Application of Application of Ethylenediamine Ethylenediamine Triaceticacid Triaceticacid Polysiloxane Polysiloxane Immobilized Ligand Immobilized Ligand System System Prepared by Prepared by Mohammad R. Matar & Mohammad R. Matar & Hussein Al. Hussein Al. Shayah Shayah Chemistry Department Chemistry Department Islamic University of Gaza Islamic University of Gaza Supervised by : Supervised by : Dr. Nizam M. El-Ashgar Dr. Nizam M. El-Ashgar
Transcript
Synthesis And Synthesis And Application of Application of
are formed in two general ways. are formed in two general ways.
a) Addition Polymers:a) Addition Polymers:
CH=CH2CH=CH2
CH=CH2
CH2CH2-CH-CH2-
-CH-CH2-CH-CH2-
+
b) Poly condensation Polymers:b) Poly condensation Polymers:
R
OH
HH
OCH2
R
OH
CH2-
OH
R
+ C + H2O
Disadvantages of Organic PolymersDisadvantages of Organic Polymers
i- They are unstable under high pressure and disintegrate i- They are unstable under high pressure and disintegrate into smaller fragments, so clog up columns at high into smaller fragments, so clog up columns at high pressure chromatographic operations . pressure chromatographic operations .
ii- They are sensitive to high temperature and radiation.ii- They are sensitive to high temperature and radiation.iii- They swell in most organic solvents.iii- They swell in most organic solvents.iv- Lack of chemical and mechanical stability.iv- Lack of chemical and mechanical stability.
So it is very important to search for other polymeric So it is very important to search for other polymeric matrices which have superior properties.matrices which have superior properties.
Polymers synthesis from elements Polymers synthesis from elements other than carbonother than carbon they are macromolecules in which a metal or they are macromolecules in which a metal or metalloid is part of the main chain backbone (soil, metalloid is part of the main chain backbone (soil, diamond, glass, stones, graphite silica gel,………..)diamond, glass, stones, graphite silica gel,………..)
AdvantagesAdvantages Physical rigidity and high mechanical resistivity.Physical rigidity and high mechanical resistivity. Negligible swelling in both aqueous and organic Negligible swelling in both aqueous and organic
solutions.solutions. Chemical inertness to analyte or production of side Chemical inertness to analyte or production of side
reactions.reactions. High biodegradational, photochemical and thermal High biodegradational, photochemical and thermal
stability.stability. Good mechanical and heat transfer properties.Good mechanical and heat transfer properties. Have good ability to withstand high pressure. Have good ability to withstand high pressure. Greater control for diffusion factors.Greater control for diffusion factors.
Insoluble cross-linked organosilicon polymers with a Insoluble cross-linked organosilicon polymers with a controllable porous structure.controllable porous structure.
They are intermediates in composition between the They are intermediates in composition between the pure inorganic silica and organic polymers such as pure inorganic silica and organic polymers such as polystyrene. polystyrene.
Although the chain is entirely inorganic, with Although the chain is entirely inorganic, with alternating Si and O atoms, organic side groups are alternating Si and O atoms, organic side groups are attached to the silicon atoms.attached to the silicon atoms.
Has an extraordinary flexibility of the siloxane Has an extraordinary flexibility of the siloxane backbone. backbone.
Si-O bond is significantly longer than the C-C bond.Si-O bond is significantly longer than the C-C bond. Si-O-Si bond angle of 143 > tetrahedral angle.Si-O-Si bond angle of 143 > tetrahedral angle.
Preparation of Polysiloxane Preparation of Polysiloxane immobilized Ligand Systemimmobilized Ligand System
Method 1: The Sol – Gel Process:Method 1: The Sol – Gel Process: Hydrolytic polycondensation of a mixture of Hydrolytic polycondensation of a mixture of tetraethyl tetraethyl
orthosilicate (TEOS) and the appropriate silaneorthosilicate (TEOS) and the appropriate silane coupling agent in a definite mole ratio using acid or coupling agent in a definite mole ratio using acid or base catalysts.base catalysts.
Method 2:Method 2: Modification of the preformed polysiloxaneModification of the preformed polysiloxane immobilized ligand system by the appropriate ligand immobilized ligand system by the appropriate ligand group.group.
Sol-gel Process.Sol-gel Process.Used for incorporation, immobilization, entrapment, Used for incorporation, immobilization, entrapment,
and encapsulation for large variety of materials and encapsulation for large variety of materials include; organic, inorganic, biomolecules, include; organic, inorganic, biomolecules, microorganisms, tissue and indicatorsmicroorganisms, tissue and indicators ..
Steps of the Sol-gel ProcessSteps of the Sol-gel Process
1- Hydrolysis.1- Hydrolysis.By mixing low molecular weight tri or/and tetra By mixing low molecular weight tri or/and tetra
alkoxysilanes with water in present of a alkoxysilanes with water in present of a homogenization agent. The hydrolysis catalyzed by homogenization agent. The hydrolysis catalyzed by acid or base.acid or base.
SiOR + H2O SiOR + H2O SiOH + ROHSiOH + ROH
2- Polycondensation. 2- Polycondensation. Through Through silanol-silanol condensation silanol-silanol condensation SiOH + SiOH + SiOH SiOH Si-O-SiSi-O-Si + H2O + H2Osilanol-ester condensation.silanol-ester condensation.SiOR + SiOR + SiOH SiOH Si-O-SiSi-O-Si + ROH + ROHWhere: R = CHWhere: R = CH33 or C or C22HH55..
Formation of Solid Silica:Formation of Solid Silica:
Hydrolysis:Hydrolysis:
CondensationCondensation..
OH OH
OH
OH
OH LOH
OH
OH
OH
OH
LOH
OH
OSi Si+ Si Si-H2O
CH3O Si
OCH3
OCH3
OCH3
OHOH
OH
OH
CH3O Si
OCH3
LOCH3
OH
OH
OH
LSi+H2O/Cat
SolventSi+
Further polycondensation to form SiO2 net workFurther polycondensation to form SiO2 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
Si Si
Si Si
Si
Si
n
The H2O and alcohol expelled from the reaction remain in the pores of the network.
Gelation, Drying and Aging.Gelation, Drying and Aging.
Gelation.Gelation.
Interconnection between particles of the sol increases forcing the Interconnection between particles of the sol increases forcing the sol to become more viscous (gel-point) so lose its fluidity. sol to become more viscous (gel-point) so lose its fluidity.
Drying .Drying .
**EvaporationEvaporation of water and organic solvent from the pores of the of water and organic solvent from the pores of the glassy material.glassy material.
**Shrinking ofShrinking of solid gradually (In some cases, the final volume of solid gradually (In some cases, the final volume of the xerogel is the xerogel is 10% of the initial volume of the gel). 10% of the initial volume of the gel).
* Large internal pressure gradients in the wet pores. This process * Large internal pressure gradients in the wet pores. This process causes cracking and causes cracking and fracture in largefracture in large monoliths. Addition of monoliths. Addition of surfactants, such as Triton-X, were suggested to prevent these surfactants, such as Triton-X, were suggested to prevent these fractures fractures
* * DryingDrying the wet gel under monitored conditions also, give free the wet gel under monitored conditions also, give free cracks monolithcracks monolith
Aging.Aging. Structure and properties of the gel continue Structure and properties of the gel continue
changing with time.changing with time. The reaction, is completed further hydrolysis and The reaction, is completed further hydrolysis and
resterification.resterification. Polycondensation reactions – New bonds Polycondensation reactions – New bonds
formation - are still occurs as a function of time.formation - are still occurs as a function of time. Additional cross-linking and spontaneous Additional cross-linking and spontaneous
shrinking occursshrinking occurs The strength of the gel increases with agingThe strength of the gel increases with aging SiOR + HSiOR + H22O O SiOH + ROHSiOH + ROH SiOH + SiOH + SiOH SiOH SiOSiSiOSi + H + H22OO
Advantages of Polysiloxane Immobilized Advantages of Polysiloxane Immobilized Ligand SystemsLigand Systems..
The physical rigidity of their structures.The physical rigidity of their structures. High abrasion resistively.High abrasion resistively. Negligible swelling in both aqueous and organic solutions.Negligible swelling in both aqueous and organic solutions. Chemical inertness (low interaction with analytes).Chemical inertness (low interaction with analytes). Slower poisoning by irreversible side reactions.Slower poisoning by irreversible side reactions. High biodegradation, photochemical and thermal stability.High biodegradation, photochemical and thermal stability. High capacity of functionalized groups.High capacity of functionalized groups. Uniform distributions of ligand sites within the polymer Uniform distributions of ligand sites within the polymer
particles.particles. Readily modified by a variety of functional groups to be Readily modified by a variety of functional groups to be
immobilized either before or after polymerization.immobilized either before or after polymerization.
Drawbacks of Polysiloxanes.Drawbacks of Polysiloxanes. Hydrolysis at high pH pH Hydrolysis at high pH pH 12). 12). Unstable for certain reaction conditions.Unstable for certain reaction conditions. Leaching of the functional groups from the support Leaching of the functional groups from the support
surface into the solution.surface into the solution.
Application of Polysiloxane Immobilized Ligand Application of Polysiloxane Immobilized Ligand Systems.Systems.
The extraction and and isolation of metal ions.The extraction and and isolation of metal ions. Metal ion separation in columns chromatography.Metal ion separation in columns chromatography. As catalysts in a variety of reactions. As catalysts in a variety of reactions.
Preparation of ethylenediaminetriacetic Preparation of ethylenediaminetriacetic acid polysiloxane immobilized ligand acid polysiloxane immobilized ligand systemsystem
1- Preparation of the silane agents by the reaction of 3-1- Preparation of the silane agents by the reaction of 3-ethylenediaminetrimethoxysilane with ethylenediaminetrimethoxysilane with ethylchloroacetate by the ratio of 1:2 ethylchloroacetate by the ratio of 1:2
(CH3O)3Si(CH2)3NH(CH2)2NH2 ClCH2COOC2H5
(CH3O)3Si(CH2)3N(CH2COOC2H5)(CH2)2N(CH2COOC2H5)2
+ 3
2- Hydrolytic polycondensation of the 2- Hydrolytic polycondensation of the triethyldiminotriacetatetrimethoxysilane agent with triethyldiminotriacetatetrimethoxysilane agent with tetraethylorthosilicate (TEOS), in the ratios 1:2 tetraethylorthosilicate (TEOS), in the ratios 1:2 respectively. respectively.
3- The new functionalized ligand system P-EDTA was 3- The new functionalized ligand system P-EDTA was obtained by acidic hydrolysis of the ester products.obtained by acidic hydrolysis of the ester products.
Separation of Co(II), Ni(II) and Cu(II) at different pH values (flow rate 1.5 mL/min
ConclusionConclusion
The immobilized ethylenediaminetriacetic acid The immobilized ethylenediaminetriacetic acid ligand system was prepared by the sol-gel ligand system was prepared by the sol-gel method. This immobilized ligand system exhibits method. This immobilized ligand system exhibits high potential for extraction and separation of high potential for extraction and separation of Cu(II), Ni(II) and Co(II) from aqueous solution.. Cu(II), Ni(II) and Co(II) from aqueous solution.. The ligand system has been shown to be an The ligand system has been shown to be an effective solid-phase for metal ion recovery at effective solid-phase for metal ion recovery at the optimum pH.the optimum pH.
