BS ISO 10678-2010 Fine ceramics (advanced ceramics advanced technical ceramics) Determination of photocatalytic activity of surfaces in an aqueous medium by degradation of methylen.pdf

1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 10678:2010Fine ceramics (advancedceramics, advanced technicalceramics) Determinationof photocatalytic activity ofsurfaces in an aqueous mediumby degradation of methylenebl

2、ueBS ISO 10678:2010 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 10678:2010.The UK participation in its preparation was entrusted to TechnicalCommittee RPI/13, Advanced technical ceramics.A list of organizations represented on this committee can beobtained o

3、n request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2010ISBN 978 0 580 63644 8ICS 81.060.30Compliance with a British Standard cannot confer immunity fromlegal obligations.This British

4、 Standard was published under the authority of theStandards Policy and Strategy Committee on 31 October 2010.Amendments issued since publicationDate Text affectedBS ISO 10678:2010Reference numberISO 10678:2010(E)ISO 2010INTERNATIONAL STANDARD ISO10678First edition2010-09-15Fine ceramics (advanced ce

5、ramics, advanced technical ceramics) Determination of photocatalytic activity of surfaces in an aqueous medium by degradation of methylene blue Cramiques techniques Dtermination de lactivit photocatalytique des surfaces dans un milieu aqueux par dgradation du bleu de mthylne BS ISO 10678:2010ISO 106

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10、ess below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2010 All rights reservedBS ISO 10678:2010ISO 10678:2010(E) ISO 20

11、10 All rights reserved iiiContents Page Foreword iv 1 Scope1 2 Terms and definitions .1 3 Symbols and units.2 4 Principle3 5 Apparatus.3 6 Calibration3 7 Measuring and conditioning solution .3 8 Sample preparation .4 9 Preparation of the measurement .4 10 Procedure of the measurement .5 11 Evaluatio

12、n of results .6 12 Precision.7 13 Test report7 Annex A (informative) Example of a data evaluation 8 Annex B (informative) Examples of suitable measuring devices 9 Annex C (informative) Results of the inter-laboratory test.11 Bibliography12 BS ISO 10678:2010ISO 10678:2010(E) iv ISO 2010 All rights re

13、servedForeword 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 whi

14、ch 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 m

15、atters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are cir

16、culated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. 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 respon

17、sible for identifying any or all such patent rights. ISO 10678 was prepared by Technical Committee ISO/TC 206, Fine ceramics. BS ISO 10678:2010INTERNATIONAL STANDARD ISO 10678:2010(E) ISO 2010 All rights reserved 1Fine ceramics (advanced ceramics, advanced technical ceramics) Determination of photoc

18、atalytic activity of surfaces in an aqueous medium by degradation of methylene blue 1 Scope This International Standard specifies a method for the determination of the photocatalytic activity of surfaces by degradation of the dye molecule methylene blue (MB) in aqueous solution using artificial ultr

19、aviolet (UV) radiation, and characterizes the ability of photoactive surfaces to degrade dissolved organic molecules on ultraviolet radiation. The test method specified is also applicable to evaluation of the specific photocatalytic self-cleaning activity of surfaces covered with respective coatings

20、. This method is not applicable to characterizing the photoactivity of surfaces on visible illumination, regarding direct soiling, degradation of gaseous molecules and the determination of antimicrobial photoactivity of surfaces. NOTE Correlations between these different kinds of photocatalytic acti

21、vity can, however, exist, in particular at surfaces exhibiting low photonic efficiencies. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 specific photocatalytic activity PMB measure of the photochemical conversion NOTE Specific photocatalyti

22、c activity is expressed in moles per square metre and hour mol/(m2h). 2.2 photonic efficiency MB measure of the selectivity of the incident photons to induce the decolourization of methylene blue NOTE 1 Photonic efficiency is expressed as a percentage of the incident photon flux. NOTE 2 It is assume

23、d that one photon can induce the decolourization of one dye molecule. 2.3 test solution aqueous methylene blue solution used to determine the photocatalytic activity of surfaces BS ISO 10678:2010ISO 10678:2010(E) 2 ISO 2010 All rights reserved2.4 measuring solution part of test solution (2.3) with a

24、 volume of u 10 % of the volume of the test solution used for external determination of the optical absorbance employing a spectrophotometer 2.5 conditioning solution aqueous methylene blue solution used for the pre-adsorption of methylene blue on the test surfaces prior to the determination of the

25、photocatalytic activity of surfaces 3 Symbols and units For the purposes of this document, the symbols and units in Table 1 apply. Table 1 Symbols and units Designation Symbol Unit Plancks constant (h = 6,626 1034Js) h Js Avogadro number (NA= 6,022 10231/mol) NA1/mol Relative molar mass M g/mol Mola

26、r extinction coefficient m2/mol Time t h Time of measurement tmh Concentration c mol/l Absorbance Aunitless Length d cm Volume of test solution V l Irradiated area A m2Wavelength m UV-radiation intensity E W/m2Average UV-radiation intensity avmdE tEt=W/m2Specific degradation rate AVRtdA=mol/(m2h) Sp

27、ecific degradation rate with UV radiation ,irrirrAVRtdA=mol/(m2h) Specific degradation rate without UV radiation ,darkdarkAVRtdA=mol/(m2h) Specific photoactivity MB dark irrP RR= mol/(m2h) Photonic UV-radiation intensity max avPA3 600EEhcN= mol/(m2h) Average photonic UV-radiation intensity EP,avmol/

28、(m2h) Photonic efficiency MBMBP100PE = % BS ISO 10678:2010ISO 10678:2010(E) ISO 2010 All rights reserved 34 Principle Methylene blue is degraded in an aqueous solution that is in contact with the potentially photocatalytically active surface by UV radiation of this surface through the solution, with

29、 light not capable of inducing the direct photolysis of the dye (320 nm u u 400 nm), with the overall result being the decolourization of the solution. The amount of dye remaining in the solution is determined at regular intervals during the UV-radiation period using UV/visible (vis)-spectroscopy. A

30、 reference measurement is either performed with the same sample without UV radiation or with an identical sample in a second container with the photoactive surface protected by a cover from the incident light beam. The results are used to calculate the specific degradation rates and the respective p

31、hotonic efficiencies characteristic of the surface tested. 5 Apparatus 5.1 General Apparatus that will be in contact with the methylene blue solution shall be made from materials exhibiting no or just a very small tendency to adsorb this dye on its surface, e.g. glass, stainless steel, polyethylene,

32、 polypropylene, polyacrylate, silicones with low organic emission. The test arrangement shall exhibit minimal stray light. 5.2 Measuring device, either two testing cylinders fixed on the sample surface by a suitable glue, or two testing cells, each consisting of a vessel with a sample holder (for a

33、schematic diagram of a suitable measuring device, see Annex B). 5.3 Glass pane, to cover the measuring cell exhibiting minimal absorbance within the spectral emission region of the UV-radiation light source (5.4). 5.4 UV-radiation light source, i.e. a narrow-band emitter in the wavelength range betw

34、een = 320 nm and = 400 nm (UV-A) with a UV-radiation intensity of E = (10 0,5) W/m2, measured at the height of the sample underneath the covering glass pane. 5.5 UV radiometer (sensor), to measure the UV-radiation intensity, calibrated to closely match the characteristic of the UV-radiation light so

35、urce. 5.6 UV/vis-spectrophotometer, calibrated in the measuring range between = 600 nm and = 700 nm, for the determination of methylene blue concentration. 5.7 Measurement cells, for the spectrophotometer made of glass or plastics, with an optical length of 10 mm and a transmittance 80 % (600 nm to

36、700 nm). 6 Calibration The apparatus according to 5.5 and 5.6, as well as the balances used, shall be calibrated following the instructions for equipment monitoring. 7 Measuring and conditioning solution Aqueous methylene blue solutions shall be used for both the measurement and the conditioning. Th

37、e methylene blue solutions shall be prepared freshly from stock solutions stored in the dark using distilled water in the absence of any other additives. The initial MB concentration c0for the test solution shall be c0= (10 0,5) mol/L. The conditioning solution shall be prepared at a concentration o

38、f c = (20 1) mol/L. The absorbance, A, of the solutions shall be calculated using Equation (1): A cd= (1) BS ISO 10678:2010ISO 10678:2010(E) 4 ISO 2010 All rights reservedNOTE 1 The absorbance amounts are A,max= 0,74 (for the test solution) and A,max= 1,48 (for the conditioning solution), at a measu

39、ring length of d = 10 mm. NOTE 2 Methylene blue (C16H18ClN3S 3H2O; M = 373,90 g/mol) is a dye with a small absorbance in the wavelength range between = 350 nm and = 450 nm. MB has a molar extinction coefficient of (664 nm) = 7402,8 m2/mol in an aqueous solution at a concentration of c = (10 0,5) mol

40、/L (see Reference 2). 8 Sample preparation The sample shall have a geometrical surface area between (100 1) mm2and (1 500 15) mm2. It shall first be cleaned following the manufacturers instructions. Following the last cleaning step, it shall be illuminated for 24 h to 72 h by UV light with a wavelen

41、gth of 10 W/m2. If the apparatus shown in Figure B.1 is used, the amount of MB solution shall be (35 0,3) mL. Afterwards, two similar samples shall be conditioned by placing each of them in a separate vessel with conditioning solution (see Clause 7). Alternatively, this conditioning solution may be

42、poured into a cylinder fixed onto the sample surface. This conditioning phase shall last for at least 12 h in the dark. If the dye concentration in the conditioning solution is lower than that of the test solution at the end of the conditioning period, the conditioning shall be repeated using a fres

43、h conditioning solution. 9 Preparation of the measurement If testing cells (see Figure B.2) are used, place both conditioned samples in the measuring device (5.2) with the test solutions (see Clause 7) and keep them in the dark. Using testing cylinders fixed onto the sample surface, replace the cond

44、itioning solution with test solution at the time t0(see Figure 1). The height of the MB test solution above the photoactive surface shall be between 20 mm and 50 mm. The volume of the test solution shall be at least ten times greater than the volume of the measuring solution required for the measure

45、ment in the spectrophotometer. Exactly determine the total volume of the test solution. NOTE For the fixed cylinder, the total volume of the test solution is usually 50 ml at a covered area of A = 1 000 mm2and a filling height of 50 mm. BS ISO 10678:2010ISO 10678:2010(E) ISO 2010 All rights reserved

46、 5YX12t0t1t2t3t4Key Y absorbance X time 1 absorbance/time curve of the measuring solution in the dark (without UV radiation) 2 absorbance/time curve of the measuring solution in the case of UV radiation Figure 1 Schematic of the obtained measuring curves 10 Procedure of the measurement Cover the mea

47、suring cells or cylinders with the UV transparent glass pane (5.3) during the whole test. Start the UV radiation of the sample if the absorbance/time curve of the test solution (see curves 1 and 2 in Figure 1) is nearly linear, i.e. in the range of t1to t2. The UV-radiation light source (5.4) shall

48、be capable of maintaining a UV-radiation intensity of E = (10 0,5) W/m2. Stir the MB solution at least every 20 min during the test to ensure a homogeneous concentration. Carry out stirring manually, with a glass stirrer, magnetic stirrer, or by purging with compressed air. During the entire measure

49、ment, measure and keep the temperature of the test solution at (23 2) C and record it. Temperature measurement and control is permitted inside, as well as near, the test cylinder. Set the detection wavelength of the spectrophotometer at = (664 5) nm. The measurement may either be performed online directly through the test solution (2.3) (see curve 2 in Figure 1) or by external measurements of measuring solutions (2.4) taken from the test solutio