The role of micropore size and chemical nature of the pore surface on the adsorption properties of activated carbon fibers

Foster, Kenneth Lee

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https://hdl.handle.net/2142/23215 Copy

Description

Title

The role of micropore size and chemical nature of the pore surface on the adsorption properties of activated carbon fibers

Author(s)

Foster, Kenneth Lee

Issue Date

1993

Doctoral Committee Chair(s)

Economy, James

Department of Study

• Environmental Sciences
• Engineering, Materials Science

Discipline

• Environmental Sciences
• Engineering, Materials Science

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Environmental Sciences
• Engineering, Materials Science

Language

eng

Abstract

The adsorption isotherms of a series of progressively activated carbon fibers (ACF) with a range of surface areas from 760 $\rm m\sp2/g$ to 2420 $\rm m\sp2/g,$ prepared from phenolic precursors were examined with acetone, n-butane, benzene and nitrogen. The experimental results revealed a counter-intuitive relationship demonstrating that lower specific surface area ACF have superior adsorption capacities for contaminants at low concentrations in comparison to higher specific surface area ACF. It was hypothesized that progressive activation increased the average micropore size and specific surface area and that adsorption at low concentrations depends not on the available specific surface area but on the average micropore size. This work was extended to examines the adsorption properties of the same series of progressively activated ACF in a packed-bed configuration with n-butane. The same counter-intuitive relationship was observed with the breakthrough time indicating that the lower surface area ACF has superior adsorption properties for low concentrations of n-butane compared to the higher surface area ACF. Gas adsorption isotherms of acetone, benzene, n-butane and nitrogen onto a series of progressively activated carbon fibers (ACF) were used to determine the average micropore size of these highly porous materials using the Dubinin-Astakhov (DA) equation and Dubinin and Plavnik's relationship between micropore size and adsorption energy. The micropore sizes increased with progressively increased activation duration, as hypothesized, and ranged from 0.48 nm to 0.81 nm for this series of ACF. Finally, chemically tailored surfaces were prepared to develop systems that have a chemical selectivity toward specific contaminants. The ACF prepared with acidic, basic, neutral, polar, and highly oxidized surfaces were characterized with adsorption isotherms of HCl in nitrogen and found a strong interaction between the acidic gas and the basic surface.

Type of Resource

text

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http://hdl.handle.net/2142/23215

Copyright and License Information

Copyright 1993 Foster, Kenneth Lee

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