USD 2159 AVL - Filtra

Parameters Affecting the Adsorption
Filtration Velocity
The available contact time is of significant
importance in adsorption processes. Using
SUPRAdisc AKS depth filter modules the
contact time can be varied by suitable
adjustment of the filtration velocity. Low
filtration velocities, resulting in long contact
times have a positive effect on the
adsorption capacity (Figure 3).
Temperature
The diffusion rate increases at higher
temperatures. Thus adjustment of the
adsorption equilibrium is obtained more
rapidly. However, the total amount of
adsorbable substances is higher at lower
temperatures (Figure 4). Hence, in most
cases a higher adsorptive capacity is
yielded at lower temperature provided that
the contact time is long enough for the
product in question. This basic statement,
however, is only applicable if the substance
to be adsorbed shows uniform structures
at varying temperatures. If the structure
changes, the temperature may have a
reverse effect.
pH-Value
Depending on the activated carbon and on
the different isoelectric points of the
substances to be adsorbed, the adsorption
capacities can vary considerably at different
pH- values (Figure 5). However, particularly
in regard to the pH-value, interactions
between different product substances
and/or the structure of a component are
possible. Therefore, no general statement
can be made about the adsorption as a
function of the pH-value.
Figure 3
Methylene adsorption g/m 2
250
240
230
220
210
200
Figure 4
Methylene adsorption in mg g -1
Comparison of the Methylene Blue Adsorption by
SUPRAdisc AKS 5 at Different Filtration Velocities
SUPRAdisc AKS
Carbon Impregnated Depth Filter Modules
190
0 250 500 750 1000 1250 1500 1750 2000
Filtration velocity in L/m -2 h -1
540
520
500
480
460
Figure 5
Methylene adsorption in mg g -1
Comparison of the Methylene Blue Adsorption by
SUPRAdisc AKS 5 at Different Filtration Temperatures
440
0 10 20 30 40 50 60
Temperature in °C
1000
900
800
700
600
Comparison of the Methylene Blue Adsorption by
SUPRAdisc AKS 5 at Different pH Values
500
4 5 6 7 8 9 10 11
pH - value