室内空气污染净化

1、2005年9月室内污染净化技术1上节课内容室内甲醛来源主要来源于建筑材料、家具、各种粘合剂涂料、合成织品等。A、人造板B、地毯等合成织物C、燃料、烟草的不完全燃烧D、藏书2甲醛的监测方法1、酚试剂比色法原理甲醛与酚试剂反应生成嗪，嗪在酸性条件下被Fe3+氧化形成蓝绿色化合物，比色定量。34甲醛与酚试剂缩合生成嗪，适宜的pH值为3-7，最佳为4-5。酚试剂法检出限为0.1ug/5mL,当采样体积为10L时，最低检出限浓度为0.01mg/m3。5酚试剂（MBTH）比色法仪器1、气泡吸收管10mL；2、空气采样器 流量范围：0-2L/min3、具塞比色管 10mL；4、分光光度计6酚试剂比色法所用试

2、剂1、吸收液2、1%FeNH4(SO4)2溶液3、甲醛标准溶液7甲醛标准溶液标定甲醛在碱性条件下被I2氧化成甲酸，剩余的I2在酸性条件下用Na2S2O3滴定，从而计算甲醛的量。反应式：HCHO+I2+H2OHCOOH+2HII2+2 Na2S2O3 Na2S4O6+2HI8标定方法吸取5mL甲醛溶液于250mL碘量瓶中，加入40mL 浓度0.1mol/L碘溶液，立即逐滴加30%NaOH溶液，至颜色褪至淡黄色。放置10min。用5mL（1+5）盐酸溶液酸化（空白滴定时需多加2mL）,9置于暗处放10min，加100-150mL水，用0.1mol/L硫代硫酸钠标准溶液滴定至淡黄色，加1.0mL新配

3、制的5%淀粉指示剂，继续滴定至蓝色刚刚褪去。空白试验用5mL水重复上述步骤。10计算甲醛溶液浓度式中v、v0分别为滴定空白溶液、甲醛溶液所消耗硫代硫酸钠标准溶液体积, mLC 硫代硫酸钠标准溶液浓度，mol/L.11甲醛标准液和样品液的稳定性甲醛直接吸收在纯水中则很不稳定。放置3-4h降低10%；放置24h降低68%；在0.005%酚试剂作吸收液中，放置24h稳定。应选用酚试剂作吸收液12氧化剂的选择氧化剂选用硫酸铁铵，硫酸铁铵水溶液易水解形成Fe(OH)3乳浊现象，影响比色。应用酸性溶剂配制。酸度不宜过大，否则颜色太深，影响比色。应选用0.1mol/L的HCl为溶剂。13注意事项加入硫酸铁铵

4、的量不宜过多，过多时空白管吸光度值偏高，影响比色。加0.4mL1%硫酸铁铵为宜。14采样用一个内装5.0mL吸收液的气泡吸收管，以0.5L/min流量，采气10L。15步骤1、标准曲线绘制取8支10 mL比色管，分别配制标准色列向各管加1%硫酸铁铵溶液0.4mL,摇匀。室温下显色20min。在630nm波长处，用1cm比色皿，以水为参比，测定吸光度。以吸光度对甲醛含量(ug)作图。1617样品测定采样后，将样品溶液移入比色管中，用少量吸收液洗涤吸收管，洗涤液并入吸收管，使总体积为5mL，室温下放置80min，以下步骤同上。18计算甲醛（mg/m3）=W/Vn式中 W样品甲醛含量，ug; Vn标

5、准状态下采样体积，L19注意事项1、绘制标准曲线与样品测定时温差不超过2。2、标定甲醛时，在摇动下逐滴加入NaOH溶液，至颜色明显减褪，再摇片刻，待褪成淡黄色，放置后应褪至无色。3、若碱量加入过多，则加5mL盐酸溶液不足以使溶液酸化。20SO2的干扰当存在SO2时，会使结果偏低。SO2产生的干扰，可以在有样时，使气体先通过装有硫酸锰滤纸的过滤器，即可排除干扰。21硫酸锰滤纸的制法取10mL浓度为100g/L的硫酸锰水溶液，滴加到250cm2玻璃纤维滤纸上，风干后切成2mm5mm的碎片，装入 15mm150mm的U形玻璃管中。22乙酰丙酮分光光度法原理甲醛吸收于水中，在铵盐存在下，与乙酰丙酮作用

6、，生成黄色的3，5-二乙酰基-1，4-二氢卢剔啶根据颜色的深浅，用分光光度法测定。酚甲醛1500倍，乙醛甲醛300倍，不干扰测定。23本方法检出限为0.25ug/5mL，当采样体积为30L时，最低检出浓度为0.008mg/m3.24乙酰丙酮分光光度法仪器1、大型气泡吸收管10mL；2、空气采样器 流量范围：0-2L/min3、具塞比色管 10mL；4、分光光度计25乙酰丙酮分光光度法试剂1、重蒸蒸馏水2、乙酰丙酮溶液：称取25g乙酸铵，加少量水溶解，加3.0mL冰乙酸及0.25mL新蒸馏的乙酰丙酮，混匀，加水稀释至100mL。3、甲醛标准液：取36-38%甲醛10mL，用水稀释至500mL,标

7、定方法同上。临用时，用水稀释至5.0ug/mL26乙酰丙酮分光光度法采样用一个内装5.0mL水及1.0mL乙酰丙酮溶液的气泡吸收管，以0.5L/min的流量，采气30L。27乙酰丙酮分光光度法步骤 标准曲线的绘制。取8支10mL具塞比色管，配制标准系列。各管混和均匀后，在室温下放置2h，使其显色完全。在波长412nm处，用1cm比色皿，以水为参比，测定吸光度。以吸光度对甲醛含量绘制标准曲线。28样品测定采样后，在室温下放置2h，然后将样品溶液移入比色皿中，以水为参比，测定吸光度。29计算甲醛（mg/m3)=W/Vn式中 W样品中甲醛含量，ug Vn标态下的采样体积，L30气相色谱法原理空气中的

8、甲醛在酸性条件下吸附在涂有2，4-二硝基苯肼的6201担体上，生成稳定的甲醛腙。用二硫化炭洗脱后，经OV-1色谱柱分离，用FID（氢火焰离子化检测器）测定，以保留时间定性，峰高定量。31仪器和设备GC 配FID采样管：用长 100mm，内径5mm的玻璃管，内装150mg吸附剂，两端用玻璃棉堵塞，采样管两端套上塑料帽，装在具塞试管中，密封备用。32空气采样器流量范围 0.2-1.0L/min，流量稳定。使用时，用皂膜流量计校准采样系列在采样前和采样后的流量，流量误差应小于5%具塞比色管 5 mL微量注射器 10uL33试剂和材料1、CS2 需重新蒸馏2、2，4-二硝基苯肼溶液称取0.5g 2，4

9、-二硝基苯肼于250mL容量瓶中，用二氯甲烷稀释至刻度。3、吸附剂 称取10g 6201担体（ 60-80 目），用40mL 2，4-二硝基苯肼的二氯甲烷溶液分两次涂敷，减压、干燥34试剂和材料盐酸溶液 2mol/L甲醛标准溶液色谱固定液 OV-1色谱担体 Shimalitew(80-100目)35采样和样品保存采样时，取下采样管两端的塑料密封帽。将采样管的进气口玻璃棉取出，向管内吸附剂上加一滴（约50uL）2mol/L的HCl溶液，然后再用玻璃棉堵好，将加入HCl溶液的一端垂直朝下，另一端连接到空气采样器上。36采样和保存以0.5L/min的流量，采气50L，采气后，将管的两端套上塑料帽，送

10、回实验室分析。记录采样的温度和大气压37GC测试条件色谱柱 柱长2m，内径3mm的玻璃管，内装OV-1+Shimalitew(1.5+100)担体。柱温 230检测室温度 260 汽化室温度 260 载气(N2)流量 70mL/minH2流量 40ml/min 空气流量 450mL/min38样品测定采样后，将采样管内吸附剂全部移入5mL具塞比色管中，加入1.0mL CS2，稍加振摇，浸泡30min。准确称取5.0uL洗脱液，在GC最佳测试条件下按操作步骤进样测定，每个样重复3次。用保留时间确定甲醛的峰，峰高定量。39气体检测管法气体检测管法是应用较广的快速测定方法之一.该方法采用检测管装置测

11、定各种有害物质，装置包括检测管、预处理管、采样管及其他部件。40气体检测管装置检测管是一种填充显色指示粉的玻璃管，管外印有刻度，管内的指示粉用吸附了显色剂的载体制成。41气体检测管装置当被测空气通过气体检测管时，有害物质与指示粉迅速发生化学反应，被测物质浓度的高低，将导致指示粉产生相应的变色长度。根据指示粉颜色变化长度从而对有害物质进行快速的定性和定量分析。42手动采样器使用手动采样器采样时，先拉动手柄，使活塞筒内呈负压状态，气流经过检测管从检测管接口进入活塞筒，采样完毕，推进活塞，气体从活塞的排气孔，通向单向阀，由后盖排出。43手动采样器44甲醛检测管反应原理1、甲醛与盐酸羟胺生成HCl使指

12、示剂变色。 HCHO+NH2OHHClHCl HCl+pH指示剂红色产物颜色变化：黄色桃红色干扰气体：其他醛类、酮类及酸性气体45甲醛检测管反应原理2、甲醛与二甲苯、发烟硫酸反应生成一种缩合物并伴随颜色变化。HCHO+C6H4(CH3)2+H2SO4缩合物颜色变化：白色奶黄色干扰气体：其他醛类、酮类及苯乙烯46甲醛检测管特点1、方法简便，容易掌握。一般的分析方法都需要专门分析人员和仪器，而此法仪器简单，对操作者要求低，一般人都能进行测定。2、测定迅速，检测管可以在几分钟之内测出环境中有害物质浓度。47甲醛检测管特点3、灵敏度高，最高灵敏度可达0.01ppm，能够检出浓度为ppm级的常见污染物质

13、。4、采气量小，一般采样体积在几十mL至几L。48甲醛检测管特点5、应用范围广，检测管能够测定无机和有机的各种状态的物质，可用于工矿企业工作环境中有害气体的测定，也可以检测工厂设备的管道泄漏情况以及大气、室内空气污染的测定等。49甲醛检测管使用方法1、取出甲醛气体检测管，将检测管的两端封口折断，然后再把检测管插在采样器的进气口上（检测管上的进气箭头指向采样器），对准所测气体，转动采样器手柄，使手柄上的红点与采样气后段盖上的红线相对。50甲醛检测管使用方法拉开手柄到所需位置（50mL或100mL，由采样器上的卡锁定位）固定。等2-3min，当检测管变色的前端不再往前移动时，取下检测管，从检测管上

14、即可读出所测气体的浓度。51甲醛检测管使用注意事项1、检测管和采样器连接时，应注意检测管所标明的箭头指示方向。2、作用现场存在有干扰气体时，应使用相应的预处理管，并注意正确的连接方法。3、有使用现场的温度超过规定温度范围时，应用温度校正表对测量值进行校正。52甲醛检测管使用注意事项4、对于双刻度检测管应注意刻度值的正确读法。5、使用检测管应注意检查有效期。6、检测管应与相应的采样器配套使用。7、采样前，应对采样器的气密性进行试验。53甲醛检测管检测范围有0.01-0.48ppm0.1-4ppm两种。54甲醛检测管使用方法2、测量完毕转动手柄使红线与刻线错开，将手柄推回原位。3、当检测管要求的采

15、气量大于100mL时，不用拔下检测管，直接再拉手柄取第二次气。55甲醛污染控制甲醛污染主要要源于室内装修和装饰材料。胶合板、细木工板、中密度纤维板和刨花板56人造板甲醛释放源本板本身释放甲醛胶粘剂中的未参与反应的游离甲醛热压时未完全固化产生的甲醛板材使用过程中结构降解释放的甲醛57降低人造板材甲醛释放胶粘剂的控制：1、降低甲醛/尿素摩尔比2、尿素分批投料（多次缩聚）3、多元改性剂共聚4、使用不含甲醛的胶粘剂5、无胶胶合工艺58降低板材甲醛释放工艺控制1、降低水分2、改进热压条件3、捕捉游离甲醛59降低板材甲醛释放后处理1、氨处理2、尿素处理3、油溱处理4、表面封闭处理60降低室内甲醛污染的其他

16、措施1、室内装修采用低甲醛或不含甲醛的材料，选用符合国家标准、高质量健康环保建材。2、使用人造板的锯口处，应涂上涂料，使其充分固化，形成稳定的保护层，防止甲醛散发。61降低室内甲醛污染的其他措施3、装修后不宜立即入住，应开窗、通风让室内污染空气散发。通常装修后通风数月可使甲醛浓度低于0.08mg/m3，达到室内合格的标准。4、板材中甲醛释放与室内温度、湿度、通风程度及材料的表面积有关，高温、高湿、负压加剧甲醛释放。62降低室内甲醛污染的其他措施5、室内绿化吊兰、芦荟等植物可有效降低室内有害气体浓度。63甲醛的室内标准公共场所卫生标准规定甲醛的最高允许浓度为：0.12mg/m3居室空气卫生标准甲

17、醛的最高允许浓度为：0.08mg/m364室内VOCs污染与净化65OutlineIntroductionWhy is IAQ important?Sources of Indoor Air Pollutants and their health effectDefinition of acceptable Indoor Air QualityThe IAQ ProgrammeIAQ Management and Control66Introduction“Acceptable Indoor air quality”:Air in an occupied space towards which

18、 a substantial majority of occupants express no dissatisfaction, and in which there are not likely to be known contaminants at concentrations leading to exposures that pose a significant health riskSources of information: web site of ASHARE ( )67IntroductionStudies from the US and Europe show that p

19、ersons in industrialized nations spend more than 90% of their time indoors. For infants, the elderly, persons with chronic diseases, and most urban residents of any age, the proportion is probably higher.Over the past several decades, our exposure to indoor air pollutants has increased due to factor

20、s such as tightly sealed buildings, reduced ventilation rates to save energy, use of synthetic materials and chemically formulated personal care products, pesticides, and other household items.68IntroductionThe locations of highest concern are those involving prolonged, continuing exposure - that is

21、, the home, school, and workplace where people live, work and play.US EPA has consistently ranked indoor air pollution among the top five environmental risks to public health in recent years.69On average, we spend more than 70% of our time at home, in offices and other indoor environments.In the pas

22、t, people focused on ambient air quality only but recently there is a trend all over the world looking at IAQ.Why is Indoor Air Quality IMPORTANT ?70What if you have Good IAQ?Good indoor air quality can :safeguard our healthcontribute to our comfort and well-beingimprove productivity at the workplac

23、e71What if you have Poor IAQ?Poor indoor air quality may lead to:discomfortill healthabsenteeism and low productivity in workplaceproblem of sick building syndrome and building related diseases72Volatile Organic Compounds (VOCs)Consists of thousands of chemicalsCome from outdoor (automobiles), indoo

24、r (occupants and building materials related sources)Can be an important IAQ contaminant in areas where there are frequent use of detergents, carpets and smoking activities, etc.Difficult to measure and can be costlyMany have irritating effect on human beings and some are carcinogenic73Health impacts

25、:eye irritation throat irritation respiratory problems headaches dizzinesstoxicological effects on the central nervous system, liver, kidney & bloodcancer (long-term exposure)Volatile Organic Compounds (VOCs)74Common indoor air pollutantsVolatile organic compounds (VOCs) A range of organic compounds

26、Examples: benzene, chloroform and xyleneEvaporate at room temperatureSome are carcinogens, e.g. benzene and formaldehyde Sources:Solvents, cleaning agents, wood, paints, plastic, dyes, office machines (fax machines,computers, printers, etc), insecticides, and etc. Effects:eye, nose, throat and respi

27、ratory tract irritation, headaches, poor concentration, dizziness and tirednessdamages of central nervous system, liver and kidney75Common indoor air pollutants Cleaning agents are also a source of indoor VOCs. (Sources: ) Some home appliance such as personal computer can release VOCs too. (Sources:

28、 ) Volatile organic compounds (VOCs)76Sick Building Syndrome (SBS) A range of symptomsincluding eyes, nose and throat irritation, flu-like symptoms, chest tightness, headaches, lethargy, poor concentration and itchy skin with rashNot life-threateningCommonly occur in air-conditioned buildingsThe syn

29、drome causes poor work performance, higher rate of absenteeism and sick leavesPoor indoor air quality is believed to be a major contributing factor77Definition of Acceptable Indoor Air QualityThe indoor air quality has strong dependence on the level of ventilation. The American Society of Heating, R

30、efrigerating and Air-conditioning Engineers, ASHRAE, defines adequate ventilation as air which fulfills the listed two requirements:78Air with which a substantial majority (usually 80%) of the people exposed do not express dissatisfaction.Air in which there is no known contaminants at harmful concen

31、trations.Definition of Acceptable Indoor Air Quality79Definition of Acceptable Indoor Air QualityTwo aspects of problem:Annoyance - Odor and irritation (eye, nose, throat)Health Impact - Acute effects vs. Long term effects80The sense of smellThe sense of smell is one of the most undervalued of our s

32、enses, both from the point of view of its significance and capacity. The olfactory organs themselves consist of small yellowish areas (about 5cm2) in the upper part of the nasal cavity. 81The sense of smellThis olfactory organ contains between five to ten million cells which are sensitive to odors.

33、Today we do not know very much about the actual process by which contact between odorous molecules and cells which are sensitive to smell is transformed into a signal to the brain.82AdaptationThe sense of smell is rapidly affected by fatigue. This is an important fact when determining ventilation re

34、quirements.People who are already present in a room accustom themselves to smell quickly, whereas people who enter the room experience the smell with full intensity.83AdaptationConcept of Visitor vs OccupantsTwo different ventilation requirements for visitors and occupants in fresh air supply rate?8

35、4Proposed Framework for the Control of IAQAdopt a set of 2-level IAQ objectives as a common benchmark for evaluating and assessing IAQ Publish a set of Guidance Notes for the better management of IAQ in offices and public places (first draft came out in 1999, final draft will come out soon!)Self-reg

36、ulation approachLaunched a public education and publicity campaign to promote public awareness of IAQ85-Represents very good indoor air quality that a high-class and comfortable building should have. -Represents the recommended indoor air quality objectives that provide protection to the public at l

37、arge including the very young and the aged. A set of 2-level indoor air quality objectives is proposed as below: Indoor Air Quality ObjectivesLevel 1Level 286IAQ Programme as Part of the Building Management ProgrammeA total awareness of the IAQ issue from both the management and the operation level,

38、 through seminars and daily educationAs HVAC takes care of a large portion of IAQ problems, a proper maintenance programme is needed on all the HVAC systemsMay need engineering support from outside to look at how to retrofit the existing ventilation systemsOther non-ventilation issues87IAQ Control i

39、n BuildingsAdvanced ventilation strategiesUse of advanced air purification systemsUse of demand control ventilation strategy for energy saving and IAQGood house keeping can help to maintain a good IAQUse of environmentally friendly building materials88Control measures Eliminate the sources of pollut

40、ant Increase ventilation Keep the ventilation system clean Upgrade, clean and sterilize the air conditioner is one way to keep the indoor air in good quality. (Sources: ) Covering the wall with wallpaper can eliminate the release of radon from concrete. (Sources: ) 89DiscussionHave you ever felt unc

41、omfortable in an indoor environment with flu-like symptoms, but they all disappear once you move out to outdoor environment? Where? How do you explain?What kind of indoor air pollutants could be found in the classroom?How do the problems associated with indoor air quality affect the social and econo

42、mic development in China?How do the government and you help to improve the indoor air quality?90Relevant WebsitesHong Kong Council on Smoking and Health ()Indoor Air Quality Association ()Indoor Air Quality Information Centre ()World Health Organisation (WHO) ()Environmental Protection Department ()

43、91Volatile Organic Compounds-VOCsVOCs are those compounds, which are found in the environment, containing carbon but excluding Elemental Carbon, Carbon Monoxide (CO), and Carbon Dioxide (CO2). This would encompass gaseous carbon containing compounds and other similar compounds adsorbed on to the sus

44、pended particulate matter in the atmosphere (Derwent, 1993)92VOCsVOCs指室温下饱和蒸气压超过70.91Pa或沸点 outdoor) Wind - Inside pressure relative to outside pressure (WC steady windspeed, 5mph)133Variables That Influence VOCs in Indoor AirSeasonSpring snowmelt and rains; high groundwater; VOCs closer to buildingW

45、inter frozen ground influences where/if VOCs emerge Summer - high temperatures; light windsFall falling temperatures; increasing winds (WC late winter/early spring)134Variables That Influence VOCs in Indoor AirVentilationNatural Ventilation Draftiness of building; Windows/Doors open/closed; Mechanic

46、al Ventilation fans; air conditioning(WC closing window/doors 24-48 hours prior to and throughout sampling)135Indoor to Outdoor RatiosFrom “Chemistry of the Upper and Lower Atmosphere”, Finlayson-Pitts and Pitts,Academic Press, 2000, page 857136137Indoor AirGreatest exposure to manufactured chemical

47、 contaminants, inside homesIn 2 N.J cities VOCs higher inside homes than outsideChief sourcesair fresheners - building materialscleaning products - domestic water supply138Personal Exposure to benzene45% from smoking36% Gasoline fumes, glue18% other products - paints, stored solvents139Personal expo

48、sure to benzeneGovernment regulations control industrial emissionsautomobile exhaustWaste managementReduce such emissions to zero, no effect on human health effects of exposure140Other examples of carcinogensTetrachloroethylene - dry cleaned clothesParadichlorbenzene -moth repellents, toilet disinfe

49、ctants, deodorizersChloroform - domestic water supply - showering, washing, laundering141Combustion productsFrom heating, cooking and other appliancesCarbon monoxide - incomplete combustion, anoxic damage, interferes with detoxificationParticulates - 10 microns respirable and produce damagePAHs, ben

50、zopyrene - potent carcinogens142Fate of combustion productsSettle in dust, stirred up by activity - long term exposureAttach to carpet fibres, soft furnishingsCannot remove by vacuum extractionChildren, pets exposed and ingestAverage child ingests 110 ng benzopyrene/day (=3 cigarettes)143PesticidesI

51、ndoor levels 5-10X outdoor levelsIncludes pesticides only approved for outdoor use3% of lawn pesticides tracked in, found in carpet dust upto 1 yrChildren ingest up to 200 mg of soil per dayPesticides inside, persist for years, no breakdown144CarpetsFavourite floor coveringTrap dirt and dust - perma

52、nentlyEmit VOCs - aliphatice & aromatic hydrocarbons, 4-PCChemicals stick to carpet fibresDust from household carpet is Toxic 145Environmental chemicals in humansPesticides in blood2,4-D in urine of children (18-23%)DDT still found - higher in fat than bloodSwimming pool exposure - trihalomethanes i

53、n bloodVOCs at low level enter body - bioaccumulation occurs146Health problems and Chemical mixturesMultiple health effects - neurotoxic most significantNeurobehavioural effects not usually consideredPesticide related illness non-specific (Lessenger 1995)Only limited specific signs & symptoms (Grand

54、jean 1991)Stress may potentiate toxicity147Toxicity of mixturesSBS more likely with higher VOCsCarpet emissions toxic to mice (Anderson 1992)DEET, permethrin & pyridostigmine toxic as mixture (Abou Donia et al 1996)Gulf War Veterans (Haley et al 1997)Sewer workers - correlation of sway with VOC leve

55、ls (Kuo 1996)148Variation in vulnerabilityIn sick buildings - c.20% develop impaired balanceEven inbred mice populations show variabilitySubpopulation particularly vulnerable to ozone (Horstman 90)5% chemically sensitiveRats - sensitive or resistant lines149Sensing the environmentSeeHearTouch Feel S

56、mellTaste150VOC控制烘烤法通风使用空气净化器活性炭吸附光催化151Fonte: Enterprise for Education, Inc. 1998152Ar limpoAr +VOCRadiadorFiltroAdsoroCarvo Ativado153154155VOCH2OVaporCondensadorDecantadorDessoro156VOCH2O157158159160161162163164N2 OuCO2VOC165CnHm + O2 = H2O + CO22 Tipos:RecuperativoRegenerativo166167168HCHO + h 2

57、HO2 + CO H2 + COHCHO + OH HO2 + CO + H2OVOC + OH . . n HCHO + OTHER PRODUCTSVOCs, HCHO and tropospheric O3VOC169EPA BEIS2 isopreneGEIAisoprene 170ppbSummertime in situ HCHO datasetsFried et al 1997 Harris et al 1989 Kleindienst et al 1988Lee et al 1995, 1998Martin et al 1991 McKeen et al 1997 OZIE -

58、 GuentherReimer et al 1998Shepson et al 1991171Relating HCHO columns to VOC emissionsAbsence of transport = Yi EiiVOCi Emission EikHCHOkHCHO172Ozone NOx chemistryNO2 + hv NO + OO + O2 O3O3 + NO NO2 + O2Chapman Cycle:No net production of ozone!This reaction sequence cannot explain urban ozone accumul

59、ation.173Add CO to the reactor.CO + OH CO2 + HOH is the real work horse in the atmosphere!OH is called hydroxyl radical & HO2 is called hydroperoxyl radical.H + O2 HO2HO2 + NO OH + NO2Why is this important?+CO + NO + O2 CO2 + NO2174Urban Ozone ProblemNO2 + hv NO + OO3 + NO NO2 + O2O + O2 O3COIn othe

60、r words, the CO is a competing for the NO with ozone.Ozone losses, sometimes and has to stick around.175Add a VOC to the reactor.RH + OH R + H2OR + O2 RO2Nomenclature, VOC = RHRO + O2 HO2 + RCHOHO2 + NO OH + NO2Ahh, two for one!RO2 + NO RO + NO2+RH + 2O2 + 2NO RCHO + H2O + 2NO2Plus, RCHO becomes the