The Effect of Methyl Oleate Variation as a Template in Synthesis of

Silica Mesoporous using Tetraethylorthosolocate (TEOS)

Silvia Afriani Sitinjak and Andriayani

Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Sumatera Utara, Medan, Indonesia

Keywords: Mesoporous Silica, Methyl Oleate, Template, BET.

Abstract: Silica material synthesis has been carried out using tetraethylortosilicate (TEOS) as a source of silica,

methyl ester oleate as a template, 3-aminopropyltrimethoxysilane as a co-structure directing agent (CSDA),

and deionized water as the solvent. The synthesis of silica material was made by varying the mass of methyl

ester oleate, namely 3.7358 g, 4.2695 g, 4.8032 g, 5.3369 g, and 5.8706 g. The TEOS and APMS mixture

was added to a mixture of methyl ester oleate, 0.1 M HCl, and deionized water and then stirred at room

temperature for 2 hours. The mixture was then cooked in an oven at 80

C for 72 hours. Separation of the

product is done by centrifugation, The resulting solid is dried and then calcined at 550

C for 6 hours. The

XRD analysis results of the product showed diffraction peaks which widened at 12

to 30

which indicated

that the resulting material was amorphous. The FT-IR spectrum shows the presence of Si-OH and Si-O-Si

groups which are characteristic of silica material. SEM analysis shows the existence of hollow particles with

non-uniform size. Nitrogen isotherm (BET) adsorption shows type IV isotherm curves and H1 type

hysteresis loops with uniform pore sizes on the variation of methyl oleate 4.8032 g, which is 2.28 nm. This

identified that the optimum conditions for the synthesis of silica mesoporous material with the methyl ester

oleate template had been achieved.

1 INTRODUCTION

Porous material according to IUPAC can be

classified into three categories based on pore

diameter, namely: (i) micropore (d <2 nm), (ii)

mesoporous (2 nm <d <50 nm), (iii) macropore (d>

50 nm) , and (iv) megapories (> 7500 nm). The

development of the synthesis, characterization, and

application of porous materials has long been carried

out due to its wide use in adsorption, drug delivery,

separation, catalysts, and sensors. Modifications to

the synthesis of porous materials are still being

carried out for the development of material

structures such as porosity and pore diameter.

Silica mesoporous material can be synthesized

by adding templates in the form of anionic, cationic,

or non-ionic surfactants, or non-surfactant

tempalates, where the surfactant charge is based on

the head group load. Pore diameter can be controlled

by changing the molecular carbon chain length of

the template. Templates are used as molds

(auxiliaries and guides) in the formation of pores,

where primary colloidal particles will fill the gaps

between the template arrangements, so that when the

template is removed from silica particles a hollow

particle is formed. Templates can form pores due to

the presence of micelles from the surfactant. Silicate

precursors are formed around the surfactant micelles

by the crystallization process and then form

amorphous silica polymers that surround the

micelles. The micelles are then removed by

calcination, thus leaving a cavity which is then

referred to as a pore.

Research on synthetic silica material using

anionic surfactant templates is undergoing

development. (Yokoi et al., 2006) Synthesized silica

material using sodium laurate and 3-

aminopropyltriethoxysilane (APS) co-structure

directing agent (CSDA). The results show that with

the increase in APS mass used, the pore diameter

decreases from 4.0 nm to 3.3 nm. (Han et al., 2011)

Synthesize mesoporous silica with oleic acid

tempalte with the addition of ethanol as a solvent.

The results show that the more ethanol used, the

pore diameter decreases regularly. (Wan & Zhao,

2007) Synthesized silica mesoporous material using

sodium n-lauroylsarcosin (Sar-Na) with variations in

HCl mass. The results show that the decrease in pH

102

Afriani Sitinjak, S. and Andriayani, .

The Effect of Methyl Oleate Variation as a Template in Synthesis of Silica Mesoporous using Tetraethylorthosolocate (TEOS).

DOI: 10.5220/0010137000002775

In Proceedings of the 1st International MIPAnet Conference on Science and Mathematics (IMC-SciMath 2019), pages 102-106

ISBN: 978-989-758-556-2

causes an increase in pore size from 3.1 nm to 3.3

nm. (Tsai et al., 2011) Synthesized mesoporous

silica nanoparticles (MSNs) with ethylene glycol

phosphate monoester surfactants (PMES) with

variations of 3-aminopropyltrimethoxysilane

(APTMS). The results show that with increasing

APTMS ratio, pore diameter will increase and

decrease regularly. (Andriayani et al., 2018)

synthesized silica material with sodium ricinoleate

with 0.1M HCl variation producing a pore size of

2.2-3.8 nm, and examined the effect of variations in

HCl concentrations in the synthesis of mesoporous

silica materials using methyl ester ricinoleate as a

template (Andriayani et al., 2018). Although

research on the synthesis of mesoporous materials

with anionic surfactant templates continues to

develop, reports of the use of methyl oleate as

templates have not been conducted so far, so that

optimum conditions for obtaining silica mesoporous

materials with good porosity and have a uniform

pore distribution.

Methyl oleate is clear yellow and has nineteen

carbon chains, an ester of oleic acid. Synthesized

through the reaction of esterification with methanol

and catalyst, both acid catalyst or base catalyst. (Ahn

et al., 2012) Synthesized graphene in which methyl

oleate epoxy from methyl oleate to form oleo-

graphene oxide (oleo-GO) which can dissolve in

water, thus forming nanocomposite graphene. (Bao

et al., 2017) esterified oleic acid to methyl oleate

using Zr-SO

H @ CMC catalyst which was used as

biofuel.

Based on the above explanation, researchers are

interested in developing research on synthetic silica

mesoporous materials with variations in the number

of methyl oleate templates. The number of templates

plays a role in determining the characteristics of

silica mesoporous material. A high amount of

surfactant will increase the formation of micelles, so

that it will produce more pores. However, if the

amount of surfactant is excessive, it will produce

more micelles and large pores and cause the formed

silica matrix to become brittle (easily broken), so

that optimum conditions will be sought.

2 MATERIALS AND METHODS

2.1 Materials

The materials used in this study include : Oleic

Acid, tetraetilorthosilicat (TEOS), 3-

aminopropiltrimetoksisilan (APMS), HCl 0.1 M,

Deionized Water,n-hexane, Calcium

Chloride(CaCl

), methanol, Methyl Oleate ,sulfuric

acid (H

2.2 Methods

Esterification of Oleic Acid

In a three neck flask (250 ml), oleic acid (40 g ;

0.134 mol), dried methanol (85.76 g; 2.68 mol), and

4(p)

(0.8 g) catalyst, then heated in reflux circuit

at a temperature of 60-70

C while stirring for 3-4

hours. The reaction results obtained added aquadest.

After that the methyl ester formed is extracted with

n-hexane. Oleic oil methyl esters obtained were

analyzed using GC-MS.

Synthesis of Mesoporous Silica

Into the beaker glass, 3.7358 g of methyl ester oleate

(0.01126 mol) are added, then add 100 ml of

demineralized water and stir for 20 minutes. Then

add 30 ml of 0.1 M HCl while stirring at room

temperature for 5 minutes. Then a mixture of 3.74 g

TEOS (0.018 mol) and 1 g APMS (0.00559 mol)

was made and stirred for 5 minutes in a closed

condition. The TEOS and APMS mixture was added

to the mixture of methyl ester oleate, demineralized

water, and HCl and then stirred for 2 hours. Then

aging in an oven at 80

C for 72 hours. The product

is separated using a centrifugator and washed with

demineralized water and then dried. The resulting

solid was calcined at 550

C for 6 hours. The results

obtained were characterized by FT-IR, XRD, SEM

and BET analysis.

Table 1: Condition reaction of synthesis mesoporous silica.

Treatment TEOS

(mol)

Methyl Oleate

(mol)

Methyl Oleate

(gram)

APMS

(mol)

HCl

(ml)

Stirrer Time

(hours)

Run-1 0.018 0.00126 3.7358 0.00559 30 2

Run-2 0.018 0.0144 4.2695 0.00559 30 2

Run-3 0.018 0.0164 4.8032 0.00559 30 2

Run-4 0.018 0.0180 5.3369 0.00559 30 2

Run-5 0.018 0.0198 5.8706 0.00559 30 2

The Effect of Methyl Oleate Variation as a Template in Synthesis of Silica Mesoporous using Tetraethylorthosolocate (TEOS)

103

3 RESULTS AND DISCUSSION

3.1 GC-MS Analysis of Methyl Oleate

The esterification results of oleic acid were analyzed

using GC-MS to see the purity of the methyl oleate

produced. The results of the GCMS analysis showed

that the percentage of methyl oleate was the largest

at 86.77%.

3.2 Synthesis of Mesoporous Silica

Into the beaker glass, methyl ester oleate is added

with demineralized water. Then added 0.1 M HCl

then stirred at room temperature for 1 hour. The

mixture of terraethylortosilicate (TEOS) and 3-

aminopropyltrimethoxysilane (APMS) was stirred

for 5 minutes, then the mixture of

terraethylortosilicate (TEOS) and 3-

aminopropyltrimethoxysilene (APMS) was added to

the beaker glass containing a mixture of methyl ester

oleate, HCl, and water in the demineralized water

room temperature for 2 hours. Aging was carried out

in the oven at 80

C for 72 hours. The product is

separated by centrifugation and then dried and then

calcined at 550

C for 6 hours. The result was 0.7873

g, 0.7932 g, 1.0904 g, 0.8576 g, and 0.8963 g.

3.3 FT-IR Analysis of Material

Mesoporous Silica

Figure 1: FT-IR analysis of mesoporous silica.

The picture above shows that the methyl ester oleate

used as a template was lost during calcination. This

can be seen from the absence of C = O uptake in the

range 1725 cm

-1

and C = C uptake in the range

1680-1640 cm

-1

. It can also be seen from the figure

above that all mesoporous materials with the

addition of various oleic methyl esters show the

absorption peak between 3448.72 cm

-1

(broad) given

by the OH group strain (ʋ

Si-OH), whereas at

802.39 and 794.67 cm

-1

is caused by the presence of

Si-OH symmetrical groups (ʋ

Si-OH). Other

absorption peaks were seen at 1095.57 and 1087.85

-1

(strong) given by the strain Si-O-Si (ʋ

Si-O-

Si), while at 462.92-455.20 cm

-1

caused by the

symmetric group Si-O-Si (ʋ

Si-O-Si).

3.4 Difraction of XRD Mesoporous

Silica

Figure 2: Difractogram for mesoporous silica.

Table 2: Functional group of mesoporous silica.

Silica Material Functional Group Wavelength

Si-OH

(as)

Si-O-Si

(as)

Si-OH

(s)

Si-O-Si

(s)

Run-1(MO 3.7358 g) 3448.72 794.67 1087.85 462.92

Run-2(MO 4.2695 g) 3448.72 802.39 1085.85 462.92

Run-3(MO 4.8032 g) 2448.72 802.39 1095.57 462.92

Run-4(MO 5.3369 g) 3448.72 794.67 1095.57 470.63

Run-5(MO 5.8706 g) 3441.01 802.39 1087.85 462.92

IMC-SciMath 2019 - The International MIPAnet Conference on Science and Mathematics (IMC-SciMath)

104

From the picture above can be seen XRD

diffractogram at an angle of 2θ which widens

between 120

to 38

. Diffraction peaks that widen

from silica material in run-1, run-2, run-3, run-4, and

run-5 are 22.32, 23.07, 21.66, 22.61, and 22.28

which shows that the material produced is silica and

has an amorphous structure. This is consistent with

the data found in the literature (Andriayani et al.,

2013; Zhao et al., 2014).

3.5 Isoterm Adsorbsi-desorbtion

Figure 3: Isoterm adsrobtion-desorbtion of mesoporous

silica.

Graphs of run-1, run-2, run-3, run-4, and run-5 silica

material isotherm silica material show loop

hysteresis at relative pressure (P/P

) between 0.45-1

and physisorption isotherm type IV according to the

IUPAC classification (Gregg & Sing, 1982). The

hysteresis loop shape in run-1, run-2, and run-3

silica material is H1 type which shows that porous

material is cylindrical, such as pore ducts or

agglomerates of solids with coarse homogeneous

fields (Roque-Malherbe, 2007). Whereas run-4 and

run-5 has hysteresis loops of type H3, namely the

existence of nonrigid aggregates of particles such as

plates which have pore-shaped gaps.

Pore size distribution of the resulting silica

material can be seen in the following figure:

Figure 4: Pore size distribution for mesopoorous silica.

In Figure 3.4, several different peaks of each of the

silica material produced indicate that the pores

formed are not uniform. The resulting pore diameter

starts from 1.59 nm - 3.65 nm, so it can be classified

into micropore and mesoporous sizes. The dominant

pore size for variations in the addition of methyl

ester oleate to run-1, run-2, run-3, run-4, and run-5

are 1.77 nm, 1.77 nm, 2.18 nm and 2.45 nm, 1.96

nm, and 2.00 nm and 2.769 nm.

3.6 Microskop Electron Scanning

(SEM)

Based on the BET test, it was found that run-3 silica

material has an even distribution of pore size, so to

find out the morphology of run-3 silica material is

done with SEM photographs with various

magnifications of 5,000 and 20,000 times. The SEM

photo is shown in the image below:

Figure 5(A): Magnification 5,000 times.

The Effect of Methyl Oleate Variation as a Template in Synthesis of Silica Mesoporous using Tetraethylorthosolocate (TEOS)

105

Figure 5(B): Magnification 20,000 times.

SEM photos in Figure (A) with a magnification of

5,000 times, it appears that the shape of the particle

is not clear and only looks uneven chunks and there

are small aggregates that are dispersed on the

surface of the material, while at magnification

20,000 times (figure B ) have started to clearly see

diverse particle shapes, such as large lumps and

spherical shapes. And inside the particle there is a

gap.

4 CONCLUSIONS

The characteristics of the mesoporous silica material

produced, namely the FT-IR spectrum shows the

presence of silanol groups (Si-OH) and siloxane

groups (Si-O-Si) which are characteristic of silica

material. XRD diffractogram shows the diffraction

peaks widened at angle of 2θ between 20-40

, so that

the silica material formed is silica mesoporous. SEM

photos show the dispersed aggregates on the surface

of the material in a non-uniform pore size condition.

The isotherm nitrogen adsorption descent with the

BET method shows a type IV isotherm curve that is

an isotherm type for mesoporous material and has

H1 hysteresis loop type in run-1, run-2, and run 3

silica material. While run-4 and run- silica material 5

has hysteresis loop type H3. The dominant pore

diameter sizes are 1.77 nm, 1.77 nm, 2.18 nm and

2.45 nm, 1.96 nm, and 2.00 nm and 2.769 nm,

respectively.

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