Jóna, Eugen

Pajtášová, Marianna

Rudinská, Eva

Sapietová, Martina

Digitale Bibliothek Thüringen

  50. Internationales  Wissenschaftliches Kolloquium   September, 19-23, 2005   Maschinenbau  von Makro bis Nano / Mechanical Engineering  from Macro to Nano   Proceedings    Fakultät für Maschinenbau / Faculty of Mechanical Engineering     Startseite / Index:  http://www.db-thueringen.de/servlets/DocumentServlet?id=15745 Impressum  Herausgeber: Der Rektor der Technischen Universität llmenau  Univ.-Prof. Dr. rer. nat. habil. Peter Scharff  Redaktion: Referat Marketing und Studentische Angelegenheiten  Andrea Schneider   Fakultät für Maschinenbau  Univ.-Prof. Dr.-Ing. habil. Peter Kurtz, Univ.-Prof. Dipl.-Ing. Dr. med. (habil.) Hartmut Witte, Univ.-Prof. Dr.-Ing. habil. Gerhard Linß,  Dr.-Ing. Beate Schlütter, Dipl.-Biol. Danja Voges,  Dipl.-Ing. Jörg Mämpel, Dipl.-Ing. Susanne Töpfer,  Dipl.-Ing. Silke Stauche  Redaktionsschluss: 31. August 2005 (CD-Rom-Ausgabe)  Technische Realisierung:  Institut für Medientechnik an der TU Ilmenau (CD-Rom-Ausgabe) Dipl.-Ing. Christian Weigel Dipl.-Ing. Helge Drumm Dipl.-Ing. Marco Albrecht  Technische Realisierung: Universitätsbibliothek Ilmenau (Online-Ausgabe)   Postfach 10 05 65  98684 Ilmenau  Verlag:   Verlag ISLE, Betriebsstätte des ISLE e.V.  Werner-von-Siemens-Str. 16  98693 llmenau   © Technische Universität llmenau (Thür.) 2005   Diese Publikationen und alle in ihr enthaltenen Beiträge und Abbildungen sind urheberrechtlich geschützt.   ISBN (Druckausgabe): 3-932633-98-9  (978-3-932633-98-0) ISBN (CD-Rom-Ausgabe): 3-932633-99-7 (978-3-932633-99-7)  Startseite / Index: http://www.db-thueringen.de/servlets/DocumentServlet?id=15745 50. Internationales Wissenschaftliches Kolloquium Technische Universität Ilmenau 19.-23. September 2005   E. Jóna a /  E. Rudinská a/  M. Sapietová a/ M. Pajtášováa   NANOMATERIALS ON THE BASIS OF LAYERED SILICATES  ABSTRACT   Thermal analysis (TG, DTG) and infrared spectroscopy were used to study the interactions of 4−methylpyridine (4−Mepy), 4−ethylpyridine (4−Etpy) and 4−hydroxylpyridine (4−OHpy) with M2+− exchanged montmorillonite (M = Co, Ni, Cu). It is shown that the bonds between the derivatives of pyridine and transition metal ions in montmorillonites (MMT) exhibit predominantly the Lewis acid character while in 4−OHpy/M2+−MMT Brönstedt−bound 4−OHpy molecules can be considered. The present results reveal that M2+-exchanged montmorillonites are suitable for the incorporation of pyridine derivatives in their layered structure and the formation of new  clay −coordination compounds.  INTRODUCTION  During the last decades much interest was devoted to the study  of the layered  silicates.  This study is connected with practical applications of these materials, because layer clay minerals act as efficient catalysts for variety of organic reactions and play also an important role as adsorbents of hazardous organic pollutans in the soil. The immobilization and detoxification of hazardous substances with clay minerals (especially montmorillonites) represent wide area for research. In this context it is important to study the nature of interactions occuring between organic compounds and montmorillonites [1, 2]. Montmorillonite (MMT) belongs to the group of expanding layered lattice silicate minerals known as smectites, having the layers formed as two tetrahedral sheets linked with an octahedral one. Negative charge of the layers is balanced by hydrated exchangeable cations [3]. Polar organic molecules (e.g. pyridine derivatives) can replace the water molecules which as a rule occupy the interlayer spaces in the montmorillonite. In introducing transition metal ions and adding suitable ligands even clay-compounds may be formed in the interlayers of MMT. Since the montmorillonite surface and its interlayer space are populated by Brösted and/or Lewis acid sites, the principal interactions between the clay and the organic compounds are those of the acid−base type [4−6].  Many authors investigated heterocyclic compounds with pyridine ring due to their strucural and biological properties and examined them as ligands in solid coordination compounds [7−9]. In this paper thermal analysis (TG, DTG and DTA) and infrared absorption spectra have been used to study the type of interactions between transition metal ions (Co2+, Ni2+, Cu2+) and pyridine derivatives (4-R pyridine, R = CH3, C2H5, OH) in montmorillonite. The presented results reveal that M 2+- exchanged montmorillonite ( M = Co,Ni,Cu) has provided siutable reaction media for the incorporation of neutral organic bases (4-Rpy) in its layer structure [10-14].   EXPERIMENTAL   Synthesis of the samples  Less than 2 µm−fraction of Jelšový Potok was separated from a bulk sample and converted into the monoionic Ca−form using standard methods [10]. The structural formula as calculated from the chemical analysis of the fine fraction is: Ca0,48 (Si7,59Al0,41)(Al3,06Fe0,34Mg0,63)(OH)4O20.The M2+−exchanged montmorillonites (M = Co, Ni and Cu) were prepared from the Ca−form (3 g) by the addition of a MCl2 solution (450 cm3, c = 1 mol.dm-3) and the mixture was stirred for a shortly and left to stand for 24 h. After decantation MCl2 solution was added again to the solid phase, stirred and left to stand as previously. This procedure was repeated four times. The solid product was then washed by water in order to remove the Cl- anions and finally dried at 60 °C.  A thin layer (≈ 250 mg) of monoionic forms was exposed to 4−Rpyridine (R = methyl, ethyl) vapours for 72 h at room temperature.  In case of solid 4-OHpy, the monoionic forms M2+−MMT were added to 5 %  of  the compound. The mixture was stirred 1 h and left to stand 3 h. This procedure was repeated three times. On the next day the solid products 4−OHpy/M2+−MMT were washed with ethanol (ten times) and dried at 60 °C.  Analytical methods and equipment The analytical methods used have been described elsewhere [10]. The thermal properties were studied with a TA Instrument SDT 2960. The measurements were carried out in air using a platinum crucible. A sample mass of 20−25 mg and heating rate 10 °C.min−1 were used in particular thermal decomposition. The X−ray diffraction profiles for pressed powder samples were recorded on a Philips PW 1050 diffractometer 2° (2Θ) min−1 using CuKα radiation. The infrared absorption spectra were recorded with Nicolet Magna 750 Fourier Transform IR spectrometer in the range of 4000−400 cm−1.  RESULTS AND DISCUSSION  As reported previously [11−14] thermal analysis combined with measuring of infrared spectra can provide a precious information about the character of interactions between the adsorbed pyridine derivativesand monoionic montmorillonite containing a metal ion in its interlayer spaces.  Thermal data from TG and DTG curves of studies samples Ι−XII are summarised in Table 1.  The thermal decomposition of M2+−MMT (samples I, V, IX) proceeds under dynamic conditions in the temperature interval 20−700°C in two distinct steps. The first step can be assigned to the release of adsorbed water molecules while the second one is connected with a lattice dehydroxylation .  Three or four steps of decomposition of 4−Rpy/ M2+−MMT are observed in the temperature interval under study for samples II−IV, VI−VIII and X−XII. The first step can be assigned to the desorption of 4−Rpy while the last one corresponds to the lattice dehydroxylation. The second peaks for samples II, III, VI, VII and X, XI and the second and third ones found for samples IV, VIII and XII can be assigned to release of chemically bonded 4−Rpy [5, 6, 10, 15].      TG: ∆m / % Steps  Sample 1                2              3  DTG: Tp / °C Co-MMT(I) 4-Mepy/Co-MMT(II) 4-Etpy/Co-MMT(III) 4-OHpy/Co-MMT(IV) 15 6,2 7,3 6,5 _ 6,3 6,2 3,5; 1,9 4,43,12,93,8103 64 67 67 _ 430 442 380; 470 652 627 629 610 Ni-MMT(V) 4-Mepy/Ni-MMT(VI) 4-Etpy/Ni-MMT(VII) 4-OHpy/Ni-MMT(VIII) 16,6 5,2 3,2 6,3 _ 8,7 11,3 3,7; 2,7 5,33,43,13,282 46 52 62 _ 420 407 380; 470 656 640 636 610 Cu-MMT(IX) 4-Mepy/Cu-MMT(X) 4-Etpy/Cu-MMT(XI) 4-OHpy/Cu-MMT(XII) 13,2 3,1 2,4 6,1 _ 7,8 8,1 1,8; 2,9 4,64,64,45,568 50 44 48 _ 380 380 280; 380 640 612 605 650  Table 1.Thermal analysis results for the release of pyridine derivatives from Co 2+-, Ni 2+ and Cu 2+-exchanged montmorillonites (20-700°C)  The data from infrared spectra  are given in Table 2. The significant difference between pure M2+−MMT (I, V, IX) and the products (II−IV, VI−VIII, X−XII) can be observed in the region 1700−1400 cm−1. Whereas samples I, V and IX show only one sharp band at ~ 1632−1635 cm-1 assigned to the deformation vibration of H−O−H groups [16], the samples with 4-Rpy exhibit in this region several peaks of 4−Rpy in the interval 1647−1622, 1520, 1512−1508 and 1451−1435 cm−1. It is known [17−19], that the peak at ~1600 cm−1, attributed to the ring vibration in the pyridine molecules (for example 4−Mepy shows peak at 1604 cm−1 [20] ) shifts to higher frequences upon complex formation. The shift of this peak to about 1647−1622 cm−1 may support the conclusion on the formation of coordination bond between M2+ central atoms and the nitrogen atom of the heterocyclic ring in these samples. This assertion also supports the presence of the „diagnostic“ Lewis peak at ∼1451−1435 cm−1. Samples containing OH group in 4−position on the pyridine ring, show two peaks in the studied region at ∼1647−1642 cm−1 and 1520 cm−1 (Table 2).    Sample ν~ ( maxima of absorption bands)/cm −1I 1632 (vs) − – – II 1645 (s), 1622 (sh) – 1512 (w) 1451(w) III 1642 (s), 1627 (vs) 1558 (w) 1508(w) 1462(w),1436(w) IV 1643 (vs) – 1520 (vs) – V 1634(vs) – – – VI 1644 (s), 1622 (vs) – 1509 (s) 1441(s) VII 1642 (s), 1622 (vs) 1558 (vw) 1508 (w) 1439 (s) VIII 1648 (vs) – 1520 (vs) – IX 1635(vs) – – – X 1642 (s), 1624 (vs) – 1510 (s) 1439(s) XI 1647 (sh), 1622 (vs) 1559 (w) 1508 (w) 1435 (s) XII 1645 (vs) – 1520 (vs) –  Table 2. Representative infrared spectral data of studied samples I-IX (1400 – 1700 cm −1). (vs – very strong, w – weak, sh – shoulder)   The first peak may be assigned both to deformation vibration of H2O molecules and the ring vibration of pyridine molecules, and thus Lewis−bound  pyridine in these samples cannot be excluded. Moreover, a peak near 1520 cm−1 suggets also the presence of same Brönsted−bound pyridine molecules [13]. This assumption can also explain the occurence of two peaks on TG and DTG curves for samples with 4−OHpy (Table 1).  CONCLUSIONS  The presented results reveal that M2+−exchanged montmorillonite (M = Co, Ni, Cu) has provided suitable reaction media for the incorporation of neutral organic bases (4−Rpy) in its layered structure. The thermal effects accompanying the escape of 4−Rpy from obtained  products in the temperature interval 20−700 °C indicate that the stoichiometry of thermal decomposition is different (samples containing 4−OHpy exhibit in this region four effects in contrast to the 4−Me and 4−Etpy/M2+−MMT).  The infrared spectra show that bonds between 4−Rpy (R = Me, Et) and M2+−exchanged montmorillonites predominantly exhibit Lewis acid character with exception of samples with 4−OHpy in which we consider Brönsted type of interactions.Thus, the influence of different substituents on the pyridine ring on the thermal and spectral properties of studied samples is evident.   References  [1]  Thomas J.M., Sheet silicate intercalates, Academic Press, New York 1982.  [2]  Kowalska M., Gűler H. and Cocke D.L.: Sci.Total Environ. 141, 223 (1994). [3]  Madejová j., Arvaiová B. and Komadel P.: Spectrochim.Acta, A 55, 2467 (1999). [4]  Yariv S.: Thermochim.Acta 273, 1 (1996). [5]  Jóna E., Kubranová M., Mojumdar S.C. and Kopcová M.: Chem.Pap. 56, 295 (2002). [6]  Kubranová M., Jóna E.,Rudinská E., Nemčeková K., Ondrušová D. and Pajtášová M.: J.Thermal Anal.Cal. 74, 251 (2003). [7]  Jóna E., Kožíšek J., Koman M. and Boča R.: Polyhedron 11, 573 (1992). [8]  Melník M., Koman M. and Glowiak T.: Polyhedron 17, 1767 (1998). [9]  Mojumdar S.C., Melník M. and Jóna E.: Thermochim.Acta 352, 129 (2000). [10]  Jóna E., Kubranová M., Sirota A. and Šimon P.: J.Thermal Anal.Cal. 52, 373 (1998). [11]  Breen C., Deane A.T. and Flynn J.J.: Clay Minerals 22, 169 (1987). [12]  Breen C.: Clay Mineral. 26, 473 (1991). [13]  Breen C.: Clay Mineral. 26, 487 (1991). [14]  Jóna E., Kubranová M., Sirota A. and Kopcová M.: J.Thermal Anal.Cal. 63, 807 (2001). [15]  Farmer V.C. and Mortland M.M.: J.Chem.Soc. (A), 344 (1966). [16]  Nakamoto K.: Infrared spectra of Inorganic and Coordination Compounds, 2nd Edittion, Wiley Interscience, New York 1970. [17]  Mojumdar S.C.: J.Thermal Anal.Cal. 64, 629 (2001). [18]  Kidani Y., Nofi M. and Koike H.: Bull.Chem.Soc.Jap. 48, 239 (1975). [19]  Mojumdar S.C. and Melník M.: Chem.Pap. 54, 1 (2000). [20]  Green J.H.S., Kynaston W. and Paisley H.M.: Spectrochim.Acta 19, 549 (1963).                       Autors :  a Prof. Ing. Eugen Jóna, DrSc. a Ing. Eva Rudinská a Ing. Martina Sapietová a Ing. Marianna  Pajtášová, PhD. Department of Chemistry and Technology Inorganic Materials I. Krasku 491 / 30 020 01 Púchov, Slovakia E-mail : jona@fpt.tnuni.sk         

Nanomaterials on the basis of layered silicates

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Nanomaterials on the basis of layered silicates

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