ISO 4907-2:2023

INTERNATIONAL ISO
STANDARD 4907-2
First edition
2023-04
Plastics — Ion exchange resin —
Part 2:
Determination of water content of
anion exchange resins in hydroxide
form by centrifugation
Reference number
© ISO 2023
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ii
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 . 2
7 Samples . 3
8 Procedure .3
8.1 Removal of the external water . 3
8.2 Determination of water content . . 3
9 Calculation . 4
10 Test Report .4
Annex A (normative) Sampling . 5
Annex B (informative) Formulae and derivations . 7
iii
Foreword
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iv
Introduction
Anion exchange resins in hydroxide form have poor thermal stability, so direct drying at high
temperatures should be avoided. This document solves this problem by form transition process and
conversion.
Formulae and derivations are given in Annex B.
v
INTERNATIONAL STANDARD ISO 4907-2:2023(E)
Plastics — Ion exchange resin —
Part 2:
Determination of water content of anion exchange resins in
hydroxide form by centrifugation
1 Scope
This document specifies test methods by centrifugation of water content of styrene anion exchange
resins in hydroxide form.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 4907-3:2023, Plastics — Ion exchange resin — Part 3: Determination of exchange capacity of anion
exchange resins in hydroxide form
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
hydroxide form styrene anion exchange resin
ionic type of styrene anion exchange resins regenerated by sodium hydroxide solution under the
conditions specified in this document
Note 1 to entry: It is a general term that includes the strong-base groups existing in hydroxide form and the
weak-base groups existing in free amine form.
3.2
water content
equilibrium water content in hydroxide form styrene anion exchange resin (3.1)
4 Principle
Remove the external water of the styrene anion exchange resin in hydroxide form absorbed enough
water by centrifugation and convert it to chloride form by hydrochloric acid. Wash away the excess acid
with anhydrous ethanol. The water content of the sample can be tested by the loss of mass on drying at
105 °C, as well as the increment of mass on the form conversion.
5 Reagents
WARNING — Reagents used in this document may can potential hazards to human health and
the environment. Ensure that the instructions for the use of reagents are strictly followed.
Unless otherwise indicated, the reagents specified in this document should be analytical grade.
Commercially available, ready-made solutions may be used.
5.1 Anhydrous ethanol
5.2 Water, grade 2 in accordance with ISO 3696.
5.3 Hydrochloric acid solution, c(HCl) = 1 mol/l.
Dilute 90 ml of hydrochloric acid (1,19 g/ml) to 1 000 ml with water.
5.4 Silver nitrate solution indicator.
Dissolve 5 g of silver nitrate in water and dilute to 100 ml. Store in an amber glass bottle.
5.5 High temperature res
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