Mineralization of the pollutants

As a well-known photocatalyst, ZnO has received much attention in the degradation and complete mineralization of environmental pollutants [109,206-208], Since ZnO has almost the same bandgap energy (3.2 eV) as TiOz, its photocatalytic capacity is anticipated to be similar to that of... 

These catalytic membranes have been successfully used in a photocatalytic membrane reactor for the mineralization of the phenol, one of the main organic pollutants in wastewater, demonstrating that these catalytic membranes are stable and recyclable [42]. 

Effect of 03. Adding ozone in dioxygen or air is a very efficient means of enhancing the photocatalytic rates of the removal and, above all, the mineralization of organic pollutants both in air and in water, even if the wavelengths are intentionally selected so as not to excite ozone (39 41). This substantial effect is attributed to the difference in electron affinity between 03 (2.1 eV) and 02 (0.44 eV). Consequently, in the presence of ozone, the electrons photopromoted to the Ti02 conduction band can be captured more easily, either directly ... 

Photocatalysis by transition metals shows an effective self-cleaning ability of soils and waters by the degradation and complete mineralization of the dissolved organic matter. Moreover, the oxidation processes are driven by sunlight and atmospheric oxygen and do not pollute the environment by risky side-products (see section 9.3, Chapter 9). 

Basic Principles of the Electrochemical Mineralization of Organic Pollutants for Wastewater Treatment... 

Fig. 1.1 Schematic representation of a hypothetical fuel cell for the mineralization of organic pollutants ASOP aqueous solution of organic pollutants...

In the photoelectro-Fenton process the mineralization of organic pollutants can be enhanced by the production of more OH from reaction (19.24) and the additional acceleration of Fenton s reaction (19.12). However, we will see that the main action of UVA irradiation is the photodecomposition of complexes between Fe3+ and some final aliphatic acids, as for example oxalic acid (Zuo and Hoigne 1992). 

As stated earlier, the rate constants of ozone with organic compounds differ greatly for both types of processes (Table 3). The first reaction is important in acid media and for solutes that react very fast with ozone such as, for example, unsaturated compounds and compounds containing amine or acid groups. The results support the electrophilic nature of the reaction, either by electrophilic substitution or by dipolar cycloaddition [37]. This route leads to a very limited mineralization of the organic compounds, and its use for the removal of pollutants must be reinforced by modification of the method. 

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