الفهرس | Only 14 pages are availabe for public view |
Abstract In this work, different types of hydrogels such as Poly acrylic acid (PAAc), Poly vinyl alcohol (PVA), Poly dimethyl amino ethyl methacrylate (PDMAEMA), Poly acrylamide (PAAm), Poly sodium alginate (NaAlg), copolymer of PVA/AAc, DMAEMA/AAc, NaAlg/AAm and clay nanocomposite of organic montmorillonite- Polyvinyl alcohol -co- poly acrylic acid (OMMTPVA/ AAc) have been prepared by γ irradiation polymerization for the purpose of separation of some heavy and toxic metals from water. The gel fraction and swelling percentage are studied as a function of monomer concentration and copolymer composition as well as the absorbed dose. Furthermore, the swelling percent as a function of time and pH are also studied. The bond and functional group structure are examined by Fourier transform infrared spectroscopy (FTIR). The free volume nanostructure is studied by positron annihilation lifetime spectroscopy (PALS). The elemental analysis is made by UV spectroscopy and energy dispersive x-ray analysis (EDX). In addition, the microstructure is studied by electron scanning microscope (SEM), x-ray diffraction (XRD) and transmission electron microscope (TEM). The thermal stability of the nanocomposite hydrogel has been determined by thermo gravimetrical analysis (TGA). The factors affecting the adsorption amount of heavy and toxic metals (Cu+2, Co+2 and Ni+2) such as contact time, pH and metal ion concentration of solution as well as temperature are studied. From Abstract Abstract XVI the results, it is found that, the three-macro hydrogels have different affinity for the three metals in comparison with the nanocomposite one. For instance, the maximum adsorption amount in case of PVA/AAc at pH 5 at 40 ppm and after a contact time of 24hrs is 194 mg/g, 185 mg/g and 144 mg/g for Cu+2, Co+2 and Ni+2 respectively. Whereas, the maximum adsorption amount for OMMT-PVA/AAc at pH5, at 100 ppm after 2 hrs. is 835 mg/g, 785 mg/g and 636 mg/g for Cu+2, Co+2 and Ni+2 respectively. The improvement of the adsorption amount by using OMMT-PVA/AAc nanocomposite is due to its larger surface area in addition to its higher thermal stability. Furthermore, a maximum swelling percent has been obtained with only 4 kGy absorbed dose compared to 20 kGy for PVA/AAc. Thus, the hydrogel nanocomposite has shown better swelling and adsorption properties compared to the macro hydrogels. This thesis consist of four chapters, list of figures & tables and list of references. The first chapter contain introduction for the decontamination methods, properties of the samples prepared and literature review and the main aim of this work. The second chapter contain theory of positron, positronium atom formation and free volume models. The third chapter consist of three parts the first about samples preparation, the second about description for the different techniques used and PALS and how to analysis its data. The fourth chapter includes the results, obtained using different |