Synthesis, Characterization And Immobilized Polysiloxane Application Of Diethyenetriaminetetraacetic acid

1. Synthesis, Characterization And Immobilized Polysiloxane Application Of Diethyenetriaminetetraacetic acid Prepared by : Abd-Erahman El-Agah Chemistry Department Islamic University of Gaza Supervised by : Dr. Nizam M. El-Ashgar July/2007

2. Preparation of the immobilized polysiloxane ligand system • To prepare the silane with complexing group and then to immobilize the complexing ligand by hydrolytic polycondensation reaction with tetra ethoxy silane. Ex: R = Me or Et R’ = Organofunctionalized ligand • The post treatment of the polysiloxane with the complexing ligand. Ex:

3. Features of polysiloxane • Insoluble cross-linked organosilicon polymers with a controllable porous structure. • They are intermediates in composition between the pure inorganic silica and organic polymers such as polystyrene. • Although the chain is entirely inorganic, with alternating Si and O atoms, organic side groups are attached to the silicon atoms. • Has an extraordinary flexibility of the siloxane backbone. • Si-O bond is significantly longer than the C-C bond. • Si-O-Si bond angle of 143 > tetrahedral angle.

4. Important application It is includes high performance elastomers, membranes, electrical insulators, water repellent sealants, adhesives, protective coatings, hydraulic, heat transfer, dielectric fluids, biomaterials, catalyst supports, chromatography, extraction and uptake of metal ions from aqueous solutions and encapsulation of organic compounds.

5. The first strategy (sol gel process) Hydrolytic polycondensation of a mixture of tetraethyl orthosilicate (TEOS) and the appropriate silane coupling agent in a definite mole ratio using acid or base catalysts. The process steps: 1- Hydrolysis By mixing low molecular weight tri or/and tetra alkoxysilanes with water in present of a homogenization agent. The hydrolysis catalyzed by acid or base. SiOR + H2O SiOH + ROH 2- Polycondensation Through silanol-silanol condensation SiOH + SiOH Si-O-Si + H2O Silanol-ester condensation. SiOR + SiOH Si-O-Si + ROH Where: R = CH3 or C2H5.

6. Further polycondensation to form SiO2 net work

7. Gelation, Drying and Aging • Gelation Interconnection between particles of the sol increases forcing the sol to become more viscous (gel-point) so lose its fluidity. • Drying Evaporationof water and organic solvent from the pores of the glassy material. Shrinkingof solid gradually (In some cases, the final volume of the xerogel is  10% of the initial volume of the gel). Large internal pressure gradients in the wet pores. This process causes cracking and fracture in large monoliths. Addition of surfactants, such as Triton-X, were suggested to prevent these fractures Drying the wet gel under monitored conditions also, give free cracks monolith.

8. Aging • The polycondensation reaction, formation of new bonds, water and alcohol still occur as a function of time. • Additional cross-linking and spontaneous shrinking occur. • So structure and properties of the gel continue changing with time. • The gel is aged to complete reaction. • The strength of the gel increase with aging. SiOR + H2O SiOH + ROH SiOH + SiOH SiOSi + H2

9. Silane coupling agent • It have the general formula X3SiR. (Where X is a hydrolyzable group and R represents an organofunctional group). • It combines the organic chemistry of organofunctional groups with inorganic chemistry of silicates. • It have been used widely to modify surfaces for chemical applications, to immobilize chelating functional groups on silica gel and to prepare organofunctionalized polysiloxanes.

10. Advantages of Polysiloxane Immobilized Ligand Systems • The physical rigidity of their structures. • High abrasion resistively. • Negligible swelling in both aqueous and organic solutions. • Chemical inertness (low interaction with analytes). • Slower poisoning by irreversible side reactions. • High biodegradation, photochemical and thermal stability. • High capacity of functionalized groups. • Uniform distributions of ligand sites within the polymer particles. • Readily modified by a variety of functional groups to be immobilized either before or after polymerization.

11. Drawbacks of Polysiloxanes • Hydrolysis at high pH ( 12). • Leaching of the functional groups from the support surface into the solution. Applications of Polysiloxane Immobilized Ligand Systems • The extraction and isolation of metal ions. • Metal ion separation in columns chromatography. • As catalysts in a variety of reactions. • Encapsulation of organic and biochemical compounds.

12. Preparation of diethylenetriaminetetraacetic acid ethyl ester 1- Reaction of diethylenetriaminopropyltrimethoxysilane with ethylchloroacetate in 1:2 molar ratio:

13. Hydrolytic polycondensation of the diethylenetriaminetetraacetic acid ethyl ester silane agent with tetraethylorthosilicate (TEOS), in the ratio 1:2 respectively.

14. Acidic hydrolysis of the ester product

15. Characterization of Functionalized Polysiloxanes • Elemental Analysis :

16. FTIR: • For P-ETTA Ester .

17. 2- For P-ETTA Acid .

18. Metal Uptake Capacity :1.For P-ETTA .Maximum Uptake Co2+ Ni2+Cu2+mg M2+/g Ligand 77.4 96.4 111.1 mmol M2+/g Ligand 1.29 1.64 1.74 Application

19. Effect of pH Uptake of metal ions by P-TA versus pH values, (48 hr shaking time).

20. Effect of Shaking Time

21. Conclusion • In this study some insoluble functionalized tetraacetic Acid Polysiloxane Immobilized Ligand System. immobilized ligand systems, have been prepared. • The preparation methods were mainly based on the sol-gel process, which summarized in hydrolytic polycondensation of TEOS and an appropriate silane coupling agent. • These polysiloxane immobilized ligand systems were well characterized by elemental analysis and FTIR. • FTIR provided strong qualitative evidences about the functional groups of the immobilized ligands.

22. Elemental analysis provided the exact content of the functionalized ligand groups that attached to the immobilized ligand systems. • These immobilized ligand systems exhibit high potential for preconcentration of divalent metal ions (Co2+, Ni2+ and Cu2+) from aqueous solutions. • The optimum experimental conditions that studied showed that maximum uptake could be attained at pH 5.5 for 48 hours.

23. Thank You