Photochemical AOPs

Kusic, H Koprivanac, N Loncaric Bozic, A Papic, S Petemel, I Vujevic, D. Reactive dye degradation by a photochemical AOP - development of a kinetic model for UV/H2O2 process. Chemical and Biochemical Engineering Quarterly, 2006 in press. 

The spectral domains of UV radiation discussed in Fig. 3-9 and the corresponding energy conversions according to Eq. 3-3 are summarized in Tab. 3-3. In addition, this table contains information about the emission hnes of several types of lamp that are of interest to photochemical AOPs. Photochemists usually use the energy unit kj moh, whereas physicists prefer the unit eV (electron volt), and spectroscopists are used to wavenumber a=l/X in cm instead of wavelength. 

The most important water treatment technologies are summarized in Fig. 5-6. Depending on the source and on the water quahty, either mechanical, biological, physical, thermal, or chemical processes or their combinations may be applied. Photochemical AOPs and AOTs are subordinated to chemical processes, mainly because the current technological versions of photochemical wastewater remediation are dependent on the addition of auxihary oxidants, such as hydrogen peroxide, ozone or special catalysts such as titanium dioxide. Photochemical AOPs are attractive alternatives to non-destructive physical water treatment processes, for example adsorption, air stripping or desorption and membrane processes. The last merely transport contaminants from one phase to another, whereas the former are able to minerahze organic water contaminants (cf. Chapter 1). 

For the sake of simphcity, the paraphrases for the description of the different photooxidation reactions should include first the auxihary oxidant or oxidant combinations and secondly the shorthand expression of the electromagnetic wavelength range. For example, H2O2-O3-UV designates all photochemical AOPs... 

However, this collection of literature has to be extended to include several important recent contributions to the fields of photochemistry, photochemical AOPs and AOTs. For example, the text book by Suppan (1994) covers the basic principles of various UV and light induced processes in different research areas and demonstrates in an excellent manner the interdisciplinary applications and potentials of photoscience. This is also emphasized by Bottcher et al. (1991) who concentrate on several important technical applications using UV/VIS radiation as a reagent, an information carrier and as an energy carrier. Unfortunately, these authors hardly mention the expanding field of photochemical AOTs for waste treatment. 

A significant new group of methods to improve disinfection has recently emerged under the banner of advanced oxidation technology (AOT) or advanced oxidation processes (AOP) (ComnineUis et aL, 2008 Joseph et al, 2009 Oiler et al, 2011 Sievers, 2011). This may be divided into chemical AOP and photochemical AOP (Tunay et ai, 2010). 

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