ISO 19722:2017

INTERNATIONAL ISO
STANDARD 19722
First edition
2017-01
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Test method for determination
of photocatalytic activity on
semiconducting photocatalytic
materials by dissolved oxygen
consumption
Céramiques techniques — Méthode d’essai relative à la détermination
de l’activité photocatalytique sur matériaux photocatalytiques
semiconducteurs par la consommation d’oxygène dissous
Reference number
©
ISO 2017
© ISO 2017, Published in Switzerland
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ii © ISO 2017 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Principle . 2
6 Materials . 3
6.1 Reagent . 3
6.2 Purified water . 3
6.3 Purified air . 3
6.4 Purified water saturated with dissolved oxygen . 3
6.5 Test solution . 3
7 Test apparatus . 3
7.1 General . 3
7.2 Ultraviolet (UV) — Irradiation light source . 3
7.3 UV radiometer . 3
7.4 UV light intensity . 3
7.5 DO analyser . 3
7.6 Magnetic stirrer and magnetic stirring bar . 4
8 Arrangement of test method . 4
8.1 Measuring device setup . 4
8.2 Test vessel and implement . 4
9 Test material . 4
9.1 Powder test sample . 4
9.2 Film test piece . 4
10 Procedure of the measurement . 5
10.1 Test temperature . 5
10.2 Preparation of water . 5
10.3 Powder test sample . 5
10.3.1 Preparation of suspension from powder test sample . 5
10.3.2 Procedure of the measurement . 5
10.4 Film test piece . 5
10.4.1 Preparation of film test piece . 5
10.4.2 Procedure of the measurement . 6
10.5 Blank POD(%) . 6
11 Evaluation of results . 6
11.1 General . 6
11.2 Evaluation of POD . 6
12 Test report . 7
Annex A (informative) Example of suitable measuring device component .8
Annex B (informative) Example of suitable test vessel and implement .10
Annex C (informative) Example of test position of test vessel .12
Annex D (informative) Example of a data evaluation .13
Annex E (informative) Results of the interlaboratory test .16
Bibliography .17
Foreword
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This document was prepared by Technical Committee ISO/TC 206, Fine ceramics.
iv © ISO 2017 – All rights reserved

Introduction
International Standards covering test methods for determination of photocatalytic activity have been
published. A wide variety of photocatalytic functions, such as water and air purification, antibacterial
effect, and self-cleaning, require different evaluation methods. However, much easier methods to
evaluate a common semiconducting photocatalytic activity are strongly demanded, in particular in
research and development activities for testing of performance of semiconducting photocatalyst and
photocatalytic materials under development.
INTERNATIONAL STANDARD ISO 19722:2017(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Test method for determination of
photocatalytic activity on semiconducting photocatalytic
materials by dissolved oxygen consumption
1 Scope
This document specifies the test method for determination of concentration of dissolved oxygen
consumed due to photocatalytic oxidation of phenol in aqueous phase by semiconducting photocatalytic
substances. The method is applicable to powder test sample or film test piece of semiconducting
photocatalystic material targeting water contaminants. This test method is not applicable for
evaluating the materials conjugated with other base material, such as organic binder which can also be
decomposed by the photocatalytic activity.
This document is applicable to the test method for the activity of powder test sample or film test piece
of semiconducting photocatalystic material targeting water contaminants.
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 5814, Water quality — Determination of dissolved oxygen — Electrochemical probe method
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
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 20507 and the following 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
semiconducting photocatalyst
substance that displays photocatalytic action based on its electronic band structure
Note 1 to entry: This applies to metal oxides like titanium dioxide and sulfides. Photocatalysts which are not
semiconducting includes metal complexes.
3.2
photocatalytic materials
material in which or on which the photocatalyst is added by coating, impregnation, mixing, etc.
Note 1 to entry: Materials include ceramic, metal, plastic, cloth, etc. for general purpose.
3.3
DO
dissolved molecular oxygen in aqueous phase
3.4
DO analyser
measuring instrument for continuous measurement of DO (3.3) in aqueous using DO electrode (3.5)
3.5
DO electrode
electrode to measure DO (3.3) in aqueous phase
3.6
photocatalytic oxygen demand
POD
quantity of molecular oxygen in aqueous phase consumed in photocatalysis
3.7
blank POD(%)
percentage of concentration of DO (3.3) consumed under a test condition without phenol addition
4 Symbols
Designation Symbol Unit
room temperature R.T. °C
water temperature W.T. °C
concentration c mol/l
concentration of DO c mg/l
DO
photocatalytic oxygen demand POD mg/l
c before UV light irradiation in the dark c mg/l
DO iDO
c after UV light irradiation in the dark c mg/l
DO fDO
volume of test solution V ml
wavelength λ nm
UV light irradiation intensity I mW/cm
5 Principle
Photocatalysis in pure water generally produces molecular oxygen(O ) from water molecule (H O)
2 2
[3]
oxidation . In the water polluted by some of the organic compounds, major photocatalysis oxidizes the
[4]
organic compounds . Photocatalyst needs O to oxidize organic compounds to CO and water in the
2 2
[4]
environment . Then the quantity of O that photocatalysis needs is much larger than O production
2 2
from H O oxidation because the organic compound is photocatalytically oxidized much easier than
water molecule. O then has major three functions in semiconducting photocatalyst. The first function
is to improve charge separation by accepting conduction band electron. The second one is to produce
active oxygen species that have the ability to oxidize organic compounds. The final one is oxidation.
O combines with organic radicals (intermediates) produced by semiconducting photocatalytic
[4]
oxidation; O is an indispensable species in the semiconducting photocatalysis . Therefore, the
photocatalysis to oxidize organic compound means O consumption. In the photocatalysis to oxidize
and mineralize the organic compounds, partially oxygenated by-products are produced. Under the
progress in the continuous oxidation of partially oxygenated by-products, the photocatalysis consume
O to mineralisation. On the basis of the photocatalytic mineralization and functions of O , the
2 2
semiconducting photocatalytic activity can be evaluated by determining O consumption. This test
method is especially effective in the photocatalysis in aqueous phase. Target photocatalytic materials
are either powder test samples or a film test pieces.
2 © ISO 2017 – All rights reserved

6 Materials
6.1 Reagent
Reagent is phenol and the assay is >99 wt%.
6.2 Purified water
Water used for the preparation of all solutions shall be distilled or deionised water.
6.3 Purified air
Air in the atmosphere aerated through 1 000 ml purified water.
6.4 Purified water saturated with dissolved oxygen
Purified water at R.T. ± 1 °C saturated with DO.
6.5 Test solution
Suspension with the powder test sample in phenol solution or phenol solution for the film test piece.
7 Test apparatus
7.1 General
Apparatus shall be used to evaluate the semiconducting photocatalytic materials with a suitable test
method. The powder test sample is suspended and the film test piece is immersed in the test solution.
The following apparatus is required.
7.2 Ultraviolet (UV) — Irradiation light source
Use black light fluorescence lamps as black light lamp (BL) and black light blue lamps (BLB). The black
light fluorescence lamps shall have a peak wavelength λ = 351 nm as specified in ISO 10677.
7.3 UV radiometer
A radiometer with a detector whose sensitivity peak is at λ = 351 nm shall be used to measure the
UV-light intensity. The radiometer shall be calibrated to closely match the characteristic of the UV
light irradiation light source as specified in ISO 10677 or be corrected to ascertain sensitivity within
the wavelength range to be adsorbed by the powder test sample or the film test piece with suitable
approaches.
7.4 UV light intensity
I is adjusted to be 1,5
...