Paper, board and pulps — Determination of pH of aqueous extracts — Part 1: Cold extraction

This document specifies a method for the determination of the pH-value defined by the electrolytes extractable by cold water from a sample of paper, board or pulp. This document is applicable to all types of paper, board and pulp. As the quantity of extractable ionic material approaches zero, as in the case of highly purified pulps, the precision of the method becomes poor because of the difficulties encountered in making pH measurements on water containing little electrolytic material. Since the extraction in this document is performed with distilled or deionised water, the pH-value measured will sometimes be different (e.g. for fully bleached pulp) from the pH-value measured under mill process conditions in which various types of process waters, e.g. chemically treated river water containing electrolytes, are used. In such cases, ISO 29681 should be used instead, as it is specifically applicable to bleached pulps from virgin fibres and to pulp samples having a low ionic strength for which the pH value will give more realistic results related to mill conditions than those obtained with this document. For cellulosic papers used for electrical purposes, the method used should be that given in IEC 60554‑2[4].

Papier, carton et pâtes — Détermination du pH des extraits aqueux — Partie 1: Extraction à froid

Le présent document spécifie une méthode pour la détermination du pH défini par les électrolytes extractibles d'un échantillon de papier, de carton ou de pâte, par de l'eau froide. Ce document est applicable à tous les types de papiers, de cartons et de pâtes. Lorsque la quantité de substance ionique extractible est presque nulle, comme dans le cas des pâtes hautement purifiées, la fidélité de la méthode devient mauvaise en raison des difficultés rencontrées lors de la réalisation des mesurages de pH d'une eau contenant peu de substances électrolytiques. Puisque, dans ce document, l'extraction est effectuée avec de l'eau distillée ou désionisée, le pH mesuré est parfois différent (par exemple pour une pâte hautement blanchie) de celui mesuré dans les conditions mises en œuvre pendant le procédé industriel lors duquel différents types d'eaux de process sont utilisés, par exemple de l'eau de rivière traitée chimiquement contenant des électrolytes. Dans de tels cas, il convient d'appliquer l'ISO 29681 qui est spécifiquement élaborée pour les pâtes blanchies à partir de fibres vierges et aux échantillons de pâtes de faible concentration ionique pour lesquels les valeurs de pH seront plus réalistes du procédé industriel que celles obtenues avec le présent document. Pour les papiers cellulosiques à usages électriques, il est recommandé d'utiliser la méthode indiquée dans la norme IEC 60554-2[4].

Papir, karton, lepenka in vlaknine - Določanje vrednosti pH vodnih ekstraktov - 1. del: Ekstrakcija v hladnem

General Information

Status
Withdrawn
Publication Date
23-Feb-2020
Withdrawal Date
23-Feb-2020
Current Stage
9599 - Withdrawal of International Standard
Start Date
23-Nov-2021
Completion Date
23-Nov-2021

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SLOVENSKI STANDARD
SIST ISO 6588-1:2020
01-november-2020

Papir, karton, lepenka in vlaknine - Določanje vrednosti pH vodnih ekstraktov - 1.

del: Ekstrakcija v hladnem

Paper, board and pulps -- Determination of pH of aqueous extracts -- Part 1: Cold

extraction
Papier, carton et pâtes -- Détermination du pH des extraits aqueux
Ta slovenski standard je istoveten z: ISO 6588-1:2020
ICS:
85.040 Vlaknine Pulps
85.060 Papir, karton in lepenka Paper and board
SIST ISO 6588-1:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST ISO 6588-1:2020
---------------------- Page: 2 ----------------------
SIST ISO 6588-1:2020
INTERNATIONAL ISO
STANDARD 6588-1
Third edition
2020-02
Paper, board and pulps —
Determination of pH of aqueous
extracts —
Part 1:
Cold extraction
Papier, carton et pâtes — Détermination du pH des extraits aqueux —
Partie 1: Extraction à froid
Reference number
ISO 6588-1:2020(E)
ISO 2020
---------------------- Page: 3 ----------------------
SIST ISO 6588-1:2020
ISO 6588-1:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 6588-1:2020
ISO 6588-1:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 1

5 Reagents ........................................................................................................................................................................................................................ 2

6 Apparatus and equipment .......................................................................................................................................................................... 2

7 Sampling and preparation of sample .............................................................................................................................................. 2

7.1 Sampling ....................................................................................................................................................................................................... 2

7.2 Preparation of sample....................................................................................................................................................................... 2

8 Procedure..................................................................................................................................................................................................................... 2

8.1 Weighing ....................................................................................................................................................................................................... 3

8.2 Extraction .................................................................................................................................................................................................... 3

8.3 Determination of pH .......................................................................................................................................................................... 3

9 Calculation .................................................................................................................................................................................................................. 3

10 Test report ................................................................................................................................................................................................................... 3

Annex A (informative) Preparation of some standard buffer solutions .......................................................................... 5

Annex B (informative) Precision ............................................................................................................................................................................... 6

Bibliography ................................................................................................................................................................................................................................ 7

© ISO 2020 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 6588-1:2020
ISO 6588-1:2020(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

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).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www .iso .org/ iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 6, Paper, board and pulps.

This third edition cancels and replaces the second edition (ISO 6588-1:2012), which has been technically

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

— addition of the last four paragraphs in the Introduction to clarify the differences, in the role and

[5]
mode of addition of a salt solution, between this document and ISO 29681 .
A list of all parts in the ISO 6588 series can be found on the ISO website.

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.
iv © ISO 2020 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 6588-1:2020
ISO 6588-1:2020(E)
Introduction

Kraft fibre is well known to contain ionisable groups that are fixed to or in the fibre wall. In order to

fulfil the electro-neutrality, these groups are balanced by an equivalent number of positive charges,

which can be either protons or various metal ions. Especially in pulp suspensions at low ionic strengths,

this can give rise to a marked uneven distribution of mobile ions between the volume held by the fibre

wall and the bulk suspension liquor. This means that the fibre acts as an ion exchanger. These ion-

[2][3]
exchange phenomena can be modelled very well with the Donnan theory .

If a relatively clean pulp fibre sample, for example bleached dried pulp, is diluted in deionised water,

the result will be a pulp suspension with a very low ionic strength. In such a system, most of the cations

present, including protons, will be concentrated in the water volume held by the fibre wall. If the pH

is measured, it will be measured in the bulk suspension liquor. By adding salt to this kind of system,

the ion exchange phenomena will be decreased, and the concentration of different cations will be the

same in the water held by the fibre wall and in the bulk suspension liquor. Since the process waters

always contain a certain amount of ions, such a salt addition will give a more realistic environment

when measuring the pH of relatively clean pulp samples.

Based on the foregoing, two ISO Standards, ISO 6588-1 and ISO 29681, are available for determination

of the pH of cold aqueous extracts of paper, board, or pulps. In ISO 29681, a salt solution is added prior

to extraction; however, in ISO 6588-1, the extraction is carried out with distilled or deionized water.

ISO 29681 is specifically applicable to bleached pulps from virgin fibres and to pulp samples having a

low ionic strength for which the pH-value will give more realistic results related to mill conditions than

those obtained with ISO 6588-1.

It is necessary to be aware that the results will not be the same when measuring pH according to

ISO 6588-1 and to ISO 29681. The difference can be significant especially when measuring pulps having

a low ionic strength.

ISO 6588-2 differs from this document only as regards the extraction conditions. No general guidance

can be given as to which of the two procedures (hot or cold) is best suited in a particular situation.

It should be noted that in ISO 6588-1, addition of a salt solution is performed after extraction and

filtration only for the purpose of obtaining a more stable and accurate pH measurement.

© ISO 2020 – All rights reserved v
---------------------- Page: 7 ----------------------
SIST ISO 6588-1:2020
---------------------- Page: 8 ----------------------
SIST ISO 6588-1:2020
INTERNATIONAL STANDARD ISO 6588-1:2020(E)
Paper, board and pulps — Determination of pH of aqueous
extracts —
Part 1:
Cold extraction
1 Scope

This document specifies a method for the determination of the pH-value defined by the electrolytes

extractable by cold water from a sample of paper, board or pulp.
This document is applicable to all types of paper, board and pulp.
As the quantity of extractable ionic material approaches zero,
...

SLOVENSKI STANDARD
oSIST ISO 6588-1:2020
01-oktober-2020

Papir, karton, lepenka in vlaknine - Določanje vrednosti pH vodnih ekstraktov - 1.

del: Ekstrakcija v hladnem

Paper, board and pulps -- Determination of pH of aqueous extracts -- Part 1: Cold

extraction
Papier, carton et pâtes -- Détermination du pH des extraits aqueux
Ta slovenski standard je istoveten z: ISO 6588-1:2020
ICS:
85.040 Vlaknine Pulps
85.060 Papir, karton in lepenka Paper and board
oSIST ISO 6588-1:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST ISO 6588-1:2020
---------------------- Page: 2 ----------------------
oSIST ISO 6588-1:2020
INTERNATIONAL ISO
STANDARD 6588-1
Third edition
2020-02
Paper, board and pulps —
Determination of pH of aqueous
extracts —
Part 1:
Cold extraction
Papier, carton et pâtes — Détermination du pH des extraits aqueux —
Partie 1: Extraction à froid
Reference number
ISO 6588-1:2020(E)
ISO 2020
---------------------- Page: 3 ----------------------
oSIST ISO 6588-1:2020
ISO 6588-1:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST ISO 6588-1:2020
ISO 6588-1:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 1

5 Reagents ........................................................................................................................................................................................................................ 2

6 Apparatus and equipment .......................................................................................................................................................................... 2

7 Sampling and preparation of sample .............................................................................................................................................. 2

7.1 Sampling ....................................................................................................................................................................................................... 2

7.2 Preparation of sample....................................................................................................................................................................... 2

8 Procedure..................................................................................................................................................................................................................... 2

8.1 Weighing ....................................................................................................................................................................................................... 3

8.2 Extraction .................................................................................................................................................................................................... 3

8.3 Determination of pH .......................................................................................................................................................................... 3

9 Calculation .................................................................................................................................................................................................................. 3

10 Test report ................................................................................................................................................................................................................... 3

Annex A (informative) Preparation of some standard buffer solutions .......................................................................... 5

Annex B (informative) Precision ............................................................................................................................................................................... 6

Bibliography ................................................................................................................................................................................................................................ 7

© ISO 2020 – All rights reserved iii
---------------------- Page: 5 ----------------------
oSIST ISO 6588-1:2020
ISO 6588-1:2020(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

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).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www .iso .org/ iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 6, Paper, board and pulps.

This third edition cancels and replaces the second edition (ISO 6588-1:2012), which has been technically

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

— addition of the last four paragraphs in the Introduction to clarify the differences, in the role and

[5]
mode of addition of a salt solution, between this document and ISO 29681 .
A list of all parts in the ISO 6588 series can be found on the ISO website.

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.
iv © ISO 2020 – All rights reserved
---------------------- Page: 6 ----------------------
oSIST ISO 6588-1:2020
ISO 6588-1:2020(E)
Introduction

Kraft fibre is well known to contain ionisable groups that are fixed to or in the fibre wall. In order to

fulfil the electro-neutrality, these groups are balanced by an equivalent number of positive charges,

which can be either protons or various metal ions. Especially in pulp suspensions at low ionic strengths,

this can give rise to a marked uneven distribution of mobile ions between the volume held by the fibre

wall and the bulk suspension liquor. This means that the fibre acts as an ion exchanger. These ion-

[2][3]
exchange phenomena can be modelled very well with the Donnan theory .

If a relatively clean pulp fibre sample, for example bleached dried pulp, is diluted in deionised water,

the result will be a pulp suspension with a very low ionic strength. In such a system, most of the cations

present, including protons, will be concentrated in the water volume held by the fibre wall. If the pH

is measured, it will be measured in the bulk suspension liquor. By adding salt to this kind of system,

the ion exchange phenomena will be decreased, and the concentration of different cations will be the

same in the water held by the fibre wall and in the bulk suspension liquor. Since the process waters

always contain a certain amount of ions, such a salt addition will give a more realistic environment

when measuring the pH of relatively clean pulp samples.

Based on the foregoing, two ISO Standards, ISO 6588-1 and ISO 29681, are available for determination

of the pH of cold aqueous extracts of paper, board, or pulps. In ISO 29681, a salt solution is added prior

to extraction; however, in ISO 6588-1, the extraction is carried out with distilled or deionized water.

ISO 29681 is specifically applicable to bleached pulps from virgin fibres and to pulp samples having a

low ionic strength for which the pH-value will give more realistic results related to mill conditions than

those obtained with ISO 6588-1.

It is necessary to be aware that the results will not be the same when measuring pH according to

ISO 6588-1 and to ISO 29681. The difference can be significant especially when measuring pulps having

a low ionic strength.

ISO 6588-2 differs from this document only as regards the extraction conditions. No general guidance

can be given as to which of the two procedures (hot or cold) is best suited in a particular situation.

It should be noted that in ISO 6588-1, addition of a salt solution is performed after extraction and

filtration only for the purpose of obtaining a more stable and accurate pH measurement.

© ISO 2020 – All rights reserved v
---------------------- Page: 7 ----------------------
oSIST ISO 6588-1:2020
---------------------- Page: 8 ----------------------
oSIST ISO 6588-1:2020
INTERNATIONAL STANDARD ISO 6588-1:2020(E)
Paper, board and pulps — Determination of pH of aqueous
extracts —
Part 1:
Cold extraction
1 Scope

This document specifies a method for the determination of the pH-value defined by the electrolytes

extractable by cold water from a sample of paper, board or pulp.
This document is applicable to all types of paper, board and pulp.
As the quantity of extractable ionic material approaches zero,
...

INTERNATIONAL ISO
STANDARD 6588-1
Third edition
2020-02
Paper, board and pulps —
Determination of pH of aqueous
extracts —
Part 1:
Cold extraction
Papier, carton et pâtes — Détermination du pH des extraits aqueux —
Partie 1: Extraction à froid
Reference number
ISO 6588-1:2020(E)
ISO 2020
---------------------- Page: 1 ----------------------
ISO 6588-1:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 6588-1:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 1

5 Reagents ........................................................................................................................................................................................................................ 2

6 Apparatus and equipment .......................................................................................................................................................................... 2

7 Sampling and preparation of sample .............................................................................................................................................. 2

7.1 Sampling ....................................................................................................................................................................................................... 2

7.2 Preparation of sample....................................................................................................................................................................... 2

8 Procedure..................................................................................................................................................................................................................... 2

8.1 Weighing ....................................................................................................................................................................................................... 3

8.2 Extraction .................................................................................................................................................................................................... 3

8.3 Determination of pH .......................................................................................................................................................................... 3

9 Calculation .................................................................................................................................................................................................................. 3

10 Test report ................................................................................................................................................................................................................... 3

Annex A (informative) Preparation of some standard buffer solutions .......................................................................... 5

Annex B (informative) Precision ............................................................................................................................................................................... 6

Bibliography ................................................................................................................................................................................................................................ 7

© ISO 2020 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 6588-1:2020(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

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).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www .iso .org/ iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 6, Paper, board and pulps.

This third edition cancels and replaces the second edition (ISO 6588-1:2012), which has been technically

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

— addition of the last four paragraphs in the Introduction to clarify the differences, in the role and

[5]
mode of addition of a salt solution, between this document and ISO 29681 .
A list of all parts in the ISO 6588 series can be found on the ISO website.

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.
iv © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 6588-1:2020(E)
Introduction

Kraft fibre is well known to contain ionisable groups that are fixed to or in the fibre wall. In order to

fulfil the electro-neutrality, these groups are balanced by an equivalent number of positive charges,

which can be either protons or various metal ions. Especially in pulp suspensions at low ionic strengths,

this can give rise to a marked uneven distribution of mobile ions between the volume held by the fibre

wall and the bulk suspension liquor. This means that the fibre acts as an ion exchanger. These ion-

[2][3]
exchange phenomena can be modelled very well with the Donnan theory .

If a relatively clean pulp fibre sample, for example bleached dried pulp, is diluted in deionised water,

the result will be a pulp suspension with a very low ionic strength. In such a system, most of the cations

present, including protons, will be concentrated in the water volume held by the fibre wall. If the pH

is measured, it will be measured in the bulk suspension liquor. By adding salt to this kind of system,

the ion exchange phenomena will be decreased, and the concentration of different cations will be the

same in the water held by the fibre wall and in the bulk suspension liquor. Since the process waters

always contain a certain amount of ions, such a salt addition will give a more realistic environment

when measuring the pH of relatively clean pulp samples.

Based on the foregoing, two ISO Standards, ISO 6588-1 and ISO 29681, are available for determination

of the pH of cold aqueous extracts of paper, board, or pulps. In ISO 29681, a salt solution is added prior

to extraction; however, in ISO 6588-1, the extraction is carried out with distilled or deionized water.

ISO 29681 is specifically applicable to bleached pulps from virgin fibres and to pulp samples having a

low ionic strength for which the pH-value will give more realistic results related to mill conditions than

those obtained with ISO 6588-1.

It is necessary to be aware that the results will not be the same when measuring pH according to

ISO 6588-1 and to ISO 29681. The difference can be significant especially when measuring pulps having

a low ionic strength.

ISO 6588-2 differs from this document only as regards the extraction conditions. No general guidance

can be given as to which of the two procedures (hot or cold) is best suited in a particular situation.

It should be noted that in ISO 6588-1, addition of a salt solution is performed after extraction and

filtration only for the purpose of obtaining a more stable and accurate pH measurement.

© ISO 2020 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 6588-1:2020(E)
Paper, board and pulps — Determination of pH of aqueous
extracts —
Part 1:
Cold extraction
1 Scope

This document specifies a method for the determination of the pH-value defined by the electrolytes

extractable by cold water from a sample of paper, board or pulp.
This document is applicable to all types of paper, board and pulp.

As the quantity of extractable ionic material approaches zero, as in the case of highly purified pulps,

the precision of the method becomes poor because of the difficulties encountered in making pH

measurements on water containing little electrolytic material.

Since the extraction in this document is performed with distilled or deionised water, the pH-value

measured will sometimes be different (e.g. for fully bleached pulp) from the pH-value measured under

mill process conditions in which various types of process waters, e.g. chemicall
...

NORME ISO
INTERNATIONALE 6588-1
Troisième édition
2020-02
Papier, carton et pâtes —
Détermination du pH des extraits
aqueux —
Partie 1:
Extraction à froid
Paper, board and pulps — Determination of pH of aqueous extracts —
Part 1: Cold extraction
Numéro de référence
ISO 6588-1:2020(F)
ISO 2020
---------------------- Page: 1 ----------------------
ISO 6588-1:2020(F)
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2020

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publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique,

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ii © ISO 2020 – Tous droits réservés
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ISO 6588-1:2020(F)
Sommaire Page

Avant-propos ..............................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Domaine d’application ................................................................................................................................................................................... 1

2 Références normatives ................................................................................................................................................................................... 1

3 Termes et définitions ....................................................................................................................................................................................... 1

4 Principe .......................................................................................................................................................................................................................... 2

5 Réactifs ........................................................................................................................................................................................................................... 2

6 Appareillage et équipement ..................................................................................................................................................................... 2

7 Échantillonnage et préparation de l’échantillon ................................................................................................................ 2

7.1 Échantillonnage ...................................................................................................................................................................................... 2

7.2 Préparation de l’échantillon ........................................................................................................................................................ 2

8 Mode opératoire.................................................................................................................................................................................................... 3

8.1 Pesée ................................................................................................................................................................................................................ 3

8.2 Extraction .................................................................................................................................................................................................... 3

8.3 Détermination du pH ......................................................................................................................................................................... 3

9 Calcul ................................................................................................................................................................................................................................ 3

10 Rapport d’essai ....................................................................................................................................................................................................... 4

Annexe A (informative) Préparation de solutions tampons étalons ................................................................................... 5

Annexe B (informative) Fidélité................................................................................................................................................................................. 6

Bibliographie .............................................................................................................................................................................................................................. 8

© ISO 2020 – Tous droits réservés iii
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ISO 6588-1:2020(F)
Avant-propos

L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes

nationaux de normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est

en général confiée aux comités techniques de l'ISO. Chaque comité membre intéressé par une étude

a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,

gouvernementales et non gouvernementales, en liaison avec l'ISO participent également aux travaux.

L'ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui

concerne la normalisation électrotechnique.

Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont

décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier, de prendre note des différents

critères d'approbation requis pour les différents types de documents ISO. Le présent document a été

rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www

.iso .org/ directives).

L'attention est attirée sur le fait que certains des éléments du présent document peuvent faire l'objet de

droits de propriété intellectuelle ou de droits analogues. L'ISO ne saurait être tenue pour responsable

de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant

les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de

l'élaboration du document sont indiqués dans l'Introduction et/ou dans la liste des déclarations de

brevets reçues par l'ISO (voir www .iso .org/ brevets).

Les appellations commerciales éventuellement mentionnées dans le présent document sont données

pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un

engagement.

Pour une explication de la nature volontaire des normes, la signification des termes et expressions

spécifiques de l'ISO liés à l'évaluation de la conformité, ou pour toute information au sujet de l'adhésion

de l'ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles

techniques au commerce (OTC), voir www .iso .org/ avant -propos.

Le présent document a été élaborée par le comité technique ISO/TC 6, Papiers, cartons et pâtes.

Cette troisième édition annule et remplace la deuxième édition (ISO 6588-1:2012) qui a fait l’objet d’une

révision technique. Les principales modifications par rapport à l’édition précédente sont les suivantes:

— ajout des quatre derniers paragraphes dans l’introduction afin de clarifier les différences, en termes

[5]

de rôle et de mode d’ajout d’une solution saline, entre la présente norme et l’ISO 29681 .

Une liste de toutes les parties de la série ISO 6588 se trouve sur le site web de l’ISO.

Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent

document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes

se trouve à l’adresse https:// www .iso .org/ fr/ members .html.
iv © ISO 2020 – Tous droits réservés
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ISO 6588-1:2020(F)
Introduction

Il est bien connu que la fibre kraft contient des groupes ionisables qui sont fixés sur ou dans la paroi

de la fibre. Afin de satisfaire l’électroneutralité, ces groupes sont équilibrés par un nombre égal de

charges positives, qui peuvent être des protons ou des ions métalliques divers. En particulier dans les

suspensions de pâtes de faible concentration ionique, cela peut mener à une distribution inégale des

ions mobiles entre le volume emprisonné dans la paroi de la fibre et le reste de la suspension. Cela

signifie que les fibres agissent comme un échangeur d’ions. Ces phénomènes d’échange d’ions peuvent

[2] [3]
être très bien modélisés à l’aide de la théorie de Donnan .

Si un échantillon de fibres d’une pâte relativement propre, par exemple une pâte blanchie et séchée,

est dilué dans de l’eau désionisée, le résultat sera une suspension de pâte de très faible concentration

ionique. Dans un tel système, la plupart des cations présents, ainsi que les protons, sont concentrés

dans un volume d’eau retenu par la paroi de la fibre. Si le pH est mesuré, il s’agit du pH de la pâte

environnante. En ajoutant un sel à ce type de système, le phénomène d’échange d’ions est diminué et

la concentration des différents cations sera identique dans l’eau emprisonnée par la paroi de la fibre

et le reste de la pâte en suspension. Puisque les eaux de procédés contiennent toujours une certaine

quantité d’ions, un tel ajout d’un sel résultera en un environnement plus réaliste lors de la mesure du pH

d’échantillons de pâtes relativement propres.

Sur la base de ce qui précède, deux normes ISO, l’ISO 6588-1 et l’ISO 29681, sont disponibles pour la

détermination du pH des extraits aqueux à froid de papier, de carton ou de pâtes. Dans l’ISO 29681, une

solution saline est ajoutée avant l’extraction; toutefois, dans l’ISO 6588-1, l’extraction est réalisée avec

de l’eau distillée ou désionisée. L’ISO 29681 s’applique spécifiquement aux pâtes blanchies à partir de

fibres vierges et aux échantillons de pâtes de faible concentration ionique dont les conditions de pH lors

du procédé industriel conduiront à des résultats plus réalistes que ceux obtenus avec l’ISO 6588-1.

Il est nécessaire d’avoir conscience du fait que les résultats obtenus en mesurant le pH conformément

à l’ISO 6588-1 seront différents de ceux obtenus à l’aide de l’ISO 29681. Ces différences peuvent être

significatives, notamment lors d’un mesurage sur des pâtes de faible concentration ionique.

L’ISO 6588-2 ne diffère du présent document qu’au sujet des conditions d’extraction. Aucune ligne

directrice générale ne peut être donnée concernant le mode opératoire le plus adapté (extraction à

chaud ou à froid) en fonction d’une situation donnée.

Il convient de noter que dans l’ISO 6588-1, l’ajout d’une solution saline est effectué après extraction et

filtration uniquement dans le but d’obtenir une mesure plus stable et exacte du pH.

© ISO 2020 – Tous droits réservés v
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NORME INTERNATIONALE ISO 6588-1:2020(F)
Papier, carton et pâtes — Détermination du pH des extraits
aqueux —
Partie 1:
Extraction à froid
1 Domaine d’application

Le présent document spécifie une méthode pour la détermination du pH défini par les électrolytes

extractibles d’un échantillon de papier, de carton ou de pâte, par de l’eau froide.

Ce document est applicable à tous les types de papiers, de cartons et de pâtes.

Lorsque la quantité de substance ionique extractible est presque nulle, comme dans le cas des pâtes

hautement purifiées, la fidélité de la méthode devient mauvaise en raison des difficultés rencontrées

lors de la réalisation des mesurages de pH d’une eau contenant peu de substances électrolytiques.

Puisque, dans ce document, l’extraction est effectuée avec de l’eau distillée ou désionisée, le pH

mesuré est parfois différent (par exemple pour une pâte hautement blanchie) de celui mesuré dans les

conditions mises en œuvre pendant le procédé industriel lors duquel différents types d’eaux de process

sont utilisés, par exemple de l’eau de rivière traitée chimiquement contenant des électrolytes. Dans de

tels cas, il convient d’appliquer l’ISO 29681 qui est spécifiquement élaborée pour les pâtes b

...

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