Absorption of NO and NO2 in Caprolactam Tetrabutyl Ammonium Halide Ionic Liquids

ABSTRACT

To explore environmentally benign solvents for the absorption of NO and NO₂, a series of caprolactam tetrabutyl ammonium halide ionic liquids were synthesized. The solubility of NO and NO₂ was measured at temperatures ranging from 298.2 to 363.2 K and atmospheric pressure, and the following trend in the solubility of NO and NO₂ in ionic liquids with various halide anions was observed, respectively: F > Br > Cl and Br > Cl > F. Moreover, as the temperature increased from 308.15 to 363.15 K and the mole ratio of caprolactam increased from 2:1 to 6:1, the solubility of NO increased. Alternatively, the solubility of NO₂ decreased as the temperature increased from 298.15 to 363.15 K, and the mole ratio of caprolactam increased from 2:1 to 6:1. The absorption and desorption of NO and NO₂ was practically reversible in the ionic liquids, which was characterized by nuclear magnetic resonance. The method, which is at least partially reversible, offers interesting possibilities for the removal of NO and NO₂.

IMPLICATIONS Basic ionic liquids with amino groups were synthesized and used to capture CO₂, SO₂, and H₂S, and to promote hydrogenation of CO₂. In this paper, the authors used caprolactam tetrabutyl ammonium halide ionic liquid (IL) as absorbing medium in which NO_x could be absorbed. NO_x desorbed from the absorbent could be efficiently reduced by right catalysts at high temperature. The absorbed NO and NO₂ gas could be desorbed at higher temperature, allowing the ionic liquids to be reused several times without loss of capability. It was believed that caprolactam tetrabutyl ammonium bromide (CPL-TBAB) ILs may be useful for NO_x removal reagent for pollution control.     

Toxicity of imidazolium salt with anion bromide to a phytoplankton Selenastrum capricornutum: effect of alkyl-chain length

Room-temperature ionic liquids are regarded as environmentally benign alternatives to volatile organic solvents. However, the product designs for this promising group of compounds should take account, not only the technological needs, but also the eco-toxicological hazards. Therefore, this study aimed to evaluate the toxicity of some important ionic liquids on the growth of the freshwater alga, Selenastrum capricornutum. The ionic liquids examined in this study included 1-propyl-3-methylimidazolium [PMIM], 1-butyl-3-methylimidazolium [BMIM], 1-hexyl-3-methylimidazolium [HMIM] and 1-octyl-3-methylimidazolium [OMIM] with a bromide anion. The susceptibility of alga to ionic liquids was strongly dependent on the alkyl-chain length. According to our results, a longer alkyl-chain resulted in stronger inhibition of algal growth. In general, the toxicity could be summarized as decreasing in the following order: [OMIM]>[HMIM]>[BMIM]>or=[PMIM]. Among the ionic liquids examined, [OMIM] [Br] was found to be most toxic to S. capricornutum, with EC(50) values ranging from 26.3 microM to 54.9 microM after an incubating time of 96 h. Although [BMIM] [Br] and [PMIM] [Br] was relatively less toxic than [OMIM] and [HMIM], their toxicity increased as increasing the incubation time from 48 h to 96 h. This fact indicates that these kinds of ionic liquids may become more toxic after being released and contacted to freshwater ecosystem.     

离子液体对三种农作物发芽和生长的毒性研究

为了考察离子液体的生态毒性,研究了5种离子液体及其浓度变化对3种农作物发芽及生长状况的影响。结果表明：就种子发芽这一生态毒理指标而言,不同作物对离子液体毒性的敏感程度不同,其次序为黄瓜>玉米>白菜;在一定浓度下,离子液体对白菜、黄瓜和玉米均具有一定的毒害作用;对于所考察的5种离子液体,阴离子为卤素的［EMIM］Br和［BMIM］Cl对植物发芽和生长的抑制作用远大于阴离子为烷基硫酸酯和烷基磷酸酯的同类离子液体 ［EMIM］［ES］、［EMIM］［DEP］和［MMIM］［DMP］。这种毒性顺序可能与卤素离子对细胞膜较强的穿透能力和由于离子液体的稳定性所造成的阴阳“离子对”的共迁移有关。     

水溶性离子液体对甲苯的吸收效果及影响因素

选择3种水溶性离子液体（十二烷基咪唑氯盐（DDMIM Cl）、十二烷基咪唑硝酸盐（DDMIM NO3）、十二烷基咪唑双氰胺盐（DDMIM DCA））作为研究对象,对模拟甲苯废气进行吸收实验,研究了吸收液的吸收性能、甲苯浓度、吸收液浓度、进气气速以及盐度等因素对吸收效果的影响以及加热蒸馏法对吸收液的再生与甲苯回收的可行性。结果表明：不同的离子液体对甲苯的吸收率不同,DDMIM DCA的吸收效果最好,在质量分数为5%时,初始吸收率达到98%,饱和吸收量为53.39 mg·L-1,而DDMIM Cl、DDMIM NO3对甲苯的初始吸收率在92%左右,饱和吸收量分别为33.60、37.01 mg·L-1;甲苯饱和吸收量与吸收液浓度、甲苯进气浓度呈正相关,与进气气速、含盐度呈负相关;传质系数与甲苯进气浓度、进气气速以及含盐度呈正相关,与吸收液浓度呈负相关;采用加热蒸馏法进行甲苯回收及吸收液再利用时,甲苯的回收效率达到85%~90%,且甲苯的饱和吸收量随着重复利用次数的增加而基本保持不变。因此利用离子液体溶液处理甲苯废气理论上是可行的。     

Simultaneous removal of NO and SO2 by high-temperature fluidized zero-valent iron processes

A new approach to simultaneously remove nitrogen monoxide (NO) and sulfur dioxide (SO2) by zero valent iron (ZVI) was investigated. Three different parameters, temperature, flux, and ZVI dosage, were tested in fluidized ZVI column studies containing 500 ppmv of NO and SO2, respectively. Under the ZVI dosage of 0.5 g at flux of 0.6 L/cm2 x min for temperature 573 K, there is neither NO nor SO2 reduction. For 623 K and 673 K, complete removal for NO and > 90% removal for SO2 were achieved. For temperatures of 723 K and 773 K, 100% removal was achieved for both NO and SO2. The amounts of NO or SO2 reduction (as milligrams of NO or SO2 per gram ZVI) increased as temperature increased, and linearities were observed with both correlation coefficients > 0.97. Compared with NO, SO2 had earlier breakthrough because of a slower diffusion rate and less reactivity but higher mass reduction because of a higher molecular weight for SO2 (64 g/mol for SO2 and 30 g/mol for NO). At same temperature, both NO and SO2 reductions (as milligrams of NO or SO2 per gram of ZVI) were constant regardless of either flux or ZVI dosage variation, but breakthrough time was affected by both flux and ZVI dosage. A parameter weight of ZVI/flux (W/F) was developed to represent these two parameters at the same time to assess the breakthrough time of NO and SO2. Higher breakthrough time was achieved for higher W/F value. Moreover, interestingly, longer breakthrough time and more NO and SO2 mass reduction were achieved for combined NO and SO2 than individual NO or SO2 treated by ZVI, and both oxidation and reduction reactions occurred instead of a reduction reaction only. Chemical reactions among ZVI/NO, ZVI/ SO2, and ZVI/NO/SO2 were also proposed and verified by X-ray diffraction analyses.     

Release of gaseous bromine from the photolysis of nitrate and hydrogen peroxide in simulated sea-salt solutions

We have carried out a series of laboratory experiments to investigate the oxidation of bromide (Br⁻) by hydroxyl radical (OH) in solutions used to mimic sea-salt particles. Aqueous halide solutions with nitrate or hydrogen peroxide (HOOH) as a photochemical source of OH were illuminated with 313 nm light and the resulting gaseous bromine (Br*(g)) was collected. While illumination of these solutions nearly always formed gaseous bromine (predominantly Br₂ based on modeling results), there was no evidence for the release of gaseous chlorine. The rate of Br*(g) release increased (up to a plateau value) with increasing concentrations of bromide and was enhanced at lower pH values for both nitrate and HOOH solutions. Increased ionic strength in nitrate solutions inhibited Br*(g) release and the extent of inhibition was dependent upon the salt used. In HOOH solutions, however, no ionic strength effects were observed and the presence of Cl⁻ strongly enhanced Br*(g) release.Overall, for conditions typical of aged, deliquesced, sea-salt particles, the efficiencies of gaseous bromine release, expressed as mole of Br*(g) released per mole of OH photochemically formed, were typically 20–30%. Using these reaction efficiencies, we calculated the Br₂(g) release rate from aged, ambient sea-salt particles due to OH oxidation to be approximately 0.07 pptv h⁻¹ with the main contributions from nitrate photolysis and partitioning of gas-phase OH into the particle. While our solution conditions are simplified compared to ambient particles, this estimated rate of Br₂ release is high enough to suggest that OH-mediated reactions in sea-salt particles could be a significant source of reactive bromine to the marine boundary layer.     

Modeling solubility of CO<Subscript>2</Subscript>/hydrocarbon gas in ionic liquid ([emim][FAP]) using Aspen Plus simulations

The Peng-Robinson equation of state with quadratic van der Waals (vdW) mixing rule model was chosen to perform the thermodynamic calculations in Flash3 column of Aspen Plus to predict the solubility of CO₂ or any one of the hydrocarbons (HCs) among methane, ethane, propane, and butane in an ionic liquid 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([emim][FAP]). Bubble point pressure, solubility, bubble point temperature, fugacity, and partial molar volume at infinite dilution were obtained from the simulations, and enthalpy of absorption, Gibbs free energy of solvation, and entropy change of absorption were estimated by thermodynamic relations. Results show that carbon chain length has a significant effect on the bubble point pressure. Methane has the highest bubble point pressure among all the considered HCs and CO₂. The bubble point pressure and fugacity variation with temperature is different for CO₂ as compared to HCs for mole fractions above 0.2. Two different profiles are noticed for enthalpy of absorption when plotted as a function of mole fraction of gas soluble in IL. Partial molar volume of CO₂ decreases with increase in temperature in [emim][FAP], while it is increased for HCs. Bubble point temperature decreases with increase in the mole fraction of the solute. Entropy of solvation increases with temperature till a particular value followed by a decrease with further increase in temperature. Gibbs free energy change of solvation showed that the process of solubility was spontaneous.     

锰铜铈氧化物催化剂氧化NO性能及动力学研究

实验以TiO2为载体采用浸渍法制备CuOx/TiO2、CeOx/TiO2、CuCeOx/TiO2和MnCuCeOx/TiO2催化剂,考察这些催化剂氧化NO活性,探究Cu、Ce摩尔比和添加Mn元素对CuCeOx/TiO2催化剂氧化NO活性的影响,使用扫描电镜观察催化剂表面结构.研究发现,Cu、Ce元素配合后的CuCeOx/TiO2催化剂氧化活性明显好于单独含Cu、Ce的催化剂,当Cu、Ce摩尔比为Cu:Ce=1:2时,CuCeOx/TiO2催化剂氧化活性最好,在NO浓度500×10-6,O2 10%,空速为24 000 h-1,350℃时,NO氧化度为0.62;添加Mn元素可以提高CuCeOx/TiO2催化剂低温氧化活性, 250℃时,MnCuCe/Ti-3和MnCuCe/Ti-5催化剂氧化度为0.53和0.69,300℃时,MnCuCe/Ti-3和MnCuCe/Ti-5催化剂氧化度均为0.76;此外,实验还研究了NO在MnCuCe/Ti-3催化剂上反应的动力学方程.     

K2S2O8氧化吸收NO的热力学与传质分析

一氧化氮（NO）是燃煤锅炉烟气中的主要污染物,因其是酸雨和光化学烟雾的前体物而受到广泛关注。采用K2S2O8作为氧化剂开展了其对模拟烟气中NO的氧化去除研究,并分析了K2S2O8氧化脱硝反应的热力学过程以及NO从气相主体到液相主体的传质过程。结果显示：以K2S2O8为氧化剂氧化NO的总反应吉布斯自由能为-659.69 kJ·mol-1,小于零,说明该反应是自发过程;气液传质分析表明NO气体的吸收传质速率主要由液膜控制。实验采用添加Fe （Ⅱ） EDTA的方法增大化学反应对液相传质速率的放大系数,致使液膜传质阻力减小,从而使NO的去除率从30%提高至91.6%。该结果为K2S2O8湿法氧化脱硝工艺的后续研究和应用提供了理论参考和技术支持。     

咪唑类离子液体对油基钻屑的处理

合成3种结构和性质呈规律性递变的离子液体1-烷基-3-甲基咪唑溴化盐[CnMIm]Br（n=8、10、12）,作为萃取剂替代有机溶剂用于油基钻屑的萃取处理。研究了离子液体结构对油去除率的影响规律,发现随着阳离子烷基链长的增加,油去除率提高。通过考察离子液体种类、加量、萃取时间及pH值等对萃取效果的影响,优选[C12MIm]Br为最佳萃取剂,油基钻屑与萃取液质量比为1：1、pH大于7时,萃取在20 min时就可以达到平衡,油基钻屑中油去除率大于85%,离子液体吸附损失率小于1%,分离后的离子液体可直接重复利用6次。     

Identification and quantification of methyl halide sources in a lowland tropical rainforest

In conjunction with the OP3 campaign in Danum Valley, Malaysian Borneo, flux measurements of methyl chloride (CH₃Cl) and methyl bromide (CH₃Br) were performed from both tropical plant branches and leaf litter in June and July 2008. Live plants were mainly from the Dipterocarpaceae family whilst leaf litter samples were representative mixtures of different plant species. Environmental parameters, including photosynthetically-active radiation, total solar radiation and air temperature, were also recorded. The dominant factor determining magnitude of methyl halide fluxes from living plants was plant species, with specimens of the genus Shorea showing persistent high emissions of both gases, e.g. Shorea pilosa: 65 ± 17 ng CH₃Cl h^?1 g^?1 (dry weight foliage) and 2.7 ± 0.6 ng CH₃Br h^?1 g^?1 (dry weight foliage). Mean CH₃Cl and CH₃Br emissions across 18 species of plant were 19 (range, <LOD ?76) and 0.4 (<LOD ?2.9) ng h^?1 g^?1 respectively; fluxes from leaf litter were 1–2 orders of magnitude smaller per dry mass. CH₃Cl and CH₃Br fluxes were weakly correlated. Overall, the findings suggest that tropical rainforests make an important contribution to global terrestrial emissions of CH₃Cl, but less so for CH₃Br.     

An Empirical, Quantitative Approach to Predict the Reactivity of Some Substituted Aromatic Compounds Towards Reactive Radical Species (Cl2-·, Br2-·, ·NO2, SO3-·, SO4-·) in Aqueous Solution (3 pp)

The Hammett approach, applied to the reaction of various classes of aromatic compounds with the radicals Cl2-*, Br2-*, *NO2, SO3-*, and SO4-* yielded good predictive models, supported by high values of the correlation coefficient r2 in the case of phenols with Cl2-* and of phenolates with *NO2 and SO3-*. Lower but statistically significant correlation coefficients could be obtained for benzoates with Cl2-*, phenolates with Br2-*, and benzoates and anisoles with SO4-*.     

Expression alterations of cytochromes P4501A1, 2E1, and 3A,and their receptors AhR and PXR caused by 1-octyl-3-methylimidazolium chloride in mouse mammary carcinoma cells

Cytochrome P450s (CYPs) play a key role in the metabolism of a wide range of environmental xenobiotics and endogenous compounds. The expression and activity levels of CYPs can be elevated by a process of induction involving the activation of nuclear receptors. The effects of the ionic liquid 1-octyl-3-methylimidazolium chloride ([C₈mim][Cl]) on the expression of cytochrome P450 members, including CYP1A1, CYP2E1, and CYP3A, as well as on aryl hydrocarbon receptor (AhR) and pregnane X receptor (PXR) in mouse mammary carcinoma cells (EMT6) were investigated by using quantitative real-time PCR in the present study. The results reveal that [C₈mim][Cl]-exposure up-regulates the expressions of CYP1A1, CYP2E1, and CYP3A at mRNA level, suggesting that imidazolium-based ionic liquids can activate CYPs. Our results also suggest that [C₈mim][Cl]-mediated CYP3A induction be PXR-dependent. This result may be beneficial to evaluating the environmental toxicity of imidazolium-based ionic liquids and investigating the metabolism of imidazolium-derivative drugs.     

Simultaneous conversion of CHClF(2) and CH(3)Br to CH(2)CF(2)

Gas phase reaction of CHClF(2) with CH(3)Br in an alumina tube reactor at 773-1123 K as a function of various input ratios of CH(3)Br to CHClF(2) is presented. The major products detected include C(2)F(4), CH(2)CF(2), and CH(4). Minor products include CH(3)Cl, CHF(3), C(2)H(4), C(2)H(2), CH(2)CF-CF(3), and C(2)H(3)F. The reaction produces a high yield of CH(2)CF(2) (53% based on CHClF(2) feed) at 1123 K and an input molar ratio of CH(3)Br to CHClF(2) of 1.8, suggesting that the reaction potentially can be developed as a process to convert two ozone depleting substances (CHClF(2) and CH(3)Br) to a highly valuable chemical, CH(2)CF(2). The reaction of CHClF(2) with CH(3)Cl and CH(3)I was also investigated under similar reaction conditions, to assist in understanding the reaction chemistry involved in the reaction of CHClF(2) with CH(3)Br.     

Ionic composition of PM(10) in the area of Thessaloniki,Greece

Airborne particulate matter (PM(10)) was collected from July 1997 to July 1998 at three locations in the city of Thessaloniki. PM(10) samples were analyzed for Cl(-), NO3(-), SO4(2-), Ca(2+), Mg(2+), Na(+), K(+) and NH4(+). The average PM(10) concentrations were found similar in all three sites with higher values in cold period. The ionic content comprised the 17-23% of the PM(10) mass and sulfate made up the 35-38% of the PM(10) ionic content with an average concentration of 4.80-7.26 microg m(-3). Good correlation was found for SO4(2-) and NO3(-) with Ca(2+), Mg(2+) and Cl(-). Two factors were found to influence the variance of ionic constituents in PM(10) by using factor analysis. Data evaluation considering wind direction showed that higher PM(10) and other ionic concentrations are associated with calm conditions, suggesting influences of local sources.     

新型MnOx/CNTs催化剂低温选择性催化还原NO

采用等体积浸渍法制备了MnOx/CNTs催化剂,用于低温NH3选择性催化还原（SCR）NO的实验。使用BET,FT-IR,TEM和XRD对催化剂进行表征,结果表明：碳纳米管经混酸超声分散,增加了羧基活性基团,锰氧化物颗粒分布较均匀。在模拟烟气条件下,考察了催化剂的MnOx负载量、煅烧温度及质量和烟气流速比（W/F）对NO脱除率的影响。煅烧温度为773 K,MnOx负载量为10%时,NO脱除率达到98.56%;W/F为2-3 mg/（mL·min^-1）时NO的脱除率更高。     

Kinetics and mechanism of nitrite oxidation by hypochlorous acid in the aqueous phase

The rate coefficient for the reaction of nitrite with hypochlorite and hypochlorous acid has been studied using spectrophotometric measurements. The reaction rate has been determined in a wide range of H(+) concentration (5< or =-log[H(+)]< or =11). The kinetics were carried out as a function of NO(2)(-), H(+) and total hypochlorite ([HOCl](total)=[HOCl]+[ClO(-)]+[ClNO(2)]) concentrations. The observed overall rate law is described by: -d[HClO](T)dt=[a[NO(2)(-)](2)+b[NO(2)(-)]][H(+)](2)c+d[H(+)]+e[NO(2)(-)][H(+)](2)[HOCl](total)At T=298 K and in Na(2)SO(4) at an ionic strength (I=1.00 M), we obtained using a nonlinear fitting procedure: a=(1.83+/-0.36)x10(7) s(-1), b=(1.14+/-0.23)x10(5) Ms(-1), c=(1.12+/-0.17)x10(-13) M, d=(1.43+/-0.29)x10(-6) M(2) and e=(1.41+/-0.28)x10(3) M where the errors represent 2sigma. According to the overall rate law, a/b=k(1)/k(3), b/e=k(3), c=K(w), d/c=K(a), d=K(a)K(w) and e=K(1)K(a). In Na(2)SO(4) at an ionic strength (I=1.00 M), the values of K(1) and K(a) are (1.1+/-0.1)x10(-4) and 1.28x10(7) M(-1), respectively. A mechanism is proposed for the NO(2)(-) oxidation which involves the reversible initial step: NO(2)(-)+HOCl left harpoon over right harpoon ClNO(2)+OH(-) (K(1)), while ClNO(2) undergoes the two parallel reactions: attack by NO(2)(-) (k(1)) and hydrolysis (k(3)). ClNO(2) and N(2)O(4) are proposed as important intermediates as they control the mechanism. The rate coefficients k(1) and k(3) have been determined at different ionic strengths in NaCl and Na(2)SO(4). The influence of the ionic strength and ionic environment has been studied in this work.     

Halogen production from aqueous tropospheric particles

Box model studies have been performed to study the role of aqueous phase chemistry with regard to halogen activation for marine and urban clouds and the marine aerosol as well. Different chemical pathways leading to halogen activation in diluted cloud droplets and highly concentrated sea salt aerosol particles are investigated. The concentration of halides in cloud droplets is significantly smaller than in sea-salt particles, and hence different reaction sequences control the overall chemical conversions. In diluted droplets radical chemistry involving OH, NO(3), Cl/Cl(2)(-)/ClOH(-), and Br/Br(2)(-)/BrOH(-) gains in importance and pH independent pathways lead to the release of halogens from the particle phase whereas the chemistry in aerosol particles with high electrolyte concentrations is controlled by non-radical reactions at high ionic strengths and relatively low pH values.For the simulation of halogen activation in tropospheric clouds and aqueous aerosol particles in different environments a halogen module was developed including both gas and aqueous phase processes of halogen containing species. This module is coupled to a base mechanism consisting of RACM (Regional Atmospheric Chemistry Mechanism) and the Chemical Aqueous Phase Radical Mechanism CAPRAM 2.4 (MODAC-mechanism). Phase exchange is described by the resistance model by Chemistry of Multiphase Atmospheric Systems, NATO ASI Series, 1986.It can be shown that under cloud conditions the bromine atom is mainly produced by OH initiated reactions, i.e. its concentration maximum is reached at noon. In contrast, the concentration level of chlorine atoms is linked to NO(3) radical chemistry leading to a smaller amplitude between day and night time concentrations.The contribution of radical processes to halogen atom formation in the particle phase is evident, e.g. by halogen atoms which undergo direct phase transfer. Furthermore, the application of the multiphase model for initial concentrations for sea-salt aerosols shows that the particle phase can act as a main source of halogen containing molecules (Cl(2), BrCl, Br(2)) which are photolysed in the gas phase to yield halogen atoms (about 70% of all Cl sources and more than 99% for Br).     

A laser flash photolysis study of the decay of SO4- and Cl2- radical anions in the presence of Cl- in aqueous solutions

The rate constant for the reaction of sulphate radical (SO4-) with Cl- has been determined using laser photolysis, at 248 nm, of peroxodisulphate anions to produce the radicals and time resolved optical absorption of the transient species (at 450 or 480 nm for SO4- and 350 nm for Cl2-) for the kinetic determinations. The experiments were performed, in the absence of added sulphate, as a function of temperature and ionic strength and yielded (at an ionic strength of 0.0157 M): kIV = (9.90+/-0.16) x 10(9) exp((-7.12+/-2.0) kJ mol(-1)/RT) M(-1) s(-1), where the errors reflect the 2sigma statistical error. This reaction produces Cl2-, the formation and decay of which were also monitored allowing a determination of the rate constant of its second-order self-recombination reaction which gave k = (6.50+/-1.40) x 10(8) M(-1) s(-1) at 293 K and zero ionic strength.     

Observed trends for CF3-containing compounds in background air at Cape Meares, Oregon, Point Barrow, Alaska, and Palmer Station, Antarctica

The concentrations of CF(3)-containing compounds in archived air samples collected at Cape Meares, Oregon, from 1978 to 1997, at Point Barrow, Alaska, from 1995 to 1998, and at Palmer Station, Antarctica, from 1991 to 1997, were determined by high resolution gas chromatography and high resolution mass spectrometry. The CF(3)-containing compounds measured by this method and discussed here are: the perfluorinated compound, C(3)F(8) (FC 218); four perhalogenated compounds, CF(3)Cl (CFC 13), CF(3)CF(2)Cl (CFC 115), CF(3)CFCl(2) (CFC 114a), and CF(3)Br (Halon 1301); and three hydrofluorocompounds, CF(3)H (HFC 23), CF(3)CH(3) (HFC 143a), and CF(3)CH(2)F (HFC 134a). For four of these compounds, very few measurements have been previously reported. The atmospheric concentrations of all of the CF(3)-containing compounds continuously increased in time over the sample collection periods. From these data, the annual rates of emission into the atmosphere have been estimated. The emission rates fall into one of three distinct categories. The annual emission rates of C(3)F(8), CF(3)H, CF(3)CH(3), and CF(3)CH(2)F have continuously increased over the last two decades. That of CF(3)CFCl(2) has decreased continuously. Emission rates for CF(3)Cl, CF(3)CF(2)Cl, and CF(3)Br reached maximum levels in the late 1980s, and have been decreasing in the 1990s. The emission rates of C(3)F(8), CF(3)CH(3) and CF(3)CH(2)F were nearly zero 20 years ago but have increased rapidly during the last decade.