ASTM D5919-96(2006)
(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.
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)
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Designation:D5919–96 (Reapproved 2006)
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.
1.3 This practice can be used to determine the adsorptive sorptive capacity of activated carbon for adsorbable constitu-
ents by contacting the aqueous solution contained in an
capacity of and Freundlich constants for volatile organic
compounds provided the handling procedures described in this essentially zero head space container with activated carbon,
determining the amount of the constituents removed, and
practice are followed carefully.
1.4 The following safety caveat applies to the procedure calculating the adsorptive capacity and the Freundlich con-
stants, K and 1/n, from a Freundlich isotherm plot.
section of this practice: This standard does not purport to
address all of the safety concerns, if any, associated with its 4.1.1 The weights of activated carbon used in this practice
may have to be adjusted to achieve reasonable levels of
use. It is the responsibility of the user of this standard to
establish appropriate safety and health practices and deter- removal of the constituent. The best data is obtained when
mine the applicability of regulatory limitations prior to use. carbondosagesareselectedthatresultinnomorethan90%or
nolessthan10%oftheadsorbableconstituentsbeingremoved
2. Referenced Documents
from the water by the carbon.
2.1 ASTM Standards: 4.1.2 If carbon dosages used are less than 1 mg, larger
D1129 Terminology Relating to Water volumes of the aqueous solution may be used, such as 1000
D1193 Specification for Reagent Water mL.
D3370 Practices for Sampling Water from Closed Conduits
5. Significance and Use
D2652 Terminology Relating to Activated Carbon
5.1 This practice allows the adsorption capacity at equilib-
D2867 Test Methods for Moisture in Activated Carbon
riumofanactivatedcarbonforadsorbableconstituentspresent
in water to be determined. The Freundlich K and 1/n constants
This practice is under the jurisdiction of ASTM Committee D28 on Activated
that can be calculated based upon information collected using
Carbon and is the direct responsibility of Subcommittee D28.02 on Liquid Phase
this practice can be used to estimate carbon loading capacities
Evaluation.
andusagesratesfortheconstituentpresentinawaterstreamat
Current edition approved Oct. 1, 2006. Published November 2006. Originally
other concentrations.
approved in 1996. Last previous edition approved in 2001 as D5919–96 (2001).
DOI: 10.1520/D5919-96R06.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
6. Interferences
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
6.1 The water shall not contain any nondissolved compo-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. nents.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5919–96 (2006)
6.2 The presence of naturally occurring organic compounds 10. Preparation of the Activated Carbon
such as humic acids in the water being studied may signifi-
10.1 This practice requires the use of well washed activated
cantly affect the ability of the carbon to adsorb the constituent
carbon that has been reduced in particle size so that 90% or
of interest. Results obtained when using water other than
greater passes through a U.S. No. 325-mesh (45 µm) sieve by
reagent grade water may be unique for the particular water
wet screening or equivalent.
used and it may not be possible to apply these results to other
10.2 Approximately 25 g of the powdered activated carbon
water systems.
sample is placed into each of four clean 250-mL bottles. The
6.3 The adsorption isotherm data collected using this prac-
remainder of the bottle is filled with reagent grade water.
tice can be affected by the ionic strength, pH and temperature
10.3 The bottle is tightly capped and inverted three to five
of the water, and the presence and growth of microorganisms.
times to mix the contents.
10.4 Thebottlesarethencentrifugedat2000rpmfor15min
7. Apparatus
to settle the activated carbon. The supernate is poured off and
the procedure is repeated until the supernatant is clear.Allow-
7.1 Equilibrator (or other rotating mixing device), a rotat-
ing the mixture to sit for a period of time to allow the carbon
ing device operating at 25 rpm which can rotate the isotherm
to settle prior to decanting is also acceptable.
bottles end over end ensuring good dispersion of the powdered
10.5 The wet carbon is next dried in an oven at 110°C to a
activated carbon in the water being treated.
constant weight and placed in a desiccator to cool.
7.2 Grinding Mill,capableofgrindingmaterialsothat90%
10.6 As an alternate technique to drying the carbon sample,
passes through a U.S. No. 325-mesh (45 µm) sieve.
carbon may be placed in a soxhlet extraction device and
7.3 Isotherm Bottles, narrow neck amber bottles with poly-
extractedforaperiodofupto1weekwithreagentgrade(Type
tetrafluoroethylene (PTFE) coated septum sealed caps of 250,
II) water.
500, and 1000 mL capacity suitable for use in a centrifuge
10.7 The dry activated carbon is transferred to clean 1-L
operating at 2000 rpm.
brown borosilicate bottles with PTFE liners in the caps and
7.4 Solution Delivery Tank, a 10-L, 316 stainless steel
stored in an inert atmosphere such as nitrogen for future use.
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.
7.5 Analytical Balance, capable of weighing to the nearest 11.1 This procedure allows the carbon to be handled at
0.1 mg.
ambient conditions by calculating a correction for water
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,inaccordancewithSpecificationD1193,
carbon is determined by weighing approximately 500 mg into
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 to Test Method D2867 for standard procedures).
tion. The ratio of change in weight between the activated carbon at
equilibrium with air and after drying is calculated and used as
8.4 Sodium Hydroxide (NaOH), 1 M solution.
a correction factor for the weighed carbon dosages.
11.4 The carbon dosages are weighed by first taking a
9. Cleaning Procedures
weighing boat, adding the desired mass of equilibrated acti-
9.1 This practice is capable of generating activated carbon
vated carbon, and re-weighing the boat after transferring the
adsorptioncapacitydataonaqueoussolutionscontainingppbw
carbon to the bottle. The carbon dosage is the difference
(µg/L) levels of adsorbable constituents. It is therefore very
between the carbon plus the boat weight and the final boat
important that all equipment and glassware that come in
weight.The weighed activated carbon dosage is then corrected
contact with the activated carbon or the water being treated be
for ambient conditions and the actual dried carbon dosage
cleaned thoroughly to remove trace organic compounds.
recorded.
9.2 All equipment and glassware should first be rigorously
12. Alternative Procedure for Addition of Known
cleanedusingproceduresrecommendedbytheEPAforpriority
Quantities of Activated Carbon to Isotherm Bottles
pollutant analysis, hot water and detergent wash, reagent grade
water, and solvent (high purity methanol) rinse followed by a
12.1 This alternate procedure makes use of a clean dry
bake-out.
activated carbon sample prepared according to procedures
9.3 The glassware is baked out in an oven at 250°C for a described in Section 10. Desired concentrations of carbon are
minimum of one hour. All PTFE and stainless steel apparatus added to each isotherm bottle volumetrically using a carbon
are dried at 110°C for one hour. slurry of known concentration.
D5919–96 (2006)
12.2 The concentrations of the slurries are chosen so that 5, 14.4 A stock solution containing the constituent(s) to be
10, and 20 mL volumes of each slurry would contain appro- adsorbed is prepared by injecting the pure component(s) into
priate amounts of carbon for 250 mL isotherm bottles. reagent grade water contained in a 250 mL bottle. For poo
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