Source: https://www.iphotocat.com/standards/
Timestamp: 2019-04-20 12:45:41+00:00

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Below is a list of the categories of photocatalyst tests offered by QIPS and the associated ISO standards. Click on any standard listed below for further details.
ISO 22197-1: 2007 – Test method for air-purification performance of semiconducting photocatalytic materials. Part 1: Removal of nitric oxide.
Construction materials in flat sheet, board or plate shape; materials in honeycomb-form; plastic or paper materials if they contain ceramic microcrystals and composites.
Nitric oxide is an important intermediate in the chemical industry and a major air pollutant produced by the combustion of substances in air, such as gasoline in automotives and fossil fuels in power stations. In the absence of a catalyst NO is oxidised relatively slowly to nitric oxide by oxygen. NO is used on a large scale in the manufacture of nitric acid, the bleaching of rayon, and as a stabiliser in the production of propene and methyl ether. It is an important signalling molecule in most biological systems and, along with NO2, is associated with sick building syndrome and acid rain production. Given its widespread commercial use and, maybe more importantly, its occurrence as a common air-borne, environmentally damaging pollutant, the removal of NO and its NOx counterpart, NO2, by semiconductor photocatalysis has resulted in the promotion of many commercial photocatalyst products, such as paint, tiles and paving stones, for their NOx removing ability.
Recent work  reveals that the accumulation of nitric acid on the surface promotes its photocatalysed reaction with NO that generates the toxic product NO2, i.e.
This can lead to an eventual steady state where the rate of NO removal is matched by the rate of NO2 production; which is clearly highly undesirable. It follows that for any NOx-removing photocatalyst product to work effectively it is necessary that the HNO3 photogenerated, via reactions (1) and (2), must be removed at regular intervals, by rinsing with water, e.g. from rain or a damp cloth.
The standard sets out to measure the photocatalyst’s overall ability to remove the oxides of nitrogen, i.e. NOx, using a NO-containing air stream. A measure of this ability is taken as the difference between the total NO removed (nNO) and NO2 generated (nNO2) during the irradiation period. A typical data set generated, i.e. NO removed and NO2 generated, is illustrated below. The hatched areas A and B are proportional to the amounts of NO adsorbed and photo-oxidised/removed, respectively. Hatched area C is proportional to the amount of NO2 generated. The key points are: 1 – start of contact with NO-containing feed, 2 – UV lights on and 3 – UV lights off and feed gas changed to zero calibration gas (i.e. air).
 Y. Ohko, Y. Nakamura, N. Negishi, S. Matsuzawa and K. Takeuchi, J. Photochem. Photobiol., A, 205 (2009) 28.
 T. Ibusuki and K. Takeuchi, J. Mol. Catal., 88 (1994) 93.
 S. Devahasdin, C. Fan, K. Li and D.H. Chen, J. Photochem. Photobiol., A, 156 (2003) 161.
 N. Bowering, G.S. Walker and P.G. Harrison, Appl. Catal., B, 62 (2006) 208.
 M.M. Ballari, M. Hunger, G. Husken and H.J.H. Brouwers, Appl. Catal., B, 95 (2010) 245.
ISO 22197-2: 2011 – Test method for air-purification performance of semiconducting photocatalytic materials. Part 2: Removal of acetaldehyde.
Acetaldehyde occurs widely in nature, since it is produced by plants as part of their metabolism and also during the ripening process. It is also a product of combustion (wood, oil, petrol and diesel) and so is a constituent of car exhaust fumes and tobacco smoke. It is a significant industrial chemical which is used in the manufacture of acetic acid, perfumes, flavours, aniline dyes, plastics and synthetic rubber. It is a cancer suspect agent, an irritant and large doses can cause death by respiratory paralysis. It is an important indoor air pollutant as it is released by building materials such as polyurethane foams, adhesives, coatings and inks. Along with formaldehyde and other volatile organic carbons, i.e. VOCs, such as toluene, it is associated with sick building syndrome.
The photocatalytic oxidation of acetaldehyde has been well studied [1-3] using titania photocatalysts, although the reaction pathway, and the major intermediates, are still the subject of debate . Recent work indicates that it is first oxidised to acetic acid and then to formic acid, formaldehyde (the acids being adsorbed onto the surface of the titania) and then, finally to CO2 , i.e.
A typical data set generated, i.e. acetaldehyde removed and carbon dioxide generated, is illustrated below. The hatched areas B and B’ are proportional to the amounts of acetaldehyde removed and carbon dioxide generated, respectively. The key points are the start of contact with the acetaldehyde feed (t=0), UV lights on (↓) and UV lights off (↑).
 M.L. Sauer and D.F. Ollis, J. Catal., 158 (1996) 570.
 Y. Ohko, D.A. Tryk, K. Hashimoto and A. Fujishima, J. Phys. Chem. B, 102 (1998) 2699.
 E. Obuchi, T. Sakamoto and K. Nakano, Chem. Eng. Sci., 54 (1999) 1525.
 B. Hauchercorne, D. Terrens, S. Verbruggen, J. A. Martens, H. Van Langenhove, K. Demeestere and S. Lenaerts, Appl. Catal., B, 106 (2011) 630.
ISO 22197-3: 2011 – Test method for air-purification performance of semiconducting photocatalytic materials. Part 3: Removal of toluene.
Toluene is a widely used chemical feedstock and industrial solvent. As a solvent, it is used in paints, paint thinners, silicone sealants, printing inks, glues, resins and disinfectants. It is also used as an octane booster in gasoline fuels. In industry it is also used in the manufacture of: benzoic acid, benzaldehyde, explosives, dyes and many other organic compounds. Toluene is toxic, and is one of the VOCs associated with sick building syndrome.
A typical data set generated, i.e. toluene removed, is illustrated below. The hatched area B is proportional to the amount of toluene removed. The key points are the start of contact with the acetaldehyde feed (t=0), UV lights on (↓) and UV lights off (↑).
 V. Augugliaro, S. Coluccia, V. Lodo, L. Marchese, G. Martra, L. Parmisano and M. Schiavelllo, Appl. Catal., B, 20 (1999) 15.
 A.J. Maira, J.M. Coronado, V. Augugliaro, K.L. Yeung, J.C. Conesa and J. Soria, J. Catal., 202 (2001) 413.
 H. Einaga, S. Futamura and T. Ibusuki, Appl. Catal., B, 38 (2002) 215.
 M. C. Blount and J.L. Falconer, Appl. Catal., B, 39 (2002) 39.
 G. Marci, M. Addamo, V. Augugliaro, S. Coluccia, E. Garcia-Lopez, V. Loddo, G. Martra, L. Parmisano and M. Schiavello, J. Photochem. Photobiol. A, 160 (2003) 105.
 J.M. Coronado and J. Soria, Catal. Today, 123 (2007) 37.
 O. Debono, F. Thevenet, P. Gravejat, V. Hequet, C. Raillard, L. Lecoq and N. Locoge, Appl. Catal., B, 106 (2011) 600.
For the best evaluation of air purification performance of photocatalytic materials, it is recommended by ISO to combine one or more of these test methods.
In all these air pollution tests the flow rate is normalised for STP and dry gas conditions and the flow ratecorrected for the water vapour present.
Other air-purification ISO standards are almost at the publication stage (e.g. for: formaldehyde and methyl mercaptan), and QIPS plans to also offer these tests in the near future.
These International Standards describe test methods for determining the water purification performance of photocatalytic materials, formed on, or attached to, another material surface for the purpose of decomposing, and thus eliminating the pollutants in water, using photocatalytic performance, thus relating to waste-water treatment.
ISO 10678: 2010 – Determination of photocatalytic activity of surfaces in an aqueous medium by degradation of methylene blue.
Using artificial ultraviolet (UV) radiation, the photocatalytic activity of surfaces by degradation of the dye molecule methylene blue (MB) in aqueous solution, which is in contact with the potentially photocatalytically active surface, is determined, with the overall result being the decolourization of the solution. The high molar absorptivity of MB+ ensures a striking and easily measured colour change, from blue to colourless, upon photobleaching of the dye by the semiconductor photocatalyst under study. The structure of MB is illustrated below.
Powder or granular photocatalytic materials; porous materials.
Methylene blue (MB+) is a highly popular test pollutant in semiconductor photocatalysis used in the assessment of such key features as: new photocatalytic materials, photoreactors and light sources. The test method is applicable to evaluation of water purification performance, and less appropriately for the evaluation of self-cleaning activity, of surfaces covered with photocatalytic coatings.
Some disadvantages stem from underlying assumptions in this standard, and obviously, it is highly desirable to ensure the conditions are such that these assumptions are likely to hold. With this in mind, we have tightened up some of the specified conditions to improve repeatability and reproducibility. The ISO standard assumes that the MB+ used is of a high purity. However, εMB values quoted in the literature span a wide range which is most likely a reflection of the different purities of commercial sources of MB . Furthermore, the kinetics of MB+ photobleaching are highly dependent, upon the MB+ concentration .
This difficulty of MB+ purity is rectified by making up the MB+ reaction solution to a defined absorbance at 665 nm in a 1 cm cell (0.74), as opposed to a defined concentration as in the original standard. Finally, the initial pH of the reaction solution is not stipulated in the current ISO test, but will be set at pH 5.5, since significant deviation from such set pH will alter the amount of MB+ adsorbed which will alter the measured rate and so the calculated value of ξMB.
A typical set of results for test samples with (●) and without (○) a photocatalyst coating are illustrated below. The solid line is the calculated maximum allowable decay curve observable under standard conditions without a significant mass transfer contribution to the final calculated value of the photonic efficiency, ξMB.
 S. Mowry and P.J. Ogren, J. Chem. Educ., 76 (1999) 970.
 J. Tschirch, R. Dillert and D. Bahnemann, J. Adv. Ox. Technol., 11 (2008) 193.
ISO 10676: 2010 – Test method for water purification performance of semiconducting photocatalytic materials by measurement of forming ability of active oxygen.
Note: it is also possible some intermediate level of formaldehyde may be generated as is known to occur during the reaction of DMSO with hydroxyl radicals.
A typical data set generated, i.e. DMSO removed vs. irradiation time, is illustrated below. The insert diagram is a log plot of the data in the main diagram, revealing the first order nature of the kinetics of DMSO removal by semiconductor photocatalysis and from which a first order rate constant, k1, and so half-life can be calculated.
 M. Mori, K. Tanaka, H. Taoda, M. Ikedo and H. Itabashi, Talanta, 70 (2006) 169.
 M.N. Abellan, R. Dillert, G. Gimenez and D. Bahnemann, J. Photochem. Photobiol., A, 202 (2009) 164.
These International Standards specify test methods for the determination of the self-cleaning performance of materials containing a photocatalyst or which have photocatalytic films on the surface, and which are usually made from semiconducting metal oxides such as titanium dioxide.
ISO 27448: 2009 – Test method for self-cleaning performance of semiconducting photocatalytic materials – Measurement of water contact angle.
Powder or granular materials; permeable, rough, or highly hydrophobic surfaces.
If it is not possible to cut a product into 10 cm x 10 cm square pieces, then the test piece may have a different shape or size, as long as its shape and size allow the measurement of the contact angle at five different points.
In the ISO test, once all of the oleic acid has been destroyed via the photocatalytic mineralization of the organic top layer, i.e.
it is then expected that the water droplet contact angle will be reduced to ≤ 5° for most photocatalytic materials used in self-cleaning systems .
A typical data set generated, i.e. water droplet contact angle, θ, vs. irradiation time, is illustrated below.
 J.T. Yates, Surf. Sci., 603 (2009) 1605.
ISO 10677: 2011 – Ultraviolet light source for testing semiconducting photocatalytic materials.
All the ISO tests utilised make reference to the use of a suitable UV light source. However, typically three different types are recommended – two types of BLB and a xenon arc lamp. The relative light intensity vs. wavelength profiles for (a – solid) a xenon arc lamp, (b – dashed) a BLB light source with λmax (other than peak at 365 nm) at ca. 351 nm and (c – bold) a BLB light source with λmax (other than peak at 365 nm) at ca. 368 nm are illustrated below.
The specification of a suitable UV light source is paramount to repeatability and reproducibility of the standard tests reported, and since the photocatalytic efficiency of a system depends upon the spectral distribution and radiant intensity of the light source, only one type of BLB, namely one with a europium-doped fluoroborate phosphor is used in our testing. In order to evaluate photocatalytic materials for use in sunlight however, xenon arc lamps are used.
At QIPS we can measure the emission spectrum and UV irradiance (units: mW/cm2) of your submitted light source using a calibrated spectroradiometer, and compare and contrast it to that of other light sources.
Black light fluorescent lamps are made as normal white light fluorescent tubes except that only one phosphor is used, and the glass envelope has a blue filter which ensures that most of the light emitted is UVA light. The two types of BLB arise because there are two types of phosphor, namely: (i) europium doped fluoroborate, which produces a UV emission peak ranging from 368-371 nm and a band width of 20 nm and (ii) lead-doped barium silicate with a UV emission peak ranging from 350-353 nm and a band width of 40 nm .
To produce solar simulated UV light (and ensure the significant visible component is removed) we use a UG5 filter (cuts out most light between 400-650 nm ) in combination with a WG320 filter (cuts out light below 300 nm ). The overall emission has been shown to be a very good fit to the actual solar UV emission spectrum. The removal of most of the visible light produced by the Xe arc lamp is also a very important feature, since the standards are designed for UV absorbing systems only.
We use a calibrated spectroradiometer, for measuring the UV irradiance.
The relative light intensity vs. wavelength profiles for (a – solid) a xenon arc lamp, (b – dashed) a BLB light source with λmax (other than peak at 365 nm) at ca. 351 nm and (c – bold) a BLB light source with λmax (other than peak at 365 nm) at ca. 368 nm are illustrated below.

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