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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
Doctoral Committee Chair(s):Economy, James
Department / Program:Environmental Sciences
Engineering, Materials Science
Discipline:Environmental Sciences
Engineering, Materials Science
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Environmental Sciences
Engineering, Materials Science
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.
Issue Date:1993
Rights Information:Copyright 1993 Foster, Kenneth Lee
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9411625
OCLC Identifier:(UMI)AAI9411625

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