Effects of Colloidal Materials and Polyelectrolytes on
Carbon Adsorption in Aqueous Solution
JU-CHANG HUANG, Associate Professor
JACK T. GARRETT, JR., Graduate Student
Department of Civil Engineering
University of Missouri-Rolla
Rolla, Missouri 65401
INTRODUCTION
During the last two decades the public's concern over pollution has increased
tremendously. Various federal, state and local regulations have been established to govern
the degree of treatment required for water and wastewater by industries and municipalities.
Stringent quality standards recently advocated for both water supply and treated waste
effluent have greatly increased the potential of using activated carbon as a treatment step
for water and wastewater. This is because activated carbon has proven to be very effective in
adsorbing various organic pollutants that have escaped conventional treatment processes.
However, in order to optimize the use of activated carbon, additional research still has to be
done in many areas so that a better understanding of the carbon adsorption phenomenon
can be obtained. Also, some important factors that may affect the carbon adsorption
process must also be evaluated.
This study was designed to seek answers to the following two questions concerning
activated carbon adsorption: First, what effects do colloidal materials have on the carbon
adsorption capacity? Second, what effect does the base material of an activated carbon have
on adsorption efficiency while colloidal materials are present? The answer to the first
question is important both in determining the suitability of using the carbon adsorption
technique as a treatment method, and also in determining the degree of pretreatment, i.e.
removal of solids, required prior to the carbon adsorption operation. The answer to the
second question is important in selecting a proper type of carbon for each specific
application.
In this country, activated carbons are generally manufactured from either coal-based
or wood-based (lignite-based) materials. There has been some indications that in the
presence of large adsorbate molecules the adsorption by wood- or lignite-based activated
carbons is more efficient than by coal-based carbons. This difference is probably due to the
variations in pore size distributions between the two different carbons (1). From the
literature made available by manufacturers and researchers, it is known that the coal-based
carbons have most of their adsorption area available in the small micropore capillaries
having a diameter range between 6 and 100 A. while the wood- or lignite-base carbons have
a substantial fraction of adsorption area available in the relatively large transitional
capillaries having a diameter range from 100 to 2,000 A   (1. 2, 3).
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