Ozone effects

When and loir are widely separated the effect of background aerosol scattering can be taken account of more effectively by employing a third wavelength, X2, between and in a three wavelength DIAL technique. With this technique, two wavelengths sample the absorption within the Hartley band and the third wavelength lies in a region just outside the band where there is little ozone absorption. For ozone detection in the troposphere the third wavelength employed, I2 in Figure 9.35, is provided by Raman shifting of the 266 nm radiation using a cell containing high pressure deuterium gas to produce radiation of wavelength 289 nm.  [c.381]

The most common treatment of incoming surface water is removal of particulate matter. This can be effected through the use of settling basins or filtration. Particle removal may involve the reduction or elimination of suspended inorganic material such as clay, sdt, and sand. It may also involve removal of organic material, including living organisms. Organisms that enter aquaculture faciUties if not filtered from the incoming water include phytoplankton and zooplankton, plants and plant parts, macroinvertebrates, and fishes. Some of the organisms, if not removed, can survive and grow to become predators on, or competitors with, the target aquaculture species. Very small organisms, such as bacteria, can be removed mechanically. However, other forms of sterilization, such as ozonation and the use of uv radiation, are more efficient and effective.  [c.19]

Tests demonstrate that methanol vehicles can meet stringent emission standards for HC, CO, and NO as indicated in Figure 2. The primary benefit of methanol, however, is not the amount of hydrocarbons emitted but rather that methanol-fueled vehicles emit mainly methanol which is less reactive in the formation of ozone than the variety of complex organic molecules in gasoline exhaust. Formaldehyde [50-00-0] emissions from methanol vehicles are increased in comparison to gasoline vehicles. Tests of 1983 Escorts showed tailpipe levels as high as 62 mg/km, well above typical gasoline levels of 2 to 7 mg/km. The 1981 Rabbits ranged from about 6 to 14 mg/km and the 1981 Escorts had levels less than 7 mg/km. AH results were obtained on relatively low mileage vehicles. Deterioration of catalyst effectiveness could increase these emissions.  [c.425]

Possible negative environmental effects of fertilizer use are the subject of iatensive evaluation and much discussion. The foUowiag negative effects of fertilizer usage have been variously suggested (113) a deterioration of food quaUty the destmction of natural soil fertility the promotion of gastroiatestiaal cancer the pollution of ground and surface water and contributions toward the destmction of the ozone layer ia the stratosphere.  [c.246]

Dyeing Characteristics. Disperse dyes, high melting crystalline compounds with low solubiUty in the dye bath, are most frequentiy used for cellulose acetate and triacetate fibers. They are milled to very small particle size, permitting effective dispersion without agglomeration in the dye bath, and diffuse into the fiber to give a uniform color. Dye-bath temperature and fiber composition affect the diffusion-controlled dyeing rate. Triacetate fibers are dyed more slowly than acetate fibers dye carriers accelerate the rate (1,17—22). Selection of the appropriate azo, anthraquinone, or diphenylamine disperse dye ensures good colorfastness. Fa ding inhibitors are used to counteract the effects of nitrogen oxides and ozone. Dyed triacetate fabrics, which are  [c.293]

Emissions from methanol vehicles are expected to produce lower HC and CO emissions than equivalent gasoline engines. However, methanol combustion produces significant amounts of formaldehyde (qv), a partial oxidation product of methanol. Eormaldehyde is classified as an air toxic and its emissions should be minimized. Eormaldehyde is also very reactive in the atmosphere and contributes to the formation of ozone. Emissions of NO may also pose a problem, especiaHy if the engine mns lean, a regime in which the standard three-way catalyst is not effective for NO reduction.  [c.195]

Kinetics and Mechanism of Ozone Reactions. Ozone attacks nucleophilic centers, ie, points of high electron density, in organic substrates. Reactivity of potential reaction sites is enhanced by the presence of electron-donating groups such as CH, and decreased by electron-withdrawing groups such as C=0, COOH, Cl, and NO2. Reaction products depend on solvent type (reactive or nonreactive) and ozonation conditions. Ozone does not totaHy mineralize, ie, convert to CO2 and water, most organic compounds during water treatment. Except in rare cases, such as the oxidation of formate, only partial oxidation is achieved on account of the low reactivity of common intermediate oxidation products, eg, acetic and oxaHc acids. Although ozone has a high thermodynamic oxidation potential, its effectiveness in water treatment depends on the kinetics of its reactions, which can vary widely indeed, rate constants can vary over 14 orders of magnitude, from for acetic acid to 10 L/(mol-s) for phenolate ion (56).  [c.493]

Cooling Requirements. Since the majority of the electrical energy input to the electric discharge is dissipated as heat, cooling is necessary to minimize decomposition of ozone and extend dielectric life. Double-sided cooling is more effective than single-sided cooling in removing heat from the ozone generator. The gas exiting an efftcientiy cooled ozone generator normally is near ambient temperatures where the rate of decomposition is low.  [c.498]

The horizontal tube-type ozone generator (Fig. 3a) was a significant improvement over the plate-type ozone generators. A single unit consists of two concentric tubes, an outer stainless steel tube that serves as the ground electrode, and an inner glass tube sealed at one end (which functions as the dielectric) with an inner conductive coating that acts as the high voltage electrode. Discharge occurs in the annular space between the two tubes through which the feed gas flows. A group of tubular units (eg, up to 1000) is arranged in parallel and enclosed in a cylindrical housing so that the ends protmde out of the cooling water jacket, which cools the outside stainless steel tube. Manifolds distribute the feed gas to the annular discharge spaces of the tubes at one end and collect the ozone-containing gas at the other. The tubular electrodes are suppHed with low frequency power (- 60 Hz). When higher production rates (>10 kg/h) are required, the use of soHd-state variable medium frequency (600—1000 Hz) power suppHes may be cost-effective.  [c.499]

Disinfection. Ozone is a more effective broad-spectmm disinfectant than chlorine-based compounds (105). Ozone is very effective against bacteria because even concentrations as low as 0.01 ppm are toxic to bacteria. Whereas disinfection of bacteria by chlorine involves the diffusion of HOGl through the ceU membrane, disinfection by ozone occurs with the lysing (ie, mpture) of the ceU wall. The disinfection rate depends on the type of organism and is affected by ozone concentration, temperature (106), pH, turbidity, clumping of organisms, oxidizable substances, and the type of contactor employed (107). The presence of oxidizable substances in ordinary water can retard disinfection until the initial ozone demand is satisfied, at which point rapid disinfection is observed.  [c.501]

Approximate indication of reactivity and selectivity ate summarized in Table 7. Chlorine and ozone are extremely reactive, whereas oxygen and hydrogen peroxide tend to react more slowly and to be more limited in the amount of lignin removed. Chlorine dioxide and, to a lesser extent, chlorine are highly selective ozone tends toward poor selectivity. Hypochlorous acid and, to a lesser extent, oxygen requite the addition of inhibitors to achieve satisfactory selectivity. Hypochlorite is selective only if the pH is maintained sufficiendy high and consumption is Limited. Approximate indication of particle bleaching ability and perceived environmental hazard are also Hsted in Table 7. Chlorine dioxide, chlorine, and hypochlorite offer good particle removal ability, whereas ozone and hydrogen peroxide are poor in this respect. Regarding environmental effects, chlorine and hypochlorite ate seen as having detrimental effects. As a result, there is a trend toward replacing both with chlorine dioxide, oxygen, ozone, and hydrogen peroxide.  [c.278]

Ozonation can be enhanced by the addition of ultraviolet (uv) radiation. This combination can be effective in degrading chlorinated organic compounds and pesticides. In addition, metal ions such as iron, nickel, chromium, and titanium [7440-32-6] can act as catalysts, as can ultrasonic mixing.  [c.163]

Hydrogen Peroxide. Hydrogen peroxide is typically used as an oxidizer in combination with uv light, ozone, and/or metal catalysts. Fenton s reagent is hydrogen peroxide with iron as a catalyst. Hydrogen peroxide/uv light has been shown to be effective in oxidizing benzene, chlorobenzene [108-90-7] chloroform, chlorophenol, 1,1-dichloroethane [75-34-3] dichloroethene [540-59-0, 75-35 ], phenol [108-95-2], tetrachloroethylene, 1,1,1-trichloroethane [71-55-6], trichloroethylene, toluene, xylenes (7—10) and many other organic compounds.  [c.164]

Ozone. Ozone is an allotropic form of oxygen, O. Because it is an unstable gas, it must be generated at the point of use. Ozone is an effective, clean oxidizing agent possessing powerful antibacterial and antiviral properties.  [c.272]

Ozone. Ozone generators are based on uv or silent discharge. Although uv ozone generators are marketed, they are not effective for treating  [c.296]

A physical antiozonant must provide an effective barrier against the penetration of ozone at the mbber surface. A chemical antiozonant, on the other hand, must first of all be extremely reactive with ozone.  [c.236]

The antiozonant should possess adequate solubiUty and diffusivity characteristics (19). Siace ozone attack is a surface phenomenon, the antiozonant must migrate to the surface of the mbber to provide protection. The antiozonant should have no adverse effects on the mbber processiag characteristics, eg, mixing, fabrication, vulcanization, or physical properties.  [c.236]

Since antiozonants are affected by most compounding ingredients, each new mbber compound requires the development of a cost-effective antiozonant system. Outdoor as weU as accelerated ozone-chamber tests are available (39—45). Laboratory tests involve exposing a statically or dynamically elongated test sample to ozone and measuring the time to crack formation, the severity of cracking, or the decay of 100% modulus with time. Cracking is affected by ozone concentration and flow rate, temperature, humidity, sample shape, and type of strain (static, dynamic, or both). Cracking is accelerated by increasing ozone concentration. Normal test concentrations are 10—25 pphm, but they can be as high as 50 pphm in accelerated tests. Above 70°C ozone decomposes, and therefore testing is usually carried out at 30 —50°C. Humidity can accelerate ozone cracking, and the maximum recommended value is e 65%.  [c.238]

Pulp Bleaching. Wood pulp bleaching is the largest use of chlorine dioxide, which is a uniquely selective oxidizer for lignin. Unlike other oxidizing bleaches such as ozone, hydrogen peroxide, oxygen, or chlorine, chlorine dioxide does not attack cellulose and thus preserves the mechanical properties of bleached pulp. Chlorine dioxide bleaching is more effective than other methods at removing incompletely defibered wood or shives (75—78). Compared with other oxidative bleaching chemicals, chlorine dioxide is the most expensive to produce, but it can actually reduce overall bleaching costs under certain conditions (78).  [c.484]

Chlorine Dioxide. Like ozone, chlorine dioxide [10049-04-4] is a powerflil oxidant. It is usually generated as used. It has been used for disinfecting drinking water and bleaching paper pulp. Its effectiveness in killing microorganisms is well documented (305,306), and it has received recent study as a gas to sterilize medical devices. It requites 50% rh or higher to be effective. Bacterial cells had a D-value of 2.6 min and spores of 24 min (307).  [c.138]

Other Ingredients. Other compounding ingredients include tackifiers, flame retarders, odorants, and lubricants. Various resins with a T higher than the elastomer act as tackifiers by altering the dynamic mechanical properties of the unvulcanized elastomer (92). Hydrocarbon resins (qv) improve tack without side reactions. On the other hand, phenol—formaldehyde resins contain reactive methylol groups that can react with halobutyl to give premature cure. Hindered phenoHc antioxidants (qv) added during manufacture prevent autoxidation during finishing steps, storage, and compounding. Antiozonants (qv) improve the resistance of butyl and halobutyl mbber vulcanizates to ozone cracking. The low segmental mobility in butyl mbber apparendy limits the crack growth rate however, antiozonants, such as A/AT-dioctyl- phenylenediarnine, are effective at high concentrations of plasticizer (93). Halogenated butyl mbber must be stabilized against dehydrohalogenation (94,12) at elevated temperature. To achieve this, calcium stearate is used for chlorinated butyl brominated butyl requites a mixture of calcium stearate and an epoxy compound, eg, epoxidized soybean oil.  [c.485]

Ethylene oxide stefilant gases are suppHed as Hquified compressed gases, either pure or as a mixture with a flame retardant. When suppHed as a pure gas, the ethylene oxide is shipped in special insulated containers. For safety reasons, nitrogen gas is added to the vapor phase up to a total pressure of 345 kPa (50 psig) at 21°C. When used in a sterilizing chamber, the flammability of ethylene oxide is usually controlled by purging the sterilization chamber with nitrogen gas at the beginning and the end of the sterilization process. In some cases, the effects of a potential deflagration are moderated by operating under great vacuum or, in the case of small hospital sterilizers, by using very small quantities of ethylene oxide. During 1960—1990, the most common flame retardants used for ethylene oxide mixtures were CO2 and dichlorodifluoromethane (CFC-12). The CFC-12 mix (27.3 vol % ethylene oxide, 72.7 vol % CFC-12) accounted for over 90% of all stefilant gas used in the United States. With concern about the role of CFC-12 in causing depletion of stratospheric ozone, sterilizers and suppHers have committed to stop using this mixture. It will be replaced by more use of ethylene oxide/nitrogen and by use of alternative flame retardants.  [c.465]

Biological corrosion and deposition may be prevented by chemical treatment, system operation, and system design. Economics alone often favor chemical treatment. However, costs can usually be further reduced by appropriate system design and operation. Water treatment using chlorine, bromine, ozone, or other chemicals can control almost any biological problem. However, discharge limitations, associated corrosion, and other problems often restrict chemical use. Shocking with massive amounts of biocides may be effective in treating some systems, but not all systems will respond identically. Shocking heavily fouled systems may produce sloughing of large biological mats that plug components. After shocking, bacterial growth may be rapid, and the system can return to its previous state quickly. It is imperative that biological control not be erratic. It is much easier and decidedly less costly to maintain good control than to bring a seriously troubled system back into control.  [c.145]

The major air pollutants which are phytotoxic to plants are ozone, sulfur dioxide, nitrogen dioxide, fluorides, and peroxyacyl nitrate (2). Table 8-1 lists some of the types of plants injured by exposure to these pollutants. The effects range from slight reduction in yield to extensive visible injury, depending on the level and duration of exposure. Examples of the distinction between air pollution injury and damage are also given in Table 8-1. Visible markings on plants or crops such as lettuce, tobacco, and orchids caused by air pollution translate into direct economic loss, i.e., damage. In contrast, visible markings on the leaves of grapes, potatoes, or corn  [c.113]

Fenner (11) has pointed out that short-lifetime constituents of the atmosphere such as nitrogen oxides, carbon monoxide, and nonmethane hydrocarbons may also play roles related to global warming because of their chemical relations to the longer-lived greenhouse gases. Also, SO, with a very short life interacts with ozone and other constituents to be converted to particulate sulfate, which has effects on cloud droplet formation.  [c.159]

A commercial form of ozoniser is illustrated in Fig. VI, 14, 1 this produces about 170 ml. of ozonised oxygen, containing 6-7 per cent, of ozone, per minute. The apparatus consists of ten ozone tubes, each with its own effective annular space, bridged in parallel across an inlet and outlet manifold. The units are suspended in a lead-lined, hardwood tank fitted with a terminal a ten-rod multiple high tension electrode, also fitted with a terminal, dips into the ozone tubes. The two terminals are connected by ozone-proof high tension leads to a transformer at 7,500 volts. The ozone tubes and tank are partially filled with 0 2 per cent, copper sulphate solution. Upon passing the silent high tension discharge across the annular space in the ozone tubes through which oxygen is flowing at a suitable ratef, ozone is formed in 6-7 per cent, yield.  [c.890]

Manganese dioxide, in combination with other metal oxides, forms a series of active catalysts (60) that participate in a variety of environmentally important oxidation and decomposition reactions. The manganese-based catalysts for these appHcations exhibit a long life and high catalytic activity. At moderately elevated temperatures, manganese dioxide catalysts (61,62) are used for the complete oxidative degradation of many organic compounds. These catalysts are particularly effective for oxygenated compounds such as alcohols, acetates, and ketones. At a contact time of ca 0.24 s, 95% hydrocarbon destmction efficiency is achieved for ethanol at 204°C ethyl acetate, 218°C propanol, 216°C propyl acetate, 238°C 2-butanone, 224°C toluene, 216°C and heptane, 316°C. Carbon monoxide oxidation occurs at ambient temperatures when no H2O is present. A contact time of ca 0.36 s gives >95% destmction efficiency. Ozone decomposition, at ambient temperatures, that is >99% efficient requites a contact time of ca 0.72 s. Manganese dioxide also catalyzes the decomposition of H2O2 at room temperature and of alkaU metal chlorates at about 270°C.  [c.511]

Tastes and Odors. The origin of most tastes and odors in water suppHes is synthetic organic compounds (eg, phenols) as weU as naturally occurring inorganic (eg, Fe , Mn , and H2S) and organic materials (biologically and chemically altered). The action of algae and actinomycetes on humic materials can produce distasteful water-soluble compounds such as geomycin and 2-methyHsobomeol. Regrowth in the distribution system also can impart taste. Additionally, oxidation during water treatment can generate other odorous compounds (eg, aldehydes). Although many taste and odorous compounds are readily oxidized by ozone (typically 1.5—2.5 ppm), some compounds are more resistant and may require biofiltration or advanced oxidation processes. A pilot-scale study showed that the Peroxone process (O —H2O2) was more effective in removing taste and odor compounds than ozone alone (111).  [c.501]

Removal of Refractory Organics. Ozone reacts slowly or insignificantly with certain micropoUutants in some source waters such as carbon tetrachloride, trichlorethylene (TCE), and perchlorethylene (PCE), as well as in chlorinated waters, ie, ttihalomethanes, THMs (eg, chloroform and bromoform), and haloacetic acids (HAAs) (eg, trichloroacetic acid). Some removal of these compounds occurs in the ozone contactor as a result of volatilization (115). Air-stripping in a packed column is effective for removing some THMs, but not CHBr. THMs can be adsorbed on granular activated carbon (GAG) but the adsorption efficiency is low.  [c.502]

Irritants. Irritant materials are corrosive or vesicant, ie, cause bUsters, and may inflame moist or mucous surfaces. These have essentially the same effect on animals as on humans. The concentration is far more significant than the duration of exposure. Some representative irritants, eg, aldehydes (qv), alkaline dusts and mists, ammonia (qv), hydrogen chloride (qv), hydrogen fluoride, sulfur dioxide, and sulfur trioxide, chiefly affect the upper respiratory tract (51). Other irritants, eg, bromine, chlorine, dimethyl sulfate, fluorine (qv), ozone (qv), sulfur chlorides, and phosphoms chlorides, affect the upper respiratory tract and lung tissues. Irritants that primarily affect terminal respiratory passages and air sacs iuclude arsenic trichloride, nitrogen oxides, and phosgene (qv). Lung irritants are similar to the chemical asphyxiants iu that the effects frequently result iu asphyxial death.  [c.95]

Ozone Bleaching. Ozone delignification has become important in nonchlorine bleaching sequences. Like oxygen, ozone is a strong oxidizing agent that effectively strips color and breaks down residual lignin. But unlike oxygen, it has the advantage of reacting at atmospheric pressure and room temperature. Typically, ozone is appHed at medium (10—12%) consistency at dosage rates of 0.3 to 0.7% based on pulp. High consistency ozonation is also practiced commercially. Some problems involve ozone s tendency to depolymetize cellulose. The drive to develop ozone treatments continues as the industry moves toward elemental chlorine-free and totally chlorine-free technologies. Pulp mills may combine ozone treatment and extended delignification together with oxygen treatment. There were nine commercial installations as of June 1994 that employed ozone in bleaching, having capacity of about 6600 t/d. AH but two installations were in Sweden and Finland. A common sequence for kraft pulp is OZEP and ZEP for sulfite pulp, but the majority of the installed sequences are the OPZP-type sequence.  [c.282]

For rapid reactions, the fraction of gas exchanged between the rising gas bubbles and the continuous emulsion phase is the important factor. For a slow reaction with a large minimum fluidization velocity, space velocity is of primary concern. With slow reactions and poor contacting, effective space—time is most important as exemplified in a study of ozone reduction catalyzed by iron scale. Good agreement was found among the various fluid-bed reactors with diameters of 50, 200, and 760 mm, bed heights of 0.9—3 m, and gas velocities of 6—24 cm/s. Scale-up in this case requires catalyst inventory to vary proportionaHy to reactor diameter and superficial velocity to vary proportionaHy to its square root (68).  [c.518]

Common oxidative bleaches are hydrogea peroxide, sodium hypochlorite, chlorine dioxide, oxygea, and ozone. Although it is a very cost-effective bleaching agent, sodium hypochlorite is not used extensively to whiten deioked pulp due to environmental coacems. Reductive bleaches iaclude sodium hydrosulfite and formamidine sulfinic acid (FAS). Improved cost effectiveness is claimed when FAS is generated ia the pulp slurry by reaction of hydrogen peroxide and thiourea (49). Oxygen gas ia combination with an alkaline agent such as sodium hydroxide has been reported to reduce the tackiaess of stickies (50).  [c.9]

Aged and Fatigued Properties. Tire compounds are subjected to static and dynamic aging throughout their entire life cycle. Static aging begins even in the green (uncured) state with exposure to oxygen, ozone, light, heat, and humidity. In the tire factory, these effects can be minimized to the point where they barely exist. Factory tire compounders are assigned to tire plants to assure the integrity of their compounds throughout the production cycle. Even as tires are warehoused they are protected by regulations drafted by compounders. It is when tires are appHed to the vehicle that this natural phenomena of aging becomes most important.  [c.252]

The N,]S3-dialkyl-/)-PDAs (where the alkyl group may be 1-methylheptyl, l-ethyl-3-methylpentyl, 1,4-dimethylpentyl or cyclohexyl) are the most effective in terms of their reactivity towards ozone (24—26). These derivatives increase the critical stress required for the initiation of crack growth, and they also reduce the rate of crack growth significantly (15). The alkyl group is most active, for reasons that ate as yet not completely clear. The drawbacks of these derivatives are their rapid destmction by oxygen, ie, shorter useful lifetimes their activity as vulcanization accelerators, and hence increased scorchiness their tendencies to cause dark red or purple discoloration and the difficulty in handling because they are Hquids. The dialkyl- -PDAs are seldom used alone in mbber compounds, although they can be used effectively when blended with alkyl-A/-aryl-/)-PDAs.  [c.237]

Any diene mbber article subjected to flexing, bending, or folding requires protection against ozone. Chemical antiozonants, primarily -PDAs, are used in general purpose commercial appHcations (mainly tires, hoses, flat belts, and transmission belts) where staining and discoloration are not serious problems. Waxes act as antiozonants for diene mbbers under conditions requiring Httle or no flexing, such as tie-down straps. Under these conditions, waxes are more effective than the -PDA antiozonants (21). However, in appHcations involving dynamic stress where discoloration caimot be tolerated, alternatives to the traditional antiozonants must be used. Typical appHcations include white tire sidewalls, gaskets, weather stripping, gloves, and sporting goods. The two principal alternatives to antiozonants are ozone-resistant elastomers and blends of ozone-resistant elastomers and diene mbbers.  [c.238]

The efficiency of an existing bioaeration plant can be increased by the addition of activated carbon (229). One successful system patented by DuPont and further developed by Zimpro is the powdered activated carbon treatment (PACT) system (230—233). Adding powdered activated carbon to the activated sludge process can be beneficial, ie, more uniform operation and effluent quaUty improved BOD, COD, and TOC removals better removal of phosphoms and nitrogen less tendency for foaming in the aerator because of the adsorption of detergents adsorption of refractory soflds and thicker sludges greater treatment flexibiUty and increased effective plant capacity at Httle or no added capital investment and enhanced color removal of dye effluents (95). The mechanism by which pollutant removals are increased with powdered activated carbon addition to activated sludge is not fully understood. The current theory is that the activated carbon aids by direct adsorption of pollutants and by providing a more favorable environment for the microorganisms to propagate. An extensive study (234) was done with the assistance of six dyestuff companies in which laboratory scale processes were conducted to estabhsh the technical feasibiUty of using ozonization, granular activated carbon adsorption, and the PACT treatment of dye manufacture wastewater. Overall, excellent removals of organic priority pollutants were achieved by the PACT process. In addition, soluble organic carbon (SOC) and color removals were enhanced by the addition of powdered activated carbon to an activated sludge system, generally in direct relation to the steady-state concentration of powdered activated carbon in the reactor. Two dyestuff companies have successfully used the PACT process (235,236).  [c.384]

The instances cited were examples of the use of DEP to filter liquids. We now turn to the use of DEP to aid in dielectrofiltratiou of gases. Fielding et al. observe that the effectiveness of high-quality fiberglass air filters is dramatically improved by a factor of 10 or more by incorporating DEP in the operation. Extremely httle current or power is required, and no detec table amounts of ozone or corona need result. The DEP force, once it has gathered the particles, continues to act on the particles already sitting on the filter medium, thereby improving adhesion and miuimiziug blowoff.  [c.2013]

Materials The damage that air pollutants can do to some materials is well known ozone in photochemical smog cracks rubber, weakens fabrics, and fades dyes hydrogen sulfide tarnishes silver smoke dirties laundry acid aerosols ruin nylon hose. Among the most important effects are discoloration, corrosion, the soiling of goods, and impairment of visibility.  [c.2174]

Vegetation damage can be measured biologically or socioeconomically. Using the latter measure, there is a 0% loss when there is no loss of the sale value of the crops or ornamental plants but a 100% loss if the crop is damaged to the extent that it cannot be sold. These responses are related to dose, i.e., concentration times duration of exposure, as shown by the percent loss curves on the chart. A number of manifestations of material damage, e.g., rubber cracking by ozone, require an exposure duration long enough for the adverse effects to be significant economically. That is, attack for just a few seconds or minutes will not affect the utility of the material for its intended use, but attack for a number of days will.  [c.58]

Ozone has also been found to cause fading of material. This was discovered when white fabrics developed a yellow discoloration (9, 10), leading researchers to investigate the effects of ozone on other chemicals added to the material, including optical brighteners, anhstatic and soil-release finishes, and softeners. A very complex process was occurring where the dyes were migrating to the permanent-press-finish materials, e.g., softeners. Softeners have been found to be good absorbers of gases. Fading results from the combination of dye and absorbed nitrogen dioxide and ozone. This combination with high relative humidities has caused color fading in numerous types of material and dye combinahons. Although some progress has been made in the development of fade-resistant dyes, they are more expensive and have poorer dyeing properties.  [c.132]

See pages that mention the term Ozone effects : [c.526]    [c.287]    [c.494]    [c.494]    [c.501]    [c.501]    [c.297]    [c.238]    [c.138]   
Fundamentals of air pollution (1994) -- [ c.0 ]

Plastics materials (1999) -- [ c.288 , c.866 ]