الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Heavy metals are one of the most toxic materials to the environment. Adsorption is the process, which is used for the removal of heavy metals from wastewater. Various adsorbents have been used to remove different types of heavy metal ions from wastewater especially those that are harmful to mankind. Biopolymers are the most common adsorbents used. Chitosan, a biopolymer produced from crustacean shells, has applications in various areas, particularly in wastewater treatment due to its ability to remove metallic ions from solutions. Chitosan has also been found to be a good candidate as a support material for gene delivery, cell culture and tissue engineering. Chitosan has also exhibiting excellent biological properties such as biodegradation in the human body, and immunological, antibacterial, and wound-healing activity. In the present work, Methyl acrylate was grafted onto chitosan using the ceric ammonium nitrate as initiator. Chitosan and grafted chitosan samples were characterized using Fourier (FTIR), and (SEM) methods. Evidence of grafting was confirmed by FTIR. The morphology of both adsorbents was evaluated by SEM. Surface area, the pore size distribution and the particle size distribution of chitosan and grafted chitosan samples were analyzed. Both chitosan and grafted chitosan were used for the removal of copper and chromium hexavalent ions from aqueous solutions. The effects of contact time, initial copper and chromium ions concentrations, dose of adsorbent and pH of solution on percentage removal of Cu(II) and Cr(VI) ions using both adsorbents were studied. It is found that the best conditions are initial concentration of 100 mg/L with contact time of 180 min at pH of 8for removal of Cu(II) ions and initial concentration of 100 mg/L with contact time of 240 min at pH of 6for removal of Cr(VI).It is proved that grafted chitosan has been found to have higher percentage removal than chitosan for both heavy metals. Also it is found that the maximum adsorption capacity of chitosan was 12.22mg/g for Cu(II) ions and 14.95mg/g for Cr(VI) ions. On the other hand, it is found that the maximum adsorption capacity of grafted chitosan was 14.6mg/g for Cu(II) ions and 22.94mg/g for Cr(VI) ions. Equilibrium Data were tested by four isotherm models like Langmuir, Freundlich, Temkin and Dubinin-Radushkevich, isotherm models. It was determined that the removal of both heavy metals (Cu(II) and Cr(VI)) using chitosan as biosorbent, was well fitted by Freundlich isotherm. On the other hand, the removal of (Cu(II) and Cr(VI)) using grafted chitosan, was well fitted by Freundlich and Langmuir isotherms respectively. Kinetics experiments were performed to study the effect of time on the metal ions removal processes using pseudo-first order, pseudo-second order and Elovish kinetics models. The analysis of kinetic models showed the pseudo-first-order adsorption mechanism is predominant for removal of both metals using chitosan. On the other hand, the pseudo-second-order adsorption mechanism is predominant for removal of both metals using commercial grafted chitosan Intra-particle diffusion and film diffusion model equations were applied to determine the mechanism of adsorption and the rate-controlling step.All the previous variables, equilibrium isotherms, adsorption kinetics and mechanisms were also studied for the removal of the same previous heavy metals but by using natural chitosan and natural grafted chitosan obtained from shrimp shells by comparing the results of both types of adsorbents (commercial chitosan and natural chitosan) and their grafted ones, it was found that the commercial chitosan and its grafted product gave a slightly higher percentage removal than the natural ones for both heavy metals.