One source of water pollutions is caused by the high use of surface-active agents (surfactants) by industries\ud
and households. As a consequence, it is required to remove such substances from the environment One of the\ud
important and widely used methods for removal of substances from solution is adsorption. In this research, MCM-41\ud
and its modification MCM41-TMCS were used to adsorb nonionic surfactant, Triton X-114. FTIR and NMR methods\ud
were used to study the interaction between the surfactants and the adsorbents. MCM-41 was synthesized\ud
hydrothermally at 100 oC and its modification was conducted by silylation of MCM-41 with trimethylchloro silane\ud
(MCM41-TMCS). Both unmodified and modified MCM-41 can adsorb the surfactant. The amount adsorbed in the\ud
unmodified material is higher than that in the modified one. The interaction of Triton X-114 with MCM-41 was\ud
hydrogen bonding between the silanol groups in MCM-41 and hydroxyl groups of Triton X-114. For modified\ud
samples, Triton X-114 interacted with alkylsilyl groups mostly through hydrophobic interaction. It is more likely that\ud
the interaction was through C12, C13, C26 and C27 of Triton X-114

Taba, P

One source of water pollutions is caused by the high use of surface-active agents (surfactants) by industries and households. As a consequence, it is required to remove such substances from the environment One of the important and widely used methods for removal of substances from solution is adsorption. In this research, MCM-41 and its modification MCM41-TMCS were used to adsorb nonionic surfactant, Triton X-114. FTIR and NMR methods were used to study the interaction between the surfactants and the adsorbents. MCM-41 was synthesized hydrothermally at 100 oC and its modification was conducted by silylation of MCM-41 with trimethylchloro silane (MCM41-TMCS). Both unmodified and modified MCM-41 can adsorb the surfactant. The amount adsorbed in the unmodified material is higher than that in the modified one. The interaction of Triton X-114 with MCM-41 was hydrogen bonding between the silanol groups in MCM-41 and hydroxyl groups of Triton X-114. For modified samples, Triton X-114 interacted with alkylsilyl groups mostly through hydrophobic interaction. It is more likely that the interaction was through C12, C13, C26 and C27 of Triton X-114.  
  
 
  
Keywords: FTIR, NMR, adsorbed Triton X-114, MCM-41 material

Paulina Taba

Directory of Open Access Journals

Indo. J. Chem., 2009, 9 (2), 184 - 188Paulina Taba184* Corresponding author.Email address : ultita@yahoo.com.auFTIR AND NMR STUDIES OF ADSORBED TRITON X-114 IN MCM-41 MATERIALSPaulina TabaDepartment of Chemistry, Hasanuddin UniversityJl. Perintis Kemerdekaan Km 10 Tamalanrea, Makassar, South Sulawesi, Indonesia 90245Received February 26, 2009; Accepted May 12, 2009ABSTRACTOne source of water pollutions is caused by the high use of surface-active agents (surfactants) by industriesand households. As a consequence, it is required to remove such substances from the environment One of theimportant and widely used methods for removal of substances from solution is adsorption. In this research, MCM-41and its modification MCM41-TMCS were used to adsorb nonionic surfactant, Triton X-114. FTIR and NMR methodswere used to study the interaction between the surfactants and the adsorbents. MCM-41 was synthesizedhydrothermally at 100oC and its modification was conducted by silylation of MCM-41 with trimethylchloro silane(MCM41-TMCS). Both unmodified and modified MCM-41 can adsorb the surfactant. The amount adsorbed in theunmodified material is higher than that in the modified one. The interaction of Triton X-114 with MCM-41 washydrogen bonding between the silanol groups in MCM-41 and hydroxyl groups of Triton X-114. For modifiedsamples, Triton X-114 interacted with alkylsilyl groups mostly through hydrophobic interaction. It is more likely thatthe interaction was through C12, C13, C26 and C27 of Triton X-114.Keywords: FTIR, NMR, adsorbed Triton X-114, MCM-41 materialsINTRODUCTIONThe widespread use of surfactants in industries aswell as at home is producing an important environmentalimpact, especially in aquatic media. As a consequence,it is required to remove such substances from theenvironment. Non-ionic surfactants, such as Triton X-114, have found widespread use in several domesticand industrial applications such as cleaning, personalcare, crop protection, paint and coating, textile finishing,emulsion stabilization, food and leather processing, andore refining. One of the largest applications of thesesurfactants is in petroleum industries where they find usein the operations involving foams, emulsions and liquid–solid operations such as stabilization of fine particles andsludge displacement [1]. It is well known that surfactantswith ramified hydrocarbon chains show high resistanceto biodegradation in aqueous media, leading to theformation of long-standing foams. Several days or weeksare required for the complete biodecomposition ofsurfactants, which often leads to the formation ofpersistent and even toxic metabolites. Adsorption is oneof the important and widely used methods for removal ofsubstances including surfactants from solution. It hasbeen reported that activated carbon and graphite [2,3],unmodified and modified silica [4], silica gel [5,6], mica[7], clays [8], polymers [9-12], and modified zeolite [13]have all previously been used as adsorbents for theremoval of surfactants from aqueous environments.Mesoporous materials, such as mesoporous silicawith diameters of 2 to 50 nm, show high promise to beused as adsorbents for such organic materials becauseof their high porosity and their large surface areas. Oneexample of mesoporous silica is MCM-41, discoveredin 1992 by Mobil Corporation [14,15]. In this research,adsorption of nonionic surfactant (Triton X-114) inMCM-41 and its modification will be discussed. Themolecular structure of the surfactant is given as follows:The amount of surfactants adsorbed wasmeasured from the carbon content of the adsorbentfollowing adsorption.13C CP MAS NMR and FTIRspectroscopy was used to study the mechanism ofinteraction between the surfactant and mesoporousmaterials. The method used for adsorption of thesurfactant in mesoporous materials was the stirringmethod, which has been described in detail elsewhere[16], in aqueous solutions for periods of 5 hours.EXPERIMENTAL SECTIONA hydrothermal method was used to synthesizeMCM-41 as described in elsewhere [17] andtrimethylchloro silane (TMCS) were used as reagentsfor silylation of MCM-41 using the procedure of [18]with some modification to produce MCM41-TMCS.Hydrostability of MCM-41 was tested by making use ofa Siemens D500 diffractometer using CuK ( =1.5412 Å) as a radiation source. For in-situIndo. J. Chem., 2009, 9 (2), 184 - 188Paulina Taba185Figure 1. Adsorption of Triton X-114 in MCM-41 as afunction of concentrationTable 1. The uptake of CTAC in MCM-41 and MCM41-TMCS on a pore volume basis together with thesurfactant uptakes in mmol per gram and mmol/cm3.Amount of TritonX-114 adsorbedSamplesPoreVolumes(cm3/g) mmol/g mmol/cm3MCM-41 1.09 1.45 1.33MCM41-TMCS 0.69 0.70 1.01Figure 2. In situ FTIR spectra of (a) calcined MCM-41,(b) MCM-41 after adsorption of 10-4M Triton X-114, and(c) MCM-41) after adsorption of 10-1M Triton X-114.experiments, a Bomem MB-100 Fourier TransformInfrared (FTIR) spectrometer equipped with a mercurycadmium telluride (MCT) detector was used to obtaininfrared spectra of samples. The29Si spectra weremeasured on a Bruker MSL-300 NMR spectrometer,using a Bruker 4 mm 4WB-BL probe, a Larmorfrequency of 59.61 MHz was used. The sample wasspun at a spin rate of 3 kHz and an acquisition time of21.5 ms.RESULT AND DISCUSSIONAdsorption of Surfactants in MCM-41 MaterialsBefore adsorption experiments were undertaken,the hydrostability of MCM-41 was tested by stirring thematerials in water at room temperature for certainperiods of time and then the XRD patterns of thematerials were recorded. As has been reported inearlier work [19], the structural order of MCM-41remained unchanged after a stirring period of 5 h,therefore the adsorption can be performed under thiscondition. The adsorption of Triton X-114 was carriedout at concentrations both below and above criticalmicelle concentration (cmc) for Triton X-114. Figure 1displays the adsorption as a function of concentrationof Triton X-114.It can be seen that the amount of Triton X-114adsorbed below the cmc is 0.58 mmol/g, and theamount of the surfactant adsorbed above the cmc is0.79 mmol/g. This suggests that for Triton X-114, theeffect of micellization on surfactant adsorption is muchless pronounced, indicating that single molecules of theneutral surfactant are readily adsorbed. This is differentcompared to adsorbed cationic surfactantcethyltrimethyl-ammonium chloride (CTAC), whereMCM-41 (C16) has a higher affinity for the micellarform of CTAC than for single molecules of thesurfactant as has been observed in the previous work[19].Surfactant adsorption experiments were alsocarried out by Inagaki et al. (1998) using FSM-16,which is a mesoporous silica similar in structure toMCM-41, as an adsorbent. In contrast with the resultsobserved in this study, Inagaki et al. reported that FSM-16 showed a high uptake of micellar surfactants, bothcationic and neutral, but very low uptake of bothsurfactants below their respective cmcs. The neutralsurfactant used by Inagaki et al.,polyoxyethyleneoctylphenylether, differs significantlyfrom Triton X-114 however, in that it contains noterminal hydroxyl group. This question of how Triton X-114 single molecules interact with the MCM-41adsorbents is considered further below. For thepurposes of comparing the amount of the surfactantadsorbed by unmodified and modified MCM-41, astandard surfactant concentration of 10-1M wasemployed in experiments. The amount of surfactantsadsorbed in unmodified and modified MCM-41 at thisconcentration is presented in Table 1. Modification ofMCM-41 with TMCS decreased slightly the uptake ofthe surfactant. This is due to the decrease of porevolume of the surfactant after being modified withTMCS.FTIR and NMR Studies of Adsorbed Triton X-114 inMCM-41 MaterialsFTIR spectra of adsorbed Triton X-114 in MCM-41 can be seen in Figure 2. After adsorption of 10-4and10-1M of Triton X-114 the peak at 3741 cm-1disappears, showing the interaction of the silanolgroups with Triton X-114. The peak centered at 3520Indo. J. Chem., 2009, 9 (2), 184 - 188Paulina Taba186Table 2. Chemical shifts of Triton X-114 peaks in solution and in calcined MCM-41 after adsorption of 10-4M and 10-1M of the surfactant.Uncertainty in chemical shift =  0.30 ppmFigure 3.13C NMR spectra of (a) Triton X-114 solution(in D2O), (b) calcined MCM-41 after adsorbed 10-4MTriton X-114 and (c) calcined MCM-41 after adsorbed10-1M Triton X-114. The solid samples (b and c) weremeasured with1H cross polarization.cm-1is also perturbed and shifts to lower wave number,centered at 3350 cm-1. This strongly suggests that theinteraction is due to the hydrogen bonding between thehydroxyl groups in Triton X-114 and the silanol groups ofMCM-41. Similar results were observed by Maeda, et al.[5], who examined immobilization of enzyme inmolecular assembly of nonionic surfactant adsorbed onsilica gel. It was found that the interaction between thehydrophilic group of Triton X-100 [C8H17-C6H4-(OCH2)9-10-OH and silica gel surface was mainly due to hydrogenFigure 4.13C CP NMR of (I) 10-4M and (II) 10-1MTriton X-114 adsorbed in MCM-41 as different contacttimes: (a) 2 ms and (b) 5 ms.bonding.13C CP NMR spectra of adsorbed Triton X-114in MCM-41 are presented in Figure 3. There are 11peaks observed in the solution NMR spectrum. Fromliterature [20], 17 peaks were obtained. Here, peaksC8, C10 and C11, which have similar chemical shift,appear as one peak whereas in the literature they wereresolved. The chemical shifts of peaks found in13CNMR of Triton X-114 in solution and in MCM-41materials are tabulated in Table 2. There is a generalbroadening of all peaks relative to the solutionspectrum, particularly in the region 60-80 ppm. Thebroadening and loss of resolution of peaks due tocarbons 26 and 27 is consistent with the suggestedinteraction of the hydroxyl end of the molecule with theMCM-41 pore walls.The spectra shown in Figure 3 were measuredwith a contact time of 2 ms. Figure 4 displays spectraof MCM-41 after adsorbed 10-4and 10-1M Triton X-114measured with contact times of 2 and 5 ms. The mainIndo. J. Chem., 2009, 9 (2), 184 - 188Paulina Taba187Figure 5. In situ FTIR of adsorbed Triton X-114 inMCM41-TMCS before (a) and after (b) adsorption.difference observed when different contact times wereused, is that the intensity of the peak at 70.9 ppm (C14-C25) using the 5 ms contact time is lower than that usingthe 2 ms contact time. The intensities ratio of C14-C25to C8, C10, C11 using the large contact time is about 3times higher than that using the small contact time forboth concentrations. This suggests that there is adifference in the effectiveness of cross polarization withthe different contact times. The cross polarization ofC14-C25 at a contact time of 5 ms is less effective thanthat measured at a contact time of 2 ms, implyingmobility of C14-C25 is higher than that of C8, C10 andC11. Another difference observed is that for theconcentration of 10-4M, several peaks at higherchemical shift (peaks of carbon in the benzene ring) cannot be seen when the measurement was performedusing a contact time of 5 ms. This indicates that protoncross-polarization to the aromatic carbons does notoccur efficiently in the adsorbed species due to themotion of the aromatic head group of Triton X-114 withinthe pore of MCM-41.FTIR spectra of Triton X-114 in modified MCM-41can be seen in Figure 5. There is an increase in intensityof the C-H bending mode in modified MCM-41 afterTriton X-114 adsorption, indicating an interactionbetween modified MCM-41 and Triton X-114. There isalso shift in the broad peak centered at 3520 cm-1to thebroad peak centered at 3380 cm-1observed. This maybe caused by hydrogen bonding between Triton X-114molecules containing OH groups or between OH groupsof Triton X-114 and water molecules.13C CP NMR spectra of Triton X-114 in modifiedMCM-41 are presented in Figure 6. The peak of methylgroups in MCM41-TMCS (at -1.5 ppm) is perturbed andshifted to higher chemical shift (at 1.3 ppm). It is alsonoted that the peaks of Triton X-114 in MCM41-TMCS,particularly C27 (72.4 ppm), C12 (67.7 ppm) and C26(60.9 ppm), are influenced by these interactions. Thepeak of C27 is not well resolved for the modified sampleand peaks at 67.7 and 60.9 ppm shift to 61.6 and 57.3ppm for MCM41-TMCS. These results confirm that thereFigure 6.13C CP NMR of (a) MCM41-TMCS and (b)MCM41-TMCS after adsorption of 10-1M Triton X-114.is a hydrophobic interaction between the methylsilylgroup and Triton X-114, more likely with C12, C26, C27and maybe also with C13. The lack of resolution of theC27 peak may be caused by hydrogen bondingbetween OH groups, attached to C27 in the moleculesof Triton X-114.CONCLUSIONFrom the results observed above, it can besummarized that both unmodified and modified MCM-41 can adsorb the nonionic surfactant (Triton X-114).The interaction of Triton X-114 with MCM-41 washydrogen bonding between the silanol groups in MCM-41 and hydroxyl groups of Triton X-114. For modifiedsamples, Triton X-114 interacted with alkylsilyl groupsmostly through hydrophobic interaction. It is more likelythat the interaction was through C12, C13, C26 andC27 of Triton X-114.ACKNOWLEDGEMENTThe author would like to express sincere thanksto Professor Russell F. Howe and Dr. Grainne M.Moran for their excellent supervision, encouragement,and valuable discussion throughout this research. Thisinvestigation was funded by AUSAID to carry out theresearch work in the University of New South Wales,Australia.REFERENCES1. Schramm, L.L. and Marangoni. D.G., “Surfactantsand their solutions: basic principles” inSurfactants: Fundamentals and Applications in thePetroleum Industry. Eds. Schramm, L.L.,Cambridge University Press, Cambridge, 2000, 3-50.2. Wanless, E.J. and Ducker. W.A., 1997, Langmuir,13, 1463-1474.Indo. J. Chem., 2009, 9 (2), 184 - 188Paulina Taba1883. Wanless, E.J., Davey, T.W., and Ducker, W.A.,1997, Langmuir, 13, 4223-4228.4. Chorro, M., Vhorro, C., Dolladille, O., Partyka, S.,and Zana, R., 1999, J. Colloid Interface Sci., 210,134-143.5. Maeda, R., Tomida, H., Matsumoto, M., and Kondo,K., 1997, J. Chem. Eng. Jpn., 30, 910-915.6. Zaporozhets, O.A., Nadzhafova, O.Y., Verba, V.V.,Dolenko, S.A., Keda, T.Y., and Sukhan, V.V., 1998,Analyst, 123, 1583-1586.7. Ducker, W.A. and Wanless, E.J., 1999, Langmuir,,15, 160-168.8. Blokhus, A.M., Høiland, H., and Gierde, M.I, 1996,J. Colloid Interface Sci., 179, 625-627.9. Yamagiwa, K., Sasaki, T., Takesono, S., andOhkawa, A., 1995, J. Chem. Eng. Jpn., 28, 697-702.10. Zhao, J. and Brown, W., 1996, J. Phys. Chem., 100,3775-3782.11. Fox, G.J., Bloor, D.M., Holzwarth, J.F., and Wyn-Jones, E., 1998, Langmuir, 14, 1026-1030.12. Maroto, J.A., and Nieves, F.J.D.I., 1998, ColloidsSurf., A., 145, 271-279.13. Kawai, T. and Tsutsumi, K., 1994, Colloid Polym.Sci., 272, 830-835.14. Beck, J.S., Vartuli, J.C., Roth, W.J., Leonowics,M.E., Kresge, C.T., Schmitt, K.D., Chu, C.T.W.,Olson, D.H., Sheppard, E.W., McCullen, S.B.,Higgins, J.B., and Schlenker. J.L., 1992. J. Am.Chem. Soc., 114, 10834-10843.15. Kresge, C.T., Leonowicz, M.E., Roth, W.J., Vartuli,J.C., and Beck, J.S., 1992, Nature 359, 710-712.16. Inagaki, S., Ogata, S., Goto, Y., and Fukushima,Y., “Mesoporous Materials Derived from LayeredSilicates and the Adsorption Properties” InMesoporous Molecular Sieve, Stud. Surf. Scie.Catal. Vol. 117, Elsevier, Baltimore. Eds.Bonneviot, L., Béland, F., Danumah, C., Giasson,S., and Kaliaguine, S., 1998, 65-7617. Kim, J.M., Kwak, J.H., Jun, S., and Ryoo, R.,1995, J. Phys. Chem., 99, 16742-16747.18. Fraile, J.M., Garcia, J.I., Gracia, D., Mayoral, J.A.,Tarnai, T., and Figueras, F., 1997, J. Mol. Catal.A: Chem., 121, 97-102.19. Taba, P., Russell, R.F., and Moran, G., 2008,Indo. J. Chem., 8, 1-6.20. Bremser, W., Ernst, L., Franke, B., Gerhards, R.,and Hardt, A., 1981, Carbon-13 NMR SpectralData [microform]: a "living" COM-microfichecollection of reference material, 3rd Ed, VerlagChemie.

Indonesian Journal of Chemistry

FTIR AND NMR STUDIES OF ADSORBED TRITON X-114 IN MCM-41 MATERIALS

ABSTRACT
One source of water pollutions is caused by the high use of surface-active agents (surfactants) by industries
and households. As a consequence, it is required to remove such substances from the environment One of the
important and widely used methods for removal of substances from solution is adsorption. In this research, MCM-41
and its modification MCM41-TMCSwere used to adsorb nonionic surfactant, TritonX-114. FTIR and NMR methods
were used to study the interaction between the surfactants and the adsorbents. MCM-41 was synthesized
hydrothermally at 100°C and its modification was conducted by silylation of MCM-41 with trimethylchloro silane
(MCM41-TMCS). Both unmodified and modified MCM-41 can adsorb the surfactant. The amount adsorbed in the
unmodified material is higher than that in the modified one. The interaction of Triton X-114 with MCM-41 was
hydrogen bonding between the silanol groups in MCM-41 and hydroxyl groups of Triton X-114. For modified
samples, Triton X-114 interacted with alkylsilyl groups mostly through hydrophobic interaction. It is more likely that
the interaction was through C12, C13, C26 and C27 of TritonX-114

UGM Journals, OAI Repository

English

FTIR AND NMRSTUDIESOF ADSORBEDTRITON X-114IN MCM-41 MATERIALS

Hasanuddin University Repository

Indo. J. Chem., 2009, 9 (2), 184 - 188
Paulina Taba
184
* Corresponding author.
Email address : ultita@yahoo.com.au
FTIR AND NMR STUDIES OF ADSORBED TRITON X-114 IN MCM-41 MATERIALS
Paulina Taba
Department of Chemistry, Hasanuddin University
Jl. Perintis Kemerdekaan Km 10 Tamalanrea, Makassar, South Sulawesi, Indonesia 90245
Received February 26, 2009; Accepted May 12, 2009
ABSTRACT
One source of water pollutions is caused by the high use of surface-active agents (surfactants) by industries
and households. As a consequence, it is required to remove such substances from the environment One of the
important and widely used methods for removal of substances from solution is adsorption. In this research, MCM-41
and its modification MCM41-TMCS were used to adsorb nonionic surfactant, Triton X-114. FTIR and NMR methods
were used to study the interaction between the surfactants and the adsorbents. MCM-41 was synthesized
hydrothermally at 100 oC and its modification was conducted by silylation of MCM-41 with trimethylchloro silane
(MCM41-TMCS). Both unmodified and modified MCM-41 can adsorb the surfactant. The amount adsorbed in the
unmodified material is higher than that in the modified one. The interaction of Triton X-114 with MCM-41 was
hydrogen bonding between the silanol groups in MCM-41 and hydroxyl groups of Triton X-114. For modified
samples, Triton X-114 interacted with alkylsilyl groups mostly through hydrophobic interaction. It is more likely that
the interaction was through C12, C13, C26 and C27 of Triton X-114.
Keywords: FTIR, NMR, adsorbed Triton X-114, MCM-41 materials
INTRODUCTION
The widespread use of surfactants in industries as
well as at home is producing an important environmental
impact, especially in aquatic media. As a consequence,
it is required to remove such substances from the
environment. Non-ionic surfactants, such as Triton X-
114, have found widespread use in several domestic
and industrial applications such as cleaning, personal
care, crop protection, paint and coating, textile finishing,
emulsion stabilization, food and leather processing, and
ore refining. One of the largest applications of these
surfactants is in petroleum industries where they find use
in the operations involving foams, emulsions and liquid–
solid operations such as stabilization of fine particles and
sludge displacement [1]. It is well known that surfactants
with ramified hydrocarbon chains show high resistance
to biodegradation in aqueous media, leading to the
formation of long-standing foams. Several days or weeks
are required for the complete biodecomposition of
surfactants, which often leads to the formation of
persistent and even toxic metabolites. Adsorption is one
of the important and widely used methods for removal of
substances including surfactants from solution. It has
been reported that activated carbon and graphite [2,3],
unmodified and modified silica [4], silica gel [5,6], mica
[7], clays [8], polymers [9-12], and modified zeolite [13]
have all previously been used as adsorbents for the
removal of surfactants from aqueous environments.
Mesoporous materials, such as mesoporous silica
with diameters of 2 to 50 nm, show high promise to be
used as adsorbents for such organic materials because
of their high porosity and their large surface areas. One
example of mesoporous silica is MCM-41, discovered
in 1992 by Mobil Corporation [14,15]. In this research,
adsorption of nonionic surfactant (Triton X-114) in
MCM-41 and its modification will be discussed. The
molecular structure of the surfactant is given as follows:
The amount of surfactants adsorbed was
measured from the carbon content of the adsorbent
following adsorption. 13C CP MAS NMR and FTIR
spectroscopy was used to study the mechanism of
interaction between the surfactant and mesoporous
materials. The method used for adsorption of the
surfactant in mesoporous materials was the stirring
method, which has been described in detail elsewhere
[16], in aqueous solutions for periods of 5 hours.
EXPERIMENTAL SECTION
A hydrothermal method was used to synthesize
MCM-41 as described in elsewhere [17] and
trimethylchloro silane (TMCS) were used as reagents
for silylation of MCM-41 using the procedure of [18]
with some modification to produce MCM41-TMCS.
Hydrostability of MCM-41 was tested by making use of
a Siemens D500 diffractometer using CuK ( =
1.5412 Å) as a radiation source. For in-situ
Indo. J. Chem., 2009, 9 (2), 184 - 188
Paulina Taba
185
Figure 1. Adsorption of Triton X-114 in MCM-41 as a
function of concentration
Table 1. The uptake of CTAC in MCM-41 and MCM41-
TMCS on a pore volume basis together with the
surfactant uptakes in mmol per gram and mmol/cm3.
Amount of Triton
X-114 adsorbedSamples
Pore
Volumes
(cm3/g) mmol/g mmol/cm3
MCM-41 1.09 1.45 1.33
MCM41-TMCS 0.69 0.70 1.01
Figure 2. In situ FTIR spectra of (a) calcined MCM-41,
(b) MCM-41 after adsorption of 10-4 M Triton X-114, and
(c) MCM-41) after adsorption of 10-1 M Triton X-114.
experiments, a Bomem MB-100 Fourier Transform
Infrared (FTIR) spectrometer equipped with a mercury
cadmium telluride (MCT) detector was used to obtain
infrared spectra of samples. The 29Si spectra were
measured on a Bruker MSL-300 NMR spectrometer,
using a Bruker 4 mm 4WB-BL probe, a Larmor
frequency of 59.61 MHz was used. The sample was
spun at a spin rate of 3 kHz and an acquisition time of
21.5 ms.
RESULT AND DISCUSSION
Adsorption of Surfactants in MCM-41 Materials
Before adsorption experiments were undertaken,
the hydrostability of MCM-41 was tested by stirring the
materials in water at room temperature for certain
periods of time and then the XRD patterns of the
materials were recorded. As has been reported in
earlier work [19], the structural order of MCM-41
remained unchanged after a stirring period of 5 h,
therefore the adsorption can be performed under this
condition. The adsorption of Triton X-114 was carried
out at concentrations both below and above critical
micelle concentration (cmc) for Triton X-114. Figure 1
displays the adsorption as a function of concentration
of Triton X-114.
It can be seen that the amount of Triton X-114
adsorbed below the cmc is 0.58 mmol/g, and the
amount of the surfactant adsorbed above the cmc is
0.79 mmol/g. This suggests that for Triton X-114, the
effect of micellization on surfactant adsorption is much
less pronounced, indicating that single molecules of the
neutral surfactant are readily adsorbed. This is different
compared to adsorbed cationic surfactant
cethyltrimethyl-ammonium chloride (CTAC), where
MCM-41 (C16) has a higher affinity for the micellar
form of CTAC than for single molecules of the
surfactant as has been observed in the previous work
[19].
Surfactant adsorption experiments were also
carried out by Inagaki et al. (1998) using FSM-16,
which is a mesoporous silica similar in structure to
MCM-41, as an adsorbent. In contrast with the results
observed in this study, Inagaki et al. reported that FSM-
16 showed a high uptake of micellar surfactants, both
cationic and neutral, but very low uptake of both
surfactants below their respective cmcs. The neutral
surfactant used by Inagaki et al.,
polyoxyethyleneoctylphenylether, differs significantly
from Triton X-114 however, in that it contains no
terminal hydroxyl group. This question of how Triton X-
114 single molecules interact with the MCM-41
adsorbents is considered further below. For the
purposes of comparing the amount of the surfactant
adsorbed by unmodified and modified MCM-41, a
standard surfactant concentration of 10-1 M was
employed in experiments. The amount of surfactants
adsorbed in unmodified and modified MCM-41 at this
concentration is presented in Table 1. Modification of
MCM-41 with TMCS decreased slightly the uptake of
the surfactant. This is due to the decrease of pore
volume of the surfactant after being modified with
TMCS.
FTIR and NMR Studies of Adsorbed Triton X-114 in
MCM-41 Materials
FTIR spectra of adsorbed Triton X-114 in MCM-
41 can be seen in Figure 2. After adsorption of 10-4 and
10-1 M of Triton X-114 the peak at 3741 cm-1
disappears, showing the interaction of the silanol
groups with Triton X-114. The peak centered at 3520
Indo. J. Chem., 2009, 9 (2), 184 - 188
Paulina Taba
186
Table 2. Chemical shifts of Triton X-114 peaks in solution and in calcined MCM-41 after adsorption of 10-4 M and 10-
1 M of the surfactant.
Uncertainty in chemical shift =  0.30 ppm
Figure 3. 13C NMR spectra of (a) Triton X-114 solution
(in D2O), (b) calcined MCM-41 after adsorbed 10-4 M
Triton X-114 and (c) calcined MCM-41 after adsorbed
10-1 M Triton X-114. The solid samples (b and c) were
measured with 1H cross polarization.
cm-1 is also perturbed and shifts to lower wave number,
centered at 3350 cm-1. This strongly suggests that the
interaction is due to the hydrogen bonding between the
hydroxyl groups in Triton X-114 and the silanol groups of
MCM-41. Similar results were observed by Maeda, et al.
[5], who examined immobilization of enzyme in
molecular assembly of nonionic surfactant adsorbed on
silica gel. It was found that the interaction between the
hydrophilic group of Triton X-100 [C8H17-C6H4-(OCH2)9-10-
OH and silica gel surface was mainly due to hydrogen
Figure 4. 13C CP NMR of (I) 10-4 M and (II) 10-1 M
Triton X-114 adsorbed in MCM-41 as different contact
times: (a) 2 ms and (b) 5 ms.
bonding.13C CP NMR spectra of adsorbed Triton X-114
in MCM-41 are presented in Figure 3. There are 11
peaks observed in the solution NMR spectrum. From
literature [20], 17 peaks were obtained. Here, peaks
C8, C10 and C11, which have similar chemical shift,
appear as one peak whereas in the literature they were
resolved. The chemical shifts of peaks found in 13C
NMR of Triton X-114 in solution and in MCM-41
materials are tabulated in Table 2. There is a general
broadening of all peaks relative to the solution
spectrum, particularly in the region 60-80 ppm. The
broadening and loss of resolution of peaks due to
carbons 26 and 27 is consistent with the suggested
interaction of the hydroxyl end of the molecule with the
MCM-41 pore walls.
The spectra shown in Figure 3 were measured
with a contact time of 2 ms. Figure 4 displays spectra
of MCM-41 after adsorbed 10-4 and 10-1 M Triton X-114
measured with contact times of 2 and 5 ms. The main
Indo. J. Chem., 2009, 9 (2), 184 - 188
Paulina Taba
187
Figure 5. In situ FTIR of adsorbed Triton X-114 in
MCM41-TMCS before (a) and after (b) adsorption.
difference observed when different contact times were
used, is that the intensity of the peak at 70.9 ppm (C14-
C25) using the 5 ms contact time is lower than that using
the 2 ms contact time. The intensities ratio of C14-C25
to C8, C10, C11 using the large contact time is about 3
times higher than that using the small contact time for
both concentrations. This suggests that there is a
difference in the effectiveness of cross polarization with
the different contact times. The cross polarization of
C14-C25 at a contact time of 5 ms is less effective than
that measured at a contact time of 2 ms, implying
mobility of C14-C25 is higher than that of C8, C10 and
C11. Another difference observed is that for the
concentration of 10-4 M, several peaks at higher
chemical shift (peaks of carbon in the benzene ring) can
not be seen when the measurement was performed
using a contact time of 5 ms. This indicates that proton
cross-polarization to the aromatic carbons does not
occur efficiently in the adsorbed species due to the
motion of the aromatic head group of Triton X-114 within
the pore of MCM-41.
FTIR spectra of Triton X-114 in modified MCM-41
can be seen in Figure 5. There is an increase in intensity
of the C-H bending mode in modified MCM-41 after
Triton X-114 adsorption, indicating an interaction
between modified MCM-41 and Triton X-114. There is
also shift in the broad peak centered at 3520 cm-1 to the
broad peak centered at 3380 cm-1 observed. This may
be caused by hydrogen bonding between Triton X-114
molecules containing OH groups or between OH groups
of Triton X-114 and water molecules.
13C CP NMR spectra of Triton X-114 in modified
MCM-41 are presented in Figure 6. The peak of methyl
groups in MCM41-TMCS (at -1.5 ppm) is perturbed and
shifted to higher chemical shift (at 1.3 ppm). It is also
noted that the peaks of Triton X-114 in MCM41-TMCS,
particularly C27 (72.4 ppm), C12 (67.7 ppm) and C26
(60.9 ppm), are influenced by these interactions. The
peak of C27 is not well resolved for the modified sample
and peaks at 67.7 and 60.9 ppm shift to 61.6 and 57.3
ppm for MCM41-TMCS. These results confirm that there
Figure 6. 13C CP NMR of (a) MCM41-TMCS and (b)
MCM41-TMCS after adsorption of 10-1 M Triton X-114.
is a hydrophobic interaction between the methylsilyl
group and Triton X-114, more likely with C12, C26, C27
and maybe also with C13. The lack of resolution of the
C27 peak may be caused by hydrogen bonding
between OH groups, attached to C27 in the molecules
of Triton X-114.
CONCLUSION
From the results observed above, it can be
summarized that both unmodified and modified MCM-
41 can adsorb the nonionic surfactant (Triton X-114).
The interaction of Triton X-114 with MCM-41 was
hydrogen bonding between the silanol groups in MCM-
41 and hydroxyl groups of Triton X-114. For modified
samples, Triton X-114 interacted with alkylsilyl groups
mostly through hydrophobic interaction. It is more likely
that the interaction was through C12, C13, C26 and
C27 of Triton X-114.
ACKNOWLEDGEMENT
The author would like to express sincere thanks
to Professor Russell F. Howe and Dr. Grainne M.
Moran for their excellent supervision, encouragement,
and valuable discussion throughout this research. This
investigation was funded by AUSAID to carry out the
research work in the University of New South Wales,
Australia.
REFERENCES
1. Schramm, L.L. and Marangoni. D.G., “Surfactants
and their solutions: basic principles” in
Surfactants: Fundamentals and Applications in the
Petroleum Industry. Eds. Schramm, L.L.,
Cambridge University Press, Cambridge, 2000, 3-
50.
2. Wanless, E.J. and Ducker. W.A., 1997, Langmuir,
13, 1463-1474.
Indo. J. Chem., 2009, 9 (2), 184 - 188
Paulina Taba
188
3. Wanless, E.J., Davey, T.W., and Ducker, W.A.,
1997, Langmuir, 13, 4223-4228.
4. Chorro, M., Vhorro, C., Dolladille, O., Partyka, S.,
and Zana, R., 1999, J. Colloid Interface Sci., 210,
134-143.
5. Maeda, R., Tomida, H., Matsumoto, M., and Kondo,
K., 1997, J. Chem. Eng. Jpn., 30, 910-915.
6. Zaporozhets, O.A., Nadzhafova, O.Y., Verba, V.V.,
Dolenko, S.A., Keda, T.Y., and Sukhan, V.V., 1998,
Analyst, 123, 1583-1586.
7. Ducker, W.A. and Wanless, E.J., 1999, Langmuir,,
15, 160-168.
8. Blokhus, A.M., Høiland, H., and Gierde, M.I, 1996,
J. Colloid Interface Sci., 179, 625-627.
9. Yamagiwa, K., Sasaki, T., Takesono, S., and
Ohkawa, A., 1995, J. Chem. Eng. Jpn., 28, 697-
702.
10. Zhao, J. and Brown, W., 1996, J. Phys. Chem., 100,
3775-3782.
11. Fox, G.J., Bloor, D.M., Holzwarth, J.F., and Wyn-
Jones, E., 1998, Langmuir, 14, 1026-1030.
12. Maroto, J.A., and Nieves, F.J.D.I., 1998, Colloids
Surf., A., 145, 271-279.
13. Kawai, T. and Tsutsumi, K., 1994, Colloid Polym.
Sci., 272, 830-835.
14. Beck, J.S., Vartuli, J.C., Roth, W.J., Leonowics,
M.E., Kresge, C.T., Schmitt, K.D., Chu, C.T.W.,
Olson, D.H., Sheppard, E.W., McCullen, S.B.,
Higgins, J.B., and Schlenker. J.L., 1992. J. Am.
Chem. Soc., 114, 10834-10843.
15. Kresge, C.T., Leonowicz, M.E., Roth, W.J., Vartuli,
J.C., and Beck, J.S., 1992, Nature 359, 710-712.
16. Inagaki, S., Ogata, S., Goto, Y., and Fukushima,
Y., “Mesoporous Materials Derived from Layered
Silicates and the Adsorption Properties” In
Mesoporous Molecular Sieve, Stud. Surf. Scie.
Catal. Vol. 117, Elsevier, Baltimore. Eds.
Bonneviot, L., Béland, F., Danumah, C., Giasson,
S., and Kaliaguine, S., 1998, 65-76
17. Kim, J.M., Kwak, J.H., Jun, S., and Ryoo, R.,
1995, J. Phys. Chem., 99, 16742-16747.
18. Fraile, J.M., Garcia, J.I., Gracia, D., Mayoral, J.A.,
Tarnai, T., and Figueras, F., 1997, J. Mol. Catal.
A: Chem., 121, 97-102.
19. Taba, P., Russell, R.F., and Moran, G., 2008,
Indo. J. Chem., 8, 1-6.
20. Bremser, W., Ernst, L., Franke, B., Gerhards, R.,
and Hardt, A., 1981, Carbon-13 NMR Spectral
Data [microform]: a "living" COM-microfiche
collection of reference material, 3rd Ed, Verlag
Chemie.


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FTIR AND NMR STUDIES OF ADSORBED TRITON X-114 IN MCM-41 MATERIALS

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