微气泡催化臭氧化酸性大红3R的性能及机理

以活性炭为催化剂,采用微气泡催化臭氧化处理酸性大红3R,考察其处理性能和机理,并与微气泡以及传统气泡臭氧化处理性能进行了比较。结果表明：微气泡催化臭氧化可加速液相臭氧分解,其分解系数为0.093 min⁻¹;同时氧化能力明显增强,其脱色速率和TOC去除速率常数分别为0.342 min⁻¹和0.024 2 min⁻¹,均显著高于微气泡和传统气泡臭氧化。微气泡催化臭氧化处理中,臭氧微气泡收缩破裂和活性炭催化的协同效应可强化·OH氧化反应,其对TOC去除的贡献率可达到75%。·OH捕获剂的存在使得微气泡催化臭氧化TOC去除率下降,其中Na₂CO₃的抑制作用最为显著。微气泡催化臭氧化中,臭氧利用效率和反应效率亦得到强化,平均臭氧利用率为98.3%,累积TOC去除量和臭氧消耗量比值R可达0.128 mg·mg⁻¹。GC-MS分析结果表明,微气泡催化臭氧化酸性大红3R降解途径包括偶氮键断裂、萘环/苯环开环、小分子有机酸矿化等过程。     

水介质中微气泡臭氧化处理高浓度甲苯气体

高浓度挥发性有机物(VOC)气体高效处理技术是大气污染控制领域关注的重点。采用微气泡臭氧化在水介质中通过吸收-氧化过程对高浓度甲苯气体进行处理,考察微气泡臭氧化强化甲苯吸收-氧化去除性能、机理以及水介质pH对该工艺处理效果的影响。结果表明,微气泡能够强化甲苯气体在水介质中的吸收过程,氮气/甲苯微气泡在水介质中的甲苯去除率和吸收量均显著高于氮气/甲苯传统气泡,同时氮气/甲苯微气泡通过产生·OH氧化反应,使得平均甲苯氧化矿化率达到40.97%。微气泡臭氧化在水介质中对甲苯气体具有更高效的去除性能,臭氧/甲苯微气泡处理中甲苯平均去除率为97.08%,甲苯可被完全矿化而几乎无中间产物积累,其平均氧化矿化率为88.56%、平均臭氧利用率为82.54%、臭氧投加量与甲苯矿化量比值为1.26,处理性能显著优于臭氧/甲苯传统气泡处理。水介质pH对臭氧/甲苯微气泡处理甲苯气体具有一定影响,不同pH条件下甲苯气体去除率基本相当,但中性条件下甲苯氧化矿化率最高;碱性和酸性条件下甲苯氧化矿化率有所下降。微气泡臭氧化为高浓度VOC气体高效处理提供了新的解决途径。     

硝酸氧化和负载铁氧化物改性活性炭催化臭氧化性能

采用硝酸氧化与硝酸铁负载对颗粒活性炭进行改性处理,研究了活性炭样品表面官能团的变化,分析了活性炭样品对酸性大红3R吸附和催化臭氧化能力,探讨了p H值与·OH捕获剂对催化臭氧化效果的影响。结果表明,硝酸改性后活性炭表面羧基、内酯基、酚羟基以及总官能团的含量均明显增加,其中羧基增幅最大;负载铁氧化物后,活性炭表面官能团数量有所降低。活性炭样品化学吸附性能随官能团含量的增加而增强。催化臭氧化对酸性大红3R的氧化降解效果明显优于单独臭氧化。增加表面官能团含量可以加速催化臭氧化反应,但反应速率随着表面官能团消耗而降低;负载金属组分具有更为稳定和有效的催化臭氧化活性。活性炭催化臭氧化性能在碱性条件下明显优于酸性条件,且随着p H值升高而提高。投加·OH捕获剂(Na2CO3)后,其对·OH的消耗使得催化臭氧化效果显著下降。     

微气泡臭氧化强化吸收-氧化处理高浓度乙酸乙酯气体

采用微气泡臭氧化处理模拟高浓度乙酸乙酯气体,考察了强化吸收与氧化去除体系的性能、反应动力学及氧化反应的过程。结果表明,微气泡臭氧化能明显提高易溶性乙酸乙酯气体吸收-氧化处理的效率,乙酸乙酯气体整体平均去除率高于96%,氧化矿化率可达到90.22%,高于普通气泡臭氧化过程的63.25%和47.15%。微气泡臭氧化可提高臭氧利用效率,累积臭氧利用率可达到85.5%,高于普通气泡中的58.6%;同时,还可强化·OH氧化反应,提高臭氧化反应效率,反应中臭氧消耗量与乙酸乙酯TOC去除量比值(R)仅为1.04 mg∙mg⁻¹,明显低于普通气泡臭氧化过程的1.53 mg∙mg⁻¹。微气泡臭氧化处理中,乙酸乙酯传质吸收和氧化矿化反应均符合表观零级动力学方程,氧化矿化速率与传质速率基本平衡。以上结果表明,微气泡臭氧化处理可实现长期稳定高效处理乙酸乙酯气体。     

臭氧微气泡曝气生物膜反应器深度处理校园污水运行性能

采用臭氧微气泡曝气生物膜反应器(MOABR)对实际校园污水二级生化处理出水进行深度处理,考察了臭氧投加量对MOABR运行性能和生物膜活性的影响,并与传统曝气生物滤池(BAF)深度处理工艺进行比较。结果表明,MOABR工艺中,臭氧微气泡曝气处理效果优于空气微气泡曝气,臭氧投加量对MOABR运行性能有明显影响。在臭氧投加量与进水COD比值(O/C)为0.007 1时,MOABR运行性能最优,COD去除率及去除负荷分别为61.7%、2.25kg/(m~3·d),氨氮去除率及去除负荷分别为17.4%、0.32kg/(m~3·d),臭氧投加量过高对生物膜活性有抑制作用。MOABR处理能力显著高于BAF,在最优臭氧投加量条件下(O/C为0.007 1),MOABR平均COD去除负荷为BAF的2.5倍,平均氨氮去除负荷为BAF的1.7倍。MOABR中微气泡臭氧氧化的作用为改善废水可生化性,COD的去除仍主要依靠生物降解实现。     

臭氧微气泡深度处理染料废水生化出水

采用臭氧氧化法对某厂染料废水生化出水进行深度处理,考察了废水初始pH值和臭氧气泡大小对废水处理效果的影响,研究了臭氧微气泡对气液传质的影响。结果表明,在pH 2.5~11范围内,废水初始pH值越大,处理效果越好;加载微孔膜片后,臭氧气泡粒径变小,增大了臭氧的传质比表面积,延长了臭氧气泡在反应柱内的停留时间,强化了传质效果,处理废水的臭氧利用率可增大10%~30%,强化了臭氧氧化作用。加载5 μm孔径的膜片相比无膜片的情况,COD去除率提高了近30%,TOC去除率提高了16%。     

低分子有机酸对染料废水电催化氧化的影响

研究了二维模式下,形稳性阳极(dimension stable anode,DSA)作为电极材料处理以不同比例混合的酸性大红3R(Acid Red 3R,3R)与草酸(oxalic acid,OA)模拟废水。通过COD、TOC的测定和紫外-可见光谱分析等手段及电化学性能测试可以得出,草酸在电催化降解时所需要的电流密度为10 m A/cm2,明显低于3R电解时所需的电流密度25 m A/cm2。在电催化降解混合模拟染料废水时,电解可以有效破坏发色基团,易降解的有机组分OA优先被氧化,同时会提高难降解有机组分3R的去除效率。此外,废水的p H的不同能导致电催化机理的差异。在p H较低时,阴极的析氢反应占主导地位,使p H升高,而p H较高时,阳极的析氯反应产生Cl2,其水解产生H3O+,同时有机组分被氧化成有机酸,使p H降低。     

微气泡催化臭氧化深度处理制药废水的效果及DOM组分特性的变化

采用镁铝层状双氢氧化物(MAL)微气泡催化臭氧化(MAL/MB/O₃)体系深度处理实际制药废水,考察了该体系对溶解性有机物(DOM)的深度去除性能及DOM组分的变化特性,并与普通气泡臭氧化(CB/O₃)、普通气泡催化臭氧化(MAL/CB/O₃)、微气泡臭氧化(MB/O₃)工艺进行了比较。结果表明,MAL/MB/O₃处理性能优于CB/O₃、MAL/CB/O₃和MB/O₃,在臭氧投加总量与处理废水初始COD值之比为0.6、气流量0.5 L·min⁻¹、催化剂投加量0.5 mg·L⁻¹的条件下,整体COD去除率可达49.79%,COD去除量与臭氧消耗量的比值为0.83,废水的可生化性得到了一定改善,生物毒性显著下降。废水DOM中疏水性组分氧化去除率高于亲水性组分。臭氧直接氧化可去除疏水性组分,而亲水性组分去除主要依赖HO·氧化。MAL/MB/O₃对DOM的去除效率最高,可达到52.51%,其中疏水性组分整体去除率56.67%,亲水性组分整体去除率46.93%。废水DOM在氧化处理中存在官能团向酸性基团转化、类腐殖质向类富里酸和类胡敏酸转化、其他组分向亲水性酸(HIA)组分转化的趋势。MAL/MB/O₃强氧化能力对于DOM组分不饱和结构和荧光结构的破坏作用最为显著。以上研究结果可为制药废水深度处理提供参考。     

钛基二氧化铅电极对酸性红G的电催化降解

采用二氧化铅电极对酸性红G溶液进行电催化降解,主要研究酸性红G的紫外-可见谱变化及其可能降解机制,考察不同因素对降解效果的影响。结果表明,酸性红G在电极表面是以间接氧化机制被羟基自由基氧化。电解过程中,偶氮键断键速率显著高于苯环及萘环,酸性红G去除率显著高于TOC去除率。电解时间延长有利于有机物去除,但会提高能耗值,且单位TOC去除能耗远高于单位酸性红G去除能耗。电流密度提高会促进酸性红G降解与TOC去除,却使单位能耗显著增加,且高电流密度会导致矿化电流效率下降。染料浓度增加使得酸性红G与TOC去除效率降低,但单位能耗随之降低,表明高有机物浓度有利于降低单位能耗值。温度升高有利于有机物降解去除。     

臭氧气泡大小对分散染料废水氧化处理效果的影响

采用臭氧氧化法处理实际分散染料废水,研究了初始pH、臭氧投加量、反应时间、臭氧气泡大小(气体洗瓶和自制的砂芯鼓泡反应柱分别作反应器)对处理效果的影响,采用动态显微高速摄影仪对反应器内的臭氧气泡进行了表征.结果表明,反应体系的初始pH、臭氧投加量越高,反应速率越快,染料废水的脱色及矿化效果越好;染料废水的臭氧氧化处理过程符合拟二级动力学方程;自制的砂芯鼓泡反应柱改善了臭氧分散效果,缩小了气泡直径,提高了臭氧传质速率和效率,强化了臭氧氧化能力.     

Optimization of Height of Release of Air Pollutants

A number of key projects in the Environmental Protection Agency (EPA) particulate R&;D program having applicability to industry are presented. For electrostatic precipitators (ESP) there is presented the result of work on large diameter discharge electrodes which provide a decrease in penetration of up to a factor of 4 when compared to conventional small diameter electrodes. Also discussed is the multistage ESP which provides a collection efficiency that would require a collecting plate area 4 or 5 times larger with conventional ESP technology. The E-SOX technology makes use of the multistage concept to free up space in the ESP for SO₂ removals of up to 90%. Electrostatically augmented fabric filtration provides a reduction in pressure drop of about 5 0% as compared to conventional fabric filtration. Wind tunnel modeling of windbreaks for material storage piles indicates a potential for providing engineering design data that would allow significant emission reduction caused by wind erosion     

Investigation of the characteristics of the reflectivity of clouds

This paper investigates some of the reflectivity characteristics that clouds (when modelled as solid bodies) must exhibit to be compatible with observations that the reflecting surface of a cloud (i) appears almost equally bright across its face, (ii) is brightest when the cloud is opposite to the Sun but decreases in brightness as the cloud moves to other positions and (iii) increases in brightness with increasing optical thickness of the cloud in the observer's line of sight. These observations, respectively, are shown to imply that the peak value of the bidirectional total reflectivity from a cloud surface (i) increases in inverse proportion to the cosine of the angle between the Sun and the normal to the cloud surface, as the incident angle increases, (ii) appears to be directed back in the direction of the incident radiation, and (iii) increases as optical thickness of the cloud in the observer's line of sight increases. The results could have application in many fields (e.g. modelling diffuse radiance distributions for cloudy skies).     

实验室质量管理体系内部审核的实施

在实施ISO／IEC17025：1999标准《检测和校准实验室能力的通用要求》过程中，通过实验室质量管理体系内部审核的实践与系统分析，识别出内部审核实施阶段的关键环节，提出召开首次会议、收集审核证据、确定审核发现和召开末次会议的技术方法，对提高内部审核的质量和有效性、获得可靠的审核结论具有重要意义。     

Estimation of uncertainty of sampling for analysis of pesticide residues

Abstract

A computer model was used to take random samples from primary sample populations obtained from field trials to simulate the uncertainty of sampling for residue analysis of plant commodities and soil. The results indicate about 40%, 30% and 20% relative uncertainty when random samples of size 5, 10 and 25 are taken respectively, from a single lot. Therefore the sample size should be the same for establishing and enforcing legal limits.     

扬中生态环境建设的思考与实践

结合扬中生态环境的基本情况和存在的不足，进行了具体分析，对扬中未来生态建设的发展方向提出了建议及实施措施。     

An application of the theory of kinematics of mixing to the study of tropospheric dispersion

The most common technique used for numerical simulations of tracer mixing is that of the numerical solution of the advection–diffusion equation with the unresolved fluxes parameterized using the similarity theory. Despite correct predictions of the overall directions of transport, models based on a numerical solution of the advection–diffusion equation lack sufficient accuracy to correctly reproduce the coupling of mixing with small scale processes which are sensitive to the microstructure of the tracer distribution. The objective of this paper is to revisit the basic formalism employed in numerical models used to investigate atmospheric tracers. The main mathematical method proposed here is the theory of kinematics of mixing which could be applied effectively for simulations of atmospheric transport processes. At the beginning of the paper, we introduce simple mathematical transformations in order to demonstrate how complex topological structures are created by mixing processes. These idealistic flow systems are essential to explain transport properties of much more complex three-dimensional geophysical flows. An example of the application of the kinematics of mixing to the analysis of tracer transport on a planetary scale is presented in the following sections. The complex filamentary structures simulated in the numerical experiment are evaluated using some commonly applied statistical measures in order to compare the results with the data published in the literature. The results of the experiment are also analysed with the help of simple conceptual models of fluid filaments. The microstructure of the tracer distribution introduced in the paper is essential to increase our understanding of atmospheric transport and to develop more realistic parameterizations of small-scale mixing. The presented results could also be used to improve calculations of the coupling between microphysical processes and tracer mixing.     

次氯酸钠发生器的研制

介绍了电解法生产次氯酸钠的原理 ,并在原有生产工艺的基础上进行了重新设计和对设备的重新选择、改造 ,得出了各个工艺参数的最佳值 ,生产出高品质的次氯酸钠     

Comparison of methods for evaluation of activity of photocatalytic films

Objective

This work aims to investigate the correlation between the photocatalytic activity determined by methylene blue bleaching (DIN 52980), stearic acid degradation, and degradation of acetone in gas phase.

Method

The photocatalytic TiO₂ coatings included in this investigation ranged from thin commercially available coatings (Activ^TM and BioClean^TM) and ready to use suspensions (Nano-X PK1245) to lab-produced PVD and sol?Cgel coatings. XRD analysis of the photocatalytic coatings showed that all the coatings consisted of nanocrystalline anatase, although the thickness and porosity varied considerably.

Results

The study showed that the reproducibility of the activity measurements was good. However, more importantly, the investigation showed that there is a good correlation between the activities determined by the different methods even though the characteristics of the photocatalytic coatings and the organic probe molecules varied considerably.

Conclusion

The overall findings of this work suggest that there is a good correlation between the investigated methods. These results are promising for the future work concerning standardization of methods for determination of the activity of photocatalytic films.     

Impact of overexploitation of shellfish: northeastern coast of India

India has a very extensive coastline of about 7515 km, rich in diverse living resources. These resources continue to deteriorate with rampant harvesting or are altered for other uses such as aquaculture and fisheries. The present paper deals with degrading coastal habitats in northeastern India, and projects the intensity of the stress arising from the collection of tiger prawn seeds (Penaeus monodon) for aquacultural farms and molluskan shells for poultry feed and edible lime. Indiscriminate exploitation of these resources leads to a heavy reduction of the species concerned and other associated marine communities. The magnitude of such destruction has been quantified. The impacts of biodiversity loss and their after-effects on the ecobalance of this coastal system have become a matter of great concern to ecologists to maintain security and sustainability. The authors propose a public awareness program on themes relating to the importance of biodiversity for human livelihoods.