الفهرس 
ِAcknowledgementOnly 14 pages are availabe for public view
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Abstract
In recent years, problem of wastewater became very important both for the sake of increasing amount and its variety. from the environment protection point of view, the textile industry is one of the special ones. Wastewaters from the textile industry are characterized mainly by high color from wastewater is a serious problem since even small amount of dye is clearly apparent. . The current treatment of dye waste in textile industries is focused on the removal of colour along with aesthetic issues. Several physico-chemical and biological methods are available for the treatment of textile wastewater. Unfortunately, these processes have high operating cost and are of limited applicability. The objective of this work is to investigate the photocatalytic degradation of two different dyes of acridine (Acridine orange hydrochloride hydrate dye and 1,3-Dihydroxy-9-Acridine carboxylic acid dye) by using UV-Visible photolysis in the presence of TiO2 (Degussa P25 suspensions) as a photocatalyst in different media. Factors affecting photodegradation such as the addition of electron acceptors, such as H2O2 and addition of anions like Cl–, CO32– will be investigated. Also, studying of CdS/TiO2 heterojunctions as an available configuration for photocatalytic degradation of two dyes. Moreover, the photochemical oxidations of (Acridine orange hydrochloride hydrate dye and 1,3-Dihydroxy-9-Acridine carboxylic acid dye) using H2O2 in aqueous solutions are also investigated. Different spectroscopic techniques have been used to follow up the progress of the photodegradation processes. The thesis consists of three chapters: Chapter 1: Deals with a general introduction of the subject and a literature review are given. Chapter 2: Includes the materials, experimental procedures instrumentation, the different advanced methods of data analysis and data transfer using Origin version 7.0. Chapter 3: Deals with the obtained results and discussions that are reported as follows: 1) The photostability of Acridine orange hydrochloride hydrate dye and 1,3-Dihydroxy-9-Acridine carboxylic acid dye were examined in aqueous medium. where The effect of light radiation on the two dyes was investigated by measuring its absorbance at different time intervals of exposure at 492nm for Acridine orange hydrochloride hydrate and (363nm, 481nm) for 1,3-Dihydroxy-9-Acridine carboxylic acid. It was found that two dyes have high photostability under UV- Visible illumination. 2) The homogeneous photochemical oxidation of Acridine orange hydrochloride hydrate dye and 1,3-Dihydroxy-9-Acridine carboxylic acid dye with hydrogen peroxide has been investigated in the acidic medium. The degree of the decolorisation of Acridine hydrochloride hydrate dye solutions reached (1.1%, 27.7%, 31.7%, and 34.4%) with H2O2 content of (0,15,20,50) x10-3M, respectively, at the irradiation time of one hour. The degree of the decolorisation of 1,3-Dihydroxy-9-Acridine carboxylic acid dye solutions reached (2.3%, 12.6%, 19.6%, and 26.3%) with H2O2 content of (0,10,20,50) x10-3M, respectively, at the irradiation time of one hour. This illuminates that H2O2 had a positive influence on the decolorisation of the Acridine orange hydrochloride hydrate dye and 1,3-Dihydroxy-9-Acridine carboxylic acid dye solutions. 3) The photodegradation of the Acridine orange hydrochloride hydrate dye and 1,3-Dihydroxy-9 Acridine carboxylic acid dye has been carried out in different media in the presence of suspended TiO2 (Degussa P25) as photocatalyst. Preliminary experiments showed that the two dyes are photostable in absence of TiO2 and not decomposed in the presence of TiO2 ruling out existing of any dark reaction such as hydrolysis. However, TiO2 slurries under UV-Visible irradiation significantly degraded it. This clearly means that the degradation observed is typically a photocatalytic reaction. 4) The effect of operating parameters are also investigated, such as: initial dye concentration, catalyst loading, effect of initial pH, effect of addition of electron acceptor as H2O2, and the effect of addition of inorganic anions (such as Cl–, CO32–). 5) The effect of CdS/TiO2 heterojunctions as an available configuration for photocatalytic degradation of Acridine orange hydrochloride hydrate dye and 1,3-Dihydroxy-9 Acridine carboxylic acid dye is also investigated. 6) The degradation rates of two were found to decrease continuously with substrate concentration (from 1.5x10-5 to 5x10-5 M) for Acridine orange hydrochloride hydrate dye and (from 5x10-5 to 1x10-4M) for 1,3-Dihydroxy-9-Acridine carboxylic acid dye. The important point for this behavior is that as the initial concentration of dye increases, the path length of photons entering the solution decreases, and in low concentration, the reverse effect is observed. The disappearance of two dyes were followed a pseudo-first kinetic order according to Langmuir-Hinshelwood model. 7) As the concentration of TiO2 increases, the plots show a maximum in initial reaction rate at 1g/l, suggestion a progressive saturation of the photonic absorption for a given radiant flux. However, as the TiO2 concentration increases continuously the reaction rates decrease. The reasons for this decrease in degradation rates are: A) Aggregation of TiO2 particles at high concentrations causing a decrease in the number of surface active sites, and B) Increase in opacity and light scattering of TiO2 particles at high concentration leading to decrease in the passage of irradiation through the sample (i.e. reduce the photonic flux within the irradiated solution). 8) In acidic medium it was found that the Acridine orange hydrochloride hydrate dye and 1,3-Dihydroxy-9-Acridine carboxylic acid dye was completely adsorbed on the surface of the TiO2 (Degussa P25) catalyst. This behavior is attributed to that the TiO2 surface is positively charged in acidic media condition. So, the electrostatic interactions between the positive TiO2 surface and the anionic form of the dye leads to a strong adsorption of the dye and to a relatively high initial rate. 9) The addition of H2O2 increases the concentration of the •OH radical since it inhibits the electron-hole recombination. Increasing in the rate of degradation of Acridine orange hydrochloride hydrate dye and 1,3-Dihydroxy-9-Acridine carboxylic acid dye from (5x10-3 to 15x10-3 M) of H2O2, Then decrease at higher concentration of H2O2 than 15x10-3 M. Consequently, the degradation rate is expected to be increase. However, further increase of H2O2 concentration, decreases the rate of degradation slowly. At high concentration, the hydrogen peroxide adsorbed on the photocatalytic surface could effectively scavenge not only the photocatalytic surface formed •OH radicals but also the photo-generated holes (h+VB) and thus inhibit the major pathway for heterogeneous generation of •OH radicals. 10) Irradiation studies have been carried out with sodium chloride in the range (0.5-2 g/l) with the Acridine orange hydrochloride hydrate dye and 1,3-Dihydroxy-9-Acridine carboxylic acid dye solutions. It was shown that the decolorisation of Acridine orange hydrochloride hydrate dye declined significantly of sodium chloride concentration from 0.5 to 2 g/l and the decolorisation of 1,3-Dihydroxy-9-Acridine carboxylic acid dye increased significantly of sodium chloride concentration from 0.5 to 2 g/l. 11) Irradiation studies have been carried out with Sodium carbonate in the range (0.5-2.0 g/l) with the Acridine orange hydrochloride hydrate dye and 1,3-Dihydroxy-9-Acridine carboxylic acid dye aqueous solution. It was found that decolorisation of Acridine orange hydrochloride hydrate dye and decolorisation of 1,3-Dihydroxy-9-Acridine carboxylic acid dye, respectively, increased significantly with sodium carbonate (Na2CO3) concentration and at higher sodium carbonate (Na2CO3) concentrations, the rate is reduced. The optimum concentration of (Na2CO3) is 1 g/l. 12) In case of CdS/TiO2 heterojunctions as an available configuration for photocatalytic degradation of Acridine orange hydrochloride hydrate dye and 1,3-Dihydroxy-9 Acridine carboxylic acid dye, the photocatalytic experiment was done under UV-Vis illumination and under visible illumination with cadmium sulfide (CdS). Irradiation studies have been carried out with cadmium sulfide (CdS) in the range (0.2-1g/l) and TiO2 (degussa P25) (1g/l) under UV-Vis light with the Acridine orange hydrochloride hydrate dye and 1,3-Dihydroxy-9-Acridine carboxylic acid dye solutions. It was shown that the decolorisation of Acridine orange hydrochloride hydrate dye increased at concentration 0.2 g/l cadmium sulfide giving large value then declined significantly to concentration 1 g/l cadmium sulfide. And the decolorisation of 1,3-Dihydroxy-9-Acridine carboxylic acid dye increased significantly at cadmium sulfide concentrations from 0.2 to 1 g/l. Irradiation studies have been carried out with cadmium sulfide of concentration (1g/l) and TiO2 (degussa P25) (1g/l) under visible light with the Acridine orange hydrochloride hydrate dye and 1,3-Dihydroxy-9-Acridine carboxylic acid dye solutions and [TiO2]=1g/l. it was shows that the rate of decolorisation of Acridine orange hydrochloride hydrate dye and 1,3-Dihydroxy-9-Acridine carboxylic acid dye decreased in case of irradiation under visible light than irradiation under UV-Vis light in the same condition.