Activated Carbon > Defining Activated Carbon Product Properties
Screen (Particle) Size Distribution
SSD is the range of screens over which activated carbon
is sized. The screen size, or mesh size to be used is
determined by a square root of two progression in screen
opening, starting with the largest screen used. The
Mean Particle Diameter (MPD) is calculated on the basis
of screen size distribution. The weight percent of activated
carbon passing through one screen sieve and remaining
on the next smaller screen is first determined (material
on the largest screen and passing through the smallest
screen is ignored). The weight fraction is multiplied
by the average screen opening for the larger screen
and the screen on which the activated carbon was retained.
The summation of these fractions is the MPD.
Iodine Number
The amount of Iodine adsorbed by activated carbon from
a 0.02 NI2/KL aqueous solution.
Iodine Number has been roughly correlated to the surface
area in pores greater that 10 †diameter. However,
it is best understood as an indicator of total pore
volume.
Molasses Number
A measure of the relative decolorization of a boiling
molasses solution by activated carbon. The Molasses
Number has been interpreted as the surface area available
in pores greater than 28 †diameter. Because molasses
is a multi-component mixture, one must be careful in
assigning too strict an interpretation to this parameter.
Apparent Density (AD)
A measure of the mass of carbon that occupies a particular
volume. The test is performed by gradually filling a
graduated cylinder to 100 cc and determining the mass
of activated carbon contained. This value, corrected
for less efficient settling in the field, is used for
calculating the amount of activated carbon needed to
fill a given adsorber volume.
Carbon Tetrachloride Number
(CCL4) aka CTC Activity
Total pore volume indicator. This is measured by passing
an airstream saturated with CCL4 at 00C through a carbon bed held
at 25°C. The weight of the CCL4 adsorbed is determined at prescribed intervals until
there is a negligible weight change in the sample.
Hardness Number
Measurement of the attrition resistance of activated
carbon. It is the change in weight, expressed as a percentage,
of a specific screen size fraction after 3 minutes of
vigorous agitation with smooth steel balls.
Abrasion Number
Measurement of the mechanical strength of activated
carbon. It is the change in weight, expressed as a percentage,
of a specific screen size fraction after 3 minutes of
vigorous agitation with smooth steel balls.
Ash Content
Inorganic material, primarily aluminum and silicon,
contained in activated carbon. Ash is the residual from
burning pulverized carbon in air for 3 hours at 1750°F
(954°C).
Moisture Content
A measure of the water content of carbon. It is determined
by boiling activated carbon in xylene using a Dean-Stark
trap and condenser. The water is condensed and trapped
in a volumetric arm in order to determine the water
content. The moisture content of virgin activated carbon
can also be estimated on the basis of the weight change
that occures after oven drying at 150°C for 3 hours.
Safety Message
Wet activated carbon preferentially
removes oxygen from air. In closed or partially closed
containers and vessels, oxygen depletion may reach hazardous
levels. If workers are to enter a vessel containing
carbon, appropriate sampling and work procedures for
potentially low oxygen spaces should be followed, including
all applicable federal and state requirements.
Limitations of Liability: The suppllier's liability and the purchaser's exclusive remedy for any cause of action arising out of this transaction, including, but not limited to, breach of warranty, negligence and/or indemnification, is expressly limited to a maximum of the purchase price of spare parts or equipment sold hereunder. All claims of any nature shall be deemed waived unless made in writing within forty-five (45) days of the occurance giving rise to the claim. In no event shall the supplier for any reason or persuant to any provision of the warranty be liable for incidental or consequential damages, or damages in excess of the purchase price, nor shall the supplier be liable for loss of profits or fines imposed by govermental agencies.
