O3、H2O2／O3及UV／O3在焦化废水深度处理中的应用

采用O3、H2O2／O3及UV／O3等高级氧化技术（AOPs）对某焦化公司的生化出水进行深度处理,考察了O3与废水的接触时间、溶液pH、反应温度等因素对废水COD去除率的影响,确定出O3氧化反应的最佳工艺参数为：接触时间40min,溶液pH8．5,反应温度25℃,此条件下废水COD及UV254的去除率最高可达47．14％和73．47％;H2O2／O3及UV／O3两种组合工艺对焦化废水COD及UV254的去除率均有一定程度的提高,但H2O2／O3系统的运行效果取决于H2O2的投加量。研究结论表明,单纯采用COD作为评价指标,并不能准确反映出O3系列AOPs对焦化废水中有机污染物的降解作用。     

Treatment of pharmaceutical wastewater containing antibiotics by O3 and O3/H2O2 processes

Ozonation of three different synthetic pharmaceutical formulation wastewater containing two human antibiotics and a veterinary antibiotic has been studied to enhance the their biodegradability. The effects of pH and initial chemical oxygen demand (COD) value as well as addition of hydrogen peroxide on ozonation process were investigated. Total organic carbon (TOC), COD, biochemical oxygen demand (BOD), and aromatic content (UV254) were the parameters followed to evaluate the performance of ozonation process. Comparison of the biodegradability of selected wastewaters containing different antibiotics confirmed that the variation of biodegradability was associated with the target compound. While BOD5/COD ratio of veterinary antibiotic formulation wastewater was increased from 0.077 to 0.38 with an applied ozone dosage of 2.96 g/l, this ratio for human antibiotic I and human antibiotic II was increased from 0 to 0.1 and 0.27 respectively. Moreover the results of this investigation showed that the ozonation process is capable of achieving high levels of COD and aromaticity removals at about their natural pH values.     

Fe2O3-Cr2O3/TiO2系列催化剂的结构和脱硝性能

研究以纳米TiO2为载体,浸渍负载过渡金属氧化物,以CO为还原剂的脱硝催化剂的脱硝性能。实验中以计算量的Ni（NO3）2和Fe（NO3）3混合溶液浸渍纳米TiO2粉末,室温下搅拌30 min至混合均匀,放入旋转蒸发器中,70℃下至水分蒸干为止;所得粉末在550℃下、空气气氛中焙烧4 h即得所需催化剂。用以上方法分别制备2%Fe2O3-10%Cr2O3/TiO2、4%Fe2O3-8%Cr2O3/TiO2、6%Fe2O3-6%Cr2O3/TiO2、8%Fe2O3-4%Cr2O3/TiO2与10%Fe2O3-2%Cr2O3/TiO2等5种催化剂样品。实验结果表明,制备的催化剂具有较好的结构,分散较为均匀。对于CO＋NO反应,Fe2O3-Cr2O3/TiO2系列催化剂具有较好的催化活性,NO的转化率都达到了100%。其中,10%Fe2O3-2%Cr2O3/TiO2样品具有最好的低温活性,H2-TPR结果表明,这是由于10%Fe2O3-2%Cr2O3/TiO2催化剂更易于被CO预还原。     

Simazine removal from water in a continuous bubble column by O3 and O3/H2O2.

Simazine, [2-chloro, 4,6-bis(ethylamino)-1,3,5-s-triazine], a common herbicide found in surface and ground water has been ozonized in continuous flow mode. Typical operating variables in ozonation processes have been investigated. Thus, the ozone dose fed to the system exerted a positive effect, while the gas flow rate did not influence the efficiency of the process provided ozone mass flow rate was kept constant. Increasing the pH led to a higher extension of the free radical degradation of simazine and, therefore, to a higher efficiency of the process. Also, addition of free radical promoters, i.e. hydrogen peroxide, did result in a significant improvement of the simazine removal rate. A first approach to process economy showed the system ozone/hydrogen peroxide as the most advantageous in terms of electrical energy requirements.     

The catalytic incineration of styrene over an Mn2O3/Fe2O3 catalyst

In this study, styrene monomer (SM) was treated by a commercial catalyst, Mn2O3/Fe2O3, in a fixed-bed reactor. The study can be classified into two major parts. First, the effects of operating factors, such as temperature, SM concentration, space velocity, and O2 concentration, on the performance of the catalyst were investigated. Second, two catalyst life tests were carried out to characterize the deactivation effect of SM. The results show that the catalyst results in higher conversion of SM at a higher inlet temperature and higher O2 concentrations. The conversion of SM decreases with increasing SM concentration and space velocity. From the statistical analysis of the data, we find that temperature is the most important factor on the catalytic incineration. Oxygen concentration, SM concentration, and space velocity are significant parameters as well. This paper also provides information on the deactivation effect of SM. The catalysts were characterized by surface and pore-size analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron spectroscopy for chemical analysis (ESCA) before and after the tests. The results show that the catalytic deactivation may be caused by carbon coating, and the pore size and surface area of the catalyst are smaller after deactivation.     

SIMAZINE REMOVAL FROM WATER IN A CONTINUOUS BUBBLE COLUMN BY O3 AND O3/H2O2

Simazine, [2-chloro, 4,6-bis(ethylamino)-1,3,5-s-triazine], a common herbicide found in surface and ground water has been ozonized in continuous flow mode. Typical operating variables in ozonation processes have been investigated. Thus, the ozone dose fed to the system exerted a positive effect, while the gas flow rate did not influence the efficiency of the process provided ozone mass flow rate was kept constant. Increasing the pH led to a higher extension of the free radical degradation of simazine and, therefore, to a higher efficiency of the process. Also, addition of free radical promoters, i.e. hydrogen peroxide, did result in a significant improvement of the simazine removal rate. A first approach to process economy showed the system ozone/hydrogen peroxide as the most advantageous in terms of electrical energy requirements.     

Catalytic destruction of 1,2-dichlorobenzene on V2O5-WO3/Al2O3-TiO2 catalyst

Studies on the catalytic destruction of 1,2-dichlorobenzene were carried out on a specially constructed semi-technical equipment whose most important element was a catalytic reactor with a monolithic catalyst in the form of 150 x 150 x 100 mm cubes. A catalyst made from cordierite with an active layer composed of Al2O3 - 64 wt%, TiO2 - 26 wt%, V2O5 - 6.6 wt% and WO3 - 3.4 wt% was used. The reactor made it possible to carry out the process in the temperature range 150-350 degrees C, at variable catalyst loading and different velocities of gas flow through the reactor. The content of 1,2-dichlorobenzene in the air was analysed by a chromatographic method. A significant effect of catalyst loading and temperature on 1,2-dichlorobenzene destruction efficiency was observed and no effect of the linear flow velocity through the catalyst on o-dichlorobenzene destruction efficiency was reported. The applied vanadium-tungsten catalyst on a monolithic carrier made from TiO2/gamma-Al2O3 revealed very good activity that resulted in an over 80% efficiency of 1,2-dichlorobenzene destruction at the temperature around 250 degrees C at a very high catalyst loading reaching ca. 8200 h(-1). Additionally, in this study the kinetics of 1,2-dichlorobenzene decomposition was determined, specifying the order of reaction and dependence of the decomposition rate constant on temperature, using a simple power-rate law model.     

O3/H2O2法去除浮选药剂丁基黄药

采用O3/H2O2法去除水中丁基黄药,考察了H2O2/O3摩尔比、pH值、丁基黄药初始浓度、温度和自由基抑制剂对丁基黄药的去除效果的影响。结果表明,在相同O3投加量下,H2O2量越大,丁基黄药去除率越高。pH值为7～9,温度在293～303 K的范围内,O3/H2O2对丁基黄药都有很高的去除率。碳酸氢根和叔丁醇能在一定程度上降低丁基黄药的降解效率。研究还发现,在O3和H2O2投加量相同的条件下,H2O2多次投加对水中丁基黄药的处理效果明显优于一次性投加。GC/MS分析表明,O3/H2O2氧化丁基黄药氧化产物为羧酸类物质。     

Fe/Ga2O3-Al2O3催化甲烷还原NO的性能

以甲烷为还原剂的选择性催化脱硝技术(SCR-CH_4)是一种很有潜力的新的脱硝方法,但催化剂的催化活性比较低。为了提高催化剂的活性以及抗水能力,可使用Fe对Al_2O_3负载的Ga_2O_3催化剂进行改性。采用共沉淀法,制备了xFe/Ga_2O_3-Al_2O_3催化剂,在固定床反应器中测试其选择性催化CH_4还原NO的性能。使用XRD、N_2吸附脱附、XPS、H_2-TPR、Py-IR等方法进行表征。结果表明:经过Fe改性后的催化剂提高了中高温的催化活性,提高了催化剂的N_2选择性,并改善了催化剂的抗水特性;5Fe/Ga_2O_3-Al_2O_3催化剂在500℃、富氧条件下,达到76%的NO转化率和100%的N_2选择性;在5%水蒸气条件下,5Fe/Ga_2O_3-Al_2O_3在500℃仍保持60%以上的NO转化率。N_2吸附脱附结果显示,引入Fe后,催化剂保持了原有比表面积,并且大大增加了催化剂孔径,可提高催化剂抗水能力。XPS与UV-vis显示,5Fe/Ga_2O_3-Al_2O_3具有高含量的游离态Fe~(3+),可提高催化剂的中高温活性。H2-TPR结果显示,Fe的引入提高了催化剂氧化还原能力,增强了原有Ga_2O_3-Al_2O_3中高温的还原活性。Py-FT-IR结果显示,催化剂表面同时存在Lewis酸和Br?nsted酸,铁的引入增加了催化剂表面的Lewis酸量。因此,Fe修饰Ga_2O_3-Al_2O_3是提高Ga_2O_3-Al_2O_3催化剂的SCR-CH_4脱硝性能的有效方法。     

The Cl-initiated oxidation of CH3C(O)OCH=CH2, CH3C(O)OCH2CH=CH2, and CH2=CHC(O)O(CH2)3CH3 in the troposphere

Background, aim, and scope  

Unsaturated esters are emitted to the atmosphere from biogenic and anthropogenic sources, including those from the polymer industry. Little information exists concerning the atmospheric degradation of unsaturated esters, which are mainly initiated by OH radicals. Limited information is available on the degradation of alkenes by Cl atoms and almost no data exists for the reactions of unsaturated esters with Cl atoms. This data is necessary to assess the impact of such reactions in maritime environments where, under circumstances, OH radical- and Cl atom-initiated oxidation of the compounds can be important. Rate coefficients for the reactions of chlorine atoms with vinyl acetate, allyl acetate, and n-butyl acrylate have been determined at 298 ± 3 K and atmospheric pressure. The kinetic data have been used in combination with that for structurally similar compounds to infer the kinetic contributions from the possible reaction channels to the overall reaction rate.     

Temperature dependence of hydroxyl radical formation in the hv/Fe3+/H2O2 and Fe3+/H2O2 systems

The thermal enhancement of the formation of *OH by the hv/Fe(III)/H2O2 system (including the Fe(III)/H2O2 system) was quantitatively investigated with reaction temperatures ranging from 25 to 50 degrees C. A temperature dependent kinetic model for the hv/Fe(III)/H2O2 system, incorporating 12 major reactions with no fitted rate constants or activation energies, was developed, and successfully explained the experimental measurements. Particularly, the thermal enhancement of Fe(OH)2+ photolysis which is the most significant step in the hv/Fe(III)/H2O2 system was effectively explained by two factors; (1) the variation of the Fe(OH)2+ concentration with temperature, and (2) the temperature dependence of the quantum yield for Fe(OH)2+ photolysis (measured activation energy=11.4 kJ mol(-1)). Although in both the hv/Fe(III)/H2O2 and Fe(III)/H2O2 systems, elevated temperatures enhanced the formation of *OH, the thermal enhancement was much higher in the dark Fe(III)/H2O2 system than the hv/Fe(III)/H2O2 system. Furthermore, it was found that the relative thermal enhancement of the formation of *OH in the presence of *OH scavengers (tert-butyl alcohol) was magnified in the Fe(III)/H2O2 system but was not in the hv/Fe(III)/H2O2 system.     

O3/H2O2高级氧化技术H2O2加入量的简易控制方法

对与臭氧有着不同反应活性的3类有机污染物,探讨并建立了O3/H2O2高级氧化技术H2O2较优投加量的简易控制方法.结果表明,水中存在溶解臭氧是H2O2与臭氧降解效率具有协同作用的必要条件,另外,H2O2的较优加入量直接依赖于目标有机污染物与臭氧的反应活性.对于不同的有机物及在常规的臭氧化水处理时间内,H2O2加入量控制在单独臭氧化处理时水中溶解臭氧的20～30倍(质量比)之间为宜.这种简易控制H2O2加入量的方法对推广O3/H2O2技术在实际废水处理中的应用具有重要的意义.     

O_3/H_2O_2深度处理印染废水二级出水

采用O3/H2O2高级氧化工艺深度处理印染废水二级出水,考察了不同反应条件对O3/H2O2工艺的影响,并且对污水二级出水有机物(Ef OM)的性质和去除行为进行了表征分析。结果表明,在p H=9,臭氧进气流量0.2 L/min,臭氧浓度116 mg/L,反应时间100 min,H2O2投加量9.79 mmol/L时,COD和色度去除率分别为82.2%、96.9%,B/C(BOD5/COD)由初始的0.10提升到0.32。此外,三维荧光光谱(3DEEM)、相对分子质量分布(MWD)以及亲疏水性分布分析表明,处理后Ef OM的荧光特性发生变化,低分子量物质大量增加,亲疏水性分布也有所改变。     

微波辐射Bi2O3/沸石-H2O2体系降解废水中的硝基苯

研究了微波辐射下,以负载于沸石上的三氧化二铋为催化剂,以双氧水为氧化剂的催化氧化体系处理硝基苯工艺。通过单因素实验法,从反应催化剂负载量、pH、双氧水用量、微波功率、反应时间、催化剂用量等方面初步考察了硝基苯在该体系中的催化氧化效果。在氧化铋负载量3%（质量比）,pH=2,2 mL 30%双氧水,火力为中火,催化剂投加量为0.7 g,反应2 m in,对降解过程所得的中间产物和终产物进行了分析。结果表明,该体系对硝基苯的去除率能够达到99.2%,COD去除率为73.91%。     

Catalytic reduction of N2O over Ag-Pd/Al2O3 bimetallic catalysts

A study of the catalytic conversion of N2O to N2 over a bimetallic Ag-Pd catalyst is described in this article. Several Ag-Pd catalytic systems were prepared supported on Al2O3 with different ratios and their catalytic activity for the direct decomposition of N2O and their reduction with CO was measured. Based on the experimental results, it was observed that Ag-Pd bimetallic catalyst (5-0.5%) was the most active for both nitrous oxide reduction and direct decomposition. This high activity seems to be connected with a synergistic effect between Ag and Pd.     

Oxidation of MCPA and 2,4-D by UV radiation, ozone, and the combinations UV/H2O2 and O3/H2O2

The phenoxyalkyl acid derivative herbicides MCPA (4-chloro 2-methylphenoxyacetic acid) and 2,4-D (2,4-dichlorophenoxyacetic acid) were oxidized in ultrapure water by means of a monochromatic UV irradiation and by ozone, as well as by the combinations UV/H2O2 and O3/H2O2. In the direct photolysis of MCPA, the quantum yield at 20 degrees C was directly evaluated and a value of 0.150 mol Eins(-1) was obtained in the pH range 5-9, while a lower value of 0.41 x 10(-2) mol Eins(-1) was determined at pH=3. Similarly, for 2,4-D a value of 0.81 x 10(-2) mol Eins(-1) was deduced, independent of the pH of work. The influence of the additional presence of hydrogen peroxide was established in the combined process UV/H2O2, and the specific contribution of the radical pathway to the global photo-degradation was evaluated. The oxidation by ozone and by the combination O3/H2O2 was also studied, with the determination of the rate constants for the reactions of both herbicides with ozone and hydroxyl radicals at 20 degrees C. These rate constants for the direct reactions with ozone were 47.7 and 21.9 M(-1) s(-1) for MCPA and 2,4-D respectively, while the found values for the rate constants corresponding to the radical reactions were 6.6 x 10(9) and 5.1 x 10(9) M(-1) s(-1).     

O3／H2O2高级氧化技术H2O2加入量的简易控制方法

对与臭氧有着不同反应活性的3类有机污染物，探讨并建立了O3／H2O2高级氧化技术H2O2较优投加量的简易控制方法。结果表明，水中存在溶解臭氧是H2O2与臭氧降解效率具有协同作用的必要条件，另外，H2O2的较优加入量直接依赖于目标有机污染物与臭氧的反应活性。对于不同的有机物及在常规的臭氧化水处理时间内，H2O2加入量控制在单独臭氧化处理时水中溶解臭氧的20-30倍（质量比）之间为宜。这种简易控制H2O2加入量的方法对推广O3／H2O2技术在实际废水处理中的应用具有重要的意义。     

O3/H2O2工艺降解1,2,4-三氯苯的优化设计

考察用不同的氧化剂降解1,2,4-三氯苯（TCB）,3种不同方法对TCB的去除效果存在较大差别,其处理效果依次为：H2O2〈O3〈O3/H2O2。采用响应面法优化O3/H2O2工艺降解TCB的条件。结果表明,TCB初始浓度和H2O2投加量对TCB去除效果影响较大。TCB的降解符合准一级反应动力学规律,最佳降解条件为TCB初始浓度0.3 mg/L,pH=8.13,H2O2投加量0.40 mmol/L,O3转化率75%。在此条件下,TCB的平均去除率为91.5%,与预测值93.1%吻合度较高。     

La2O3-CeO2/γ-Al2O3催化剂还原脱硫耐氧特性及其反应机理研究

用浸渍法制备了一系列稀土催化剂,研究了其催化CO还原SO2为单质硫的耐氧特性及影响其耐氧性能的主要因素,运用XRD技术分析了催化剂物相的变化及脱硫产物成分.结果表明,12% La2O3-8% CeO2/γ-Al2O3复组分催化剂比其他La2O3-CeO2/γ-Al2O3催化剂具有更好的耐氧性能;脱硫温度、催化剂用量、SO2与CO的摩尔比等对催化剂的耐氧性能均有明显的影响.最后,探讨了稀土催化剂脱硫机理,并分析在有O2条件下,引起脱硫率下降的原因是反应过程中O2与CO、S发生了竞争性反应.     

A theoretical estimate of O3 and H2O2 dry deposition over the northeast United States

Estimates of short-term, regional-scale spatial distributions of ozone (O₃) and hydrogen peroxide (H₂O₂) dry deposition over the northeast U.S. are presented. Dry deposition fluxes to surfaces are computed using a regional tropospheric chemistry model with deposition velocities which vary with local meteorology, land type, insolation, seasonal factors and surface wetness. A compilation of O₃ surface resistances is presented based on a survey of O₃ dry deposition measurements. The surface resistance for H₂O₂ is assumed to be small under most conditions, causing H₂O₂ to dry deposit at a rate which is frequently limited by surface-layer turbulence. Regional patterns of dry deposition velocities for these oxidants over the northeast U.S. are computed using landuse data and meteorological information predicted using a mesoscale meteorology model. Domain-averaged O₃ deposition velocities during a spring period reach a mid-day peak of 0.7–0.8 cm s⁻¹ and drop to 0.1–0.2 cm s⁻¹ at night. Domain-averaged H₂O₂ deposition velocities at a height of approximately 80 m are predicted to reach a mid-day peak of 1.6–2.0cm s⁻¹, and fall to 0.6–0.9 cm s⁻¹ at night. Time-averaged surface-layer H₂O₂ concentrations show a latitude dependence, with higher concentrations in the south. H₂O₂ concentrations are significantly reduced due to efficient wet removal and chemical destruction during the passage of a cyclonic frontal system. In contrast, O₃ concentrations are predicted to rise during the passage of a frontal system due to efficient vertical exchange of midtropospheric air into the boundary layer during convective conditions, followed by synoptic-scale subsidence occurring in the high pressure airmass following a cyclone. Maximum O₃ deposition during this 3-day springtime period occurs in polluted agricultural areas. In contrast, H₂O₂ dry deposition exhibits a latitude dependence with maximum 3-day accumulations occurring in the south. Domain-averaged mid-day deposition rates for O₃ and H₂O₂ were 45–50 μmol m⁻² h⁻¹ and 4–5 μmol m⁻² h⁻¹. At night, deposition rates were approximately 5–10 μmol m⁻² h⁻¹ and 1.5–2.5 μmol m⁻² h⁻¹ for O₃ and H₂O₂. These model results show that regional patterns of oxidant dry deposition are strongly influenced by oxidant concentrations, atmospheric stability, surface roughness and numerous other surface and meteorological factors. Each of these factors must be well-characterized before regional patterns of biological damage associated with oxidant dry deposition can be quantified.