الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
The application of illuminated semiconductors for the remediation of water contaminants has been used for a wide range of compounds and in most cases complete mineralization was achieved. The combination of UV irradiation and oxidants or catalysts (e.g. Ti02) has attracted interest for the treatment of industrial wastewater as an alternative to conventional methods. The textile residual waters create environmental problems not only due to their colour but also because some dyes (azo dyes) may undergo natural anaerobic degradation to potentially carcinogenic amines.
It was found that Ti02 was the best photocatalyst for photodegradation of all dyes. This work involves the photodegradation of Erythrosine B dye by different systems (UV/Ti02, UV/Ti02/H202, UV/Ti02/S2082\ UV/Ti02/I04’, UV/H202, UV/S2082\ and UV/IO4) using a slurry photochemical reactor.
The photocatalytic degradation of Erythrosine B was found to increase with increasing Ti02 loading from 0.4 to 3.2 g/L. It was found that the photocatalytic degradation of Erythrosine B in the presence of irradiated Ti02 was enhanced in the presence of low concentrations of inorganic oxidants (H202, S2082" ~ " and IO4’). This may be due to the trapping of the photogenerated conduction band electrons from Ti02 more efficiently than 02. On the other hand, UV/TiC^/ICV system was found to be more effective than UV/Ti02/H202 and UV/Ti02/S2082’ systems. This may be due to the higher trapping ability of IO4” to the photogenerated conduction band electrons of Ti02. Also the photolytic decomposion of IO4’ under UV irradiation involves the formation of highly reactive radical and non-radical intermediates ( OH, IO3’, IO4’ and IO3 ).These intermediates contribute to the dye degradation. The degradation efficiency of these catalytic systems could be arranged in ascending order as follows: UV/Ti02< UV/Ti02/H202< UV/Ti02/S2082’ < JV/Ti02/I04\
t can be seen also that, the photodegradation obeys a first order rate equation and .angmuir-Hinshelwood-type behavior can be used to describe the photodegradationeaction.
’hephotodegradation of Erythrosine B dye was studied also by homogeneous systems. It an be seen that the three oxidants, H202, S2082’ and IO4’ enhance the rate of UV-induced ecolourization of the dye. The rate of decolourization was greatest in the presence of IO4’ 3mpared to H202 and S2082’ . The degradation efficiency of the homogenous systems )llows the following order: UV/IO4’ >UV/S2082" ~ " >UV/H202. On the other hand, sterogeneous systems were found to be more effective than homogenous systems in the igradation of Erythrosine B dye. This may be attributed to the enhance production of OH Dm Ti02 and the inorganic oxidants.
Ticiency parameters such as apparent quantum yield (Qapp) and electrical energy per der (EE/O) were estimated and compared for heterogeneous and homogeneous systems, was found that Qapp for UV/Ti02/I04’ system is higher than those for UV/Ti02/H202, //Ti02/S2082‘ and UV/Ti02 systems. Also Qapp for UV/IO4’ system is higher than those •UV/H202, UV/S2082* systems.
e EE/O for heterogeneous and homogeneous systems shows that periodate exhibited a v energy consumption compared to peroxide and persulfate.