ISO 22197-1:2016

INTERNATIONAL ISO
STANDARD 22197-1
Second edition
2016-11-01
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Test method for air-purification
performance of semiconducting
photocatalytic materials —
Part 1:
Removal of nitric oxide
Céramiques techniques — Méthodes d’essai relatives à la performance
des matériaux photocatalytiques semi-conducteurs pour la
purification de l’air —
Partie 1: Élimination de l’oxyde nitrique
Reference number
ISO 22197-1:2016(E)
©
ISO 2016

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ISO 22197-1:2016(E)

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ii © ISO 2016 – All rights reserved

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ISO 22197-1:2016(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols . 2
5 Principle . 3
6 Apparatus . 3
6.1 Test equipment . 3
6.2 Test gas supply . 3
6.3 Photoreactor . 6
6.4 Light source . 6
6.5 Analyser of pollutants . 6
7 Test piece . 6
8 Procedure. 6
8.1 Pretreatment of test piece . 6
8.2 Pollutant-removal test . 7
8.3 Elution test . 8
9 Calculation . 8
9.1 Calculation method . 8
9.2 Amount of NO adsorption by the test piece . 9
x
9.3 Amount of NO removed by the test piece . 9
9.4 Amount of NO formed by the test piece . 9
2
9.5 Amount of NO desorbed from the test piece .10
x
9.6 Net amount of NO removed by the test piece .10
x
9.7 Nitrogen eluted from the test piece .10
9.8 Recovery of washing with water .11
10 Test method for test pieces with lower performance .11
11 Test report .11
Annex A (informative) Results of round-robin test .12
Bibliography .13
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ISO 22197-1:2016(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 on 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 the following URL: www.iso.org/iso/foreword.html.
The committee responsible for this document is ISO/TC 206, Fine ceramics.
This second edition cancels and replaces the first edition (ISO 22197-1:2007), which has been technically
revised with the following changes:
— deletion of reference to ISO 4677-1 (withdrawn) from Clause 2 and 8.2.2;
— addition of a definition of “dark condition” (3.7);
— change of air-flow rate measurement to a wet gas basis (6.2);
— change of tolerance on dimensions of test piece in Clause 7;
— update of procedure in Clause 8 to reflect the latest knowledge;
— addition of a test method for test pieces with lower performance (new Clause 10).
A list of all parts in the ISO 22197 series can be found on the ISO website.
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INTERNATIONAL STANDARD ISO 22197-1:2016(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Test method for air-purification performance
of semiconducting photocatalytic materials —
Part 1:
Removal of nitric oxide
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 illumination with ultraviolet light. 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 materials in honeycomb-form 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 nitric oxide.
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 4892-1, Plastics — Methods of exposure to laboratory light sources — Part 1: General guidance
ISO 4892-3, Plastics — Methods of exposure to laboratory light sources — Part 3: Fluorescent UV lamps
ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method
for the determination of repeatability and reproducibility of a standard measurement method
ISO 6145-7, Gas analysis — Preparation of calibration gas mixtures using dynamic volumetric methods —
Part 7: Thermal mass-flow controllers
ISO 7996, Ambient air — Determination of the mass concentration of nitrogen oxides —
Chemiluminescence method
ISO 10304-1, Water quality — Determination of dissolved anions by liquid chromatography of ions —
Part 1: Determination of bromide, chloride, fluoride, nitrate, nitrite, phosphate and sulfate
ISO 10523, Water quality — Determination of pH
ISO 80000-1, Quantities and units — Part 1: General
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
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ISO 22197-1:2016(E)

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:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
photocatalyst
substance that performs one or more functions based on oxidation 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 coating, impregnation, mixing, etc.
Note 1 to entry: Such photocatalytic materials are intended primarily for use as building and road construction
materials to obtain the above-mentioned functions.
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 gases of known concentrations 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
purified water
water to be used for elution, etc., with a specific conductivity lower than 1 µS/cm, prepared by the ion
exchange method or distillation
3.7
dark condition
test condition with no light illumination by the light source for testing and room lightings
4 Symbols
f air-flow rate converted into that at the standard state (0 °C, 101,3 kPa) (l/min)
nitric oxide volume fraction at the reactor exit (µl/l)
φ
NO
supply volume fraction of nitric oxide (µl/l)
φ
NOi
nitrogen dioxide volume fraction at the reactor exit (µl/l)
φ
NO2
φ volume fraction of nitrogen oxides (φ + φ ) at the reactor exit (µl/l)
NOx NO NO2
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ISO 22197-1:2016(E)

nitrite ion concentration in the eluent from the test piece (mg/l)
ρ
-
NO
2
nitrate ion concentration in the eluent from the test piece (mg/l)
ρ
-
NO
3
t time of adsorption, removal or desorption operation (min)
n amount of NO adsorbed by the test piece (µmol)
ads x
n amount of NO desorbed from the test piece (µmol)
des x
n amount of NO removed by the test piece (µmol)
NO
amount of NO formed by the test piece (µmol)
n 2
NO2
amount of NO removed by the test piece (µmol)
n x
NOx
amount of nitrogen eluted from the test piece (µmol); w , w are the 1st and 2nd elutions,
1 2
n
w
respectively
V volume of collected washings (ml); w , w are the 1st and 2nd elutions, respectively
w 1 2
η fractional recovery of nitrogen
w
5 Principle
This document concerns the development, comparison, quality assurance, characterization, reliability,
[1]
and design data generation of photocatalytic materials. The method described is intended to obtain
the air-purification performance of photocatalytic materials by exposing a test piece to model polluted
[2]
air under illumination by ultraviolet (UV) light. Nitric oxide (NO) is chosen as a typical air pollutant
that gives nonvolatile products on the photocatalyst. The test piece, placed in a flow-type photoreactor,
is activated by UV illumination, and adsorbs and oxidizes gas-phase NO to form nitric acid (or nitrate)
[3]
on its surface. A part of the NO is converted to nitrogen dioxide (NO ) on the test piece. The air-
2
purification performance is determined from the amount of the net removal of nitrogen oxides (NO )
x
(= NO removed – NO formed). The simple adsorption and desorption of NO by the test piece (not due
2
to photocatalysis) are evaluated by tests in the dark. Although the photocatalytic activity is reduced by
[4]
the accumulation of reaction products, it is usually restored by washing with water. The elution test
provided here gives information about the ease of regeneration and material balance of the pollutants.
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.
It 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 ultraviolet (UV) radiation, for example, acrylic resin, stainless steel,
glass and fluorocarbon polymers. An example of a test system is shown in Figure 1.
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, etc. 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 the knowledge of calibrated
gas flow rate and temperature in accordance with ISO 6
...