Activated Charcoal Filters Research Articles

Chromatograph with external column evaluated for determining breath hydrogen in clinical studies.

A novel breath-hydrogen analyzer involving an external chromatographic column in the form of a cartridge packed with molecular-sieve material and dessicant is described. The instrument incorporates a sintered SnO2 solid-state sensor into the detector, which registers a change in electrical potential in response to the adsorption of reducing gases; ambient room air is drawn through an activated charcoal filter by a small, internal pump and used as the carrier gas. Once calibrated with a gas of known H2 concentration, a digital meter registers the concentration of H2 in an unknown sample of breath air. The response is linear with concentration up to 160 microL/L. The external column is both necessary and effective for screening out contaminating reducing gases. The correlation coefficient for 250 gas samples measured simultaneously with an external-cartridge instrument and with an internal column chromatography is greater than 0.99. Results by the new analyzer corresponded 100% with those by the conventional machine for detecting carbohydrate malabsorption; for diagnosing efficient carbohydrate absorption, results by the two instruments agreed for 96% of the tests.

Activated charcoal filter counting for radioiodine effluent concentration determination in protein iodinations.

Regulatory agencies have recently placed emphasis upon quantification of 125I released to the environment during protein iodinations at radioiodination facilities. This necessitates air sampling in order to determine the concentration of 125I in the effluent. Air sample trapping mechanisms generally employed are activated charcoal filters. Difficulty arises in quantifying the activity of 125I trapped because of the attenuation of the 125I decay photons by the charcoal. Evaluation of the activity incident upon commercially available filters using a scintillation detector and large detector source separation is considered here. It is demonstrated that the activity in the filter may be treated as an exponential distribution within an attentuating matrix. This treatment essentially adds a constant correction factor to the counting efficiency of a given geometry for a filter-affluent flow rate combination. Finally, it is shown that an approximation assuming a uniform distribution of activity produces a large error in correction factor to the counting efficiency for the filters examined.

A behaviorally relevant component of the scent signals of male Tupaia belangeri: 2,5-dimethylpyrazine

1 Male tree-shrews (Tupaia belangeri) produce odor substances that trigger marking with the jugulosternal gland (chinning) in conspecifics. The chinning responses to the odor substances of castrates and to those of fertile males differ quantitatively. 2. The odor substances can be collected by accumulation on an activated-charcoal filter and subsequent extraction with suitable solvents. Gaschromatographic analysis of such samples provides scent profiles that characterize the odor traits of the species and the sex. 3. The scent profiles of fertile and castrated males differ in the quantitative representation of their components. The most striking feature is the different contribution of 2,5-dimethylpyrazine to the two scent profiles; the concentration of this substance is ca. 100 times as great in samples from fertile males as in those from castrates. 4. The biogenesis of 2,5-dimethylpyrazine in male tree-shrews is androgen-dependent. In the chinning test 2,5-dimethylpyrazine enhances the stimulating action of the odor substances of castrated males when added in a suitable concentration. 5. The action of 2,5-dimethylpyrazine is highly specific. Other odor substances such as 2,3-dimethylpyrazine (synthetic isomere) or 3-hydroxy-2-butanone (unspecific tree-shrew odor component) cause no increase in chinning.

Environment in Open‐top Field Chambers Utilized for Air Pollution Studies

AbstractCylindrical open‐top chambers were established in an alfalfa field (Medicago sativa L.) 50 km north of Madison, Wis. Chambers were set up with and without activated charcoal filters. Environmental measurements were made at different times during the summer growing season. The environment of open‐top chambers was found to differ somewhat from open areas. Light intensity was as much as 20% lower, temperature increases as great as 2°C were measured, and evaporative water loss was 10% less in the chambers than open areas. The filtered and nonfiltered chambers had slightly different environments as a result of variations in air flow rates and dust accumulation in the plenums of the two types of chambers. Across the chambers, there was a gradient in light intensity and evaporative water loss, but no significant gradient in temperature or air velocity. There was no evidence of pollution injury to alfalfa in this study.The environmental changes in chambers were shown to cause differences in plant growth which likely caused changes in pollution sensitivity of plants within the chambers. However, it is postulated that this altered plant growth would likely not result in either a consistent increase or decrease in sensitivity at different times during the growing season or in different years. Thus, when open‐top chambers are utilized for the determination of crop yield losses, assessments should be based on studies conducted over several different growing periods.

Design against Weathering of Iodine Filters

Control of the release of radioactive iodine is an important task of the air filtration system in a nuclear installation. The filtration efficiency of an active charcoal filter for methyl iodide is shown to decrease due to the poisoning of the filter by secondary materials in the gas stream. A model is developed that appears to reproduce the decrease in filtration efficiency. Lack of detailed information on the poison-filter interaction prevents definitive confirmation of the model The model facilitates the choice of the optimum values of certain micro-structural and operational parameters of the filter, to reduce the effect of secondary poisons on the filter and thereby to lengthen the usable life of the filter. The microstructural properties addressed by the model are catalyst pellet size, porosity, surface area per gram, and pore radius. The operational parameters of the filter are the gas transit time and the gas diffusivity in the catalyst pores as controlled by the gas temperature.

A down-draft fume hood for the control of toxic vapours of heavy liquids used for mineral separations

An inexpensive, down-draft, canopy-type fume hood incorporating activated charcoal filters has been designed and built for the control and disposal of the fumes of heavy liquids such as diiodomethane used during the separation of specific minerals from their host rock matrices.

Method for Improving the Collecting Performance of Iodine Samplers under High Relative Humidity

In airborne radioiodine monitoring, it is essential to establish an effective sampling technique that gives results independent of the form taken by the radioiodine and that works effectively under high humidity. Experiments were made to improve the performance of an iodine sampler embodying (a) cellulose asbestos filter paper (Toyo Roshi, Type HE-40) and activated charcoal filter paper (Toyo Roshi, Type CP-20) and (b) HE-40 filter paper and activated charcoal cartridge (Toyo Roshi, Type CHC-50). Based on the results, a new sampler was devised in which the air is heated to 70°∼90°C before reaching the filters. The dependence of the collecting efficiency on the chemical form taken by the airborne iodine and also on the duration of sampling period was studied. Severe conditions of environment, such as high humidity, were simulated in the experimental apparatus. The airborne radioiodine used was a mixture of inorganic and organic iodides, identified by radio-gaschromatography. It was found that the collecting efficiency of the sampler with activated charcoal cartridge and the activated charcoal filter paper, respectively, exceeded 99.5% and 85%, regardless of the form of airborne iodine even at 100% relative humidity throughout the whole range of sampling duration up to 16 hr. Under conditions of high humidity, the collecting efficiencies were found superior to that of charcoal filter paper and charcoal cartridge impregnated with TEDA or SnI2 used without air heating.

Effect of Filtered Cigarette Smoke on Rats

THE gas phase of cigarette smoke (Cambridge and activated charcoal filter) has been shown to have a detrimental effect on several performance tests with rats, including swimming endurance1 and avoidance response2. The gas-vapour phase (Cambridge filter alone) had a significantly less toxic effect in these tests. These results were attributed to differences in respiration, in which breathing was apparently more inhibited by the irritants3 in the gas-vapour phase, resulting in a larger intake of toxic CO4 when the gas phase was presented alone. The purpose of this study was to test this hypothesis by measuring the respiratory response to these filter conditions, and to correlate this with %COHb measured immediately after “smoking”. As an index of respiratory dynamics, the breathing rate was used because it has been shown to be the most reliable and sensitive parameter5.

35. ヨウ素-131大量製造施設排気〓過装置の〓過性能

An air-cleaning system embodying activated charcoal filters was constructed for a large-scale 131I production facility at the Japan Atomic Energy Research Institute, for the purpose of removing 131I released continuously into the exhaust air stream from the production facility.The system was continuously operated for about 47 months, and changes in the removal efficiency of the 131I filter for the exhaust air stream was observed during this period.In one run of 131I production, the removal efficiency changed significantly, possibly due to a change in the chemical form of 131I released, accompanying the progress of the 131I production process.When operated at the maximum air flow rate of the filter, it showed an efficiency greater than 90% on the average over a period of 20 months.

26. 活性炭フィルタからのフロン(R-112)漏洩率測定に関する実験

This experimental study has been performed to obtain fundamental data for in situ tests of activated charcoal filters installed in reactor exhaust systems using R-112 as a tracer.The results have shown that the leakage flow less than 0.1% by channelings around gasket seals and the defects caused by settling in activated charcoal filters could be evaluated by analyzing the R-112 adsorption efficiency curves. Moreover, it was found that the very high adsorption of R-112 tracer on activated charcoal (more than 99.995%) was not affected by in situ test conditions such as temperature, humidity, flow velocity. These results agreed with those determined by the theoretical calculation, assuming that mass transfer through a gas film was the controlling factor in adsorption of R-112 by activated charcoal.

Biological effects of urban air pollution: Riverside summary.

Animals were raised in rooms ventilated with ambient air or air passed through absolute particulate and activated charcoal filters. Average ambient concentration for 2½ years of oxidant was 0.057 ppm and of carbon monoxide was 1.7 ppm. Pulmonary alkaline phosphatase in exposed rats and serum glutamic oxaloacetic transaminase in exposed rabbits were lower. Pneumonitis was significantly more prevalent in mice from ambient air. Male, but not female, C57BL mice survived significantly longer in filtered air. A/J mice in ambient air were heavier and survived longer. Old guinea pigs during ten-minute exposures had identical pulmonary resistance to filtered air and equal increases due to 0.5 ppm of sulfur dioxide, but those from filtered air showed significantly greater response to 0.5 ppm of ozone. Decreased running activity of male C57BL mice was highly correlated with oxidant concentration.

Scrubbed Diesel Exhaust for Carbon Dioxide Enrichment of Greenhouse Vegetables1

Abstract Diesel exhaust was used for CO2 enrichment of vegetable crops in inflated plastic houses. Fuel source and components of the recovery system crucially affected the elimination of other harmful gases. The absence of an activated charcoal filter and the use of fuel high in sulfur content increased ethylene, sulfur dioxide, nitrogen dioxide, and probably others. In the gas-added environment, as compared with the ambient one, lettuce grew more slowly, and leaf size and yield decreased in cucumber and eggplant. Plants were exposed to the gas-added environment for about 5 months, after which the system was discontinued. Plants did not recover, and symptoms continued despite discontinuing gas addition.

Effect of Filtering Ozone-Polluted Dryer Air Through Activated Charcoal on the Flavor of Foam Spray-Dried Whole Milk

To determine whether the flavor of dried milk manufactured with ozone-polluted air could be improved by filtering the air through activated charcoal, a series of foam spray-dried whole milks were manufactured using, alternately in each experiment, standard cellulose dust filters and activated charcoal filters in the dryer air inlet.Using cellulose filters, ozone levels of air entering the dryer were 4–17 parts per billion (average 8 ppb) and powder flavor 0.6–4.0 flavor points (average 2.0 points on a 10-point scale) lower than their parent concentrates. Using charcoal filters, ozone levels of air entering the dryer were zero, and powder flavor varied from 0.2 point higher to 0.7 point lower (average 0.1 point lower) than concentrates.Ozone levels as low as 6 parts per billion,if added to charcoal-purified air, had a definitely damaging effect on the powder's flavor. Powder manufactured in ozone-free air, and cooled before exposure, retained its high flavor quality during moderate subsequent exposure to polluted air.

Further cytological and cytochemical studies on the biological significance of the gas phase of fresh cigarette smoke

Cultures of primary mouse kidney tissue and of the myxomycete physarum polycephalum, exposed once to puffs of the gas phase from fresh unfiltered cigarette smoke, display a sequence of inhibition of RNA synthesis, loss of RNA, pycnosis and cell destruction from 1–24 hours after exposure. The same gas phase after passing through an activated charcoal filter does not produce any alterations in both types of cultures. Acrolein, a gas phase constituent of fresh cigarette smoke, has essentially the same cell damaging effects on mouse kidneys and slime mold as the gas phase from unfiltered cigarettes.

Monostyrene vapor concentrations from a plastic concrete.

Abstract Monostyrene vapor concentrations during the pouring of a plastic concrete in an underground room near the bottom of a 4200-foot vertical shaft are reported. Ventilation, personal protection, and the performance of an activated charcoal filter, used for the control of exposures, are discussed.