National foreword

This British Standard is the UK implementation of ISO 9277:2022. It supersedes BS ISO 9277:2010, which is withdrawn.

The UK participation in its preparation was entrusted to Technical Committee LBI/37, Particle characterization including sieving.

A list of organizations represented on this committee can be obtained on request to its committee manager.

Contractual and legal considerations

This publication has been prepared in good faith, however no representation, warranty, assurance or undertaking (express or implied) is or will be made, and no responsibility or liability is or will be accepted by BSI in relation to the adequacy, accuracy, completeness or reasonableness of this publication. All and any such responsibility and liability is expressly disclaimed to the full extent permitted by the law.

This publication is provided as is, and is to be used at the recipient’s own risk.

The recipient is advised to consider seeking professional guidance with respect to its use of this publication.

This publication is not intended to constitute a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 November 2022.

Foreword

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The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

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This document was prepared by Technical Committee ISO/TC 24, Particle characterization including sieving, Subcommittee SC 4, Particle characterization.

This third edition cancels and replaces the second edition (ISO 9277:2010), which has been technically revised.

The main changes compared to the previous edition are as follows:

the IUPAC classification of adsorption isotherms has been updated according to Reference [3];
the description of dynamic vapour sorption (DVS) method in 6.3.6 has been added;
Annex A has been revised;
Annex B has been removed;
the former Annex C (now Annex B) has been revised.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Introduction

Gas adsorption allows for assessing surface area of nonporous materials and porous materials with accessible porosity (which depends on the chosen adsorptive) via the Brunauer, Emmett and Teller (BET) theory^[¹^],[²^]. The BET theory is applicable only to adsorption isotherms of type II (disperse, nonporous or macroporous solids) and type IV (mesoporous solids) (see Figure 1, Type II and Type IVa isotherms). However, in the case of Type IVb isotherms, caution is required since pore condensation can occur at quite low p/p₀ (see IUPAC recommendations^[³^]). The BET method cannot reliably be applied to solids which absorb the measuring gas. A strategy for BET area determination of microporous materials (type I isotherms) is described in Annex B.

1 Scope

This document specifies the determination of the overall specific external and internal surface area of either disperse (e.g. nano-powders) or porous, solids by measuring the amount of physically adsorbed gas according to the method of Brunauer, Emmett and Teller method,^[¹^] based on the 2015 International Union for Pure and Applied Chemistry (IUPAC) recommendations^[³^].

NOTE For solids exhibiting a chemically heterogeneous surface, for example, metal-carrying catalyst, the BET method gives the overall surface area, whereas the metallic portion of the surface area can be measured by chemisorption methods.

2 Normative references

3 Terms and definitions

4 Symbols

5 Principle

6 Procedure

6.1 Sample preparation

6.2 Experimental conditions

6.3 Measuring methods for the assessment of the amount of adsorbed gas

7 Evaluation of adsorption data

7.1 General

7.2 Multipoint determination

7.3 Single-point determination

8 Test report

9 Use of reference materials

Bibliography

BS ISO 9277:2022

Determination of the specific surface area of solids by gas adsorption. BET method

Current

Published:

30 Nov 2022