Synthesis, Characterization And

Immobilized Polysiloxane Application

Of Diethyenetriaminetetraac

etic acid

Synthesis, Characterization And

Immobilized Polysiloxane Application

Of Diethyenetriaminetetraac

etic acidPrepared by :

Abd-Erahman El-Agah

Chemistry DepartmentChemistry DepartmentIslamic University of GazaIslamic University of Gaza

Supervised bySupervised by : : Dr. Nizam M. El-Dr. Nizam M. El-

AshgarAshgarJuly/2007July/2007

Preparation of the Preparation of the immobilized polysiloxane immobilized polysiloxane

ligand systemligand 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:

Si(OR)4 (RO)3SiR'ROH

O

O

Si

O

R'+ H2O/Cat.

O

O

O

Si(CH2)3Cl

O

O

O

Si(CH2)3IAcetone

+ NaI 48 hr, 70 C

o

Features of Features of polysiloxanepolysiloxane

• 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.

Important applicationImportant 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.

The first strategy (sol The first strategy (sol gel process)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- HydrolysisBy 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.

Further polycondensation Further polycondensation to form SiOto form SiO22 net work net work

OH

OH

OH

LOH

OH

O O OO

O O

O O

O

O

O

O

L

L

L

O

O

OOO

O

O

O O O

Si Si Si Si Si

S Si

S S

Si

Si

n

Gelation, Drying and Gelation, Drying and AgingAging

• GelationInterconnection between particles of the sol increases forcing

the sol to become more viscous (gel-point) so lose its fluidity.

• DryingEvaporation of water and organic solvent from the pores of the

glassy material.Shrinking of 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.

• AgingThe 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 + ROHSiOH + SiOH SiOSi + H2

Silane coupling agentSilane 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.

Advantages of Polysiloxane Advantages of Polysiloxane Immobilized Ligand SystemsImmobilized 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.

Drawbacks of Drawbacks of PolysiloxanesPolysiloxanes

• Hydrolysis at high pH ( 12).

• Leaching of the functional groups from the support surface into the solution.

Applications of Polysiloxane Applications of Polysiloxane Immobilized Ligand SystemsImmobilized 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.

Preparation of Preparation of diethylenetriaminetetraacetic acid ethyl diethylenetriaminetetraacetic acid ethyl

esterester 1- Reaction of diethylenetriaminopropyltrimethoxysilane

with ethylchloroacetate in 1:2 molar ratio:

(CH3O)3Si(CH2)3NH(CH2)2NH(CH2)2NH2ClCH2COOC2H5

(CH3O)3Si(CH2)3N(CH2COOC2H5)(CH2)2N(COOC2H5)(CH2)2N(CH2COOC2H5)2

+ 4

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

O

O

O

SiCH2-CH2-CH2-N(CH2)2N(CH2)2N

CH2COOC2H5

CH2COOC2H5

CH2COOC2H5

CH2COOC2H5

(C2H5O)4Si

H2O/Ethanol

(CH3O)3Si(CH2)3N(CH2COOC2H5)(CH2)2N(COOC2H5)(CH2)2N(CH2COOC2H5)2

P-DTTA-Ester

+ 4

1. Acidic hydrolysis of the ester product

O

O

O

SiCH2-CH2-CH2-N(CH2)2N(CH2)2N

CH2COOC2H5

CH2COOC2H5

CH2COOC2H5

CH2COOC2H5

O

O

O

SiCH2-CH2-CH2-N(CH2)2N(CH2)2N

CH2COOH

CH2COOH

CH2COOH

CH2COOH

HCl

P-ETTA-Ester

P-ETTA

Characterization of Characterization of Functionalized PolysiloxanesFunctionalized Polysiloxanes

Elemental Analysis :

Polysiloxane

%C%H%NC/N

P-ETTA-Ester

Expected40.76.26.27.7

Found32.75.05.27.3

P-ETTAExpected26.03.86.15.0

Found24.94.15.75.1

FTIR :1. For P-ETTA Ester .

4000.0 3000 2000 1500 1000 600 .0

33.7

40

45

50

55

60

65

69.8

cm-1

%T

3425

1744

1662

1083

948

793

2- For P-ETTA Acid .

4000.0 3000 2000 1500 1000 600 .0

29.9

35

40

45

50

55

60

62.3

cm-1

%T

3444

1654

1085

952

795

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

ApplicationApplication

Effect of pH

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

0

20

40

60

80

100

120

3 3.5 4 4.5 5 5.5 6

pH

mg

M(I

I)/g

Lig

and

mg Co(II)/g mgl Ni(II)/g mg Cu(II)/g

Effect of Shaking Time

0

20

40

60

80

100

120

0 10 20 30 40 50 60 70 80

Time (Hours)

mg

M9

II)/g

Lig

an

d

pH=3.6 pH=4 pH=4.4 pH=4.8 pH=5.2 pH=5.6

ConclusionConclusion• 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.

• 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.

Thank You