الفهرس 
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Abstract
There has been substantial research on the inorganic ion exchangers as well as organic resins commonly known as ion exchange media for the remediation of wastewater from hazardous metal containing.
Many investigators have introduced organic–inorganic hybrid ion–exchangers consisting of inorganic ion–exchangers and organic binding matrices, creating a new class of hybrid organic–inorganic materials called composite ion exchangers with better mechanical, chemical, thermal and radiation stabilities, reproducibility and possessing good selectivity for heavy toxic metals.
This work had been done in an attempt to synthesize a new novel ‘organic–inorganic’ hybrid cation-exchanger: polyaniline silicotitanate by incorporation of polyaniline into the matrix of inorganic cation-exchanger silicotitanate.
The work carried out in this thesis is summarized in to three main parts; namely, introduction, experimental and finally results and discussion.
First chapter:
The first chapter is the introduction which includes different tools used for the management of waste water, literature survey which includes a brief account on the classification of ion exchange, also the literature survey includes the last three decades related to composite ion exchangers and the proposed subject, silicotitanate and polyaniline silicotitanate. Also this chapter involves a study of the kinetics of exchange ,equilibria of the sorption process and applications of ion exchangers.
Second chapter:
The second chapter is the experimental which includes the chemicals used and their purity, the method of preparation of polyaniline silicotitanate as well as the instrumentation, the analytical techniques and the procedures used in this thesis.
Third chapter:
The third chapter deals with the results and discussion and is divided into main sections namely; preparation and characterization of adsorbent materials, distribution studies, kinetic studies, sorption isotherms and column operations in the first section from third chapter is the preparation and characterization, brief account on the preparation of polyaniline silicotitanate was required and composition studies indicate the molar ratio of Si,Ti, C, H and N in the material as 1:4:6:13:1 which tentatively suggests the following formula:
[Ti4O9H7Si + (– C6H5NH–)] 4H2O
The pH titration curve shows only one inflection point indicating that the polyaniline silicotitanate behave as monofunctional. The solubility of the prepared materials was determined in H2O, acidic and basic solution, the prepared polyaniline silicotitanate and silicotitanate samples are stable in water and acid solutions up to 6 M HNO3 and HCl, while the samples are completely dissolved at 7 M acids. polyaniline silicotitanate and silicotitanate are completely dissolved in 0.1 and 1 M base [NaOH and KOH]. The chemical stability of the prepared polyaniline silicotitanate is higher than silicotitanate, this prove thate the prepared composite overcame the low chemical stability of inorganic silicotitanate. polyaniline silicotitanate is more stable than other compsite ion exchangers. Also the I.R of the prepared materials was determined at different drying temperatures, 50, 200, 400, 600 and 850oC.
The XRD patterns of the prepared material was determined at different drying temperatures and the results showed that, the prepared silicotitanate heated at 50±1oC has amorphous structure, and the degree of crystallinity of the prepared silicotitanate slightly improved when doped with the organic part polyaniline. The prepared polyaniline silicotitanate heated at 50±1oC has crystal structure and the degree of crystallinity of the prepared polyaniline silicotitanate slightly improved with the increase of heating temperatures from 50oC to 600±1oC.
Effect of heating at different temperature for 4 h, indicated that on heating at elevated temperature the mass, physical appearance and ion-exchange capacity of the dried hybrid cation-exchanger was changed as the temperature increased. It was also observed that the hybrid cation-exchanger possessed higher thermal stability as the sample maintained about 76.72% of the initial mass by heating up to 400◦C and maintained about 47.07% of the initial mass by heating up to 800◦C higher than the other composite ion exchangers, However, in terms of ion-exchange capacity, this hybrid material was found stable up to 400◦C and it retained about 59.32% of the initial ion-exchange capacity by heating up to 400◦C, and this support the fact that polyaniline silicotitanate has a good thermal stability compared with other composite ion exchangers.
These results indicate that the prepared material has a good thermal and chemical stability compared to other organic, inorganic and composite ion exchangers.
The water content of polyaniline silicotitanate in the H+, Pb2+, Cs+, Cd2+, Cu2+ and Co2+ forms were determined by using thermal analysis
technique (TG and DTA). The water loss of H+, Cs+, Pb+, Co2+, Cu+2 and Cd2+ at 850oC are 54.091%, 58.115%, 54.800%, 52.073% and 52.078 %w/w, respectively, the results indicate that all the studied cations were exchanged as hydrated
The second section from the third chapter is the distribution studies, the ion exchange properties have been studied using five cations (Co2+, Cu2+, Cd2+, Cs+ and Pb2+) which represent the main different categories of the nuclear and industrial waste solution.
The distribution coefficient of the studied cations (Co2+, Cu2+, Cd2+, Cs+ and Pb2+) was investigated in polyaniline silicotitanate at different pH values at 25oC±1oC. The obtained results showed the Kd values increase with increasing the pH of the solution. from the plots of log Kd vs. pH, (Co2+, Cu2+, Cd2+, Cs+ and Pb2+) ions were found to deviate from the ideal ion exchange reaction mechanism. The selectivity order of the investigated cations on polyaniline silicotitanate in the same conditions has the following sequence;
Cs+ > Pb2+ > Co2+ > Cu2+ > Cd+2
The distribution coefficient values of polyaniline silicotitanate for the studied metal ions were compared to the other ion exchange materials.
The effect of reaction temperature on the adsorption of Co2+, Cu2+, Cd2+, Cs+ and Pb2+ ions (pH 3.45) on polyaniline silicotitanate sample was carried out in the temperature range 25-65±1oC, the distribution coefficient (Kd) of Co2+, Cu2+, Cd2+, Cs+ and Pb2+ on polyaniline silicotitanate increased with increasing temperature from 25oC to 65oC and the thermodynamic parameters (ΔHo, ΔSo and ΔGo) for the adsorption of Co2+, Cu2+, Cd2+, Cs+ and Pb2+ ions on polyaniline silicotitanate) were calculated.
The distribution coefficient of Co2+, Cu2+, Cd2+, Cs+ and Pb2+ increases with the presence of organic solvents than water, and the data show that the decrease of the distribution coefficient for the Co2+, Cu2+, Cd2+, Cs+ and Pb2+ on polyaniline silicotitanate is in the order;
propanol > ethanol > methanol
The ion-exchange capacity of the hybrid cation-exchanger polyaniline silicotitanate for the studied metal ions increases according to the decrease in the hydrated ionic radii and hydration energy and have the following sequence;
Cs+ > Pb 2+ > Co2+ > Cu2+ > Cd+2
polyaniline silicotitanate composite cation ion exchanger gives higher ion exchange capacity than other inorganic ion exchangers. The ion exchange capacities of polyaniline silicotitanate sample for Co2+, Cu2+, Cd2+, Cs+ and Pb2+ ions has been determined as a function of pH with constant ionic strength (0.1). The obtained results showed that, the capacity of the studied metal ions increases by increasing the pH. The ion exchange capacity of polyaniline silicotitanate for Cs+ ion at different drying temperature has been determined and showed that, polyaniline silicotitanate shows decrease in its capacities by increasing the drying temperatures from 50oC to 400oC.
The third section from the third chapter is the kinetic studies, the kinetics of exchange of Co2+, Cu2+, Cd2+, Cs+ and Pb2+ ions on polyaniline silicotitanate are studied as a function of particle radius, heating temperatures and reaction temperatures (all experiments were carried out under particle diffusion control as a limited batch techniques only).
The results showed that, the rate of exchange of different metal ions on polyaniline silicotitanate is independent of metal concentrations in solutions up to 5x10−2 M. The rate increases with decreasing the particle size. Also, the rate increases with decreasing the heating temperature of the exchange materials, while it increases with increasing the reaction temperature and the pH value. The values of the effective diffusion coefficients (Di), entropy of activation (ΔS*) and energy of activation (Ea) for Co2+, Cu2+, Cd2+, Cs+ and Pb2+ ions on polyaniline silicotitanate have been determined and are compared with the values reported in literature.. The results were found that the values of diffusion coefficient (Di) inside polyaniline silicotitanate sample follow the order;
Co2+ > Cs+ > Cd2+ > Cu2+ > Pb2+
The average values of diffusion coefficients (Di) of Co2+, Cu2+, Cd2+, Cs+ and Pb2+ on polyaniline silicotitanate of different particle diameters were calculated. The obtained results showed the diffusion coefficients calculated for larger particle sizes are slightly higher. Also, the average values of diffusion coefficients (Di) of Co2+, Cu2+, Cd2+, Cs+ and Pb2+ on polyaniline silicotitanate dried at (50, 200 and 400◦C) were calculated. The obtained results showed that there is an appreciable decrease of self-diffusion of Co2+, Cu2+, Cd2+, Cs+ and Pb2+ with an increase in the drying temperature of polyaniline silicotitanate from 50 to 400◦C. on contrast, the values of Di increase with increasing the reaction temperatures from 25 to 65oC.
The activation energy for the investigated metal ions (heating at 50 ◦C) was calculated and has the order:
Cu2+> Cd2+< Pb2+< Cs+<Co2+
The fourth section from third chapter is the sorption isotherm, the effect of concentration on the sorption of Co2+, Cu2+, Cd2+, Cs+ and Pb2+ ions has been studied at different reaction temperatures (25, 45 and 65oC) using concentration range 10-3 – 0.1 M. The results proved that the sorption of these ions is endothermic process and the sorption capacities of the studied metal ions increased with increasing the reaction temperature for all studied adsorption isotherms models (Langmuir, Freundlich and D-R isotherm).
Also, the results suggest that the adsorption of the studied metal ions (Co2+, Cu2+, Cd2+, Cs+ and Pb2+ ions) on polyaniline silicotitanate is favorable for the Freundlich isotherm more than Langmuir and D-R isotherm. Conformation of the experimental data with Freundlich isotherm assumes that sorption occurs on a structurally heterogeneous adsorbent with minimum interaction between the adsorbed atoms. from the above discussion, all the studied elements (Co2+, Cu+2, Cd2+, Cs+ and Pb2+ ions) are physically adsorbed.
The column investigations were studied and it was found that the Cs+ ions can be separated from polyaniline silicotitanate column by 0.5 and 1 M HNO3, so we can expect using the column in the regeneration process.