الفهرس 
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Abstract
This thesis consists of three main chapters.
Chapter 1, the introduction:
The first chapter is the introduction in which an outline on the importance of nano materials and their applications in different fields is presented. This chapter also includes a literature survey on the previous work performed on the biological effect of the nano particles and on their use in removal of different organic pollutants from water samples.
Chapter 2, the experimental:
This chapter includes complete description of the materials and methods used for the preparation of the nanosized AgCl and AgBr particles. This chapter also describes the instrument used in characterization of the prepared samples such as thermogravimetric – differential thermal analysis (TGA/DTA), X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), Fourier Transform Infrared spectra (FTIR), EDX and UV-Visible spectra.
Chapter 3, results and discussion:
This chapter contains the discussion of the results obtained and their analysis which can be summarize as follows:
- Silver halide Nanoparticulate (AgX NP; X = Cl or Br) was prepared by titrating 500 mL aqueous solution of KCl or KBr (0.02 M) DROP wisely to 100 mL aqueous solution of AgNO3 (0.01 M) mixed with a solution of polyvinylpyrrolidone (PVP) at room temperature. The prepared nanoparticles were characterized as follows:
- TGA/DTA analysis showed that the nano particles degrade through two steps; the first represents the dehydration of physically adsorbed water molecule while the second represents the decomposition of the AgX molecules to the nanosized metal oxide (Ag2O).
- The FTIR spectra show the expected characteristic bands in the shortwave region around 690-650 cm−1 due to the stretching vibration associated with bonds containing the silver atom. The bands related to each peak in these spectra are summarized as: i- Symmetric and asymmetric stretching vibration of Ag-Cl and Ag-Br bonds at 690-650 cm−1 and ii- Bending vibration of C-N bonds at 586 cm-1.
- The TEM images clearly show that they are cube-shaped single crystallites with the size in the range of 20 nm, which reflects the intrinsic cubic symmetry of AgCl. The TEM image of the AgBr NPs, indicates that they are spherical in shape and uniform in size, with an average particle size of 35 nm. These images also show that the NPs are well dispersed and not aggregated.
- EDX analysis for AgCl displayed high intensity two absorption peaks at 3.04 and 2.54 kV, indicating the presence of Ag and Cl, respectively. A semiquantitative analysis showed that silver constitutes 45.78 % while chlorine constitutes 50.29% and the atomic ratio Ag: Cl elements is approximately 1:1.
- EDX analysis of the AgBr nanoparticle displayed a medium intensity peak at 1.50 kV indicating the presence of bromine constitutes and a high intensity peak at 3.01 kV, due to silver. The percentages of bromine and chlorine in the sample amount to 42.60 % and 44.39 %, respectively proofing the presence of silver bromide nanoparticle.
- The UV-Visible spectra allow direct determination of band gap using the Tauc equation The value of optical band gap is calculated by plotting the relation between (αhv)2 vs hv and extrapolating the straight line portion to the hv axis. The extrapolation of linear portion to the hv axis gives values of energy gap as 3.5 ev and 3.8 ev for AgCl and AgBr NP’s, respectively.
- The antimicrobial susceptibilities against two Gram – positive bacteria and four Gram – negative bacteria in addition to five fungi were tested by the disk diffusion technique. Standard drug; tetracycline (500 µg ml-1) and dimethyformamide (DMF) were screened separately for their antibacterial activity as positive and negative controls, respectively, while Nystatin (1000 Unit ml-1) and DMF were screened separately for their antifungal activity as positive and negative controls, respectively The antibacterial and antifungal results suggest that the prepared AgXNP’s show high activity against the tested organisms compared to tetracycline and Nystatin taken as standard drugs.
- The photodegradation of Malathion as VX chemical warfare agent (CWA) stimulant and as widely used insecticide was studied without using catalyst and with using AgCl and AgBr NP,s as catalysts. The results shows that, after 240 min Malathion degraded maximally up to 48.5 % under the effect of UV radiation only, while the percent degradation efficiencies reach 99.2 % and 82.4 % on using AgCl and AgBr nanoparticles, respectively as catalyst within only 120 min. This reflects the high efficiency of these materials for the removal of such toxic organic insecticide pollutant.