Mercury Adsorption Characteristics of Carbon Sorbent with Low Surface Area

The effects of final pyrolysis temperature Tend from 300 ºC to 550 ºC, heating rates β of 2 ºC/min, 3 ºC/min and 5 ºC/min, retention time RT from 45 min to 90 min, and the moisture content MC from 0 to 70% on characteristics of the pyrolysis char from sewage sludge were investigated using a tube furnace in this study. The resulting chars were characterized by sorption of nitrogen (surface area and pore volume). Their adsorption characteristics were evaluated via iodine value and methylene blue value. Either the pore structures or adsorption characteristics depend on the pyrolysis processing and moisture content of the sludge precursors. In terms of iodine value and surface area of the char, Tend of 450 ºC, RT of 75 min and β of 3 ºC/min proved the optimum combination of pyrolysis parameters. The chars have an undeveloped mesopore and macropore structure and a developed micropore structure. The sodium phenoxide adsorption equilibrium data fit well with the Langmuir model of adsorption, suggesting monolayer coverage of sodium phenoxide molecules at the surface of the char. Its adsorption mechanism is mainly physical in nature, enhanced by chemisorption.

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Adsorption Characteristics of Activated Carbon Fibers in Respirator Cartridges for Toluene

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18168505 ◽

2021 ◽

Vol 18 (16) ◽

pp. 8505

Author(s):

Jo Anne G. Balanay ◽

Jonghwa Oh

Keyword(s):

Activated Carbon ◽

Specific Surface ◽

Surface Area ◽

Carbon Fibers ◽

Breakthrough Curves ◽

Activated Carbon Fiber ◽

Respiratory Protection ◽

Adsorption Characteristics ◽

Surface Areas ◽

Adsorption Capacities

Respirator use has been shown to be associated with overall discomfort. Activated carbon fiber (ACF) has potential as an alternative adsorbent for developing thinner, lightweight, and efficient respirators due to its larger surface area, microporosity, and fabric form. The purpose of this pilot study was to determine the adsorption characteristics of commercially available ACF in respirator cartridges with varying ACF composition for toluene protection. Seven ACF types (one cloth, six felt) with varying properties were tested. Seven ACF cartridge configurations with varying ACF composition were challenged with five toluene concentrations (20–500 ppm) at constant air temperature (23 °C), relative humidity (50%), and air flow (32 LPM). Breakthrough curves were obtained using photoionization detectors. Breakthrough times (10%, 50%, and 5 ppm) and adsorption capacities were compared among ACF cartridge configurations to determine their suitable application in respiratory protection. Results showed that ACF cartridges containing the densest ACF felt types had the longest average breakthrough times (e.g., ~250–270 min to reach 5 ppm breakthrough time) and those containing ACF felt types with the highest specific surface areas had the highest average adsorption capacity (~450–470 mg/g). The ACF cartridges demonstrated breakthrough times of <1 h for 500 ppm toluene and 8–16 h for 20 ppm toluene. The ACF cartridges are more reliable for use at low ambient toluene concentrations but still have potential for use at higher concentrations for short-term protection. ACF felt forms with appropriate properties (density of ~0.07 g/cm3; specific surface area of ~2000 m2/g) have shown promising potential for the development of lighter and thinner respirators for protection against toluene.

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Assessment of H2O Adsorption Characteristics Based on Zeolite Type

Korean Journal of Metals and Materials ◽

10.3365/kjmm.2020.58.7.501 ◽

2020 ◽

Vol 58 (7) ◽

pp. 501-506

Author(s):

Kwangbae Kim ◽

Yesol Lim ◽

Eunseok kim ◽

Saera Jin ◽

Hyunjun Lee ◽

...

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Inert Gases ◽

Gas Purification ◽

Characteristic Analysis ◽

Adsorption Characteristics ◽

Surface Areas ◽

Bet Analysis ◽

Specific Surface Areas

The properties and H2O adsorption characteristics of two types of zeolites (3A and 13X) with the same shape but different element composition were identified. These zeolites are used in gas purification processes to manufacture 9N ultra-pure inert gases for semiconductor process applications. To analyze the shape and microstructure of the zeolites, an optical microscope and FE-SEM were used. EDS, micro-Raman, and XRD analysis were conducted to analyze their compositions and properties. BET analysis was performed to identify their specific surface areas. Finally, a breakthrough analysis was conducted at room temperature. Based on the results of the optical and microstructure analyses, the cylindrical shaped 3A and 13X were determined to be composed of 2.5-um polyhedrons and 1.4-um massive shapes, respectively. The results of the compositional analysis showed that the main components of both zeolites were Si and Al, whereas K and Na existed in 3A and 13X, respectively. The results of the specific surface area analysis demonstrated that the surface area of 13X was 32 times larger than that of 3A. Specifically, the total specific surface areas were 22.42 and 720.33 m<sup>2</sup>/g for 3A and 13X, respectively. The results of the H2O adsorption characteristic analysis showed that the H2O concentration of 13X was 1.33 times higher than that of 3A. Therefore, with respect to using zeolite for gas purification process applications, 13X might be more suitable to achieve excellent specific surface area and remarkable H2O adsorption.

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