利用螺旋切割强化臭氧氧化降解苯酚废水的研究

针对臭氧在水中不易溶解的现象,采用自制静态螺旋切割装置强化臭氧氧化苯酚废水,考察了臭氧进气流量、液体流量以及初始pH对苯酚降解率的影响,并对比了不同气液混合方式下臭氧传质效果及苯酚降解率。结果表明,静态螺旋切割装置可以强化臭氧在水中的传质,9min后液相臭氧质量浓度可达12mg/L左右,远高于常规曝气及循环气液混合方式下的液相臭氧浓度。在臭氧进气流量为2.0L/min、液体流量6L/min、初始pH为7时,反应12min,螺旋切割强化臭氧氧化的苯酚降解率可达97.09%,比常规曝气和循环气液混合下的苯酚降解率分别提升64.21百分点和35.53百分点。     

磁场强化臭氧液相传质

对不同种气液接触方式的臭氧气液传质性能进行了研究,考察了磁场作用下的臭氧进气量,液面高度以及液相p H值对微气泡臭氧传质效果的影响规律。实验研究表明,相同实验条件下,采用微气泡附加磁场(磁铁相吸)比底部曝气盘和微气泡发生器接触方式,液相中溶解的臭氧浓度分别提高了72.6%和11.4%,经过30 min后,水中溶解的臭氧浓度为8.91 mg/L,传质系数为0.2272 min-1,传质系数显著提高;在磁场的作用下的微气泡臭氧接触方式,臭氧气体流量较小的情况下,臭氧在液相溶解效率较高,液面高度h越高溶解的臭氧浓度越低,传质系数kLa值随着气液流量的增加而增加,但是随着液面高度h的增加而降低,液相的p H值也影响着传质效果,p H越低,水中溶解的臭氧浓度越高,传质系数越高。     

柴油机微粒捕集器臭氧再生法离线再生

由R175型柴油机、微粒捕集器(Φ90 mm×150 mm)、CF-G10型臭氧发生器组成实验系统,进行了臭氧再生法离线再生研究。研究表明,在190℃温度下,再生气从DPF上游侧进气再生时,臭氧可以有效再生DPF,再生效率可达90%以上,再生效率达到65%左右时发生臭氧穿透,臭氧利用率下降;穿透时间点随微粒捕集时的柴油机载荷增大而提前,随微粒捕集时间增加而提前;臭氧供给量不变,再生气流量越大,再生效果越明显;再生气从DPF下游侧进气再生时,臭氧穿透时间点较上游侧进气再生滞后,但发生穿透后DPF几乎不再再生,总再生效率低于70%。结果表明,微粒捕集器臭氧再生法是可行的,对于如何提高臭氧利用率需进一步研究。     

中空纤维膜吸收甲苯气体

采用疏水性聚偏氟乙烯(PDVF)中空纤维膜为气液接触膜,n-甲酰吗啉(NFM)水溶液为吸收剂,研究了膜吸收技术分离甲苯/空气混合气的性能。考察了进气气体浓度、气体停留时间、吸收液体积分数和吸收液流量等诸因素对分离性能的影响。研究结果表明,膜吸收技术可以有效地分离甲苯/空气混合气,甲苯去除率可达90%;提高NFM吸收液的浓度和流量可同时增加甲苯的去除效率η和总传质系数K;气体停留时间的减小导致η降低,K反而增大;进气甲苯浓度的增加导致η下降,同时降低总传质系数K。     

膜吸收法脱除恶臭气体H_2S

选用聚丙烯中空纤维膜接触器为吸收器,Na OH水溶液为吸收剂,考察膜吸收法对H_2S的脱除效果。结果表明:正流程、逆流方式的脱硫效果优于反流程、并流;随着液体流量和液体浓度的增加,H_2S脱除率和总传质系数随之增大,但随气体流量的增加,H_2S脱除率减小,总传质系数增大;正交实验得出吸收剂浓度0.2 mol·L~(-1)、进气流量1 L·min-1、液体流量2.2 L·min-1为较优的膜吸收参数,此条件下H_2S脱除率可达99.94%,且各因子对H_2S脱除率的影响次序为:进气流量液体流量吸收剂浓度。     

膜吸收法净化低浓度甲醛和氨气

基于膜吸收技术自制双层平板式膜吸收器,搭建净化低浓度甲醛和氨气污染模拟系统,考察不同膜结构参数、进气流量、吸收剂流量等因素对其净化效果的影响。结果表明,聚偏氟乙烯PVDF对低浓度甲醛和氨气的净化效率高于聚四氟乙烯PTFE。对同一材质膜,随着膜孔隙率的增大,甲醛和氨气的净化率呈上升趋势。随着进气流量的增加。甲醛和氨气的净化效率降低;而吸收剂流量对其净化效率影响不大。对于所有实验条件,平均膜孔径为0．22μm的PVDF4#在进气流量ug=120L／h时,甲醛和氨气的净化效率最高,分别达94．7％和96．3％。     

膜吸收法净化低浓度甲醛和氨气简

基于膜吸收技术自制双层平板式膜吸收器,搭建净化低浓度甲醛和氨气污染模拟系统,考察不同膜结构参数、进气流量、吸收剂流量等因素对其净化效果的影响。结果表明,聚偏氟乙烯PVDF对低浓度甲醛和氨气的净化效率高于聚四氟乙烯PTFE。对同一材质膜,随着膜孔隙率的增大,甲醛和氨气的净化率呈上升趋势。随着进气流量的增加,甲醛和氨气的净化效率降低;而吸收剂流量对其净化效率影响不大。对于所有实验条件,平均膜孔径为0.22 μm的PVDF 4^#在进气流量u_g=120 L/h时,甲醛和氨气的净化效率最高,分别达94.7%和96.3%。     

双循环多级水幕吸收塔烟气除尘脱硫性能研究

以改进后的双循环多级水幕塔对烟气进行除尘脱硫性能的研究,利用双循环不同pH值控制的优点和多级水幕的效果,增加气液接触面积和传质动力,提高SO₂吸收效果。在正交实验的最佳运行工况基础上,实验从烟气流量、上下两段pH、L/G和SO₂进气浓度等方面进行单因素研究。结果表明,除尘效率维持在98%以上,进气SO₂浓度在5 000 mg/m³以下时,脱硫率在93%以上。上段pH值为6、下段pH值为5、L/G在15左右的脱硫效率和运行工况最佳,无结垢现象发生。改进后的吸收塔具有良好的应用前景,实验结果对于现场脱硫设备的调试和运行有很好的参考价值。     

基于电催化疏水膜的新型膜接触臭氧氧化工艺

膜接触臭氧氧化(MCO)工艺以疏水膜为臭氧提供丰富的气液接触界面,具有较高臭氧传质效率。然而,MCO工艺以臭氧直接氧化为主,对废水中有机污染物的去除有较强的选择性,氧化能力有待提高。通过电催化疏水膜将MCO工艺与电化学技术相结合,构建了新型的膜接触电催化臭氧氧化(ECMCO)工艺。ECMCO工艺以高级氧化过程为主,对水中硝基苯的去除效率明显增强,同步提高了臭氧传质效率和体系的氧化能力。ECMCO工艺对酒厂废水的生化出水进行深度处理后,水中COD降至50 mg·L-1以下,色度完全脱除,总运行能耗明显低于MCO和MCO+H2O2工艺。针对臭氧工艺在水处理应用中传质效率低、矿化能力差、运行能耗高的问题,ECMCO技术提供了可行的解决方案,有较好的研究价值和应用前景。     

填料塔中Na_2CO_3吸收高浓度H_2S的传质特性

在填料吸收塔中考察了Na2CO3溶液吸收高浓度H2S气体的气液传质特性。通过测量填料塔进出口气体中H2S浓度计算了Na2CO3溶液吸收高浓度H2S气体的总体积传质系数(KGa),并研究了进气流速、吸收液流量、吸收温度和吸收液浓度对KGa的影响。结果表明,KGa随Na2CO3浓度、吸收液流量的增加而增加,随吸收温度、进气流速的升高而降低;在高浓度H2S吸收过程中液相传质阻力不能忽略。     

制取高浓度臭氧水的实验研究

采用介质阻挡强电离放电技术制取高浓度臭氧 ,使用射流器和气液溶解分离器溶解臭氧制取高浓度臭氧水。讨论了应用臭氧量、气液比、系统压力和气液溶解方式对臭氧水浓度和臭氧有效溶解效率的影响     

A comparison of measured and modeled ozone uptake into plant leaves

Ozone uptake into plant leaves was measured in gas exchange chambers using a mass balance and a variable conductance approach. The variable conductance approach was found to more reliably measure ozone flux through stomata. Measurements using this approach were contrasted with estimates obtained by measuring stomatal conductance g(sw) and modeling ozone uptake using a diffusion equation, assuming a negligible ozone concentration in the substomatal cavity. Actual measurements of uptake were close, but slightly higher than modeled values, providing some support to the idea that substomatal ozone concentrations are close to zero. However, the difference between measured and modeled uptake values suggests either that (i) variable conductance approach measures more ozone uptake than caused by stomatal uptake alone or (ii) ozone conductance is underestimated.     

Enhanced ozonation of simulated dyestuff wastewater by microbubbles

The ozonation of synthetic wastewater containing azo dye, CI Reactive Black 5, was investigated using a microbubble generator and a conventional bubble contactor. The microbubble generator produced a milky and high intensity microbubble solution in which the bubbles had a mean diameter of less than 58 microm and a numerical density of more than 2.9 x 10(4) counts ml(-1) at a gas flow rate of less than 0.5 l min(-1). Compared with the bubble contactor, the total mass transfer coefficient was 1.8 times higher and the pseudo-first order rate constant was 3.2-3.6 times higher at the same initial dye concentration of 100 mg l(-1), 230 mg l(-1) and 530 mg l(-1) in the proposed microbubble system. The amount of total organic carbon removed per g of ozone consumed was about 1.3 times higher in the microbubble system than in the bubble contactor. The test using terephthalic acid as the chemical probe implied that more hydroxyl radicals were produced in the microbubble system, which contributed to the degradation of the dye molecules. The results suggested that in addition to the enhancement of mass transfer, microbubbles, which had higher inner pressure, could accelerate the formation of hydroxyl radicals and hence improve the oxidation of dye molecules.     

Ozone uptake to the polar snowpack at Summit,Greenland

The uptake of atmospheric ozone to the polar, year-round snowpack on glacial ice was studied at Summit, Greenland during three experiments in 2003, 2004, and 2005. Ozone was measured at up to three depths in the snowpack, on the surface, and above the surface at three heights on a tower along with supporting meteorological parameters. Ozone in interstitial air decreased with depth, albeit ozone gradients showed a high variation depending on environmental conditions of solar radiation and wind speed. Under low irradiance levels, up to 90% of ozone was preserved up to 1 m depth in the snowpack. Ozone depletion rates increased significantly with the seasonal and diurnal cycle of solar irradiance, resulting in only 10% of ozone remaining in the snowpack following solar noon during summertime. Faster snowpack air exchange from wind pumping resulted in smaller above-surface-to-within snowpack ozone gradients. These data indicate that the uptake of ozone to polar snowpack is strongly dependent on solar irradiance and wind pumping. Ozone deposition fluxes to the polar snowpack are consequently expected to follow incoming solar radiation levels and to exhibit diurnal and seasonal cycles. The Summit observations are in stark contrast to recent findings in the seasonal, midlatitude snowpack [Bocquet, F., Helmig, D., Oltmans, S.J., 2007. Ozone in the mid-latitude snowpack at Niwot Ridge, Colorado. Arctic, Antarctic and Alpine Research, in press], where mostly light-independent ozone behavior was observed. These contrasting results imply different ozone chemistry and snowpack–atmosphere gas exchange in the snow-covered polar, glacial conditions compared to the temperate, mid-latitude environment.     

Evaluation of the treatment efficiencies of paper mill whitewaters in terms of organic composition and toxicity

The efficiency of several lab scale treatments (aerobic, anaerobic and ozone or combination of these) was evaluated using two packaging board mill whitewaters. The effect of the different treatments on the elimination of the organic load, the chemical oxygen demand (COD) and the toxicity was tested as well as the relationship between these parameters. Biocides, phenolic compounds, surfactants, plasticiziers and wood extractives were identified in untreated and treated whitewaters by liquid chromatography coupled with mass spectrometry (LC-MS) or gas chromatography coupled with mass spectrometry (GC-MS). A strong dependency on the water type and treatment efficiency was observed, being the combination of anaerobic and aerobic treatments the best option to reduce the organic contaminants in these waters, although in some cases, the toxicity did not decrease. However, ozone as post-treatment permitted a further reduction of organic compounds, toxicity and COD.     

臭氧氧化苯乙烯有机气体性能及机制

采用臭氧高级氧化处理高浓度苯乙烯有机废气,研究了进气苯乙烯浓度、臭氧浓度、停留时间、O₃/C₈H₈摩尔比对苯乙烯去除效率的影响。研究结果表明,臭氧氧化能有效净化苯乙烯有机废气,苯乙烯去除效率可达66.6%。适宜运行条件为：停留时间为3.6 s,O₃/C₈H₈摩尔比为0.46。采用GC-MS分析臭氧氧化苯乙烯出口气样,研究结果表明,苯甲醛（C₆H₅CHO）和苯甲酸（C₆H₅COOH）为臭氧氧化苯乙烯的中间产物。臭氧高级氧化苯乙烯机制为苯乙烯气体被臭氧氧化为苯甲醛和苯甲酸,然后继续臭氧氧化为最终产物二氧化碳和水。     

Effects of various ozone exposures on the susceptibility of bean leaves (Phaseolus vulgaris L.) to Botrytis cinerea

The effects of various ozone exposures in predisposing bean leaves (Phaseolus vulgaris L.) to Botrytis cinerea have been investigated under laboratory conditions. Seedlings of two bean cultivars were exposed to incremental ozone concentrations (120, 180 and 270 microg m(-3) for 8-h day(-1)) for five days and primary leaves were subsequently inoculated with conidia suspended in water or in an inorganic phosphate solution (Pi), and with mycelium. Ozone injury increased with increasing ozone concentration and was much higher in the ozone-sensitive cultivar 'Pros' than in the ozone-insensitive 'Groffy'. Ozone only increased the number of lesions on leaves of Pros after inoculation with either of the conidial suspensions. The Pi-stimulated infection in Groffy was reduced by the lower ozone concentrations. Ozone decreased lesion expansion after inoculation with mycelium. In a chronic fumigation experiment, plants of the two cultivars were exposed to 90 microg m(-3) (7-h day(-1)) and the primary and the oldest tree trifoliate leaves were inoculated after five and seven weeks of exposure. Ozone enhanced the senescence-related injury only in Pros. The number of lesions was not influenced by ozone for either cultivar, conidial suspension or inoculation date. Lesion expansion after inoculation with mycelium was generally reduced in exposed plants. Thus, contrasting effects of ozone on the susceptibility of bean leaves to B. cinerea were observed depending on the cultivar, the conidial suspension, the disease parameter and the ozone exposure pattern. In extrapolating the laboratory results to the field, it is suggested that episodic and chronic exposures to ambient ozone are of minor importance in increasing the susceptibility of bean leaves to B. cinerea.     

The Effect of Water Vapor on Ozone Synthesis in the Photo-oxidation of Alpha-pinene

A study of the effect of water vapor on the photochemical system NO₂ + alphapinene + hv was conducted. A Hotpack Environmental Room was used as a constant temperature chamber, a bank of ultraviolet and fluorescent lamps as a source of simulated solar radiation, and a 150-liter FEP Teflon bag as a reaction vessel. Representative concentrations of 10 pphm NO₂ and 50 pphm alphapinene were used in a 3 × 2 × 2 factorial design where absolute humidities of 0.0000, 0.0090, 0.01 80 g H₂O/g dry air were varied.

Matheson zero air was passed through a clean air train and used as the diluent. Nitrogen dioxide was added to the reaction mixture by a permeation tube, and water and alpha-pinene by evaporation techniques.

Variables measured as a function of time over a 2-hour irradiation period were total oxidants (Mast Ozone Meter), condensation nuclei (General Electric Small Particle Detector), ozone (Regener Chemiluminescent Ozone Meter), nitrogen dioxide and nitric oxide (Technicon Autoanalyzer), and alpha-pinene (Perkin- Elmer Model 800 gas chromatograph).

Upon irradiation, systems containing nitrogen dioxide and alpha-pinene formed oxidants, ozone, condensation nuclei, and nitric oxide. Based on the differences between simultaneous oxidant and ozone measurements, the formation of peroxide- like compounds may be inferred. During the course of the irradiation, nitrogen dioxide and alpha-pinene were consumed. The concentration-time profiles of all variables were characteristic of those exhibited by typical photochemical smog systems.

An effect of water vapor on the systems studied was demonstrated. Increasing humidity decreased net mean/time oxidant and ozone production and net maximum condensation nuclei production. These effects were significant at a 0.05 confidence level. Effects of water on average mean/time NO₂, NO, and alphapinene concentrations were insignificant at this level. The oxidant to ozone ratio was found to decrease with increasing humidity.

The significant decreases in net oxidant and ozone production and NO₂ consumption with increasing water vapor concentration in systems of nitrogen dioxide alone, suggests that water manifests an effect on pertinent inorganic reactions, and the data also suggest additional water participation in the organic reactions.     

微气泡曝气中氧传质特性研究

气泡曝气过程中氧传质对于好氧生物处理过程具有重要意义。采用水力旋转剪切微气泡发生装置,考察了运行条件和水质特性对微气泡曝气中氧传质特性的影响。结果表明,微气泡曝气可获得较高的气含率和气泡停留时间;表面活性剂十二烷基磺酸钠(SDS)可以提高微气泡曝气的气含率和气泡停留时间。微气泡曝气中氧的总体积传质系数明显高于传统气泡曝气。总体积传质系数随着空气流量的增加而增加;氧传质效率随着空气流量的增加而减小,且对空气流量的变化更为敏感。在温度15~35℃范围内,微气泡曝气中氧的总体积传质系数随着温度的增加而增加,变化关系与传统气泡曝气基本相同,但对温度的变化更为敏感。微气泡曝气中,表面活性剂SDS会使氧的总体积传质系数略有降低,其不利影响明显小于传统气泡曝气;氧的总体积传质系数随盐度(NaC l浓度)增加而逐渐增加,并在NaC l浓度5 000 mg/L后趋于稳定。     

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.