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Chapter 8

Standardization

The chapter deals with the efforts done by the scientific and industrial community in order to define standardization criteria of heterogeneous photocatalytic systems. Despite the photocatalysis industry has grown very much in the last 10 years, the lacking of standard evaluation methods for photocatalytic products hinders that the consumers understand well the performance of photocatalytic products, or that they may correctly compare the products from several producers. The establishment of standard evaluation methods for photocatalytic products is therefore a challenge for increasing their diffusion in the industrial and private field. The Chapter describes the efficiency parameters proposed for evaluating the photocatalytic systems as quantum yield, the photochemical thermodynamic efficiency factor, and two figures-of-merit: the “Electric Energy per Mass” and the “Electric Energy per Order”.

The comparison of photocatalytic systems is also carried out experimentally. The evaluation of photocatalytic films is based on the decolourisation of different dyes, such as methylene blue, or on the photo-oxidation of organic solid films such as stearic acid deposited on the surfaces. In the general field of self cleaning surfaces a scale application of TiO2 is in the building sector as an additive of cementitious materials. A method based on a specially designed stirred flow reactor has been developed in order to measure the photocatalytic activity of TiO2 dispersed in cementitious building materials. For testing the performance of photocatalytic paving blocks NOx is proposed as a suited compound to be used as model pollutant A standard method has been recently proposed by ISO (ISO 22197-1:2007;46); this test method utilizes NOx for determining the air-purification performance shown by fine ceramics that contain a photocatalyst or have photocatalytic films on their surface.

Print publication date: 24 Aug 2010
Copyright year: 2011
Print ISBN: 978-1-84755-870-1
PDF eISBN: 978-1-84973-203-1