ISO 22197-3:2019

INTERNATIONAL ISO
STANDARD 22197-3
Second edition
2019-10
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Test method for air-purification
performance of semiconducting
photocatalytic materials —
Part 3:
Removal of toluene
Céramiques techniques — Méthodes d'essai relatives à la performance
des matériaux photocatalytiques semi-conducteurs pour la
purification de l'air —
Partie 3: Élimination du toluène
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Principle . 2
6 Apparatus . 3
6.1 Test equipment . 3
6.2 Test gas supply . 4
6.3 Photoreactor . 4
6.4 Light source . 6
6.5 Analytical system . 6
7 Test piece . 7
8 Procedure. 7
8.1 General aspects . 7
8.2 Pretreatment of test piece . 8
8.3 Toluene removal test . 8
9 Calculation . 9
10 Test method for test pieces with lower performance .10
11 Test report .10
Annex A (informative) Results of round-robin test .11
Bibliography .12
Foreword
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.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 22197-3:2011), 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— deletion of reference to ISO 2718 (withdrawn) from Clause 2 and 6.5;
— deletion of ISO 4677-1 (withdrawn) from Clause 2 and 8.3.1;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 toluene (Clause 9).
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

INTERNATIONAL STANDARD ISO 22197-3:2019(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Test method for air-purification performance
of semiconducting photocatalytic materials —
Part 3:
Removal of toluene
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 on the surface, 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 toluene.
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 4892-3, Plastics — Methods of exposure to laboratory light sources — Part 3: Fluorescent UV lamps
ISO 10677, Fine ceramics (advanced ceramics, advanced technical ceramics) — Ultraviolet light source for
testing semiconducting photocatalytic materials
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO 80000-1, 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/
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)
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 flow rate of test gas converted into that at the standard state (0 °C and 101,3 kPa) (l/min)
ϕ volume fraction of toluene at the reactor exit (µl/l)
T
ϕ supply volume fraction of toluene (µl/l)
T0
ϕ toluene volume fraction at the reactor exit under dark condition (µl/l)
TD
n quantity of toluene removed by the test piece (µmol)
T
R removal percentage, by test piece, of toluene (%)
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 (Reference [2]). Toluene (C H ) is
7 8
[3]
chosen as a typical aromatic volatile organic compound (VOC) with offensive odour . The test piece,
placed in a flow-type photoreactor, is activated by UV irradiation, and adsorbs and oxidizes gas-phase
toluene to form carbon dioxide (CO ) and other oxidation products (References [4] to [6]). The air-
purification performance is determined from the amount of toluene removed by the test piece, in
2 © ISO 2019 – All rights reserved

micromoles (μmol). The simple adsorption by the test piece (not due to photocatalysis) is evaluated by
tests in the dark. However, some test pieces adsorb toluene very strongly, and a stable concentration
of toluene 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.
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 the 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
[7]
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
...