ASTM D5919-96(2011)
(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
SIGNIFICANCE AND USE
This practice allows the adsorption capacity at equilibrium of an activated carbon for adsorbable constituents present in water to be determined. The Freundlich K and 1/n constants that can be calculated based upon information collected using this practice can be used to estimate carbon loading capacities and usages rates for the constituent present in a water stream at other 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 values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D5919 − 96 (Reapproved 2011)
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 D5919; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This practice covers the assessment of activated carbon 3.1 Definitions:
for the removal of low concentrations of adsorbable constitu- 3.1.1 Fordefinitionsoftermsusedinthispracticerelatingto
entsfromwaterandwastewaterusingthebottlepointisotherm activated carbon, refer to Terminology D2652.
technique. It can be used to characterize the adsorptive 3.1.2 Fordefinitionsoftermsusedinthispracticerelatingto
properties of virgin and reactivated activated carbons. water, refer to Terminology D1129.
1.2 This practice can be used in systems with constituent
4. Summary of Practice
concentrations in the low milligrams per litre or micrograms
4.1 This practice consists of the determination of the ad-
per litre concentration ranges.
sorptive capacity of activated carbon for adsorbable constitu-
1.3 This practice can be used to determine the adsorptive
ents by contacting the aqueous solution contained in an
capacity of and Freundlich constants for volatile organic
essentially zero head space container with activated carbon,
compounds provided the handling procedures described in this
determining the amount of the constituents removed, and
practice are followed carefully.
calculating the adsorptive capacity and the Freundlich
1.4 The values stated in SI units are to be regarded as
constants, K and 1/n, from a Freundlich isotherm plot.
standard. No other units of measurement are included in this
4.1.1 The weights of activated carbon used in this practice
standard.
may have to be adjusted to achieve reasonable levels of
removal of the constituent. The best data is obtained when
1.5 The following safety caveat applies to the procedure
section of this practice: This standard does not purport to carbondosagesareselectedthatresultinnomorethan90%or
address all of the safety concerns, if any, associated with its nolessthan10%oftheadsorbableconstituentsbeingremoved
use. It is the responsibility of the user of this standard to from the water by the carbon.
establish appropriate safety and health practices and deter- 4.1.2 If carbon dosages used are less than 1 mg, larger
mine the applicability of regulatory limitations prior to use. volumes of the aqueous solution may be used, such as 1000
mL.
2. Referenced Documents
5. Significance and Use
2.1 ASTM Standards:
D1129Terminology Relating to Water
5.1 This practice allows the adsorption capacity at equilib-
D1193Specification for Reagent Water
riumofanactivatedcarbonforadsorbableconstituentspresent
D3370Practices for Sampling Water from Closed Conduits
in water to be determined.The Freundlich K and 1/n constants
D2652Terminology Relating to Activated Carbon
that can be calculated based upon information collected using
D2867Test Methods for Moisture in Activated Carbon
this practice can be used to estimate carbon loading capacities
andusagesratesfortheconstituentpresentinawaterstreamat
other concentrations.
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
6. Interferences
Evaluation.
Current edition approved March 1, 2011. Published May 2011. Originally
6.1 The water shall not contain any nondissolved compo-
approved in 1996. Last previous edition approved in 2006 as D5919–96 (2006).
nents.
DOI: 10.1520/D5919-96R11.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
6.2 The presence of naturally occurring organic compounds
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
such as humic acids in the water being studied may signifi-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. cantly affect the ability of the carbon to adsorb the constituent
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5919 − 96 (2011)
of interest. Results obtained when using water other than 10. Preparation of the Activated Carbon
reagent grade water may be unique for the particular water
10.1 This practice requires the use of well washed activated
used and it may not be possible to apply these results to other
carbon that has been reduced in particle size so that 90% or
water systems.
greater passes through a U.S. No. 325-mesh (45 µm) sieve by
6.3 The adsorption isotherm data collected using this prac- wet screening or equivalent.
tice can be affected by the ionic strength, pH and temperature
10.2 Approximately 25 g of the powdered activated carbon
of the water, and the presence and growth of microorganisms.
sample is placed into each of four clean 250-mL bottles. The
remainder of the bottle is filled with reagent grade water.
7. Apparatus
10.3 The bottle is tightly capped and inverted three to five
7.1 Equilibrator(orotherrotatingmixingdevice),arotating
times to mix the contents.
device operating at 25 rpm which can rotate the isotherm
10.4 Thebottlesarethencentrifugedat2000rpmfor15min
bottlesendoverendensuringgooddispersionofthepowdered
to settle the activated carbon. The supernate is poured off and
activated carbon in the water being treated.
the procedure is repeated until the supernatant is clear.Allow-
7.2 Grinding Mill,capableofgrindingmaterialsothat90%
ing the mixture to sit for a period of time to allow the carbon
passes through a U.S. No. 325-mesh (45 µm) sieve.
to settle prior to decanting is also acceptable.
7.3 Isotherm Bottles, narrow neck amber bottles with poly-
10.5 The wet carbon is next dried in an oven at 110°C to a
tetrafluoroethylene (PTFE) coated septum sealed caps of 250,
constant weight and placed in a desiccator to cool.
500, and 1000 mL capacity suitable for use in a centrifuge
10.6 As an alternate technique to drying the carbon sample,
operating at 2000 rpm.
carbon may be placed in a soxhlet extraction device and
7.4 Solution Delivery Tank, a 10-L, 316 stainless steel
extractedforaperiodofupto1weekwithreagentgrade(Type
container equipped with a PTFE coated floating lid and a 316
II) water.
stainless ball valve to control flow during bottle filling.
10.7 The dry activated carbon is transferred to clean 1-L
7.5 Analytical Balance, capable of weighing to the nearest
brown borosilicate bottles with PTFE liners in the caps and
0.1 mg.
stored in an inert atmosphere such as nitrogen for future use.
7.6 Oven, forced-air circulation, capable of temperature
11. Activated Carbon Sample Weighing Procedure
regulation up to 250°C.
11.1 This procedure allows the carbon to be handled at
7.7 Centrifuge, capable of handling isotherm bottles up to 1
ambient conditions by calculating a correction for water
L in size at 2000 rpm.
adsorbed from the air.
7.8 Magnetic Stirring Bars and Stirrers.
11.2 The powdered activated carbon sample is allowed to
come to equilibrium in a desiccator containing a saturated salt
8. Reagents
solution that will produce a relative humidity comparable to
ambient laboratory conditions. During the 24 h conditioning
8.1 Reagent Water,inaccordancewithSpecificationD1193,
period care shall be taken not to expose the carbon to organic
Type II.
vapors.
8.2 Methanol, high purity HPLC grade.
11.3 The moisture picked up by the conditioned activated
8.3 Potassium Monobasic Phosphate (KHPO4), 1 M solu-
carbon is determined by weighing approximately 500 mg into
tion.
a tared (constant weight) bottle, drying for2hat110°C,
cooling in a desiccator, and re-weighing to determine weight
8.4 Sodium Hydroxide (NaOH), 1 M solution.
change (refer to Test Method D2867 for standard procedures).
The ratio of change in weight between the activated carbon at
9. Cleaning Procedures
equilibrium with air and after drying is calculated and used as
9.1 This practice is capable of generating activated carbon
a correction factor for the weighed carbon dosages.
adsorptioncapacitydataonaqueoussolutionscontainingppbw
11.4 The carbon dosages are weighed by first taking a
(µg/L) levels of adsorbable constituents. It is therefore very
weighing boat, adding the desired mass of equilibrated acti-
important that all equipment and glassware that come in
vated carbon, and re-weighing the boat after transferring the
contact with the activated carbon or the water being treated be
carbon to the bottle. The carbon dosage is the difference
cleaned thoroughly to remove trace organic compounds.
between the carbon plus the boat weight and the final boat
9.2 All equipment and glassware should first be rigorously
weight.The weighed activated carbon dosage is then corrected
cleanedusingproceduresrecommendedbytheEPAforpriority
for ambient conditions and the actual dried carbon dosage
pollutantanalysis,hotwateranddetergentwash,reagentgrade
recorded.
water, and solvent (high purity methanol) rinse followed by a
bake-out.
12. Alternative Procedure for Addition of Known
Quantities of Activated Carbon to Isotherm Bottles
9.3 The glassware is baked out in an oven at 250°C for a
minimum of one hour. All PTFE and stainless steel apparatus 12.1 This alternate procedure makes use of a clean dry
are dried at 110°C for one hour. activated carbon sample prepared according to procedures
D5919 − 96 (2011)
described in Section 10. Desired concentrations of carbon are phosphate buffer will change the ionic strength of the solution
added to each isotherm bottle volumetrically using a carbon and may promote biological activity. Other buffer relations
slurry of known concentration. may be used provided that they do not interfere with the
adsorption process.
12.2 The concentrations of the slurries are chosen so that 5,
10,
...
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