CEN/TS 16981:2016

SLOVENSKI STANDARD
01-januar-2017
Fotokataliza - Slovar izrazov
Photocatalysis - Glossary of terms
Photokatalyse - Glossar der Begriffe
Photocatalyse - Glossaire de termes
Ta slovenski standard je istoveten z: CEN/TS 16981:2016
ICS:
01.040.25 Izdelavna tehnika (Slovarji) Manufacturing engineering
(Vocabularies)
25.220.20 Površinska obdelava Surface treatment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN/TS 16981
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
November 2016
TECHNISCHE SPEZIFIKATION
ICS 01.040.25; 25.220.20
English Version
Photocatalysis - Glossary of terms
Photokatalyse - Glossar der Begriffe
This Technical Specification (CEN/TS) was approved by CEN on 15 August 2016 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to
submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS
available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in
parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
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United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 16981:2016 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Generalities . 5
2.1 Note on units . 5
2.2 Note on symbols . 5
2.3 Note on the relationship between spectral, radiometric, and photonic quantities . 5
3 Terms and definitions . 6
Bibliography . 53

European foreword
This document (CEN/TS 16981:2016) has been prepared by Technical Committee CEN/TC 386
“Photocatalyse”, the secretariat of which is held by AFNOR.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
According to the CEN/CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Introduction
Photocatalysis is a very efficient advanced oxidation technique which enables the production of active
species following light absorption by the photocatalyst, such as bound/free hydroxyl radicals (∙OH),
perhydroxyl radicals (∙OOH), conduction band electrons and valence band holes, capable of partly or
completely mineralising/oxidising the majority of organic compounds. The most commonly used
photocatalyst is titanium dioxide (TiO ), the latter being thermodynamically stable, non-toxic and
economical. It can be used in powder form or deposited on a substrate (glass fibre, fabrics,
plates/sheets, etc.). The objective is to introduce performance standards for photo-induced effects
(including photocatalysis). These standards will mainly concern test and analysis methods.
Safety statement
Persons using this document should be familiar with the normal laboratory practice, if applicable. This
document cannot address all of the safety problems, if any, associated with its use. It is the
responsibility of the user to establish appropriate safety and health practices and to ensure compliance
with any regulatory conditions.
Environmental statement
It is understood that some of the material permitted in this Technical Specification may have negative
environmental impact. As technological advantages lead to better alternatives for these materials, they
will be eliminated from this Technical Specification to the extent possible.
At the end of the test, the user of the Technical Specification will take care to carry out an appropriate
disposal of the wastes, according to local regulation.
1 Scope
A common language for standards, disclosed to a wide audience and referring only to the operational
protocols and to their outcomes, is needed both for a consistent set of standards and the connection
with the scientific literature. This glossary will take into account existing glossary of terms used in
photocatalysis and photochemistry. Because in photocatalysis numerous properties are difficult to be
evaluated, it is strongly recommended in standard norms to avoid reporting properties depending on
number of actives sites, the mechanisms of adsorption or kinetic mechanisms of photocatalytic
reactions. For the same reason instead of the quantum yield and related quantities it is easier to report
the photonic efficiency.
Most of the definitions reported in this Technical Specification are a sub-set of the IUPAC definitions in
photocatalysis and radiocatalysis [1]. Some other definitions, in particular for the photocatalytic rate
and reactors are taken from a dedicated work [2]. The use and many technical specifications on the
physical values suggested for irradiation conditions in the standards are reported in a separate
Technical Specification [3].
The arrangement of entries is alphabetical, and the criterion adopted by the IUPAC has been followed
for the typeface used: italicized words in a definition or following it indicate a cross-reference in the
Glossary.
2 Generalities
2.1 Note on units
SI units are adopted, with some exceptions, prominently in the use of the molar decadic absorption
3 –1 –1
coefficient, ε, with common units dm mol cm and a mole of photons denoted as an einstein. Note that
“amount concentration” is the preferred term for what has been known as “molar concentration”, and is
complementary to the terms “mass concentration” and “number concentration”.
2.2 Note on symbols
Functional dependence of a physical quantity f on a variable x is indicated by placing the variable in
parentheses following the symbol for the function; e.g., ε(λ). Differentiation of a physical quantity f with
respect to a variable x is indicated by a subscript x; e.g., the typical spectral radiant power quantity P
λ
= dP/dλ. The natural logarithm is indicated with ln, and the logarithm to base 10 with log.
For the magnitudes implying energy or photons incident on a surface from all directions, the set of
symbols recommended by the International Organization for Standardization (ISO) [4] and included in
the IUPAC "Green Book", and by the International Commission on Illumination [5] are adopted, i.e., H
o
or F for fluence, E for fluence rate, H or F for photon fluence, and E for photon fluence rate, note
o o p,o p,o p,o
the letter o as subscript. This has been done primarily to comply with internationally agreed-upon
symbols. It is important, however, to avoid confusion with the terms used to designate an amount of
energy (or photons) prior to absorption. In these cases, the superscript 0 (zero) is used.
2.3 Note on the relationship between spectral, radiometric, and photonic quantities
When a quantity expressed in photonic units (G ) covers a wavelength range (polychromatic irradiation
p
between λ and λ ), then G is the integral between λ and λ of the corresponding spectral photonic
1 2 p 1 2
quantity, G (λ):
p
λ2
Gp = Gp (λ) dλ (e.g., spectral photon flux).
∫
λ1
Since a spectral radiometric or energetic quantity at a given wavelength λ (G , e.g., spectral radiant
e,λ
−1
power, P nm , is related to the corresponding photonic quantity at the same wavelength (G , e.g.,
λ/W p,λ
−1 −1
spectral photon flux / s nm ) by the relation:
G = E(λ) G
e,λ p,λ
with
E(λ) = h c/λ, the energy of a photon of wavelength λ.
The relation between photonic (Gp) and corresponding radiometric (or energetic, Ge) quantity is given
by:
λ2
G = h c G (λ) 1/λ dλ
e p
∫
λ1
or, more useful in practice:
λ2
G = (1/h c) G (λ)λ dλ
p e
∫
λ1
Therefore, for example, to calculate a photon flux over a wavelength interval, the spectral distribution of
the radiant power is necessary. Note that in the Glossary no sub-index e has been used for the
radiometric quantities. Radiometric quantities (G , as above, radiant power and others) are needed
e
because lamp providers usually give the spectral distribution of the lamps in these units, and not in
, photon flux and other photonic quantities) and because of quantification of radiation
photonic units (Gp
using, e.g., radiometers.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
absorbance, A
e
logarithm to the base 10 (linear absorbance) of the incident (prior to absorption) spectral radiant power,
P divided by the transmitted spectral radiant power, P :
λ
λ
 
P
λ
Aλλ= log =−logT
( ) ( )
 
P
λ
 
Note 1 to entry: T(λ) is the (internal) transmittance at the defined wavelength. The terms absorbancy, extinction,
and optical density should no longer be used. When natural logarithms are used, the napierian absorbance is the
logarithm to the base e of the incident spectral radiant power, P divided by the transmitted spectral radiant
λ
power, P :
λ
 
P
λ
ATλ = ln =−ln λ
( ) ( )
e
 
P
λ
 
Note 2 to entry: These definitions suppose that all the incident ultraviolet, visible, or infrared radiation is either
transmitted or absorbed, reflection or scattering being negligible. Attenuance should be used when this
supposition cannot be made.
Note 3 to entry: In practice, A is the logarithm to the base 10 of the spectral radiant power of ultraviolet, visible,
or infrared radiation transmitted through a reference sample divided by that transmitted through the investigated
sample, both observed in identical cells.
Note 4 to entry: In common usage, A is given for a path length of 1 cm, unless otherwise specified.
Note 5 to entry: Traditionally, (spectral) radiant intensity, I , was used instead of spectral radiant power, P , now
λ λ
the accepted term.
Note 6 to entry: The wavelength symbol as a subscript for P and in parenthesis for T and A may be omitted.
However, the wavelength should be specified for which the value of the particular property is reported.
Note 7 to entry: Same as internal optical density, which is a term not recommended.
Note 8 to entry: See also absorption coefficient, absorptance, attenuance, Beer–Lambert law, Lambert law, molar
absorption coefficient.
3.2
absorbed (spectral) photon flux density
number of photons of a particular wavelength, per time interval (spectral photon flux, number basis, q ,
p,λ
or spectral photon flux, amount basis, q ) absorbed by a system per volume, V
n,p,λ
-1 –4 –1 –3 –1
Note 1 to entry: On number basis, SI unit is s m ; common unit is s cm nm . On amount basis, SI unit is mol
–1 –4 -1 -3 –1
m ; common unit is einstein s cm nm
s
−Aλ −Aλ
0 ( ) 0  ( )
q 1−10 q 1− 10
p,λ n,p,λ
  
  
Note 2 to entry: Mathematical expression: on number basis, on amount
V V
basis, where A(λ) is the absorbance at wavelength λ and superscript 0 (zero) indicates incident photons.
Note 3 to entry: Absorbed (spectral) photon flux density (number basis or amount basis) is used in the
denominator when calculating a differential quantum yield and using in the numerator the rate of change of the
number, dC/dt, or the rate of change of the amount concentration, dc/dt, respectively.
3.3
absorbed (spectral) radiant power density
spectral radiant energy per time interval (spectral radiant power, P ) absorbed by a system per volume,
λ
V
–4 –3 –1
Note 1 to entry: SI unit is W m ; common unit is W cm nm .
−Aλ
0 ( )
P 1-10
λ
 
 
Note 2 to entry: Mathematical expression: where A(λ) is the absorbance at wavelength λ and
V
superscript 0 (zero) indicates incident radiant power.
3.4
absorptance, a
fraction of ultraviolet, visible, or infrared radiation abs
...