Application of Wheeler–Jonas equation and relative breakthrough time (RBT) in activated carbon beds of respirator gas filters

Abiko, Hironobu; Furuse, Mitsuya; Takano, Tsuguo

doi:10.1007/s11869-020-00857-z

Cited by 6 publications

(2 citation statements)

References 16 publications

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“…Adsorption rate constant k a (s −1 ) is the time for EBCT to capture an adsorbate. According to the Wheeler-Jonas equation, the adsorption rate constant is calculated by Equation ( 2) [35]. The experiment set-up is as specified in Section 2.3.1.…”

Section: Dynamic Adsorption Experimentsmentioning

confidence: 99%

Ozone Catalytic Oxidation for Gaseous Dimethyl Sulfide Removal by Using Vacuum-Ultra-Violet Lamp and Impregnated Activated Carbon

et al. 2022

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Gaseous sulfur compounds are emitted from many facilities, such as wastewater facilities or biomass power plants, due to the decay of organic compounds. Gaseous dimethyl sulfide removal by ozone catalytic oxidation was investigated in this study. A Vacuum-Ultra-Violet (VUV) xenon excimer lamp of 172 nm was used for ozone generation without NOx generation, and activated carbon impregnated with iodic acid and H2SO4 was utilized as a catalyst. Performance assessment of dimethyl sulfide removal ability was carried out by a dynamic adsorption experiment. Empty-Bed-Contact-Time (EBCT), superficial velocity, concentration of dimethyl sulfide, temperature and humidity were set at 0.48 s, 0.15 m/s, 3.0 ppm, 25 °C and 45%, respectively. Without ozone addition, the adsorption capacity of impregnated activated carbon was 0.01 kg/kg. When ozone of 7.5 ppm was added, the adsorption capacity of impregnated activated carbon was increased to 0.15 kg/kg. Methane sulfonic acid, a reaction product of dimethyl sulfide and ozone, was detected from the activated carbon. The results suggest that the VUV and activated carbon impregnated with iodic acid and H2SO4 are workable for ozone catalytic oxidation for gas treatments.

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Section: Dynamic Adsorption Experimentsmentioning

confidence: 99%

Ozone Catalytic Oxidation for Gaseous Dimethyl Sulfide Removal by Using Vacuum-Ultra-Violet Lamp and Impregnated Activated Carbon

et al. 2022

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“…Thus, the National Institute of Occupational Safety and Health (NIOSH) Malaysia has been concerned about toxic gas vapor exposure which might be affected directly the employee, especially in the oil and gas industries [5,23] The usage of the respirator equipped with the gas mask filter approval by DOSH SIRIM is compulsory regulation before the workers' exposure to the emission of gas and vapor pollutants from the chemical processing plant [9]. The gas mask filter consists of the activated carbon and organic filter being effective adsorbents for a variety of airborne pollutants [1,8,15].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Preferential Flow at the Front Mesh Cartridge of the Gas Mask Filter: Cases in Malaysia Climate Environment

Noraini¹,

Azmir

Taib

et al. 2022

ARASET

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A gas mask respirator is essential for human protection from the hazardous and toxic chemical environment. The gas mask filter should be regularly checked, and the filter must be changed abruptly based on the temporal exposure to the toxic environment. Furthermore, the filter is exposed to a highly humid climate, and the high gas concentration speeds up the expiry cycle of the gas mask filter. Thus, this study aims to investigate the preferential flow absorbed into the gas mask filter and predict the potential area that presents the dead zone. In this study, a three-dimensional model of the commercial gas mask filter was modeled using the computational aided design (CAD) software. Four different humidity ratios of 50%, 60%,70%, and 80% as well as Five different filter concentrations of 20ppm, 100ppm, 200ppm, 300ppm, and 1000 ppm were simulated. The computational fluid dynamic (CFD) method was governed by continuity and Navier-stokes equation to investigate the presence of the dead zone based on several flow parameters. The result showed that the effects of the pressure, velocity, temperature, humidity, and concentration on the gas mask filter were analyzed. The pressure drop is seen in the charcoal filter region which experiences high-velocity circulation. The highest effect on the pressure drop, humidity, and concentration was seen for the case V filter. The high humidity ratio with the pressure drop in the gas mask filter also decreases the efficiency of filter concentration even though the temperature is constant. The high humidity ratio in the mask filter will retain the heat inside the gas mask filter, thus reducing the life cycle of the filter.

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Design and Integration of a Gas Sensor Module that Indicates the End of Service Life of a Gas Mask Canister

Moon

Lee

Min

et al. 2021

Adv Materials Technologies

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adsorbent material has limited adsorption capacity, the chemical cartridge or the filter needs to be replaced before the adsorption capacity is exceeded. End of service life indicator (ESLI), a system that informs the users as to when to replace the filter, has been widely employed in consumer products such as air conditioners and water/air purifiers. For these products, replacing the filters on time is advisable but not mandatory. By contrast, for the filtration of toxic gases, such as chemical warfare agents (CWAs) and toxic industrial chemicals (TICs), the expired filter must be promptly replaced for the safety of the users. Developing an ESLI in those systems, however, has been sluggish. [2] ESLI for filtration of CWAs is not available, and ESLI developed for canisters against TICs uses colorimetric sensors that are slow and have low sensitivity as compared to electronic sensors. Occupational Safety and Health Administration (Department of Labor, USA) presents a guideline for replacing the filter based on mathematical models, [3] whose input parameters are the type of gases, and their concentrations, temperature, humidity, flow rate, etc. Application of such models, however, is not practical as the parameters not only are difficult to measure but also vary In a filtration system, a chemical cartridge packed with porous adsorbents needs to be replaced when its maximum adsorption capacity is exceeded. An end of service life indicator (ESLI) informs when to replace the cartridge. However, ESLI technology for filtration of toxic gases is overlooked despite high toxicity of the gases even at low concentrations. In this study, a real-time ESLI is demonstrated for filtration of chemical warfare agents by inserting four chemiresistors made of carbon nanotubes into the adsorbent layer of a canister for gas masks. The sensors are installed on a flexible printed circuit board with a 3D structure to minimize the channeling effect in the canister. As the breakthrough of dimethyl methylphosphonate, a nerve agent simulant, progresses in the canister, the resistance of the sensors increases sequentially with time. The inflection points in the responses from sensors designated #1-#4 indicate that the percentage of remaining service life is 75%, 50%, 25%, and 0%, respectively. The ESLI potentially applies to a wide range of toxic gases and cartridge designs, regardless of the sensitivity and selectivity of the sensors, as supported by the breakthrough of ammonia as well as the results from a smaller canister.

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Application of Wheeler–Jonas equation and relative breakthrough time (RBT) in activated carbon beds of respirator gas filters

Cited by 6 publications

References 16 publications

Ozone Catalytic Oxidation for Gaseous Dimethyl Sulfide Removal by Using Vacuum-Ultra-Violet Lamp and Impregnated Activated Carbon

Ozone Catalytic Oxidation for Gaseous Dimethyl Sulfide Removal by Using Vacuum-Ultra-Violet Lamp and Impregnated Activated Carbon

Analysis of Preferential Flow at the Front Mesh Cartridge of the Gas Mask Filter: Cases in Malaysia Climate Environment

Design and Integration of a Gas Sensor Module that Indicates the End of Service Life of a Gas Mask Canister

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