الفهرس 
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Abstract
The work in this thesis comprises three main chapters: Chapter 1 (Introduction): This chapter represents a literature survey for the work done in this area of research which dealt with the modification and grafting of chitosan. Besides, the tools used for structure characterization of the resulting modified materials have been also discussed and explained as represented by the authors. In addition, the application of these materials in different areas of interest has been also included. Chapter 2 (Experimental): Describes the materials, methods of preparing the chitosan derivatives, tools used for product characterization e.g. FTIR, SEM, TEM, XRD, STA, TGA, EDX and elemental analysis. In addition, the applications of these modified materials in heavy metal ions adsorption and in dye removal have been experimentally described. Chapter 3 (Results and discussion) is divided to four main parts. The first part was dealing with the characterization and identification of the new five modified materials using the different tools. These materials were crosslinked chitosan, CS-E, resulting from the treatment of chitosan with epichlorohydrin, aminated chitosan, CS-I, resulting from treatment with polyethyleneimine. Moreover, upon treatment of CS-E with sodium sulfite, sulfated chitosan, CS-S, was produced. On the other hand, when aminated chitosan was treated with monochloroacetic acid, carboxylated chitosan, CSMC, was produced. The latter was then treated with sodium sulfite producing carboxylated - sulfated chitosan, CS-MC-S. The second part was dealing with the adsorption of heavy metal ions e.g. Cd(II), Cu(II), Ag(I), Ni(II), Cr(III), and Mn(II). The maximum adsorption capacity for all modified materials was observed for the adsorption of Ag(I) ions compared to the other metals. Moreover, the adsorption of Cd(II) ions is preferable by CS-E and CS-I whereas the adsorption of Cu(II) ions is preferable by CS-MC-S which has a lower affinity for adsorption of Cr(III) ions. Cr(III) ions, on the other hand, has almost similar adsorbability power showed by the other four modified materials. The third part was concerned with the application of these materi als in dye removal. It was found that, the adsorption capacities of modified chitosan vary according to the type of adsorbent, type of the dye and the pH of the external solutions. The result also indicated that cationic dyes were adsorbed successfully by sulfated, carboxylated and carboxylated sulfated chitosan which was attributed to the increased electrostatics attraction between the negativity charged anions on the adsorbents and cationic dye molecules. The adsorption kinetics were tested for pseudo first order, pseudo second order and intraparticle diffusion and the results correlate very well with pseudo first order kinetics. The fourth part was dealing with the antimicrobial activities of these modified materials. The results indicated that chitosan itself is not a powerful agent to inhibit the growth of tested bacterial species except in case of S.aureus which gave 1.9 ± 0.09 cm inhibition zone. The minimal inhibitory concentrations of chitosan and its derivatives were recorded inhibition zone at 15, 20, 15, 20, and 25 mg/well with CS-E, CS-S, CS-I, CS-MC and CS-MC-S respectively when evaluated against the pathogenic bacteria (K.penumonia) as well as against the pathogenic bacteria (S.aureus). However, K.penumonia was resistant to chitosan itself. In addition, chitosan and its modified derivatives were less effective against tested fungi when compared with that of bacteria. The inhibition zone was ranged between 0.5 ± 0.02 in case of chitosan, CS, and 1.9 ± 0.07 in case of sulfated chitosan, CS-S with Malassezia furfur. The results suggested the mechanism that chitosan can penetrate the nucleus of microbes and binds to DNA which inhibit the mRNA binding site to DNA, thus the cell wall protein cannot be synthesized.