Decolorization of Brown Chitooligomers in Aqueous Solution by Ozonation

Brown chitooligomers were obtained by gamma irradiation. Decolorization of brown chitooligomers in aqueous solution by ozonation was investigated. It was found that ozone could decolorize the brown chitooligomers in aqueous solution. When the pH value was below 2.93, the ozone treatment could inhibit yellowing and browning of chitooligomers in aqueous solution. As a result, the chitooligomers were slightly depolymerized by ozonation. The characterization showed that the decolorization by ozonation did not lead to the significant modification of chemical structure of the chitooligomers.     

Decolorization of Wastewater Produced in a Pyrolysis Process by Ozone: Enhancing the Performance of Ozonation

This paper shows the results of color removal from a wastewater produced in a plastic pyrolysis process by ozonation. The influence of parameters such as temperature, reactor geometry, UVA, ozone input, and finally spraying of wastewater on performance enhancement of the decolorization process will be discussed. Due to the long residence time of O₃ molecules in the gaseous phase, recycling and spraying the wastewater in a pre-filled ozone chamber show a remarkable effect on decreasing the decolorization process time. At the end of this paper, an application of “micro-bubble producer” in this field, and its advantages will be introduced.     

Ozonation,Ozone/UV and UV/H2O2 Degradation of Chlorophenols

The performance of the O₃, O₃/UV and UV/H₂O₂ processes for degradation of six chlorophenols (4-chlorophenol, 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol) were studied in laboratory reactors. Comparative study showed that chlorophenols can be degraded successfully by all of the methods studied, whilst traditional ozonation at high pH was determined to be the most effective method to treat chlorophenols. Even though the molar absorptivity of chlorophenols is known to be relatively high in the UV-region, the combination of UV-radiation with ozone did not accelerate the degradation of chlorophenols further. The toxicity of degradation products formed during ozonation of chlorophenols has been compared with the toxicity of pure chlorophenols utilizing Daphnia magna 24 hours test. Ozonation of chlorophenols yielded less toxic or even nontoxic products for Daphnia magna compared with parent compounds.     

Impact of Ozonation on Decolorization and Mineralization of Azo Dyes: Biodegradability Enhancement,By-Products Formation,Required Energy and Cost

In the present study ozonation process was implemented to analyze the effect of ozonation time on the rate of chemical oxygen demand (COD) removal, mineralization and rate of decolorization of azo dyes. Three types of azo dyes i.e. Acid Red 14, Direct Red 28 and Reactive Black 5 were selected. Decolorization and mineralization of samples were conducted in batch scale. The COD and color removal efficiency were found to be increasing at a certain time of ozonation. The results with Acid Red 14, Congo Red and Reactive Black 5 dyes solutions lead to maximum COD reduction of 75%, 67% & 50% respectively. 93%, 92% and 94% color removal were achieved after 25 min of ozonation time of the same dyes which highlighted that ozonation process was found to be more efficient for reactive dye decolorization. Ozonation by-products analyzed by ion chromatography resulted that it partially mineralized with the formation of chloride, fluoride, sulphate, nitrate and oxalate ions. During ozonation process a rapid decrease in pH value indicated the acidic nature of by-products. The effect of buffered dye solutions on the ozonoation process highlighted that the decolorization efficiency decreases in comparison to unbuffered dye solutions. Ozonation led to enhancement of biodegradability ratio (BOD₅/COD) and increased electrical conductivity of the dye solutions. Optimum ozonation time required for degradation of dye solutions reflected the evaluation of energy consumption and cost of the treatment after ozonation.     

The Treatment of Spa Water with Ozone Produced by UV Light

Some North American manufacturers are selling devices which produce ozone from UV radiation, which is pumped or sucked into spas, presumably to disinfect the water, without having to use chlorine. To test this claim, a private spa used by two people at least once a day was equipped with a UV radiation unit and an ozone (generating by UV) unit. Bacterial analyses were conducted during experiments carried out using chlorine alone, ozone generated by UV radiation, unit and an ozone (generating by UV) unit. Bacterial analyses were conducted during experiments carried out using chlorine alone, ozone generaed by UV radiation, and ozoen in combination with UV radiation.

Heterotrophic plate counts, and counts of Staphyiococcus aureus and Pseudomonas aeruginosa were lowest when using chlorine, next lowest when using ozone #x002B; UV radiation, and highest when using UV-generated ozone. It is concluded that insufficient dissolved ozone is present for a sufficient reaction time to effect disinfection of these organisms by ozone generated by UV radiation. The fact that the odor of ozone was present above the spa water indicates that contacting also was inefficient.     

纤维素分解菌的筛选及其紫外诱变

利用羧甲基纤维素钠为唯一碳源培养基从朽木、腐烂的竹叶与稻草中分离得到8株纤维素分解菌,测定了其产酶活性。对其中产酶活性较高的2#菌株进行紫外线诱变,进一步筛选得到突变株M10,其相对酶活较出发菌株提高了89.1%。     

Evaluation of O3/UV and O3/H2O2 as Practical Advanced Oxidation Processes for Degradation of 1,4-Dioxane

The degradation of 1,4-dioxane was investigated on a laboratory scale. The extents of degradation and/or removal of 1,4-dioxane by ozonation at pH 6–8, UV irradiation, aeration, and addition of H₂O₂ were very limited. On the other hand, the degradation of 1,4-dioxane by O₃/UV and O₃/H₂O₂ was accelerated compared with the above respective methods. The amounts of 1,4-dioxane degraded per amount of ozone consumed in O₃/UV and O₃/H₂O₂ were also higher than in ozonation. The amount of 1,4-dioxane degraded in O₃/UV was affected by the intensity of UV irradiation, and that in O₃/H₂O₂ was affected by the amount of H₂O₂ added only in the case of a high initial concentration of 1,4-dioxane.     

Removal of the UV Filter Benzophenone-2 in Aqueous Solution by Ozonation: Kinetics,Intermediates, Pathways and Toxicity

Benzophenone-2 (BP-2) is an important type of UV filter that has been widely used and detected in the aquatic environment with greater estrogenic toxicity. In our work, the removal of BP-2 with the initial concentration of 25 mg L^?1 was first carried out by ozone at different pH (ranging from pH 3.0 to 11.0), and we found a positive correlation between the pH values and the degradation efficiency of BP-2, among which the more rapid removal of BP-2 in alkaline condition was observed than acidic and neutral conditions. For the influence of aqueous humic acid (HA, the concentration ranged from 0 ppm to 100 ppm), the degradation rate of BP-2 by ozonation was first increased with the growth of humic acid concentration (from 0 ppm to 5 ppm), reaching to maximum at 5 ppm of HA and subsequently decreased with the growth of HA concentration (from 5 ppm to 100 ppm). Fourteen intermediate products in the ozonation process were distinguished by an electrospray time-of-flight mass spectrometer and then two degradation pathways were proposed. Through the theoretical calculation, we found the carbanyl group of BP-2 has the most reactivity to be easily attacked by ozone, providing us guides and theoretical basis on the supposed intermediate products. Furthermore, the P. phosphoreum acute toxicity test was conducted to evaluate the potential toxicity during the ozonation process.     

The Combination of Ozone/Hydrogen Peroxide and Ozone/UV Radiation for Reduction of Trihalomethane Formation Potential in Surface Water

Applied ozone dosages of 20, 25, and 30 mg/L to lake water utilized by the city of Shreveport, LA produced no significant reductions in trihalomethane formation potentials (THMFP). However, the addition of 20 mg/L of hydrogen peroxide and/or 0.67 W/L of UV radiation (254 nm) in combination with ozone produced decreases in THMFP of over 60% in 60 minutes. Smaller THMFP decreases were seen with shorter contact times. The use of H₂O₂ and/or UV in combination with O₃ increased the percentage of applied ozone consumed by the lake water (i.e., enhanced the ozone mass transfer) five times over simple ozonation.     

紫外光照射对掺铝氧化锌薄膜导电和透光性质的影响

本文采用光助溶胶—凝胶法制备了掺铝氧化锌(AZO)透明导电薄膜.研究了紫外光照射对薄膜导电性和透光性质的影响.结果表明:光照使薄膜的导电性显著提高,且光照后薄膜方阻的降低幅度随薄膜晶粒尺寸的减小而逐渐增加;而随着紫外光照射时间延长,薄膜的紫外吸收边蓝移,近红外区透光率降低.以上实验现象可能与表面吸附氧解吸引起的载流子浓度增加、迁移率升高以及分层退火处理形成的薄膜结构有关.     

Effect of UV Radiation on the Removal of Carboxylic Acids from Water by H2O2 and O3 in the Presence of Metallic Ions

The effect of UV radiation on the removal of formic, oxalic and maleic acids from water by metallic ion (Fe²⁺ or Cu²⁺)/H₂O₂ and metallic ion/O₃ was studied and compared. The results showed that metallic ion/O₃/UV has higher efficiency than metallic ion/H₂O₂/UV for oxalic acid removal. UV radiation significantly increases the efficiency of metallic ion/H₂O₂ for formic and maleic acids removal while its effect on the efficiency of metallic ion/O₃ for formic acid removal is minor_. However, at pH 2, O₃ alone showed higher efficiency than metallic ion/H₂O₂/UV for formic acid removal. Contrary to the relative efficiency of metallic ions in the previous systems, Cu²⁺ exhibited higher rate than Fe²⁺ for the removal of the degradation products of maleic acid by O₃. UV radiation exhibited a minor effect on the efficiency of Cu²⁺/O₃, while it exhibited a large effect on the efficiency of Fe²⁺/O₃ for the removal of the degradation products of maleic acid.     

Oxidation by UV and Ozone of Organic Contaminants Dissolved in Deionized and Raw Mains Water

Organic contaminants dissolved in deionized pretreated and raw mains water were reacted with ultraviolet light and ozone. Ozone first was used for partial oxidation followed by ozone combined with ultraviolet radiation to produce total oxidation. The reduction of TOC level and direct oxidation of halogenated compounds were measured throughout the treatment process. The rate of TOC reduction was compared for ozone injected upstream and inside the reactor.     

Comparison of the Effects of Ozone,UV and Combined Ozone/UV Treatment on the Color and Microbial Counts of Wheat Flour

The effects of direct ozone treatment, UV treatment and combined ozone/UV treatment on the color and microbiological count of milled wheat flour were compared. The changes in color and microbiological properties during a 19-week storage period were also examined. Each of the treatments significantly reduced the microbial count of the flour and resulted in whiter flour. The results showed that only the combined treatment furnished flour suitable for consumption. The effect of the combined treatment was similar to, but more pronounced than that of ozone treatment. Changes in the quality of the dough were observable, similar by as in response to other oxidizing agents.     

O/W型生漆光固化膜的理化性能

以漆酚(U)/聚乙烯醇(PVA)为混合乳化剂,借助相反转技术,将W/O型天然生漆转化成可直接用水稀释的O/W型生漆,用紫外光固化法使其固化成膜;采用红外光谱、扫描电镜、热分析等手段对该固化膜进行结构表征和性能测试。结果表明:在紫外光辐照下,O/W型生漆可在2min内快速固化成膜,固化膜具有优良的理化性能。     

UV、UV/H2O2及UV/O3法去除饮用水中有机残留物的应用效果比较

分别采用UV、UV/H2O2及UV/O3对饮用水进行深度氧化处理,考察水样中药物残留（复方新诺明及碘普罗胺）和燃油添加剂残留（MTBE及TAME）的消解情况。     

The pH Dependence and Effects of the Oxidative Products of Some Aromatic Compounds in Ozonation under Irradiation

Some aromatic compounds (o–nitrotoluene, p–nitrotoluene–2–sulfonic acid, and p–medthylaniline–3–sulfonic acid), were ozonized under UV irradiation separately, and the oxidative efficiencies of these reactions were studied. In order to ensure continued oxidation, it is advantageous to choose a proper pH value so as to fit the requirements of the chain reaction and also diminish the amound of HO. scavengers such as CO₃ ⁼ and HCO₃ ^? in oxidation Products. Removal of carbon dioxide could be effected by acidification of the reaction mixture. In order to decrease the inhibiting effect of the oxidation products, it is advisable to vary the pH value at different stages of UV ozonation. Many refractory organics usually encountered in industrial wastewater may resist degradative oxdation by ozonation alone, but can be destroyed rapidly by UV–radiation combined with ozonation.     

Decomposition of phenols in aqueous solution by a UV/O3 process

The decomposition of several non‐biodegradable phenols by the UV/O₃ and ozonation processes was studied and compared under various solution pH values, O₃ input mass flow rates and UV intensities to investigate the removal efficiencies of reactants and organic intermediates. The decomposition rate of phenols by the UV/O₃ process was found to increase with increasing O₃ input dosage, light intensity and solution pH value. The mineralization efficiencies of phenols in aqueous solution would be above 98% under adequate reaction conditions within three hours, but would be retarded for alkaline solutions because of the dissolution of CO₂ formed by mineralization of phenols. The increment of ozone input dosage had little effect on the mineralization of organic intermediates at the latter course of the reaction. The order of the decomposition rate of the phenols used in this research was 2,4‐dichlorophenol > 2‐chlorophenol > 2‐nitrophenol for low and neutral pH solutions, whereas they were nearly alike for alkaline solutions. The two‐step consecutive kinetic model was found to fit well in modeling the behavior of species during the decomposition of phenols in aqueous solutions by the UV/O₃ process.     

Oxidation of Parachloronitrobenzene in Dilute Aqueous Solution by O3 + UV and H2O2 + UV : A Comparative Study

This laboratory study was designed to investigate the degradation of 4-chloronitrobenzene ([CNB] = 2.4 × 10^?6 mol L^?1; pH = 7.5) by H₂O₂/UV and by O₃/UV oxidation processes which involve the generation of very reactive and oxidizing hydroxyl free radicals. The effects of the oxidant doses (H₂O₂ or aqueous O₃), liquid flow rate (or the contact time), and bicarbonate ions acting as OH· radical scavengers on the CNB removal rates were studied. For a constant oxidant dose, the results show that the O₃/UV system appears to be more efficient than the H₂O₂/UV system to remove CNB because of the greatest rate of OH· generation by ozone photodecomposition compared to H₂O₂ photolysis. However, for a given amount of oxidant decomposed, the H₂O₂/UV oxidant system was found to be more efficient than O₃/UV. Moreover, high levels of bicarbonate ions in solution (4 × 10^?3 mol L^?1) significantly decrease the efficiency of CNB removal by H₂O₂/UV and by O₃/UV oxidation processes.     

Effectiveness of Pre- and Intermediate Ozonation on the Enhanced Coagulation of Disinfection By-product Precursors in Drinking Water

This study evaluated the impact of pre- and intermediate ozonation coupled with enhanced coagulation in controlling halogenated disinfection by-product formation in drinking water. Raw waters from utilities representing each of the nine elements of the enhanced coagulation matrix presented in Table I were examined. All testing was completed using bench-scale, batch experimental procedures. The various waters were analyzed for turbidity, total organic carbon, dissolved organic carbon, ultraviolet absorbance, trihalomethane formation potential, and haloacetic acid formation potential before and after ozonation. The results indicated that formation of trihalomethanes and haloacetic acids following enhanced coagulation decreased with both pre- and intermediate ozonation applications relative to the decreases observed by enhanced coagulation alone. The amount of trihalomethanes and haloacetic acids formed were lower for the waters that were pre-ozonated and then coagulated compared to those that were coagulated first and then ozonated. This comparison must be tempered by the fact that the settled waters treated by intermediate ozonation were not subjected to subsequent biofiltration which is commonly used in water treatment practice to remove additional DBP precursors. Strong correlations between disinfection by-product formation potentials and ultraviolet absorbance at 254?nm were observed for enhanced coagulation with and without pre- and intermediate ozonation.