ISO 22197-2:2019

Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for air-purification performance of semiconducting photocatalytic materials — Part 2: Removal of acetaldehyde

This document specifies a test method for the determination of the air-purification performance of materials that contain a photocatalyst or have photocatalytic films, usually made from semiconducting metal oxides, such as titanium dioxide or other ceramic materials, by continuous exposure of a test piece to the model air pollutant under irradiation with ultraviolet light (UV-A). This document is intended for use with different kinds of materials, such as construction materials in flat sheet, board or plate shape, that are the basic forms of materials for various applications. This document also applies to structured filter materials including honeycomb-form, woven and non-woven fabrics, and to plastic or paper materials if they contain ceramic microcrystals and composites. This document does not apply to powder or granular photocatalytic materials. This test method is usually applicable to photocatalytic materials produced for air purification. This method is not suitable for the determination of other performance attributes of photocatalytic materials, i.e. decomposition of water contaminants, self-cleaning, antifogging and antibacterial actions. It concerns the removal of acetaldehyde.

Céramiques techniques — Méthodes d'essai relatives à la performance des matériaux photocatalytiques semi-conducteurs pour la purification de l'air — Partie 2: Élimination de l'acétaldéhyde

General Information

• Status: Published
• Publication Date: 14-Oct-2019
• ICS: 81.060.30 - Advanced ceramics
• Technical Committee: ISO/TC 206 - Fine ceramics
• Drafting Committee: ISO/TC 206/WG 9 - Photocatalysis
• Current Stage: 6060 - International Standard published
• Start Date: 15-Oct-2019
• Due Date: 20-Sep-2019
• Completion Date: 15-Oct-2019

Relations

• Revises: ISO 22197-2:2011 - Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for air-purification performance of semiconducting photocatalytic materials — Part 2: Removal of acetaldehyde
• Effective Date: 10-Dec-2016
• Consolidated By: ISO 24032:2021 - Soil quality — In situ caging of snails to assess bioaccumulation of contaminants
• Effective Date: 06-Jun-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 22197-2
Second edition
2019-10
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Test method for air-purification
performance of semiconducting
photocatalytic materials —
Part 2:
Removal of acetaldehyde
Céramiques techniques — Méthodes d'essai relatives à la performance
des matériaux photocatalytiques semi-conducteurs pour la
purification de l'air —
Partie 2: Élimination de l'acétaldéhyde
Reference number
ISO 22197-2:2019(E)
©
ISO 2019

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ISO 22197-2:2019(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
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
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Phone: [phone]
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Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

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ISO 22197-2:2019(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Principle . 3
6 Apparatus . 3
6.1 Test equipment . 3
6.2 Test gas supply . 4
6.3 Photoreactor . 5
6.4 Light source . 6
6.5 Analytical system for acetaldehyde . 6
6.6 Analytical system for CO . 7
2
7 Test piece . 7
8 Procedure. 7
8.1 General aspects . 7
8.2 Pretreatment of test piece . 8
8.3 Preparation for the test . 8
8.4 Pretest . 9
8.5 Test of acetaldehyde removal and CO conversion . 9
2
8.6 Test of acetaldehyde removal (when the CO concentration cannot be measured) .10
2
9 Calculation .11
9.1 Calculation method .11
9.2 Removal percentage and removed quantity of acetaldehyde .11
9.3 Conversion to CO .11
2
10 Test method for test pieces with lower performance .12
11 Test report .13
Annex A (informative) Results of round-robin test .14
Bibliography .16
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ISO 22197-2:2019(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 206, Fine ceramics.
This second edition cancels and replaces the first edition (ISO 22197-2:2011), which has been technically
revised. The main changes compared to the previous edition are as follows:
— deletion of reference to ISO 2718 (withdrawn) from Clause 2 and 6.5;
— deletion of ISO 4677-1 (withdrawn) from Clause 2 and 8.3.1;
— change of gas flow measurement from dry-gas basis to wet-gas basis in 6.2;
— change of tolerance on dimensions of test piece in Clause 7;
— addition of procedures for removing water-soluble contaminants (8.2);
— addition of criterion for acceptable adsorption of acetaldehyde (9.2).
A list of all parts in the ISO 22197 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 2019 – All rights reserved

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INTERNATIONAL STANDARD ISO 22197-2:2019(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Test method for air-purification performance
of semiconducting photocatalytic materials —
Part 2:
Removal of acetaldehyde
1 Scope
This document specifies a test method for the determination of the air-purification performance of
materials that contain a photocatalyst or have photocatalytic films, usually made from semiconducting
metal oxides, such as titanium dioxide or other ceramic materials, by continuous exposure of a test
piece to the model air pollutant under irradiation with ultraviolet light (UV-A).
This document is intended for use with different kinds of materials, such as construction materials in
flat sheet, board or plate shape, that are the basic forms of materials for various applications.
This document also applies to structured filter materials including honeycomb-form, woven and non-
woven fabrics, and to plastic or paper materials if they contain ceramic microcrystals and composites.
This document does not apply to powder or granular photocatalytic materials.
This test method is usually applicable to photocatalytic materials produced for air purification.
This method is not suitable for the determination of other performance attributes of photocatalytic
materials, i.e. decomposition of water contaminants, self-cleaning, antifogging and antibacterial
actions. It concerns the removal of acetaldehyde.
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 4224, Ambient air — Determination of carbon monoxide — Non-dispersive infrared spectrometric method
ISO 10677, Fine ceramics (advanced ceramics, advanced technical ceramics) — Ultraviolet light source for
testing semiconducting photocatalytic materials
ISO 16000-3, Indoor air — Part 3: Determination of formaldehyde and other carbonyl compounds in indoor
air and test chamber air — Active sampling method
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO 80000-1:2009, Quantities and units — Part 1: General
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 http: //www .electropedia .org/
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ISO 22197-2:2019(E)

3.1
photocatalyst
substance that performs one or more functions based on oxidization and reduction reactions under
photoirradiation, including decomposition and removal of air and water contaminants, deodorization,
and antibacterial, self-cleaning and antifogging actions
3.2
photocatalytic materials
materials in which or on which the photocatalyst is added by, for example, coating, impregnation or mixing
Note 1 to entry: Such photocatalytic materials are intended primarily for use as building and road construction
materials to obtain the functions described in 3.1.
3.3
zero-calibration gas
air that does not contain pollutants (i.e. in which common pollutants are below 0,01 µl/l and carbon
dioxide is below 0,1 µl/l)
Note 1 to entry: The zero-calibration gas is prepared from indoor air using a laboratory air-purification system,
or supplied as synthetic air in a gas cylinder.
3.4
standard gas
diluted gas of known concentration supplied in cylinders and certified by an accredited laboratory
3.5
test gas
mixture of air and pollutant(s) of known concentration prepared from a standard gas or a zero-
calibration gas, to be used for the performance test of a photocatalytic material
3.6
dark condition
test condition with no light irradiation by the light source for testing and room lighting
4 Symbols
For the purposes of this document, the following symbols apply.
f air-flow rate converted into that at the standard state (0 °C and 101,3 kPa) (l/min)
ϕ volume fraction of acetaldehyde at the reactor exit (µl/l)
A
ϕ acetaldehyde volume fraction at the reactor exit under dark conditions (µl/l)
AD
ϕ supply volume fraction of acetaldehyde (µl/l)
A0
carbon dioxide (CO ) volume fraction generated by UV irradiation (µl/l)
2
φ
CO
2
CO volume fraction at the reactor exit under UV irradiation (µl/l)
2
φ
CO ,L
2
CO volume fraction at the reactor exit under dark conditions (µl/l)
2
φ
CO ,D
2
CO volume fraction in the dark after UV irradiation (µl/l)
2
φ
CO ,Dpost
2
CO volume fraction in the dark before UV irradiation (µl/l)
2
φ
CO ,Dpre
2
n quantity of acetaldehyde removed by the test piece (µmol)
A
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ISO 22197-2:2019(E)

quantity of CO converted from acetaldehyde (µmol)
2
n
CO
2
R the removal percentage, by test piece, of acetaldehyde (%)
A
the conversion from acetaldehyde to CO (%)
2
R
CO
2
5 Principle
This document concerns the development, comparison, quality assurance, characterization, reliability,
and design data generation of photocatalytic materials (see Reference [1]). The method described is
intended to obtain the air-purification performance of photocatalytic materials by exposing a test
piece to model polluted air under irradiation by ultraviolet (UV) light (see Reference [2]). Acetaldehyde
(CH CHO) is chosen as a typical volatile organic compound (VOC) with lower molecular mass and
3
[3]
offensive odour . The test piece, put in a flow-type photoreactor, is activated by UV irradiation,
and adsorbs and oxidizes gas-phase acetaldehyde to form carbon dioxide (CO ) and other oxidation
2
products. The air-purification performance is determined from the amount of acetaldehyde, in percent,
adsorbed by the test piece, in micromoles (µmol). The simple adsorption by the test piece (not due to
photocatalysis) is evaluated by the tests in the dark. However, some test pieces adsorb acetaldehyde
very strongly, and a stable concentration of acetaldehyde may not be attained in the designated time
of test. The photocatalytic activity may depend on physical and chemical properties of pollutants
mainly due to the adsorption process involved. For a better evaluation of air purification performance
of photocatalytic materials, it is recommended that one or more suitable test methods are combined as
described in other parts of the ISO 22197 series.
6 Apparatus
6.1 Test equipment
The test equipment enables a photocatalytic material to be examined for its pollutant-removal capability
by supplying the test gas continuously, while providing photoirradiation to activate the photocatalyst.
[2]
It is the same as that used in the test method for the removal of nitric oxide (ISO 22197-1 ) and consists
of a test gas supply, a photoreactor, a light source and pollutant-measurement equipment. Since low
concentrations of pollutants are to be tested, the system shall be constructed with materials of low
adsorption and resistant to UV radiation (e.g. acrylic resin, borosilicate glass). An example of a testing
system is shown in Figure 1.
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ISO 22197-2:2019(E)

Key
1 test gas supply 9 4-way valve
2 air compressor 10 photoreactor
3 air-purification system 11 test piece
4 standard gas (pollutant) 12 air-tight optical window
5 pressure regulator 13 light source
6 mass-flow controller 14 analyser
7 humidifier 15 vent
8 gas mixer
Figure 1 — Schematic diagram of test equipment
6.2 Test gas supply
The test gas supply provides air polluted with model contaminant at a predetermined concentration,
temperature and humidity, and supplies it continuously to the photoreactor. It consists of flow
regulators, a humidifier, gas mixers and so forth. The flow rate of each gas should be within 5 % of the
designated value, which is easily attained by using thermal mass-flow controllers with knowledge of
[4]
the temperature and gas type at calibration in accordance with ISO 6145-7 . The expression of gas flow
rate in this document is that converted to the standard state (0 °C and 101,3 kPa). Typical capacities
of flow controller for pollutant gas, dry air and wet air are 100 ml/min, 1 000 ml/min and 1 000 ml/
min, respectively. The standard acetaldehyde gas before dilution, normally balanced with nitrogen in a
cylinder, shall have a volume fraction of 50 µl/l to 250 µl/l. Synthetic air (N + O , such as that supplied
2 2
in cylinders) shall be used for dilution when the CO from acetaldehyde is also measured.
2
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ISO 22197-2:2019(E)

6.3 Photoreactor
The photoreactor holds a planar test piece within a 50 mm wide trough, with its surface parallel to an
optical window for photoirradiation. The reactor shall be fabricated from materials that adsorb little
test gas and withstand irradiation of near-UV light. The test piece shall be separated from the window
by a 5,0 mm ± 0,5 mm-thick air layer. The test gas shall pass only through the space between the test
piece and the window. This gap shall be accurately set up according to the thickness of the test piece, for
example, by using height-adjusting plates with different thicknesses, as shown in Figure 2 a). When a
filter-type material is tested, an alternative type of test-piece holder shall be used, which holds the test
piece while allowing the test gas to pass through the cells of the filter under irradiation [Figure 2 b)].
Quartz or borosilicate glass that absorbs minimal light at wavelengths longer than 300 nm should be
used for the window.
a)  For flat test pieces
b)  For filter-type test pieces
test piece length l test piece width l air layer thickness l
1 2 g
99,0 ± 1,0 mm 49,0 ± 1,0 mm 5,0 ± 0,5 mm
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ISO 22197-2:2019(E)

Key
1 test gas inlet 6 auxiliary plate
2 baffle 7 test piece (flat-type)
3 air-tight optical window 8 test gas outlet
4 flow channel 9 test piece holder
5 height-adjusting plate 10 test piece (filter-type)
Figure 2 — Cross-sectional view of photoreactor
6.4 Light source
The light source shall provide UV-A irradiation within a wavelength range of 300 nm to 400 nm.
Suitable sources include the so-called black light (BL) and black light blue (BLB) fluorescent lamps, with
a maximum at 351 nm or 368 nm, as specified in ISO 10677, and xenon arc lamps with optical filters
that block radiation below 300 nm. In the case of a xenon arc lamp, a cooling system shall be used in
accordance with ISO 10677. The test piece shall be irradiated uniformly through the window by the
light source. In the case of testing filter-type photocatalysts, the light source shall irradiate one end of
the test piece. A light source that requires warming up shall be equipped with a shutter. The distance
between the light source and the reactor shall be adjusted so that the UV irradiance (300 nm to 400 nm)
2 2
at the sample surface is 10 W/m ± 0,5 W/m . This distance shall be determined independently without
using the photoreactor. A UV radiometer in conformity with ISO 10677 shall be put behind the optical
window or its equivalent, at the same level as the test piece to be tested. The irradiance along the length
of the test piece shall also be constant within ±5 %. The reactor shall be shielded from external light if
necessary.
6.5 Analytical system for acetaldehyde
The concentration of acetaldehyde shall be determined by gas chromatography or
2,4-dinitrophenylhydrazine-derivatized high-performance liquid chromatography (DNPH/HPLC).
In the case of gas chromatography, either a packed column or capillary column can be used, as long as it
can separate lower organic compounds. The detection shall be m
...