ASTM D6385-22

Standard Test Method for Determining Acid-Extractable Content in Activated Carbon by Ashing

SIGNIFICANCE AND USE
4.1 The quantitative determination of acid-extractable content is useful in evaluating activated carbon samples that contain acid-soluble impurities. These acid-soluble impurities can affect applications of activated carbon.  
4.2 Limitations of Method—Hydrochloric acid is used in this test method as the extracting acid. All elements or compounds present in the activated carbon sample, which can be acid extracted, are assumed to form water-soluble chloride salts. Hydrochloric acid may not solubilize all impurities of activated carbon.
SCOPE
1.1 This test method is to be used for determination of the acid-extractable content of a sample of activated carbon. This test method presupposes the existence of substances other than carbon to be present with activated carbon but does not purport to address or identify those substances which may be present. This test method should be applicable to any form in which activated carbon may exist and requires the performance of Test Method D2866.  
1.2 This test method requires the use of concentrated hydrochloric acid, which should be used in an appropriate and safe manner, with eye protection, skin protection, and handling carried out in a properly operating fume hood. The proper use of a muffle furnace is addressed in Test Method D2866.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Aug-2022
• ICS: 73.040 - Coals
• Technical Committee: D28 - Activated Carbon
• Drafting Committee: D28.02 - Liquid Phase Evaluation

Relations

• Refers: ASTM D2866-11(2018) - Standard Test Method for Total Ash Content of Activated Carbon
• Effective Date: 01-Jun-2018
• Refers: ASTM D2866-11 - Standard Test Method for Total Ash Content of Activated Carbon
• Effective Date: 01-May-2011
• Refers: ASTM D2867-09 - Standard Test Methods for Moisture in Activated Carbon
• Effective Date: 01-Nov-2009
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D2867-04 - Standard Test Methods for Moisture in Activated Carbon
• Effective Date: 01-Apr-2004
• Refers: ASTM D2866-94(2004) - Standard Test Method for Total Ash Content of Activated Carbon
• Effective Date: 01-Apr-2004
• Refers: ASTM D2867-99 - Standard Test Methods for Moisture in Activated Carbon
• Effective Date: 10-Feb-1999
• Refers: ASTM D1193-99e1 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D1193-99 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D2866-94(1999) - Standard Test Method for Total Ash Content of Activated Carbon
• Effective Date: 10-Feb-1999

Overview

ASTM D6385-22 is the recognized standard test method for determining acid-extractable content in activated carbon by ashing. Developed by ASTM International, this method is crucial for industries that rely on the purity and performance of activated carbon. Acid-extractable impurities present in activated carbon, often soluble in hydrochloric acid, can significantly impact the effectiveness of activated carbon in various applications such as water and air purification, food processing, and pharmaceutical manufacturing.

This standard provides guidance for laboratories and quality control operations to assess and quantify acid-soluble impurities, supporting consistency, compliance, and product performance across the activated carbon supply chain.

Key Topics

• Purpose: The test method quantitatively determines the amount of acid-extractable material in activated carbon, which may include ash-forming impurities that impact carbon quality.
• Scope: Applicable to all forms of activated carbon. This method assumes that impurities present will react with hydrochloric acid to form water-soluble chloride salts. However, not all impurities may be fully solubilized using hydrochloric acid alone.
• Safety Considerations: Use of concentrated hydrochloric acid and high-temperature muffle furnaces requires stringent safety measures. Eye and skin protection, fume hoods, and proper lab protocols are essential.
• Sample Preparation: Accurate results depend on representative sampling, sample drying, and standardized sample processing (including size reduction and thorough mixing).
• Quantitative Measurement: The acid-extractable content is calculated by the difference in total ash content determined before and after acid extraction.
• Units: Only SI units are used, ensuring consistency with international measurement standards.
• Limitations: This method may not detect all types of acid-soluble impurities and does not attempt to identify the specific substances present.

Applications

The ASTM D6385-22 standard is widely adopted in industries that utilize activated carbon, providing several practical benefits:

• Quality Control: Helps manufacturers and suppliers verify that activated carbon meets required purity specifications by quantifying acid-extractable contaminants.
• Product Comparison: Facilitates objective comparison between different batches or suppliers of activated carbon on the basis of impurity content.
• Process Optimization: Identifying elevated acid-extractable content can help optimize raw material selection and production processes.
• Regulatory Compliance: Supports documentation for regulatory submissions where impurity limits in activated carbon are specified for environmental, food contact, or pharmaceutical-grade materials.
• End-use Suitability: Ensures the suitability of activated carbon for sensitive applications by limiting potential negative impacts from acid-soluble ash components.

Related Standards

Several ASTM standards complement the procedures and requirements of ASTM D6385-22:

• ASTM D2866: Test Method for Total Ash Content of Activated Carbon (required for ash measurements in this method)
• ASTM D1193: Specification for Reagent Water (ensures water purity during testing)
• ASTM D2867: Test Methods for Moisture in Activated Carbon (important for sample preparation and correction)
• ASTM E300: Practice for Sampling Industrial Chemicals (guides representative sampling techniques)

Summary

ASTM D6385-22 provides a standardized, reliable test method for determining acid-extractable impurities in activated carbon, supporting the assurance of product quality, purity, and performance. Proper implementation of this methodology contributes to industrial best practices, regulatory compliance, and safe application across diverse sectors relying on high-quality activated carbon.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6385 − 22
Standard Test Method for
Determining Acid-Extractable Content in Activated Carbon
by Ashing
This standard is issued under the fixed designation D6385; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D2866 Test Method for Total Ash Content of Activated
Carbon
1.1 This test method is to be used for determination of the
D2867 Test Methods for Moisture in Activated Carbon
acid-extractable content of a sample of activated carbon. This
E300 Practice for Sampling Industrial Chemicals
test method presupposes the existence of substances other than
carbon to be present with activated carbon but does not purport
3. Summary of Test Method
to address or identify those substances which may be present.
This test method should be applicable to any form in which 3.1 The percent acid-extractable content of an activated
activated carbon may exist and requires the performance of
carbon sample is determined by the difference between the
Test Method D2866. percent mass of total ash of a sample and the percent mass of
total ash of a sample which has been acid extracted.
1.2 This test method requires the use of concentrated
hydrochloric acid, which should be used in an appropriate and
4. Significance and Use
safe manner, with eye protection, skin protection, and handling
carried out in a properly operating fume hood. The proper use 4.1 The quantitative determination of acid-extractable con-
of a muffle furnace is addressed in Test Method D2866.
tent is useful in evaluating activated carbon samples that
contain acid-soluble impurities. These acid-soluble impurities
1.3 The values stated in SI units are to be regarded as
can affect applications of activated carbon.
standard. No other units of measurement are included in this
standard. 4.2 Limitations of Method—Hydrochloric acid is used in
this test method as the extracting acid. All elements or
1.4 This standard does not purport to address all of the
compounds present in the activated carbon sample, which can
safety concerns, if any, associated with its use. It is the
be acid extracted, are assumed to form water-soluble chloride
responsibility of the user of this standard to establish appro-
salts. Hydrochloric acid may not solubilize all impurities of
priate safety, health, and environmental practices and deter-
activated carbon.
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor-
5. Apparatus
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
5.1 250 mL Glass Beakers or 125 mL Capacity Block
Development of International Standards, Guides and Recom-
Heater Digestion Vessel, for boiling and drying the sample.
mendations issued by the World Trade Organization Technical
5.2 Watch Glass, suitable for 250 mL beaker or 125 mL
Barriers to Trade (TBT) Committee.
Capacity Block Heater Digestion Vessel.
5.3 Graduated Cylinders, of 100 mL (TD) and 25 mL (TD)
2. Referenced Documents
2 size.
2.1 ASTM Standards:
5.4 Buchner Vacuum Funnel, 7cm ID or equivalent filtering
D1193 Specification for Reagent Water
device.
5.5 Vacuum Filter Flask, with side arm, 500 mL.
This test method is under the jurisdiction ofASTM Committee D28 on Liquid
5.6 Vacuum Filter Collar, for the above filter flask.
Phase Evaluation.
Current edition approved Sept. 1, 2022. Published October 2022. Originally
5.7 Filter Paper, which is hardened, ashless paper, ≤ 8
approved in 1999. Last previous edition approved in 2017 as D6385 – 99 (2017).
micron pore size and 7 cm in diameter is recommended, or a
DOI: 10.1520/D6385-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or diameter which matches the vacuum funnel. The paper will be
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
ashed with the carbon, so ashless paper is necessary.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 5.8 Drying Oven, maintained at 150 °C 6 5 °C.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6385 − 22
5.9 Muffle Furnace, as specified in Test Method D2866. mixture to boil for 5 min 6 10 s.Awatch glass should be used
to cover the beaker (or digestion vessel) while boiling the
5.10 Porcelain Crucibles, as specified in Test Method
carbon acid-water mixture.
D2866.
8.7 After boiling, remove the beaker (or digestion vessel)
5.11 Desicator, containing indicating silica gel or any other
from heat, and then vacuum filter the hot carbon acid-water
desicant, which is effective in maintaining dryness of cooling
mixture immediately through the 7 cm filter funnel with
hot crucibles or oven dried carbon samples.
hardened filter paper in place. Wash the carbon
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D6385 − 99 (Reapproved 2017) D6385 − 22
Standard Test Method for
Determining Acid-Extractable Content in Activated Carbon
by Ashing
This standard is issued under the fixed designation D6385; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method is to be used for determination of the acid-extractable content of a sample of activated carbon. This test
method presupposes the existence of substances other than carbon to be present with activated carbon but does not purport to
address or identify those substances which may be present. This test method should be applicable to any form in which activated
carbon may exist and requires the performance of Test Method D2866.
1.2 This test method requires the use of concentrated hydrochloric acid, which should be used in an appropriate and safe manner,
with eye protection, skin protection, and handling carried out in a properly operating fume hood. The proper use of a muffle furnace
is addressed in Test Method D2866.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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 safety, health, and healthenvironmental practices and determinesde-
termine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
D2866 Test Method for Total Ash Content of Activated Carbon
D2867 Test Methods for Moisture in Activated Carbon
E300 Practice for Sampling Industrial Chemicals
3. Summary of Test Method
3.1 The percent acid-extractable content of an activated carbon sample is determined by the difference between the percent mass
of total ash of a sample and the percent mass of total ash of a sample which has been acid extracted.
This test method is under the jurisdiction of ASTM Committee D28 on Liquid Phase Evaluation.
Current edition approved March 1, 2017Sept. 1, 2022. Published March 2017October 2022. Originally approved in 1999. Last previous edition approved in 20112017 as
D6385 – 99 (2011).(2017). DOI: 10.1520/D6385-99R17.10.1520/D6385-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6385 − 22
4. Significance and Use
4.1 The quantitative determination of acid-extractable content is useful in evaluating activated carbon samples that contain
acid-soluble impurities. These acid-soluble impurities can affect applications of activated carbon.
4.2 Limitations of Method—Hydrochloric acid is used in this test method as the extracting acid. All elements or compounds present
in the activated carbon sample, which can be acid extracted, are assumed to form water-soluble chloride salts. Hydrochloric acid
may not solubilize all impurities of activated carbon.
5. Apparatus
5.1 250-mL Glass Beakers, 250 mL Glass Beakers or 125 mL Capacity Block Heater Digestion Vessel, for boiling and drying the
sample.
5.2 Watch Glass, suitable for 250-mL beaker.250 mL beaker or 125 mL Capacity Block Heater Digestion Vessel.
5.3 Graduated Cylinders, of 100-mL 100 mL (TD) and 25-mL 25 mL (TD) size.
5.4 Buchner Vacuum Funnel, 7-cm7cm ID or equivalent filtering device.
5.5 Vacuum Filter Flask, with side arm, 500 mL.
5.6 Vacuum Filter Collar, for the above filter flask.
5.7 Filter Paper, which is hardened, ashless paper, ≤ 8 micron pore size and 7 cm in diameter is recommended, or a diameter which
matches the vacuum funnel. The paper will be ashed with the carbon, so ashless paper is necessary.
5.8 Drying Oven, maintained at 150 °C 6 5 °C.
5.9 Muffle Furnace, as specified in Test Method D2866.
5.10 Porcelain Crucibles, as specified in Test Method D2866.
5.11 Desicator, containing indicating silica gel or any other desicant, which is effective in maintaining dryness of cooling hot
crucibles or oven dried carbon samples.
5.12 Balance, capable of measurement of 0.1 mg.
5.13 Carbon Particle Size Reduction, a mortar and pestle, or any other means of systematically reducing activated carbon particle
size to pass through a No. 325 U.S. mesh screen. The size reduction device must be constructed of material that will not
contaminate the carbon sample with acid-soluble materials.
5.14 No.
...