ISO 17168-1:2018

Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for air-purification performance of semiconducting photocatalytic materials under indoor lighting environment — Part 1: Removal of nitric oxide

This document specifies a test method for the determination of the air purification performance, with regards to removal of nitric oxide, 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 from indoor light. This document is intended for use with different kinds of materials, such as construction materials in flat sheet, board or plate shape, which are the basic forms of materials for various applications. This document also applies to materials in honeycomb form and to plastic or paper materials containing ceramic microcrystals and composites. This document does not apply to certain test pieces that contain a large amount of adsorbent, due to unattained adsorption equilibrium. 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.

Titre manque — Partie 1: Titre manque

General Information

• Status: Published
• Publication Date: 18-Sep-2018
• 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: 19-Sep-2018
• Completion Date: 19-Sep-2018

RELATIONS

• Revised: ISO 22197-1:2007 - Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for air-purification performance of semiconducting photocatalytic materials — Part 1: Removal of nitric oxide
• Effective Date: 01-Jun-2013

Standards Content (sample)

INTERNATIONAL ISO
STANDARD 17168-1
First edition
2018-09
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Test method for air-purification
performance of semiconducting
photocatalytic materials under indoor
lighting environment —
Part 1:
Removal of nitric oxide
Reference number
ISO 17168-1:2018(E)
ISO 2018
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ISO 17168-1:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

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

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ii © ISO 2018 – All rights reserved
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ISO 17168-1:2018(E)
Contents Page

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

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

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

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

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

4 Symbols .......................................................................................................................................................................................................................... 3

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 ............................................................................................................................................................................................... 7

6.5 UV sharp cut-off filter ........................................................................................................................................................................ 7

6.6 Analyser of pollutants ....................................................................................................................................................................... 7

7 Test piece ...................................................................................................................................................................................................................... 7

8 Procedure..................................................................................................................................................................................................................... 7

8.1 General aspects ....................................................................................................................................................................................... 7

8.2 Pretreatment of test piece ............................................................................................................................................................. 7

8.3 Pollutant removal test ....................................................................................................................................................................... 8

8.4 Elution test ................................................................................................................................................................................................. 9

9 Calculation .................................................................................................................................................................................................................. 9

9.1 Calculation method ............................................................................................................................................................................. 9

9.2 Amount of NO adsorption by the test piece ..............................................................................................................10

9.3 Amount of NO removed by the test piece .....................................................................................................................10

9.4 Amount of NO formed by the test piece .......................................................................................................................10

9.5 Amount of NO desorbed from the test piece ............................................................................................................10

9.6 Net amount of NO removed by the test piece ..........................................................................................................11

9.7 Nitrogen eluted from the test piece ...................................................................................................................................11

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 an interlaboratory test ...........................................................................................................13

Bibliography .............................................................................................................................................................................................................................15

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ISO 17168-1:2018(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.

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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.
This document was prepared by Technical Committee ISO/TC 206, Fine ceramics.
A list of all parts in the ISO 17168 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 2018 – All rights reserved
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ISO 17168-1:2018(E)
Introduction

Photocatalyst is a substance that performs decomposition and removal of contaminants, self-

cleaning, antifogging, deodorization and antibacterial actions under photoirradiation. Its application

has expanded considerably in recent years. The application of photocatalysts for indoor spaces

has increasingly been sought as a solution to indoor environmental problems. Since conventional

photocatalysts are responsive only to ultraviolet light, studies have been made to develop an indoor-

light-active photocatalyst that makes effective use of indoor light, which room lights mainly emit, and

thus demonstrates high photocatalytic performance indoors. The development has recently led to the

commercialization of various indoor-light-active photocatalytic products, and there has been demand

for the establishment of test methods to evaluate the performance of this type of photocatalyst.

This document is based on ISO 22197-1, a test method for air purification performance of photocatalytic

materials under UV light, and is intended to provide a testing method to determine the performance of

indoor-light-active photocatalytic materials with regards to the removal of nitric oxide, enabling swift

distribution of photocatalytic products and thus contributing to a safe and clean environment.

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INTERNATIONAL STANDARD ISO 17168-1:2018(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Test method for air-purification performance
of semiconducting photocatalytic materials under indoor
lighting environment —
Part 1:
Removal of nitric oxide
1 Scope

This document specifies a test method for the determination of the air purification performance, with

regards to removal of nitric oxide, 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

from indoor light.

This document is intended for use with different kinds of materials, such as construction materials in

flat sheet, board or plate shape, which are the basic forms of materials for various applications. This

document also applies to materials in honeycomb form and to plastic or paper materials containing

ceramic microcrystals and composites. This document does not apply to certain test pieces that contain

a large amount of adsorbent, due to unattained adsorption equilibrium. 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.

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 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 14605, Fine ceramics (advanced ceramics, advanced technical ceramics) — Light source for testing

semiconducting photocatalytic materials used under indoor lighting environment

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.
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ISO 17168-1:2018(E)

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 oxidation and reduction reactions under

photoirradiation, including decomposition and removal of air and water contaminants, deodorization,

and antibacterial, self-cleaning and antifogging actions; a type of functional fine ceramics

3.2
indoor light

light from an artificial light source for general lighting service that does not include sunlight

3.3
indoor-light-active photocatalyst
photocatalyst (3.1) that performs under indoor light irradiation
3.4
photocatalytic material

material in which or on which the photocatalyst is added by, for example, coating, impregnation or mixing

Note 1 to entry: Photocatalytic materials are intended primarily for use as building and road construction

materials to obtain the above-mentioned functions.
3.5
zero-calibration gas
air in which common pollutants are below 0,01 µl/l

Note 1 to entry: Zero-calibration gas is prepared from indoor air using a laboratory air purification system, or

supplied as synthetic air in a gas cylinder.
3.6
standard gas

diluted gas of known concentration supplied in cylinders and certified by an accredited laboratory

3.7
test gas

mixture of air and pollutant(s) of known concentration prepared from the standard gas (3.6) or the

zero-calibration gas (3.5), or from the standard gas (3.6) only, to be used for the performance test of a

photocatalytic material (3.4)
3.8
purified water

water with a specific conductivity lower than 1 µS/cm, prepared by the ion exchange method or

distillation
3.9
dark conditions

test conditions of no light illumination by the light source for testing and room lighting

Note 1 to entry: Usually the test gas is supplied for comparison with the illuminated reaction.

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ISO 17168-1:2018(E)
4 Symbols

f air-flow rate converted into that at the standard state (0 °C, 101,3 kPa) (l/min)

ϕ nitric oxide concentration at the reactor exit (µl/l)
ϕ supply concentration of nitric oxide (µl/l)
NOi
ϕ nitrogen dioxide concentration at the reactor exit (µl/l)
NO2
concentration of nitrogen oxides (ϕ + ϕ ) at the reactor exit (µl/l)
NO NO2
ρ nitrite ion concentration in the eluent from the test piece (mg/l)
NO2-
ρ nitrate ion concentration in the eluent from the test piece (mg/l)
NO3-
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)
n amount of NO formed by the test piece (µmol)
NO2 2
amount of NO removed by the test piece (µmol)

n amount of nitrogen eluted from the test piece (µmol) [w , w are the first and second elu-

w 1 2
tion, respectively]

V volume of collected washings (ml) [w , w are the first and second elution, respectively]

w 1 2
η fractional recovery of nitrogen
5 Principle

This document deals with 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 indoor light . Nitric oxide (NO) is chosen as a typical air pollutant that gives

[2]

non-volatile products on the photocatalyst . The test piece, placed in a flow-type photoreactor, is

activated by indoor-light illumination, and adsorbs and oxidizes gas-phase NO to form nitric acid (or

[3]

nitrate) on its surface . A part of the NO is converted to nitrogen dioxide (NO ) on the test piece. The

air purification performance is determined from the amount of the net removal of nitrogen oxides

(NO ) (= NO removed – NO formed). The simple adsorption and desorption of NO by the test piece (not

x 2

due to photocatalysis) is evaluated by tests in the dark. Although the photocatalytic activity is reduced

[4]

by the accumulation of reaction products, it is usually restored by washing with water . The elution

test provided gives information about the ease of regeneration and material balance of the pollutants.

The results of an interlaboratory test are given in Annex A.
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

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ISO 17168-1:2018(E)

photocatalyst. It consists of a test gas supply, a photoreactor, a light source, a UV sharp cut-off filter and

pollutant measurement equipment. Since low concentrations of pollutants are to be tested, the system

shall be constructed with materials of low adsorption, for example acrylic resin, stainless steel, glass

and fluorocarbon polymers. An example of a testing 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
...