ASTM D5919-96(2001)
(Practice)Standard Practice for Determination of Adsorptive Capacity of Activated Carbon by a Micro-Isotherm Technique for Adsorbates at ppb Concentrations
Standard Practice for Determination of Adsorptive Capacity of Activated Carbon by a Micro-Isotherm Technique for Adsorbates at ppb Concentrations
SCOPE
1.1 This practice covers the assessment of activated carbon for the removal of low concentrations of adsorbable constituents from water and wastewater using the bottle point isotherm technique. It can be used to characterize the adsorptive properties of virgin and reactivated activated carbons.
1.2 This practice can be used in systems with constituent concentrations in the low milligrams per litre or micrograms per litre concentration ranges.
1.3 This practice can be used to determine the adsorptive capacity of and Freundlich constants for volatile organic compounds provided the handling procedures described in this practice are followed carefully.
1.4 The following safety caveat applies to the procedure section of this practice: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D 5919–96 (Reapproved 2001)
Standard Practice for
Determination of Adsorptive Capacity of Activated Carbon
by a Micro-Isotherm Technique for Adsorbates at ppb
Concentrations
This standard is issued under the fixed designation D 5919; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.2 Fordefinitionsoftermsusedinthispracticerelatingto
water, refer to Terminology D1129.
1.1 This practice covers the assessment of activated carbon
for the removal of low concentrations of adsorbable constitu-
4. Summary of Practice
entsfromwaterandwastewaterusingthebottlepointisotherm
4.1 This practice consists of the determination of the ad-
technique. It can be used to characterize the adsorptive
sorptive capacity of activated carbon for adsorbable constitu-
properties of virgin and reactivated activated carbons.
ents by contacting the aqueous solution contained in an
1.2 This practice can be used in systems with constituent
essentially zero head space container with activated carbon,
concentrations in the low milligrams per litre or micrograms
determining the amount of the constituents removed, and
per litre concentration ranges.
calculating the adsorptive capacity and the Freundlich con-
1.3 This practice can be used to determine the adsorptive
stants, K and 1/n, from a Freundlich isotherm plot.
capacity of and Freundlich constants for volatile organic
4.1.1 The weights of activated carbon used in this practice
compounds provided the handling procedures described in this
may have to be adjusted to achieve reasonable levels of
practice are followed carefully.
removal of the constituent. The best data is obtained when
1.4 The following safety caveat applies to the procedure
carbondosagesareselectedthatresultinnomorethan90%or
section of this practice: This standard does not purport to
nolessthan10%oftheadsorbableconstituentsbeingremoved
address all of the safety concerns, if any, associated with its
from the water by the carbon.
use. It is the responsibility of the user of this standard to
4.1.2 If carbon dosages used are less than 1 mg, larger
establish appropriate safety and health practices and deter-
volumes of the aqueous solution may be used, such as 1000
mine the applicability of regulatory limitations prior to use.
mL.
2. Referenced Documents
5. Significance and Use
2.1 ASTM Standards:
2 5.1 This practice allows the adsorption capacity at equilib-
D1129 Terminology Relating to Water
2 riumofanactivatedcarbonforadsorbableconstituentspresent
D1193 Specification for Reagent Water
in water to be determined.The Freundlich K and 1/n constants
D3370 Practices for Sampling Water from Closed Con-
2 that can be calculated based upon information collected using
duits
3 this practice can be used to estimate carbon loading capacities
D2652 Terminology Relating to Activated Carbon
3 andusagesratesfortheconstituentpresentinawaterstreamat
D2867 Test Method for Moisture in Activated Carbon
other concentrations.
3. Terminology
6. Interferences
3.1 Definitions:
6.1 The water shall not contain any nondissolved compo-
3.1.1 Fordefinitionsoftermsusedinthispracticerelatingto
nents.
activated carbon, refer to Terminology D2652.
6.2 The presence of naturally occurring organic compounds
such as humic acids in the water being studied may signifi-
cantly affect the ability of the carbon to adsorb the constituent
This practice is under the jurisdiction of ASTM Committee D28 on Activated
Carbon and is the direct responsibility of Subcommittee D28.02 on Liquid Phase
of interest. Results obtained when using water other than
Evaluation.
reagent grade water may be unique for the particular water
Current edition approved March 10, 1996. Published May 1996.
2 used and it may not be possible to apply these results to other
Annual Book of ASTM Standards, Vol 11.01.
Annual Book of ASTM Standards, Vol 15.01. water systems.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 5919–96 (2001)
6.3 The adsorption isotherm data collected using this prac- 10.3 The bottle is tightly capped and inverted three to five
tice can be affected by the ionic strength, pH and temperature times to mix the contents.
of the water, and the presence and growth of microorganisms. 10.4 Thebottlesarethencentrifugedat2000rpmfor15min
to settle the activated carbon. The supernate is poured off and
7. Apparatus the procedure is repeated until the supernatant is clear.Allow-
ing the mixture to sit for a period of time to allow the carbon
7.1 Equilibrator (or other rotating mixing device), a rotat-
to settle prior to decanting is also acceptable.
ing device operating at 25 rpm which can rotate the isotherm
10.5 The wet carbon is next dried in an oven at 110°C to a
bottlesendoverendensuringgooddispersionofthepowdered
constant weight and placed in a desiccator to cool.
activated carbon in the water being treated.
10.6 As an alternate technique to drying the carbon sample,
7.2 Grinding Mill,capableofgrindingmaterialsothat90%
carbon may be placed in a soxhlet extraction device and
passes through a U.S. No. 325-mesh (45 µm) sieve.
extractedforaperiodofupto1weekwithreagentgrade(Type
7.3 Isotherm Bottles, narrow neck amber bottles with poly-
II) water.
tetrafluoroethylene (PTFE) coated septum sealed caps of 250,
10.7 The dry activated carbon is transferred to clean 1-L
500, and 1000 mL capacity suitable for use in a centrifuge
brown borosilicate bottles with PTFE liners in the caps and
operating at 2000 rpm.
stored in an inert atmosphere such as nitrogen for future use.
7.4 Solution Delivery Tank, a 10-L, 316 stainless steel
container equipped with a PTFE coated floating lid and a 316
11. Activated Carbon Sample Weighing Procedure
stainless ball valve to control flow during bottle filling.
11.1 This procedure allows the carbon to be handled at
7.5 Analytical Balance, capable of weighing to the nearest
ambient conditions by calculating a correction for water
0.1 mg.
adsorbed from the air.
7.6 Oven, forced-air circulation, capable of temperature
11.2 The powdered activated carbon sample is allowed to
regulation up to 250°C.
come to equilibrium in a desiccator containing a saturated salt
7.7 Centrifuge, capable of handling isotherm bottles up to 1
solution that will produce a relative humidity comparable to
L in size at 2000 rpm.
ambient laboratory conditions. During the 24 h conditioning
7.8 Magnetic Stirring Bars and Stirrers.
period care shall be taken not to expose the carbon to organic
vapors.
8. Reagents
11.3 The moisture picked up by the conditioned activated
8.1 Reagent Water, in accordance with Specification
carbon is determined by weighing approximately 500 mg into
D1193, Type II.
a tared (constant weight) bottle, drying for2hat110°C,
8.2 Methanol, high purity HPLC grade.
cooling in a desiccator, and re-weighing to determine weight
8.3 Potassium Monobasic Phosphate (KHPO4), 1 M solu-
change (refer toTest Method D2867 for standard procedures).
tion.
The ratio of change in weight between the activated carbon at
8.4 Sodium Hydroxide (NaOH), 1 M solution.
equilibrium with air and after drying is calculated and used as
a correction factor for the weighed carbon dosages.
9. Cleaning Procedures
11.4 The carbon dosages are weighed by first taking a
9.1 This practice is capable of generating activated carbon
weighing boat, adding the desired mass of equilibrated acti-
adsorptioncapacitydataonaqueoussolutionscontainingppbw
vated carbon, and re-weighing the boat after transferring the
(µg/L) levels of adsorbable constituents. It is therefore very
carbon to the bottle. The carbon dosage is the difference
important that all equipment and glassware that come in
between the carbon plus the boat weight and the final boat
contact with the activated carbon or the water being treated be
weight.The weighed activated carbon dosage is then corrected
cleaned thoroughly to remove trace organic compounds.
for ambient conditions and the actual dried carbon dosage
9.2 All equipment and glassware should first be rigorously
recorded.
cleanedusingproceduresrecommendedbytheEPAforpriority
pollutantanalysis,hotwateranddetergentwash,reagentgrade 12. Alternative Procedure for Addition of Known
water, and solvent (high purity methanol) rinse followed by a Quantities of Activated Carbon to Isotherm Bottles
bake-out.
12.1 This alternate procedure makes use of a clean dry
9.3 The glassware is baked out in an oven at 250°C for a
activated carbon sample prepared according to procedures
minimum of one hour. All PTFE and stainless steel apparatus
described in Section 10. Desired concentrations of carbon are
are dried at 110°C for one hour.
added to each isotherm bottle volumetrically using a carbon
slurry of known concentration.
10. Preparation of the Activated Carbon
12.2 The concentrations of the slurries are chosen so that 5,
10.1 This practice requires the use of well washed activated 10, and 20 mL volumes of each slurry would contain appro-
carbon that has been reduced in particle size so that 90% or priate amounts of carbon for 250 mL isotherm bottles.
greater passes through a U.S. No. 325-mesh (45 µm) sieve by 12.3 The slurries are pipetted into a pre-weighed baked-out
wet screening or equivalent. isotherm bottle, baked dry in a 105°C oven, cooled, and
10.2 Approximately 25 g of the powdered activated carbon re-weighed to determine the exact quantity of carbon added to
sample is placed into each of four clean 250-mL bottles. The the bottle.This drying technique eliminates any dilution of the
remainder of the bottle is filled with reagent grade water. water sample to be tested, allows the slurry pipet
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