الفهرس 
Chapter1 1. IntroductionOnly 14 pages are availabe for public view
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Abstract
Radioactive liquid waste produced from nuclear power plants, research reactors, and all institutes that use radioisotopes, have some impacts on man and his environment since they possess some radiological effects on living organisms. Therefore, reduction or removal of some hazardous radionuclides from radioactive liquid wastes is of main concern.
Sorbent materials such as polymers have raised considerable attention owing to their water absorption and retention properties. Natural polymers including alginate salt have been adopted to be composed with synthetic polymers including acrylic acid and its derivatives. These kinds of materials often present the best properties of each of its components in a synergic way and have high performances of physical, chemical and mechanical properties. So it is used as good adsorbent agents.
This thesis aims to remove certain radionuclides namely, iodine, cesium and europium from liquid radioactive waste solution using some synthesized polymers.
Three polymers, poly (acrylamide/acrylic acid/sodium styrene sulfonate)(p1), poly (sodium alginate-acrylic acid)(p2) and poly (sodium alginate-acrylic acid-methacrylic acid) (p3)were prepared using Gamma radiation polymerization technique.
The work carried out in this thesis is presented in three main chapters, Introduction, experimental and the results and discussion.
Chapter 1: Introduction:
It includes a general background on the liquid radioactive waste, its classification, types of treatment (precipitation, ion exchange, solvent extraction, sorption…etc) and types of radiation. Explanation of adsorption process and their types (as physical and chemical) and adsorption kinetics were also included.
Some aspects of the radionuclides under investigation, which are ; iodine as representive for anion radionuclides and europium and caesium as cation radionuclides were outlined.
This chapter includes also the general introduction about natural polymer , their classification according to structure and origin, and their advantages and disadvantages. Sodium alginate as one of natural polymer to be modified and used as monomer in the preparation of polymers was selected. The polymerization process was induced by (γ)gamma radiation. It is ended by a literature survey on the removal of the nuclides under study.
Chapter 2: Experimental :
This chapter includes the various chemicals used and also the laboratory equipment and instruments which have been used for this purpose. A detailed description of the methods for preparation of the different solutions and methods for preparation of polymers were presented.
i) Poly acrylamide-¬acrylic acid-¬sodium p¬-styrene sulfonate polymer (PAAM-AcA-SSS), p1 was synthesized by polymerization of poly acrylamide (PAAM) with ¬acrylic acid (AcA) and ¬sodium p¬-styrene sulfonate (SSS) as monomers and N,N′¬methylene bisacrylamide(NBMA) as a crosslinking agent. The optimum synthetic conditions were as follow: AcA 10 mL, PAM 3.3 g, SSS 0.5 g and crosslinking agent 0.010 g.
ii) Preparation of sodium alginate (Na Alg)-¬acrylic acid (AcA) polymer (Na Alg-AcA) p2 was synthesized using AcA 20 wt%, Na Alg 0.4 wt% and NMBA 0.03 wt%.
iii) The polymer (Na Alg - AcA- MAcA) p3 was synthesized using 20 wt %AcA, 10% MAcA and 0.4 wt%Na.Alg and 0.03 wt % of NMBA as a crosslinker.
In all cases, all components were mixed in glass tubes and subjected to 60Co γ- rays irradiation of 25kGy
Chapter 3: Results and Discussion
The results and discussion are divided into four main parts.
A- Preparation and characterization of the prepared sorbent materials.
The factors Affecting the two polymers(p2 and p3) such as irradiation dose (from 15-30 kGy) , pH ( from 1-13 pH) and concentration of the monomers used and concentration of the cross-linker (from 0.01-0.06 wt %). from the results obtained showed that the optimium conditions for the preparation process are as follows:
P1 was prepared using 3.3 g of poly acrylamide(PAM), 0.5 g of sodium styrene sulfonate (sss), 10 mL of acrylic acid and 0.01 g of NMBA as cross linker.
from the results obtained from the factor affecting the swelling showed that the optimium conditions for the preparation process(p2 and p3) are as follows using 20%AcA, 0.4 wt% NaAlg and 10% MAcA in p3 only at irradiation dose 25 KGy with addition of 0.03 % of NMBA as a crosslinker.
The swelling of poly (Na.Alg-AcA-MAcA) (p3) was found to be lower than that of poly (Na.Alg-AcA)(p2) .
The characterization of the prepared polymers were investigated. The FTIR spectra of the copolymer (P1) showed the presence of carboxylate, hydroxylic, amide and sulphate groups. FTIR spectra of p2 and p3 showed presence of amide, hydroxylic and carboxylic groups and the spectra of p3 showed appearance of methyl group of MAcA at 1150cm-1.
Thermogravemetric analysis (TGA) and differential thermal analysis (DTA) indicated the thermal stability of the prepared sorbents. Scanning electron microscopy (SEM) showed a homogenous surface for the prepared polymers.
B- Sorption of 131I
The effect of pH of the solution from 1 to 10 on the removal % of iodine ions was studied. The results obtained showed that the removal % increases with the increase of pH values till 3 , afterwhich it decreases.
The effect of shaking time showed that the removal of 131I ions increases with increase of time from 5 min to near 30 min, after that it shows a steady state. This trend is nearly the same for the three prepared sorbent materials under study.
The sequence of removal of 131I using the investigated sorbents is as follows; P1<P3<P2 with values of 88.9%, 77.5% and 83.0%, respectively at pH value of 3.0 which was selected as the optimum pH for removal of iodine.
Using kinetic models to analyze the results obtained from contact time effect showed that sorption on all prepared polymers is applied by a pseudo-second-order. The intraparticle diffusion mechanism is not the only process controlled the reaction. The applicability of Elovich model supports that the reaction may be chemically.
To analyze the results and clarify the sorption mechanism obtained from effect of iodine concentration, Dubinin-Radushkviech isotherm was found to be applicable as R2 is 0.997, 0.989 and 0.991for p1, p2 and p3 ,respectively. E(activation energy) is 39.4, 37.2 and 38.6 kJ/mole for p1, p2 and p3 ,respectively.
To investigate the variation in decontamination factor (DF) on the basis of amount of adsorbents, various amounts ranging from 0.0125 to 0.2 g of the adsorbents were used. The result showed that increasing sorbent weight increases both the removal percent and DF of 131I for the three investigated polymers. Also the effect of bicarbonate and sulfate anions concentration as interfering anions on the sorption of iodine-131 by the three investigated polymers was studied. It was found that, increasing bicarbonate concentrations from 0.5 to 5 mM decreases iodine sorption substantially which reaches to 24.7% , 19.9% and 17.8%for P1, P2 and P3 ,respectively. Sulphate anions has less effect on sorption of iodine nuclides than bicarbonate.
C- Sorption of 152+154Eu and 137Cs
The same factors affecting the sorption of131 I was applied on 152+154Eu and 137Cs.
The effect of pH of the solution showed that the removal of 152+154Eu ions increases with the increase in pH from 2 to 4 after that it shows a plateau shape.
The effect of shaking time showed that the removal of Eu ions increases with increase of time from 5 min to near 120 min, after that it shows an equilibrium state. This trend is nearly the same for the three prepared sorbent materials under study. The sequence of removal of 152+154Eu on the investigated sorbents are as follows; p2˃ p1˃p3 with values of removal% equal 86, 92 and 60%, for P1, P2 and P3, respectively.
The data obtained showed that the sorption on the polymers prepared were applied by a pseudo-second-oder. The intraparticle diffusion mechanism is not the only process controlled the reaction. The applicability of Elovich showed that the reaction may be chemically.
The increase in temperature from 25 to 550C, leads to the increase in the removal of 152+154Eu and this means that the adsorption process is endothermic. The calculated thermodynamic parameters indicate that the adsorption process is endothermic and spontaneous in nature. The negative values of ΔG indicate that the process is spontaneous.
Langmuir and Freundlich, Dubinin-Radushkviech and Temkin models have been used to analyze the results that have been obtained from the data of effect of concentration of Eu ions and constants for each isotherm were calculated. Freundlich is applied by p1, p2 and p3 and 1/n was found to be lower than 1 indicating favorable reaction. DR is applied by the three polymers and E values are in the range 8-16 which means that the reaction may be of ion exchange type.
The same batch experiments were studied for 137Cs. The effect of pH of the solution showed that the optimum pH is 8 for the removal of Cs. .
The effect of shaking time showed that the removal of Cs ions increases with increase of time from 5 min to near 120 min, after that it shows a steady state. This trend is nearly the same for the three prepared sorbent materials under study. The removal of 137Cs is of the order P3˃P1˃P2 with values of R% equal 73, 60 and 92%, for P1, P2 and P3 respectively.
It was found that all polymers prepared were applied by a pseudo-second-order. The intraparticle diffusion mechanism is not the only process controlled the reaction. The applicability of Elovich showed that the reaction may be ion exchange process.
As the temperature increases from 25 to 550C the removal of 137Cs increases and this means that adsorption process is endothermic. The thermodynamic parameters were calculated and the data obtained showed that the adsorption process is endothermic and spontaneous in nature.
To analyze the results that have been obtained from the data of effect of concentration of Cs ions and calculating constants for each isotherm, Freundlich and DR are applied by the three polymers and E values are in range 8-16 which indicated that the reaction may be of ion-exchange type.
from all the previous results, it can be concluded that: p1 is a good adsorbent material for 131I, p2 for 152+154Eu and p3 for 137Cs.
D- Application on real readioactive waste
Based on the optimum conditions applied for the sorption process on the prepared polymers, a real sample from radioactive waste solution was taken and testing for removal or even diminishing some of the radioactivity it contains using the polymers under investigation. Radiometric analysis of this sample showed that it contains iodine and europium radionuclides besides other nuclides. [50 ml from this real liquid sample was taken, its pH was adjusted to 4, mixed with 0.05 g from both p1 and p2 polymers, and shaked for 120 min at room temperature]. After the treatment process, a decontamination factor of 33 was achieved for Eu and of 24 for I and removal % of I and Eu was 95 and 97%. In addition, the results obtained showed that the radioactivity of some other radionuclides such as Ce and Co which are not under study, were also found to be diminished.