الفهرس 
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Abstract
This thesis discusses the issue of the removal of some radioactive nuclides and heavy metals as a result of water pollution using fly ash carbon, which is a low cost and effective to remove various organic and inorganic pollutants from polluted water. Fly ash is produced in large quantities from combustion of fuel in power plants using diesel, coal and other fuels on wide range. Also carbon nanotube was also used as an effective adsorbent which has great potential to be used as an effective sorbent for the metalloid contaminants. In this study, one of the most famous techniques, namely adsorption, was used to remove radioactive elements and toxic metals such as uranium, thorium, potassium, lead, and copper. The thesis consists of six chapters.
The first chapter is the introduction, it contains an introduction on water pollution and its challenges; In addition, it contains an explanation of radioactivity and sources of water pollution, whether by radioactive waste or heavy metals and a survey on modern techniques used to remove pollution from water. Moreover, this chapter includes an introduction of the adsorption techniques used in this thesis. It also contains definitions of the materials used. It also contains definitions of the toxic properties of radioactive elements and specific heavy metals. At the end of this chapter, there is a desk survey of the most recent research and data dealing with this issue as well as the most important objectives of this thesis.
The second chapter concerns with the experimental work used in this study; It represents the experimental techniques, which was used to study the research issue beginning with materials, chemicals, apparatus, instruments and procedures.
Chapter three is devoted for the results and the discussion for copper and lead ions removal from aqueous solutions. The removal was conducted in batch system under various conditions of pH, contact time, initial concentration of metal ions, adsorbent dose and temperatures. Isotherms from Langmuir, Freundlich, and Dubinin-Radushkevich at different temperatures (303-333 K) were evaluated and the results were compared.
Both pseudo-first and pseudo-second-order adsorption kinetics were also tested. Thermodynamic parameters; ΔH°, ΔG°, and ΔS° are calculated. SEM is used to assess morphological changed in the fly ash surfaces following adsorption of copper and lead ions. The obtained results showed an equilibrium within 20 min and maximum adsorption and removal of 95 -100% of the metal ions at pH 6-7. The pseudo-second order adsorption model was found to be more suitable for describing the adsorption kinetics. Langmuir adsorption model displayed the best RL values for copper ions adsorption ranged from 2.5 to 10.1 and lead ions adsorption ranged from 0.23 to 1.06.
The Freundlich value of 1/n was less than 1, indicating favorable adsorption process and confirming adsorbent’s heterogeneity. The thermodynamic parameters (∆G, ∆H, ∆S) were found to be in the range of -502 to -1424 kJ/mol, -4.5 kJ/mol and 16.6 kJ/mol, respectively for copper and from -1525 to -3236 kJ/mol, -1.052 kJ/mol and 3.675 kJ/mol for lead ions. The mean free energy for copper was 0.002 kJ/mol, and for lead 0.0007 kJ/mol, confirming a physical adsorption mechanism.
Chapter four is devoted for the results and the discussion for removal of uranium-238 ions from contaminated ground water containing NORM by adsorption on fly ash carbon. Fly ash’s particles were used to investigate the removal of uranium-238 ions, in the concentration range of 27.9, 55.8 and 111.6 Bq/l from ground water. The effects of various parameters including pH, contact time, initial metal ion concentration, dose adsorbent and temperatures are investigated. The optimum contact time was 30 minutes and the appropriate pH was found to be 4.5.
The temperature effects on kinetics and equilibrium were closely investigated in fly ash pores. Exothermic findings and a temperature rise resulted in an increase in the adsorption rate of uranium-238. Data was applied at different temperatures (293, 303 and 313 K) with the Langmuir, Freundlich and Dubinin – Radushkevich isotherms. Langmuir Adsorption Model was the best way to explain the data. Adsorption kinetics have been studied in pseudo-first and pseudo-second order. A pseudo-second-order mechanism was the best at fitting the data. Thermodynamic parameters; ΔH°, ΔG°, and ΔS° have been studied. SEM is used to assess morphological changes in the fly ash surfaces following the adsorption of uranium-238 ions.
Chapter five is devoted to the results and discussion of the removal of thorium-232 and potassium-40 radioactive nuclide ions onto fly ash carbon. Studies have been carried out to investigate the using of an efficient and low-cost adsorbent for water purification from radionuclides using fly ash carbon produced from fuel combustion products in power plants where mazote, coal and other fuels are commonly used to generate electricity. At different concentration range of 5.91, 11.83, and 23.67 Bq/l for thorium-232 and 19.3, 38.61, and 77.22 Bq /l for potassium-40 from ground water, fly ash carbon particles were used for the elimination of thorium-232 and potassium-40 ions. Batch adsorption experiments were performed to study the influence of various parameters such as the pH, contact time, concentration of the initial metal ions, adsorbent dose and temperature. The ideal contact time was 30 minutes and the pH was 7.0 for thorium-232 and 2.8 for potassium-40.
Temperatures have been closely studied in the kinetics and thermodynamic of the thorium-232 and potassium-40 ions adsorption on fly ash carbon. The Langmuir adsorption model was found to be the fit. Pseudo-first, pseudo-second-order, and adsorption kinetics are tested.
The best match for the data was a pseudo-second - order process. Thermodynamic parameters were tested; ΔH°, ΔG° and ΔS° were studied. Thorium-232 and potassium-40 adsorption concentrations resulted in findings associated with an exothermic reaction. Isotherms from Langmuir, Freundlich, and Dubinin-Radushkevich were studied at different temperatures (293, 303 and 313 K). SEM is used to test morphological changes in the surfaces of fly ash carbon after thorium-232 and potassium-40 ion adsorption.
Chapter six is devoted for the results and the discussion for removal of uranium-238, thorium-232 and potassium-40 from waste water. The optimum conditions for the removal of uranium-238, thorium-232 and potassium-40 from waste water and the discharge of nuclear facilities using multi-walled carbon nanotubes (CNTs) are described. The adsorption mechanism is mainly attributed to chemical interactions between the metal ions and surface functional groups of the CNTs.
Batch adsorption experiments are carried out in order to study the effect of different parameters such as pH, contact time, initial metal ions concentration, adsorbent dose, and temperatures. Maximum metal removal ( > 98 %) from solutions containing 20 – 120 Bq/L metal ions are achieved using a contact time of 15 minutes, a pH of 6.0 and 10 mg/L of carbon nanotubes.
The effect of temperature on the kinetics and equilibrium of adsorption on CNTs particles is examined. Consistent with an exothermic reaction, an increase in the temperature resulted in an increase in the adsorption rate. Langmuir, Freundlich, and Dubinin–Radushkevich isotherms are applied to the data obtained at various temperatures. Langmuir adsorption model is the best for data interpretations.
The kinetics of adsorption reveals a pseudo-second-order mechanism. Thermodynamic parameters at 293 K (ΔG°, ΔH° and ΔS°) for U-238, Th-232 and K-40 are (-14590.7 kJ/mol, -6.66 kJ/mol, 26.47 J/mol.K), (-9696.5 kJ/mol, -2.48 kJ/mol, 14.17 J/mol.K) and (-3922.09 kJ/mol, -1.32kJ/mol, 6.12 J/mol.K), respectively.
Finally, references and appendices are cited at the end of the thesis. The appendices contain experimental data for adsorption under different conditions. Besides, there are other illustrations to further confirm the study results.