Conversion of plastic/cellulose waste into composites. II. Improving adhesion between polyethylene and cellulose using ozone

The effect of ozone gas treatment on the adhesion between low-density polyethylene (LDPE) and cellulose was investigated. The ozone treatment of LDPE resulted in a significant increase in the interfacial shear strength as measured by the single fiber fragmentation test, whereas the ozone treatment of cellulose was not successful in improving the adhesion. An extensive surface characterization was performed to elucidate the adhesion mechanism using ESCA, ATR-FTIR, contact angle measurements and iodometry. Among the species formed during the ozone treatment were several different carbonylic compounds, as well as hydroperoxides. The polar component of the surface energy increased for the ozone-treated materials as a result of the oxidation. Extraction of LDPE laminated with a re-generated cellulose film showed that strong bonding as achieved between the ozone-treated LDPE and cellulose during the lamination procedure. The suggestion proposed here for the adhesion mechanism is based on interactions between oxygen-containing species in both materials and the formation of covalent bonds originating from the decomposition of hydroperoxides. © 1996 John Wiley & Sons, Inc.     

Investigation of Ozone Loss Rate Influenced by the Surface Material of a Discharge Chamber

Decay characteristics of ozone concentration in oxygen in a chamber with three types of wall material (stainless steel, copper, and aluminum) are measured using the 254 nm photoabsorption method. Effective lifetimes of ozone are estimated from decay curves of ozone concentration. These values depend on the wall material: They are largest for stainless steel and smallest for aluminum. The relationship between effective lifetime and gas pressure is investigated precisely to determine three values. The equivalent diffusion coefficient of ozone in oxygen and the reflection coefficient of ozone at the wall correspond to the loss rate of ozone at the wall. The collisional loss (quenching) rate coefficient of ozone in oxygen is also determined.     

Degradation of Cellulose Models During an Ozone Treatment. Ozonation of Glucose and Cellobiose With Oxygen or Nitrogen as Carrier Gas at Different pH

Many parameters can influence the kinetics of cellulose models ozonation. In this work the effect of pH and oxygen as gas carrier on the evolution of the reaction was studied. The involvement of free radical species seemed to be unimportant in high ozone concentration available in water, even at high pH with regard to the reaction rate and by-product formation. Conversely, in basic pH conditions better reaction selectivity with formation in a higher yield of gluconic acid and cellobionic acid was found during the glucose and the cellobiose ozonation. The participation of the solvent and the partial ionization of the hydroxyl group at the Cl position explain this enhanced selectivity. Furthermore, the formation of compounds with a low molecular weight has been proved to be due to a hydrotrioxide fragmentation mechanism involving oxygen.     

Ozone Yields from Oxygen Irradiated at 193 nm

The use of ArF laser radiation at wavelength 193 nm to generate ozone from various pressures of oxygen gases was investigated. Kinetic results were interpreted from molecular spectroscopy and dynamics points of view. The 193 nm radiation can dissociate both oxygen molecules and ozone to produce oxygen atoms. This is an essential process in ozone generation. In this investigation, we focused on the mechanisms that ozone dissociates into three oxygen atoms or vibrationally excited oxygen molecules. The above mechanisms imply a potential process to improve the efficiency of ozone generation.     

The oxidative degradation of imide polymers. I: Ozonolysis of a model compound,N-phenylphthalimide

The reactions of N-phenylphthalimide films with ozone have been studied under a variety of conditions: dry ozone, moist ozone, ozone plus ultraviolet light, as well as ozone plus water vapor plus ultraviolet light. This compound is a conveniently available model for imide polymers. These reaction conditions represent simulation of certain aspects of the space environment. For each set of reaction conditions the reaction products were determined by combined gas chromatography/mass spectrometry. Semiempirical molecular orbital computations were made of the relative energetics of possible reaction pathways consistent with the generation of the observed products. The reaction products found indicate fragmentation of the imidic moiety for which the energetics are favorable.     

Biogas Production of Ozone and/or Microwave-Pretreated Canned Maize Production Sludge

The production of canned maize is accompanied by formation of large volumes of waste water, with high contents of starch, and high chemical- and biochemical oxygen demand. In our work the effects of acidic, microwave and ozone pretreatment on the biogas production and aerobic biodegradability of canned maize production sludge were examined and the energy balance of the processes were determined when different sludge pretreatments were used. It was found that ozone treatment decreased the chemical oxygen demand, while the biochemical oxygen demand and the aerobic biodegradability increased. The combination of microwave and ozone treatment increased the biodegradability relative to ozone treatment alone.     

Application and Kinetics of Ozone in Food Preservation

Ozone is activated oxygen and it is referred to as a triatomic form of oxygen. It is a natural agent and has a broad antimicrobial property, which together with an oxidation potential, make it an attractive option for the food industry. This article focuses on the use of ozone for preservation of vegetables, fruits and fruit juices, and highlights the inactivation mechanism of microorganisms. The application of ozone in grain storage and the quality of ozone treated grains is discussed, along with the reaction kinetics of ozone in grains.     

Characterization of the ozone zero phenomenon by infrared spectroscopy

The presence of a small amount of nitrogen in the feed gas is necessary to generate ozone efficiently out of oxygen. Operating an ozone generator with ultra-pure oxygen for extended periods results in highly deteriorated ozone generation efficiency. In extreme cases, when the nitrogen levels in the feed gas are in the lower ppm range, the efficiency of the ozone generation process even drops to zero. In this article, we present our results concerning the correlation between the N₂O₅ concentration in the off-gas and the ozone generation efficiency. After the ozone generator is run for a well-defined amount of time with an oxygen–nitrogen mixture, the N₂ supply is shut off, and the behavior of the system is monitored by near-infrared spectroscopy. Different surface materials lead to different temporal behavior of both the nitrogen oxide levels and the ozone concentration after shutting down the nitrogen supply. The measurements show a good correlation between the evolution of ozone generation efficiency and the changes of the N₂O₅ concentration in the off-gas.     

Ozonation of Sulfur Dioxide in Sulphuric Acid Solution

In this study, the oxidation rates of sulfur dioxide (SO₂) in sulphuric acid solution by ozone and oxygen were compared, and the oxidation mechanism of ozone on SO₂ was investigated. The results showed that the oxidation-reduction potential of the acidic solution was enhanced, the transformation rate of sulfuric acid to sulphuric acid was increased and the absorption driving force was improved in the presence of ozone. By comparing the amount of sulfate ions measured in the experiments and the theoretical amount of sulfate ions calculated from the amount of ozone consumed in the reaction, it can be confirmed that oxygen free radicals from dissociation of ozone are reactive as an efficient oxidant and oxygen from ozone generator participates in the reaction with SO₂. 0.602 mol of effective oxygen was introduced into the reaction by one mole of ozone in 10.15 min at sulphuric acid concentration of 3% (by mass), SO₂ concentration of 1.33% (by volume) and oxygen flow rate of 1.5 L·min^-1 from ozone generator.     

Comparison of Economics of Various Ozone Generation Systems

The specific production costs of ozone are presented for a capacity range of 1 to 1,000 kg/h ozone for various plant configurations and air or oxygen as feed gas, and for air preparation, liquid oxygen delivered to site, oxygen produced on–site and/or oxygen recycle systems. The influence of operating parameters such as ozone concentration or on–stream time are studied. Ozone is often considered to be “expensive”. It is difficult to pinpoint the rationale behind this statement. It could be caused by the difficulty to compare a chemical (ozone) which is produced on–site and requires a plant investment, with chemicals (such as chlorine) which are bought as such and delivered to the plant. It is certainly influenced by the fact that the economy of utilizing ozone s i not easily quantified. This paper presents an attempt to quantify the economics of ozone production for a wide range of production capacities, ranging from 1 to 1,000 kg/h. Different operating conditions are compared as well as different plant concepts. In order t o assure a meaningful comparison, certain parameters are common for all cases.     

臭氧尾气回用对曝气池污泥影响研究

将活性污泥分别在14.68、30.72、43.84 mg/L 3种臭氧浓度下进行氧化,同时以纯氧曝气作为平行实验,考察臭氧尾气对活性污泥的影响。结果表明,污泥经纯氧曝气后,在反应时间内并无明显变化,但在臭氧氧化过程中,污泥ATP下降,同时上清液中COD、TP、TN上升,且臭氧浓度越高,变化速率越大,其原因为污泥发生了溶胞现象;臭氧氧化后,污泥MLSS、MLVSS减少,污泥呼吸速率下降,但沉降性得到改善,同样随着臭氧浓度的升高,变化更为显著。经14.68、30.72 mg/L臭氧氧化后的污泥,其硝化能力、生化能力与反应前并无明显差距,而经43.84 mg/L臭氧氧化后污泥的硝化能力、生化能力明显弱于反应前。     

Oxidatives Verfahren zur Herstellung kurzkettiger Carbonsäuren aus ungesättigten Fettsäuren

Oxidative Procedure for Production of Short-Chain Carbon Acids from Unsaturated Fatty Acids For decades, the oxidation of oleic acid to acelaic and pelargonic acid has been carried out in industrial scale by ozone. The high costs of ozone production are a problematical point in this procedure. Thanks to the high selectivity the procedure is today still economic. Efforts to replace the ozone oxidation by an oxygen one haven't yet led to a procedure which can be applied in industry. In this work the oxygen oxidation of oleic acid with aldehyds as intermediary carrier of oxygen is reported.     

Editorial

The dynamics of the ozone formation in an oxygen-fed micro-discharge was studied by observing the dispersed emission from the reacting species. The correlation between the ozone production with the physical factors of a micro-discharge was described by a mathematical model where the distribution of the mean electronic energy is considered. The results showed that the oxygen atom is mostly produced from the oxygen molecule dissociating from the Schumann-Runge band, instead of being produced by direct electron bombardment. This is the reason why pressure has a negative effect role in ozone formation.     

Ozone formation with (V)UV‐enhanced dielectric barrier discharges in dry and humid gas mixtures of O2, N2/O2, and Ar/O2

The effect of (V)UV illumination at 172 run and 253.7 run on ozone formation with dielectric barrier discharges in air‐like mixtures of nitrogen/oxygen and argon/oxygen as function of the water concentration is presented. Although (V)UV at these wavelengths efficiently cleaves ozone, the ozone concentration in a combined (V)UV/dielectric barrier discharge in oxygen‐containing gases is reduced only very little. This corresponds to an enhanced concentration of atomic singlet oxygen, which, in presence of water, increases the production of hydroxyl radicals. This is confirmed by measurements of the removal rates of 2‐propanol and of its byproducts in dry and humid air in a combined (V)UV/dielectric barrier discharge treatment.     

Ozone assisted partial oxidation of DMS to DMSO on Fe based catalyst

Iron–zirconia catalysts are prepared with varying Fe content by co-precipitation method. Catalysts activity and stability are elucidated in vapour phase oxidation of DMS using ozone as an oxidant and compared with that of oxygen. In absence of ozone the catalysts are observed very low activity whereas the ozone is directly influencing the Fe₂O₃ redox cycle. Results reveal that the Fe content and reaction temperature have significant influence on the activity. The activation energy for conversion process is observed to be considerably low with ozone compared to that of oxygen. The 20% Fe containing catalyst is not deactivated for 80 h of operation.     

The role of hindered piperidine (HALS) compounds for the stabilization of polypropylene against oxidation reactions caused by ozone and oxidative products formed during photolysis of ozone

The role of hindered piperidine (HALS) photostabilizers for the photostabilization of polypropylene films against oxidative reactions caused by ozone and oxidative species formed during photolysis of ozone under UV irradiation (i.e., atomic oxygen and singlet oxygen) has been investigated and discussed. It has been found that ozonization and/or photoozonization of 2,2,6,6-tetramethyl-piperidine (I) and piperidinoxy radical (2,2,6,6-tetramethylpiperidino-1-oxy) (II) gives a high yield (91–98%) 2,6-dimethyl-2-hydroxy-6-nitro-heptane. Ozonization and/or photoozonization of HALS probably occur by a similar mechanism as reported for (I) and (II). HALS photostabilizer reacts with ozone and/or photolysis products of ozone (atomic oxygen and/or singlet oxygen) and loses its function in the photostabilization process. For that reason protection of polypropylene against photooxidative degradation and photoozonization is of great commercial importance.     

粘土/橡胶纳米复合材料老化性能研究

研究粘土 /SBR及粘土 /NR纳米复合材料的耐热氧老化和耐臭氧老化性能 ,并考察粘土 /SBR纳米复合材料的热失重和气体阻隔性。结果表明 ,粘土 /SBR纳米复合材料的耐热氧老化和耐臭氧老化性能均优于炭黑 /SBR复合材料 ;粘土 /NR纳米复合材料的耐热氧老化性能略优于炭黑 /NR复合材料 ,耐臭氧老化性能与炭黑 /NR复合材料相差不大 ;均匀分散的纳米粘土可提高橡胶的热稳定性和气体阻隔性 ,减缓氧及臭氧在橡胶中的扩散 ,降低橡胶分子链受攻击的几率 ,有利于提高橡胶耐热氧老化和耐臭氧老化性能     

Use of Ozone to Prepare Silver Oxides

The possible use of ozone to produce higher oxides was analyzed thermodynamically. Because the activity of oxygen in ozone is ∼10¹⁸ at room temperature and ∼10⁸ at 773 K, ozone may react with metals to yield higher-oxidation-state products than does an ambient pressure of pure oxygen. In agreement with this thermodynamic prediction, silver oxides (AgO and Ag₂O) were synthesized experimentally by blowing a gas mixture of 6 vol% ozone and oxygen through a water-cooled lance. Neither Ag₃O₄ nor Ag₂O₃ was detected. Slow oxygen diffusion into a metal and/or reaction products and decomposition of unstable oxides that are formed successively are obstacles to practical applications of syntheses via ozone oxidation.     

Effect of Ozone on Engorged Rhipicephalus microplus (Acari: Ixodidae) Females During the Pre-Laying Period

The Rhipicephalus microplus is an important ectoparasite of livestock as it results in loss to the producer. The present study analyzed the effects of ozone gas, a fluid with acaricidal potential, on this species of cattle tick. Engorged females of R. microplus were divided into two groups: control, oxygen and ozone groups. The results indicated that ticks in the control and oxygen groups maintained the oviposition process intact. Females exposed to the ozone gas died before eggs were deposited and damage on the cuticle was observed, proving that the ozone gas had an acaricidal effect on the ticks.     

Ozonolysis of 1-phenylazo-2-naphthol

The ozonolysis of 1-phenylazo-2-naphthol was studied using ozone in an oxygen stream. 1-Phenylazo-2-naphthol reacts with ozone to give benzene, chlorobenzene, phenol, o-naphthoquinone, phthalide and phthalic anhydride. The mechanism of the reaction is explained as an electrophilic attack of ozone with the hydrazone tautomer of 1-phenylazo-2-naphthol.