The Hygienic Aspects of the Production and Use of Lead Antiknock Compounds

Hydrogen sulfide and other sulfides can be determined in the part per billion range in air if the air is bubbled through an absorption mixture of an alkaline suspension of cadmium hydroxide contained in a macro impinger. Rates as high as 1 cubic foot per minute can be used, or 0.1 cubic foot per minute with a midget impinger. The concentration of the trapped sulfides is then estimated by the methylene blue method. A colorimetric method and a spectrophotometric method are described.     

Collection efficiency of a midget impinger for nanoparticles in the range of 3–100 nm

Impingers have been employed for collection of biological particles for a long time and the collection efficiency for submicron particles has been well studied for a few impinger models, like the SKC Biosampler and the AGI 30. These efficiency studies have been limited to particles larger than about 15 nm. The aim of this research is to determine the collection efficiency of ultrafine particles (from 3 to 100 nm) of a 25 ml midget impinger. The effect of different collection parameters (particle type, collection fluid volume and type and flow rate) was studied and results are presented here. All results showed minimum collection efficiencies from 3 to 10% at approximately 40–57 nm. Increasing the volume of the collection liquid and flow rate improved the collection efficiency of the impinger.     

Evaluation of an Ion Selective Electrode Monitor for Total Oxidants

The iodide ion selective electrode has potential use for continuous monitoring of total oxidants in ambient air. Total oxidants are measured coulometrically or colorimetrically after oxidation of neutral buffered Kl solution (0.6-1.2M) to free iodine. On the other hand, the iodide electrode can measure much more dilute solutions (<10^-4M). The iodide electrode measures the disappearance of iodide from the absorbing solution. The detector is made from an iodide electrode, reference electrode, an expanded scale pH meter, and millivolt recorder. The iodide electrode shows a constant Nernstian —59 mv change per decade over a dilute solution range although the absolute voltage shows a drift of 1 mv/day. A continuous iodide electrode air monitor was set up and investigated for ambient monitoring. Operational parameters as air and solution flow rates and electrode parameters as response time at different iodide concentrations were investigated. Statistical comparison was made with a Beekman colorimetric total oxidant monitor and a prototype REM chemiluminescent ozone monitor. The iodide electrode monitor was shown capable of continuously monitoring oxidants in the atmosphere being sensitive to changes in ambient concentrations.     

The Determination of Formaldehyde,Acrolein, and Low Molecular Weight Aldehydes in Industrial Emissions on a Single Collection Sample

Formaldehyde, acrolein, and low molecular weight aldehydes are collected in 1% NaHSO₃ solution in Greenberg-Smith or midget impingers from industrial effluents. Efficiency of collection is excellent when two impingers are used in series. Formaldehyde is measured in an aliquot of the collection medium by the chromo-tropic acid procedure, acrolein by a modified mercuric-chloride-hexylresorcinol procedure, and C₂-C₅ aldehydes by a gas chromatographic procedure. The method permits the analysis of all C₁-C₅ aldehydes on a single collection sample. Data on aldehyde concentrations from a variety of effluents are presented.     

Integrated Sampling and Analysis Methods for Determining NO x Emissions at Electric Utility Plants

Two integrated sampling and analysis methods for determining NO_x emissions in electric utility plants were developed and field tested. The collection systems consist of: a 4.0% potassium permanganate-2.0% sodium hydroxide solution in restricted-orifice impingers, and a 5A° molecular sieve in midget impingers. Sample analysis is accomplished by a colorimetric or ion-chromatographic procedure with the alkaline-permanganate method and by a colorimetric procedure with the molecular sieve method. The alkalinepermanganate method gives excellent agreement with the EPA reference method, Method 7, for NO _x measurements. The molecular sieve method shows a significant negative bias relative to Method 7. It is anticipated that the permanganate methods will be proposed as alternates to Method 7, for NO _x determinations, under the EPA New Source Performance Standards.     

Atmospheric H2O2 measurement: comparison of cold trap method with impinger bubbling method.

Collection of atmospheric H2O2 was performed by a cold trap method using dry ice-acetone as the refrigerant. The air was drawn by a pump into a glass gas trap immersed in the dry ice-acetone slush in a dewar flask at a flow rate of 2.5 l min-1 for approximately 2 h. Collection efficiency was > 99% and negligible interferences by O3, SO2 or organic matter with the collected H2O2 in the trap were observed. This method was compared with the air impinger bubbling method which has been previously described (Kok et al., 1978a, b, Envir. Sci. Technol. 12, 1072-1080). The measured total peroxide (H2O2 + organic peroxide) values in a series of aim samples collected by the impinger bubbling method (0.06-3.7 ppb) were always higher than those obtained by the cold trap method (0.02-1.2 ppb). Laboratory experiments suggest that the difference in values between the two methods probably results from the aqueous phase generation of H2O2 and organic peroxide in the impinger solution by a reaction of atmospheric O3 with olefinic and aromatic compounds. If these O3-organic compound reactions which occur in the impinger also occur in aqueous droplets in the atmosphere, the process could be very important for aqueous phase generation of H2O2 in clouds and rainwater.     

Particle-Molecule Collection by Sonic Flow Impingers

The information presented in this paper is directed to those industrialists and researchers interested in molecule and near micron and submicron particle sampling by a convenient, inexpensive, and sufficiently accurate method. The use of two sonic flow impingers in series is predicted to collect 98-99% of a phosphoric acid aerosol having a mass median diameter of 0.7 p. The first impinger of a new design is shown, in field sampling, to collect simultaneously 90-98% of the aerosol and 95% of molecular fluoride compounds. On the same aerosol, the standard Greenburg-Smith impinger shows a low collection performance, less than 50% at 1 cfm and 65% at sonic velocity. The use of a first impinger at sonic flow greatly simplifies sampling procedures by eliminating the need for a test meter and associated pressure and temperature measurements. Also, for small particle sizes isokinetic sampling is not necessary and sampling line losses by deposition are shown to be less than 1%. The low initial cost of the sampling units and the low manpower requirements for setting up and supervising sampling make possible the taking of a number of samples sufficient to establish emissions over extended intervals of time. The equipment is especially suited to locations having multiple emission sources, or for locations requiring simultaneous sampling of many points.     

Hot Filter/Impinger and Dilution Sampling for Fine Particulate Matter Characterization from Ferrous Metal Casting Processes

Abstract

A study using two stack-sampling methodologies for collecting particulate matter (PM) emissions was conducted using a hot filter followed by a cold impinger sampling train and a dilution sampler. Samples were collected from ferrous iron metal casting processes that included pouring molten iron into a sand mold containing an organic binder, metal cooling, removal of the sand from the cooled casting (shakeout), and postshakeout cooling. The shakeout process contributed more to PM emissions than the metal pouring and cooling processes. Particulate matter less than 2.5 μm in aerodynamic diameter (PM_2.5) mass emissions for the entire casting cycle ranged from 3.4 to 4.7 lb/t of metal for the hot filter/impinger method and from 0.8 to 1.8 lb/t of metal for the dilution method. Most of the difference was due to PM captured by the impingers, much of which was probably dissolved gases rather than condensable vapors. Of the PM fraction captured by the impingers, 96–98% was organic in nature. The impinger PM fraction contributed 32–38% to the total suspended particle mass and caused a factor of 2–4 positive bias for PM_2.5 emissions. For the pouring and cooling processes only, the factor increased to over seven times.     

Issues Related to Solution Chemistry in Mercury Sampling Impingers

ABSTRACT

Analysis of Hg speciation in combustion flue gases is often accomplished in standardized sampling trains in which the sample is passed sequentially through a series of aqueous solutions to capture and separate oxidized Hg (Hg²⁺) and elemental Hg (Hg⁰). Such methods include the Ontario Hydro (OH) and the Alkaline Mercury Speciation (AMS) methods, which were investigated in the laboratory to determine whether the presence of Cl₂ and other common flue gas species can bias the partitioning of Hg⁰ to front impingers intended to isolate Hg²⁺ species. Using only a single impinger to represent the front three impingers for each method, it was found that as little as 1-ppm Cl₂ in a simulated flue gas mixture led to a bias of approximately 10-20% of Hg⁰ misreported as Hg²+ for both the OH and the AMS methods. Experiments using 100-ppm Cl₂ led to a similar bias in the OH method, but to a 30-60% bias in the AMS method. These false readings are shown to be due to liquid-phase chemistry in the impinger solutions, and not necessarily to the gas-phase reactions between Cl₂ and Hg as previously proposed. The pertinent solution chemistry causing the interference     

Issues related to solution chemistry in mercury sampling impingers

Analysis of Hg speciation in combustion flue gases is often accomplished in standardized sampling trains in which the sample is passed sequentially through a series of aqueous solutions to capture and separate oxidized Hg (Hg2+) and elemental Hg (Hg0). Such methods include the Ontario Hydro (OH) and the Alkaline Mercury Speciation (AMS) methods, which were investigated in the laboratory to determine whether the presence of Cl2 and other common flue gas species can bias the partitioning of Hg0 to front impingers intended to isolate Hg2+ species. Using only a single impinger to represent the front three impingers for each method, it was found that as little as 1-ppm Cl2 in a simulated flue gas mixture led to a bias of approximately 10-20% of Hg0 misreported as Hg2+ for both the OH and the AMS methods. Experiments using 100-ppm Cl2 led to a similar bias in the OH method, but to a 30-60% bias in the AMS method. These false readings are shown to be due to liquid-phase chemistry in the impinger solutions, and not necessarily to the gas-phase reactions between Cl2 and Hg as previously proposed. The pertinent solution chemistry causing the interference involves the hypochlorite ion (OCl-), which oxidizes Hg0 to soluble Hg2+. Addition of sodium thiosulfate (Na2S2O3) to the front impinger solutions eliminates this false positive measurement of Hg2+ by selectively reacting with the OCl- ion. In general, the presence of SO2 also mitigates this interference in the same way, and so this bias is not likely to be a factor for Hg speciation measurements from actual coal combustion flue gases. It might, however, be a problem for those few combustor flue gas measurements and research studies where Cl2 is present without appreciable amounts of SO2.     

Ambient Oxidant Exposure andHealth Costs in the United States—1973

The body of information presented in this paper is directed to policy makers and administrators involved in the evaluation and assessment of damages caused by oxidant air pollution on human health and welfare and of possible benefits of control.

To provide a comparison of some of the benefits that can be obtained by reducing photochemical oxidant levels, estimated health costs were derived from data relating adverse health effects to hourly oxidant concentrations. Hourly oxidant or ozone concentrations were measured at approximately 400 monitoring stations scattered throughout the U.S. Most of these sites were located in major urban areas or in other areas where high oxidant concentrations prevailed. Estimates of populations at risk and per capita health costs were generated for those areas where oxidant data was available.

During the period 1971-1973, nearly two-thirds of the U.S. population resided in areas where the hourly primary standard for oxidants of 160 µg/m³ was exceeded. The total annual health cost attributable to oxidants was estimated to range from $120 to over $240 million in the U.S.     

The Effect of Rapid Transit on San Francisco Bay Air Quality

Classical procedures for the microdetermination of fluoride in vegetation are extremely time consuming. They generally involve ashing, fusion with alkali, distillation, and finally fluoride estimation. Sample size requirements for such procedures are on the order of a gram or more, making the procedure useless for determining low fluoride concentrations in small samples. A procedure for micro-fluoride determination in vegetation is proposed which utilizes the oxygen flask combustion technique (Schoniger flask). The gaseous products of combustion are absorbed in 10.0 ml of 0.05N sodium hydroxide containing 1.00 µg of fluoride. The analysis of the fluoride is performed directly on the absorption solution after addition of a combination complexing-buffer solution, using a specific fluoride ion electrode. The sensitivity of the electrode is such that 0.2 µg of fluoride can be easily detected in this volume. Added oxidant was required in the combustion step for some vegetation samples to completely free the fluoride from its organic matrix. Comparisons with the standard Willard-Winter procedure gave excellent results. Combustion of sodium fluoride standards as well as submicrogram quantities of a fluoro-organic compound showed recoveries greater than 90%. The direct combustion, coupled with fluoride ion electrode determination, reduces analysis time drastically. A complete analysis can be performed in 1/2 hr, with a minimum amount of equipment.     

Evaluation of Probes Used for Source Sampling of Hydrogen Fluoride

The body of information presented in this paper is directed to those individuals concerned with methods for the sampling and measurement of fluorides contained in stack gases produced during the manufacture of phosphate fertilizer or aluminum. An air stream containing gaseous hydrogen fluoride (HF), at concentrations of from 87 to 1700 µg F m^-3, was generated and passed through 193 to 198 cm lengths of Pyrex glass, type 316 stainless steel, TFE Teflon, and methyl methacrylate-coated aluminum probes at flow rates of 28 I min^-1. HF passing through the probes was collected in deionized water contained in a Greenburg-Smith impinger. The Teflon probe exhibited no loss of HF and no trend toward increased passage of HF with time. Significant amounts of fluoride were lost in 18 out of 20 tests with the methacrylate probe and in 4 out of 20 tests with the Pyrex and stainless steel probes. Trends toward increased passage of HF with time occurred with the latter three probe materials. The selective ion electrode and semiautomated methods gave equivalent results when samples were made alkaline to avoid sorption of fluoride by Tygon tubing used in the semiautomated method. These results demonstrated that a Teflon probe gave the most representative sample of gaseous HF. However, additional tests are needed before a final recommendation is made for a probe to sample fluorides in stack gases.     

Photochemical Reactivities of Paraffinic Hydrocarbon-Nitrogen Oxide Mixtures Upon Addition of Propylene or Toluene

Effects associated with photochemical air pollution were measured during irradiation of n-butane-nitrogen oxide or n-butane-ethane-nitrogen oxide mixtures, with small amounts of propylene or toluene added. The effects measured including nitrogen dioxide and oxidant dosages, yields of formaldehyde and peroxy-acetyl nitrate, and eye irritation response. The results obtained clearly show that beneficial effects result from selective changes in hydrocarbon composition as well as from reduction of total hydrocarbon concenfration. Exclusion of olefins and alkylbenzenes was highly effective in reducing oxidant dosage, formaldehyde and peroxyacetyl nitrate concentrations, and eye irritation response. The only penalty was a modest increase in nitrogen dioxide dosage. A large reduction in nitrogen oxide concentration reduced nitrogen dioxide dosage and eye irritation response, but with the penalty of a large increase in oxidant dosage. The desirability of preferentially reducing olefins and alkylbenzenes rather than paraffinic hydrocarbons, acetylene, and benzene is strongly supported by this study. Research and development efforts should be directed toward preferential hydrocarbon control by mechanical or catalytic control     

Measurements of Primary Sulfates with an Acid Condensation System

Two techniques were used to measure primary sulfuric acid and sulfate emissions from two small package boilers burning nominal 0.3% sulfur fuels, one with 11 ppm vanadium and one with 4.3 ppm vanadium. Several of the particulate fractions from both sampling methods were analyzed for sulfuric acid using a selective solvent determination (SSD) procedure. The sulfuric acid present on the filters accounted for a minimum of 11% of the particulate emission rates. The observed conversion of sulfur dioxide to primary sulfate or primary sulfuric acid is reduced considerably when sulfate ion detected in an isopropanol impinger is attributed to sulfur dioxide conversion in the solution rather than to primary sulfuric acid. An additional reduction occurs when the method of calculating the conversion is based solely on sulfur weight. This study gives a fourfold reduction in percent conversion when compared to a similar study conducted earlier. Suggestions are offered for improvements in measurement methods and for a consistent technique for calculating sulfur conversion.     

Hot filter/impinger and dilution sampling for fine particulate matter characterization from ferrous metal casting processes

A study using two stack-sampling methodologies for collecting particulate matter (PM) emissions was conducted using a hot filter followed by a cold impinger sampling train and a dilution sampler. Samples were collected from ferrous iron metal casting processes that included pouring molten iron into a sand mold containing an organic binder, metal cooling, removal of the sand from the cooled casting (shakeout), and postshakeout cooling. The shakeout process contributed more to PM emissions than the metal pouring and cooling processes. Particulate matter less than 2.5 microm in aerodynamic diameter (PM2.5) mass emissions for the entire casting cycle ranged from 3.4 to 4.7 lb/t of metal for the hot filter/impinger method and from 0.8 to 1.8 lb/t of metal for the dilution method. Most of the difference was due to PM captured by the impingers, much of which was probably dissolved gases rather than condensable vapors. Of the PM fraction captured by the impingers, 96-98% was organic in nature. The impinger PM fraction contributed 32-38% to the total suspended particle mass and caused a factor of 2-4 positive bias for PM2.5 emissions. For the pouring and cooling processes only, the factor increased to over seven times.     

Consultant Guide/1986

ABSTRACT

To obtain annual odor emission profiles from intensive swine operations, odor concentrations and emission rates were measured monthly from swine nursery, farrowing, and gestation rooms for a year. Large annual variations in odor concentrations and emissions were found in all the rooms and the impact of the seasonal factor (month) was significant (P < 0.05). Odor concentration was low in summer when ventilation rate was high but high in winter when ventilation rate was low, ranging from 362 (farrowing room in July) to 8934 (nursery room in December) olfactory unit (OU) m^?3. This indicates that the air quality regarding odor was significantly better in summer than that in winter. Odor emission rate did not show obvious seasonal pattern as odor concentration did, ranging from 2 (gestation room in November) to 90 (nursery room in April) OU m^?2 sec^?1; this explains why the odor complaints for swine barns have occurred all year round. The annual geometric mean odor concentration and emission rate of the nursery room was significantly higher than the other rooms (P < 0.05). In order to obtain the representative annual emission rate, measurements have to be taken at least monthly, and then the geometric mean of the monthly values will represent the annual emission rate. Incorporating odor control technologies in the nursery area will be the most efficient in reducing odor emission from the farm considering its emission rate was 2 to 3 times of the other areas. The swine grower-finisher area was the major odor source contributing 53% of odor emission of the farm and should also be targeted for odor control. Relatively positive correlations between odor concentration and both H₂S and CO₂ concentrations (R ² = 0.58) means that high level of these two gases might likely indicate high odor concentration in swine barns.

IMPLICATIONS The emissions of air pollutants including odors, greenhouse gases, and toxic gases have become a major environmental issue facing animal farms in the U.S.A. and Canada. To ensure the air quality in the vicinity of intensive livestock farms, air dispersion models have been used to determine setback distances between livestock facilities and neighboring residences based on certain air quality requirement on odor and gases. Due to the limited odor emission data available, none of the existing models can take account of seasonal variations of odor emissions, which may result in great uncertainties in setback distance calculations. Therefore, the obtained seasonal odor and gas emission rates by this study can be used by the government regulatory organizations and researchers in air dispersion modeling to get improved calculation of setback distances.     

Stack Dust Sampling: in-Stack Filter or E.P.A. Train

The Environmental Protection Agency has recommended or specified methods for the measurement of participate concentrations in flue gases. The EPA Train for this measurement originally comprised two segments: the front half and the impinger train downstream from the filter proper. This review examines the controversial areas implicit in the use of this EPA Train or the revised EPA train which eliminates the impinger train.     

Degradation Kinetics of Biofilter Media Treating Reduced Sulfur Odors and VOCs

ABSTRACT

A lab-scale study was conducted to determine the rate and extent of decomposition of three biofilter media materials—compost, hog fuel, and a mixture of the two in 1:1 ratio—used in biofiltration applied to removal of reduced sulfur odorous compounds from pulp mill air emissions. The rate of carbon mineralization, as a measure of biofilter media degradation, was determined by monitoring respiratory CO₂ evolution and measuring the changes in carbon and nitrogen fractions of the biofilter materials over a period of 127 days. Both ambient air and air containing reduced sulfur (RS) compounds were used, and the results were compared. After 127 days of incubation with ambient air, about 17% of the media carbon was evolved as CO₂ from compost as compared to 6 and 12% from hog fuel and the mixture, respectively. The decomposition showed sequential breakdown of carbon moieties, and three distinct stages were observed for each of the biofilter media. First-order rate kinetics were used to describe the decomposition stages. Decomposition rates in the initial stages were at least twice those of the following stages. Carbon mineralization showed close dependence on the C/N ratio of the biofilter material. Media decomposition was enhanced in the presence of RS gases as a result of increased bioactivity by sulfur-oxidizing bacteria and other microorganisms, thus reducing the media half-life by more than 50%. At higher concentrations of RS gases, the CO₂ evolution rates were proportionally lower than those at the low concentrations because of the limited acid buffering capacity of the biofilter materials.     

A rapid spectrophotometric determination of persulfate anion in ISCO

Due to a gradual increase in the use of persulfate as an in situ chemical oxidation (ISCO) oxidant, a simple measurement of persulfate concentration is desirable to analyze persulfate distribution at designated time intervals on/off a site. Such a distribution helps evaluate efficacy of ISCO treatment at a site. This work proposes a spectrophotometric determination of persulfate based on modification of the iodometric titration method. The analysis of absorption spectra of a yellow color solution resulting from the reaction of persulfate and iodide in the presence of sodium bicarbonate reveals an absorbance at 352 nm, without significant interferences from the reagent matrix. The calibration graph was linear in the range of persulfate solution concentration of 0-70 mM at 352 nm. The proposed method is validated by the iodometric titration method. The solution pH was at near neutral and the presence of iron activator does not interfere with the absorption measurement. Also, analysis of persulfate in a groundwater sample using the proposed method indicates a good agreement with measurements by the titration method. This proposed spectrophotometric quantification of persulfate provides a simple and rapid method for evaluation of ISCO effectiveness at a remediation site.