Ti⁴⁺ and Fe²⁺ showed insignificant effect at this pH value. On the other hand, at pH=7 the investigated catalysts showed no obvious catalytic efficiency for the decomposition of citric acid by ozone.     

Degradation of 2,4-D By Ozone And Light

The decomposition of 2,4-dichlorophenoxyacetic acid in aqueous solutions has bsen studied using ozone and ultraviolet radiation at different pH, ozone production, and initial concentration of pesticide. A mathematical model which incorporates the rate of mass transfer of ozone, the oxidation kinetics of 2,4-D and the kinetics of formation and oxidation of the intermediates was used. A global rate constant was calculated and an empirical equation which correlated that constant with ozone production, initial concentration of 2,4-D and pH at the same temperature was determined.     

Enhancement of Radical Chain Reactions of Ozone in Water in the Presence of an Aquatic Fulvic Acid

In this work, the rate constants of ozone consumption by an aquatic fulvic acid were determined in a special batch reactor atifferent pH values and in the presence or absence of t–butyl alcohol, a well known free–radical scavenger. We have found, for ratios [FA]_o/[O₃]_o 17 mole C/mole O₃, that reactions are of first order for ozone consumption (between pH 2 and 8). Results show that the fulvic acid does not participate in the radical type decomposition of ozone at strongly acidic pH (pH = 2), and that it becomes, with increasing pH (increased dissociation degree of its acidic groups), promoter of the decomposition of ozone in water.     

Formation of Ketoacids in Ozonated Drinking Water

Three ketoacids; glyoxylic acid, pyruvic acid and ketomalonic acid, were identified in ozonated drinking waters and fulvic acid solutions using gas chromatography-mass spectrometry. It was found that the concentrations of ketoacids were much higher than those of aldehydes in ozonated waters. The significance of ketoacids in finished drinking waters is discussed.     

Degradation By Ozone and UV Radiation of the Herbicide Cyanazine

The degradation of the herbicide cyanazine in aqueous solution by ozone and UV radiation separately have been developed. In the ozonation process, the influence of the operating variables is observed, the stotchiometric ratio for the reaction is obtained, and a free radical reaction mechanism is proposed. The kinetic study establishes that the process is controlled by the chemical reaction, which takes place in the very slow kinetic regime. The reaction rate constants are determined as a function of temperature and pH.     

Degradation Of Selected Herbicides In A Lowland Surface Water By Ozone And Ozone-Hydrogen Peroxide

The efficiency of ozone, and ozone in combination with hydrogen peroxide, for the degradation of five herbicides: Atrazine, Benazolin, Bentazone, Imazapyr and Triclopyr, under controlled laboratory conditions was investigated. Experiments were conducted at pH 7.5 in a bubble contactor column with a raw lowland surface water spiked with initial active ingredient concentrations of 2 μg/L. Mean consumed ozone doses were approximately 1, 2 and 3 mg O₃/L. Hydrogen peroxide was added simultaneously to the application of ozone in a series of six mass ratios, between 0.0 and 1.0, with each of the consumed ozone doses. The results demonstrated a greater but varying removal of all herbicides achieved with increasing consumed ozone and applied hydrogen peroxide doses.     

生物技术黄腐酸微肥的生产与应用

介绍了生物技术黄腐酸微肥的配方及生产方法，使用，结果表明，该微肥具有补充作物所需的微量元素和提高作物抗旱等能力的双重功效，是很有发展前途的新型肥料。     

Removal of Organic Pollutants from Soil: The Ozonation of Clofibric Acid in Aqueous Slurries

Ozonation is particularly suited for the treatment of recalcitrant soil contaminants. Clofibric acid, an active metabolite of some blood lipid regulators, was used as a model organic contaminant, and quartzite as a model soil. The measurements performed at different pHs, both in slurries of contaminated soil and in clofibric acid aqueous solutions, indicate that a markedly higher TOC removal can be obtained in the slurry mode. Ozonation kinetics in aqueous slurries was also studied in a well-mixed reactor. Suitable mathematical models were used to describe the experiments and to estimate the best values of the unknown parameters.     

Pyruvic Acid Removal from Water by the Simultaneous Action of Ozone and Activated Carbon

Activated carbon (AC) has been used to catalyze the ozonation of pyruvic acid in water. Pyruvic acid conversions were found to be 9 and 37% after 90 min of single ozonation and single adsorption with 40 gL^?1 AC, respectively, while 82% was reached at the same conditions during the AC catalytic ozonation. Also, for similar conditions, mineralization reached values of 67% in the AC catalytic ozonation against hardly 5% in the non-catalytic experiment. The process likely develops through both adsorption of ozone and pyruvic acid on the AC surface and generation of hydroxyl radicals that eventually is the responsible oxidizing species. Rate constants for both non-catalytic ozonation and AC-Ozone catalytic surface reaction, at 20°C and pH 7.5, were found to be 0.025 min^?1 and 87.9 Lg^?1s^?1, respectively. For AC concentrations higher than 2.5 gL^?1 gas-liquid mass transfer of ozone constituted the limiting step. At lower concentrations, internal diffusion plus surface reaction controlled the process rate.     

Degradation of Poplar Lignin with Ozone

In this paper, the degradation of poplar lignin with ozone is studied. Experiments are conducted in a fixed bed reactor. Effect of moisture content of the lignocellulosic material, gas flow, ozone content in the oxygen flow and space velocity are studied using a complete factorial scheme. Moreover, water soluble products are analyzed by H.P.L.C.     

Oxidation of Cyanuric Acid in Aqueous Solution by Catalytic Ozonation

The aim of this work was studying the activity of a Ru/CeO₂ powder catalyst in the ozonation of aqueous solution of cyanuric acid (CYA). Ozonation in the presence of the catalyst significantly enhances CYA degradation. Within this work, investigation of the influence of pH and initial concentration on the catalytic ozonation of CYA has been done in a semicontinuous reactor. The removing degree of CYA at pH 5.9 show better response in comparison to pH 2.5 and pH 8.2. The mineralization of CYA by catalytic ozonation formed nitrate ions (0.7 mol of NO₃^?/mol of CYA removed for 50% initial CYA abatement) and nitrite and ammonium ions in small amounts. Three transformation products formed during catalytic ozonation were identified from LC/MS and MS/MS analyses. The impact of oxidation on the toxicity was measured from the inhibition of Vibrio fisheri, which was found to increase continuously.     

Ozonation Of Sulfur-Containing Aliphatic Compounds In Aqueous Solutions. II. Cysteine,Cystine and Thioglycolic Acid

In view of the possible reaction of ozone with sulfur-containing natural and anthropogenic compounds, the ozonation of cysteine, cystine, thioglycolic acid and their oxidation products at pH 3 and 7 (initial concentration 1 mmol/L) was investigated. The oxidation of cysteine at pH 3 leads to cysteic acid; at pH 7 sulfoacetic acid, sulfate, ammonia and nitrate are formed besides cysteic acid. Cysteinesulfinic acid as intermediate oxidation product was not identified because of the very fast reaction with ozone forming cysteic acid.     

Effective Catalysts for Wet Oxidation Of Formic Acid by Oxygen and Ozone

The catalytic wet-air oxidation and catalytic ozonation of a formic acid solution have been studied at room temperature using more than 20 kinds of catalysts including Pt/C, Pt/Al₂O₃, Pd/Al₂O₃, etc. The most effective catalyst was Pt/Al₂O₃. The apparent activation energies for the catalytic wet-air oxidation and ozonation on Pt/Al₂O₃ were both about 5 kcal/mol. This fact suggests that these reactions on the catalyst were diffusion controlled, and thus, the potential of the catalyst is likely much higher.     

Treatment of Humic Waters By Ozone

Two different generators for ozone were tested, a traditional electrical discharge generator and a generator based upon UV–irradiation of air at 150–180 nm. It was demonstrated that the traditional generator gave slightly higher reductions in levels of color for equivalent ozone dosages. Both gases affected the molecular weight distribution in the way that the bigger molecules were broken down to smaller ones. No significant difference between the molecular weight reduction efficiency of the gases was found.     

Study of the Sonication/Ozone/Argon Process for Saturated Free Fatty Acids Degradation in Aqueous Solution

In the present work, study of the sonication process was investigated for saturated fatty acids degradation. Saturated fatty acids are the most hard-degradable compounds of FOG (fats, oils, and greases) wastewater contaminants. The influence of various conditions (probe immersion level into the liquid, simultaneous ultrasound irradiation and bubbling of Ar, O₂, air, and O₃) on the sonochemical and energy efficiency of the sonication process were studied. According to our experimental data and the state of the art, the most appropriate conditions were selected on purpose to decompose hydrophobic compounds, such as saturated free fatty acids. The most effective degradation treatment method for saturated free fatty acids was the simultaneous sonication (with high probe immersion level into the liquid) and argon bubbling (at low flow rate) under controlled temperature.     

Degradation of Diclofenac and Clofibric Acid using Ozone-Loaded Perfluorinated Solvent

The removal of pharmaceuticals (diclofenac and clofibric acid) from aqueous solution by using single and two-phase ozonation system was investigated. The second phase consisted of a reusable, fluorinated hydrocarbon (FC 40), with an ozone solubility of 10–12 times that of water. The research was carried out in a continuous and semi-continuous system. The influence of pharmaceuticals concentration, ozone dosage and contact time between FC 40 phase and aqueous solution were measured. Low extraction coefficients of pharmaceuticals suggest the aqueous phase as a reaction medium, while ozonation in the presence of tert-butanol indicates a radical mechanism of the destruction reactions. The results show that the removal efficiency of pharmaceuticals by fluorinated solvent/ozone combined system is higher when compared with aqueous phase ozonation.     

Degradation of Phenolic Compounds in Aqueous Sucrose Solutions by Ozonation

The sugar industry is concerned with color formation due to the oxidation of phenolic compounds in the presence of carbohydrates. In this study, we investigated the ozonation of a mixture of five phenolic compounds in water and aqueous sucrose solution: p-coumaric (p-COU), caffeic (CAF), syringic (SYR), and chlorogenic (CHO) acids, as well as the flavonoid quercetin (QUE). The experiments were carried out in a 3-L glass reactor with magnetic stirring and a diffuser plate at the bottom to feed the ozone-oxygen gas mixture. Initial solution concentrations of 5 mg L?1 of each acid, 15 mg L?1 of quercetin, and 40 g L?1 of sucrose were used. The degradation of phenolic compounds followed apparent first-order kinetics, with rate constants and percent removals decreasing in the presence of sucrose. In water, average consumed ozone dosages of 10.4 and 18.7 mg L?1 were necessary for 50% and 90% removals, respectively, for CHO, CAF, and p-COU; for QUE they were slightly higher (13.9 and 20.5 mg L?1, respectively). At a consumed dosage of 20.8 mg O3 L?1, more than 99% removal was obtained for CHO, CAF, and p-COU, while 96.2% was achieved for SYR. In contrast, QUE revealed to be more recalcitrant during ozonation in the absence of sucrose, with only 70% removal at the highest consumed O3 dosage. The consumed ozone dosages for 50% and 90% removals were higher for CHO, CAF, and p-COU in aqueous sucrose solution, which may impact ozone consumption during real sugarcane juice treatment. Sucrose and t-butanol were the main influential parameters that significantly affected the total amount of phenolic compounds degraded.