الفهرس 
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Abstract
Radioactive waste as well as industrial waste is a great problem, which faced the world, we can not hide this problem from our live but we can reduce it by several methods as the environment need. This work discusses solving this problem by using SAC.
This work contains three chapters:–
Chapter 1: “Introduction”
This chapter includes an introduction about waste (definition, types of waste), an introduction about radioactive waste management (definition, steps of radioactive waste management), an introduction about heavy metals (nickel, chromium), an introduction about clay (definition, types of clay), an introduction about edible oil refining process (steps of edible oil refining industry), and a literature survey on the previous studies on SAC and adsorption of heavy metals is given.
Chapter 2: “Experimental methods”
The experimental part includes description of chemicals used, treatment of SAC with different organic solvents, characterization of adsorbent, adsorption of both Ni2+ and Cr3+ ions on treated-SAC, polymerization process, EDS analysis, SEM, and XRD analysis.
Chapter3: “Results and discussion”
AC is used to bleach the crude oil in the refining process to improve the quality of this oil as it has the capacity to remove coloured substances, and pull out metals. After bleaching process SAC not only presents a fire hazard (i.e., spontaneous autoignition), but also has unpleasant odor. Some organic solvents were used to extract the oil which is loaded into the AC. The amount of oil extracted increases with the increase in volume of organic solvent used. By using 450 mL of methanol, the maximum percentage of extracted oil is 27.08 wt%. Consequently, treated-SAC with methanol is recommended to be used in adsorption process. The FTIR spectra of clay show two important groups OH and Si–O and surface area analyzer appears that the washing process has cleared the pore of the SAC particle from residual oil, thereby cleaning its pore size and surface area that allowed more sorption processes.
The application of the treated-SAC on the removal of Ni2+ and Cr3+ ions shows that, the adsorption percentage for both Ni2+ and Cr3+ ions increases with the contact time until reaches equilibrium after about 180 min. The pH of aqueous solution is the most important variable affecting the adsorption of metals on the adsorbents. The adsorption percentage for both Ni2+ and Cr3+ ions increases with increasing pH of aqueous solution. The adsorption percentage of removed Ni2+ increased from 13.03% to 36.33% with increasing the initial concentration of Ni2+ from 20 to 60 mg/L then decreased to 18.32% with increasing the initial concentration of Ni2+ to 100 mg/L. This behavior is due to the adsorption sites, on the surface of treated-SAC, become saturated and reach equilibrium at initial concentration of Ni2+ ions 60 mg/L, while The percent adsorption of Cr3+ ions increased from 23.9% to 59.8% with increasing the initial concentration of Cr3+ ions in aqueous solution. The percentage adsorption for both Ni2+ and Cr3+ ions increases with increase of amount of adsorbent from 0.5 to 6 g. This trend is obvious because as adsorbent dose increases the number of adsorbent particles also increase that makes the greater availability of exchangeable sites for adsorption, while amount of metal ions adsorbed per unit mass decreased with an increase in adsorbent dosage. This result attributed to the metal ions can easily access to the adsorption sites when the amount of treated-SAC is small. The adsorption percentage for both Ni2+ and Cr3+ ions increases with increasing the temperature range from 20 to 60 °C. The adsorption kinetics for both Ni2+ and Cr3+ ions onto treated-SAC were evaluated and the data follows well the pseudo–second–order kinetic. The thermodynamic parameters for the present system including Gibbes free energy of adsorption ΔG°, changes in enthalpy of adsorption ΔH°, and changes in entropy of adsorption ΔS° were calculated using van’t Hoff equation. Negative value of ΔG° indicates that adsorption is spontaneous. The positive value of ΔH° may suggest endothermic process of adsorption. The positive value of ΔS° suggests an increased randomness at solid/solution interface during the adsorption for both Ni2+ and Cr3+ ions onto treated-SAC.
The elemental analysis of AC, SAC, and treated-SAC were confirmed by EDS analysis. The EDS analysis of AC, SAC, and treated-SAC have been found that oxygen, silicon, and aluminum atoms are the main constituents while Fe, Mg are the minor substitute elements in this layer silicate mineral; Ca, Na, K are in traces. The observation of new peak of Ni2+ ions in EDS analysis confirms that Ni2+ ions have been adsorbed on the surface of treated-SAC through one of adsorption mechanism. According to the presence of additional peak of Cr3+ ions in EDS analysis may imply the dispersion of Cr3+ ions on the surface of treated-SAC. Thus, it may be reasonable to speculate that treated-SAC has excellent sorption properties and possesses available sorption sites within its interlayer space. The SEM image for AC shows that the layers of AC are separated and it has high surface area and more porous nature. In contrast, The SEM image for SAC indicates that the surface of SAC particles is covered by oily–like materials and it is almost non–porous. The SEM image for treated-SAC shows some similarity to AC after. The SEM image for treated-SAC after adsorption of Ni2+ ions shows that the structure of the Ni adsorbed on treated-SAC is different from that of treated-SAC. Also, the SEM image for treated-SAC after the adsorption process of Cr3+ ions shows that the surface of treated-SAC is covered by Cr3+ ions. It also demonstrates that both Ni2+ and Cr3+ ions may disperse inside and on the surface of treated-SAC via sorption mechanism. As a result, the structure of treated-SAC may be changed. This result implies that metal ions were sorbed on treated-SAC introducing some changes into the crystal structure of treated-SAC. Moreover, The XRD analysis for AC, SAC, and treated-SAC shows that the observable crystalline structures of XRD patterns are very similar. We deduce that the edible oil bleaching process and the treatment of the SAC with methanol did not affect the main structure of the AC. The XRD analysis for treated-SAC after adsorption of both Ni2+ and Cr3+ ions presents a slight shifting in basal spacing as well as obvious change in diffraction intensity. The data reveal that Ni2+ and Cr3+ ions were sorbed on treated-SAC introducing some changes into the crystal structure of treated-SAC
After polymerization process, it has been observed from XRD measurements a general broad of XRD peaks, loss of intensity, and number of peaks decreases dramatically compared to those of the same type of clay before polymerization process occurred. The reaction of styrene with treated-SAC leads to a decrease in basal spacing. This observation is consistent with reducing desorption rate of Ni2+, and Cr3+ ions. This reduction can decrease the release of heavy metals from disposal site into the environment. Consequently, treatment of treated-SAC with styrene has significant influence on enhancing sorption processes for long term storage and disposal of heavy metals specially radionuclides.