“…Therefore, the ACFC provides an adsorption capacity comparable to that of a CMS for low adsorbate concentrations as well. Experimental results indicate similar trends for adsorption capacities of tested TCVs in the ACFC. − ,, ,, 1 Pore size distribution of ACFC-20 determined from acetone isotherm data.…”
Section: Introductionmentioning
confidence: 55%
“…In this research, a new bench-scale ACFC sorption system was designed, developed, and characterized to separate and recover TCVs from gas streams. − The adsorption dynamics of TCV through ACFC is numerically modeled to predict the system for scale-up and optimization applications. To describe adsorption dynamics, knowledge of TCV/ACFC adsorption thermodynamics and effective diffusivities into an ACF is required.…”
Section: Introductionmentioning
confidence: 99%
“…The overlap of dispersion and Coulombic force fields from opposite walls in the adsorbent's micropores enhances the adsorption in the ACFC. ACFC can provide three main advantages over conventional adsorbents: (1) zero ash content, (2) structured connectivity and appropriate electrical conductivity for electrothermal regeneration, and (3) large pore volume in an appropriate pore size distribution to provide a high adsorption capacity and rapid rate of adsorption. − ACFC is >95% by mass pure carbon with the balance containing hydrogen, oxygen, and nitrogen. − The risk of polymerization side reactions is minimal due to the zero ash content of ACFC. Such reactions can cause fires in conventional carbon beds.…”
Section: Introductionmentioning
confidence: 99%
“…Another advantage of electrothermal desorption is that the energy transfer rate can be very high, easily controlled, and with low energy loss to the bulk gas stream. Vapor concentration in the N 2 carrier gas is controlled by the amount of applied electrical power, N 2 flow rate, and temperature. − The concentrated vapor stream is then directed to a custom-designed shell-and-packed-tube cryogenic condenser 23 for adsorbate recovery. Due to its high cooling capacity, liquid nitrogen (LN 2 ) is used to liquify the vapor.…”
A new activated-carbon fiber-cloth (ACFC) adsorber coupled with an electrothermal regenerator and a cryogenic condenser was designed and developed to efficiently capture and recover toxic chemical vapors (TCVs) from simulated industrial gas streams. The system was characterized for adsorption by ACFC, electrothermal desorption, and cryogenic condensation to separate acetone and methyl ethyl ketone from gas streams. Adsorption dynamics are numerically modeled to predict system characteristics during scale-up and optimization of the process in the future. The model requires diffusivities of TCVs into an activated-carbon fiber (ACF) as an input. Effective diffusivities of TCVs into ACFs were modeled as a function of temperature, concentration, and pore size distribution. Effective diffusivities for acetone at 65°C and 30-60 ppmv were measured using a chromatography method. The energy factor for surface diffusion was determined from comparison between the experimental and modeled effective diffusivities. The modeled effective diffusivities were used in a dispersive computational model to predict mass transfer zones of TCVs in fixed beds of ACFC under realistic conditions for industrial applications.
“…Therefore, the ACFC provides an adsorption capacity comparable to that of a CMS for low adsorbate concentrations as well. Experimental results indicate similar trends for adsorption capacities of tested TCVs in the ACFC. − ,, ,, 1 Pore size distribution of ACFC-20 determined from acetone isotherm data.…”
Section: Introductionmentioning
confidence: 55%
“…In this research, a new bench-scale ACFC sorption system was designed, developed, and characterized to separate and recover TCVs from gas streams. − The adsorption dynamics of TCV through ACFC is numerically modeled to predict the system for scale-up and optimization applications. To describe adsorption dynamics, knowledge of TCV/ACFC adsorption thermodynamics and effective diffusivities into an ACF is required.…”
Section: Introductionmentioning
confidence: 99%
“…The overlap of dispersion and Coulombic force fields from opposite walls in the adsorbent's micropores enhances the adsorption in the ACFC. ACFC can provide three main advantages over conventional adsorbents: (1) zero ash content, (2) structured connectivity and appropriate electrical conductivity for electrothermal regeneration, and (3) large pore volume in an appropriate pore size distribution to provide a high adsorption capacity and rapid rate of adsorption. − ACFC is >95% by mass pure carbon with the balance containing hydrogen, oxygen, and nitrogen. − The risk of polymerization side reactions is minimal due to the zero ash content of ACFC. Such reactions can cause fires in conventional carbon beds.…”
Section: Introductionmentioning
confidence: 99%
“…Another advantage of electrothermal desorption is that the energy transfer rate can be very high, easily controlled, and with low energy loss to the bulk gas stream. Vapor concentration in the N 2 carrier gas is controlled by the amount of applied electrical power, N 2 flow rate, and temperature. − The concentrated vapor stream is then directed to a custom-designed shell-and-packed-tube cryogenic condenser 23 for adsorbate recovery. Due to its high cooling capacity, liquid nitrogen (LN 2 ) is used to liquify the vapor.…”
A new activated-carbon fiber-cloth (ACFC) adsorber coupled with an electrothermal regenerator and a cryogenic condenser was designed and developed to efficiently capture and recover toxic chemical vapors (TCVs) from simulated industrial gas streams. The system was characterized for adsorption by ACFC, electrothermal desorption, and cryogenic condensation to separate acetone and methyl ethyl ketone from gas streams. Adsorption dynamics are numerically modeled to predict system characteristics during scale-up and optimization of the process in the future. The model requires diffusivities of TCVs into an activated-carbon fiber (ACF) as an input. Effective diffusivities of TCVs into ACFs were modeled as a function of temperature, concentration, and pore size distribution. Effective diffusivities for acetone at 65°C and 30-60 ppmv were measured using a chromatography method. The energy factor for surface diffusion was determined from comparison between the experimental and modeled effective diffusivities. The modeled effective diffusivities were used in a dispersive computational model to predict mass transfer zones of TCVs in fixed beds of ACFC under realistic conditions for industrial applications.
“…Compared with conventional granular or powdered activated carbon, ACF has higher adsorption capacity, faster adsorption/ desorption rates, and is suitable for in situ electrothermal regeneration (Petkovska, et al 1991;Suzuki 1994;Rood et al 1998;Sullivan et al 1999). These advantages can lead to considerable reduction in the size of adsorption systems and the effort required to regenerate saturated adsorbent.…”
Adsorption capacities of adsorbents are necessary for selecting and designing adsorption systems for separation and removal processes, such as air quality control devices, because they are indicators of service life. This paper describes the use of the Dubinin-Radushkevich (DR) equation and the quantitative structureactivated relationship to predict the equilibrium adsorption of select organic vapor by activated carbon fiber (ACF) adsorbents. The DR isotherm parameter, k, depends on the adsorbate as well as the adsorbent, and the prediction for k can be obtained indirectly from the affinity coefficient. A correlation is developed to compute the affinity coefficient from the modified, first-order, valence molecular connectivity index. This method provides an improved way to predict equilibrium adsorption capacities for select volatile organic compound adsorbates and activated carbon fiber adsorbents.
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