ASİT AKTİFLEŞTİRİLMİŞ BENTONİT (ÜNYE) NUMELERİNDEKİ ASİDİK MERKEZLERİNİN TEŞHİSİ

Abstract

Tutunmuş piridin türlerine ait 1540 cm-1’deki ve 1450 ve 1610-1605 cm-1’deki piklerin şiddetleri esas alınarak asitle aktifleştirilmiş bentonit numunelerinin Brønsted asitlikleri 6A-8A->4A->2A->10A-bentonit biçiminde verilmiştir. Saf bentonitin yüzey alanı asitle aktifleştirme ile artmış ve 4A-bentonitte en yüksek değere ulaşmıştır. Tüm bentonit numunelerine piridin tutunmasının akabinde yüzey alanlarının azalması mikro- ve mezogözenek girişlerinin tutunan piridin molekülleri tarafından kapatılmasıyla ilişkilidir. Saf bentonitin DTA eğrisinde tutunan suyun ve tabakalar arası katyona bağlı suyun uzaklaşmasından doğan 99 ve 166 ºC merkezli iki endotermik pik tespit edilmiştir. Buna ilaveten numunelerde H-bağlı piridin moleküllerinin uzaklaşmasından kaynaklanan endotermik DTA pikleri yaklaşık 200 ºC’de ve Brønsted merkezlerine bağlı piridin moleküllerine ait endotermik pikleri ise yaklaşık 300 ºC’de gözlenmiştir.

Keywords

• Bentonit, Brİnsted ve Lewis asitliği, piridin, ATR

References

1. Alemdaroğlu, T., Akkuş, G., Önal, M., Sarıkaya, Y. (2003). Investigation of the Surface Acidity of a Bentonite Modified by Acid Activation and Thermal Treatment. Turk. J. Chem., 27, 675-681.
2. Benesi, H.A. (1956). Acidity of Catalyst Surfaces I. Acid Strength from Colors of Adsorbed Indicators. J. Phys. Chem., 78, 5490-5494.
3. Benesi, H.A. (1957). Acidity of Catayst Surfaces II. Amine Titration Using Hammett Indicators. J. Phys. Chem., 61, 970-973.
4. Caglar, B., Afsin, B., Tabak, A. (2007). Benzamide Species Retained by DMSO Composites at a Kaolinite Surface. J. Therm. Anal. Cal., 87, 429-432.
5. Caglar, B., Afsin, B., Tabak, A., and Eren, E. (2009). Characterization of Cation Exchanged Bentonites by XRPD, ATR, DTA/TG and BET measurement Investigation of. Chemical Engineering Journal, 149, 242- 248.
6. Chitnis, S.R., Sharma, M.M. (1997). Industrial Applications of Acid-Treated Clays as Catalyst. React. Funct. Polym., 32, 93-115.
7. Christidis, G.E., Scott, P.W., Dunham, A.C. (1997). Acid Activation and Bleaching Capacity of Bentonites from the Islands of Milos and Chios, Aegean, Greece. Appl. Clay Sci., 12, 329-347.
8. Flessner, U., Jones, D.J., Roziere, J., Zajac, J., Storaro, L., Lenarda, M., Pavan, M., Lopez, A.J., Castellon, E.R., Trombetta, M., Busca, G. (2001). A Study of the Surface Acidity of Acid-Treated Montmorillonite Clay Catalyst. J. Mol. Catal. A: Chemical, 168, 247-256.

9. Heyding, R.D., Ironside, R., Norris, A.R., ve Prysiazniuk, R.Y. (1960). Acid Activation of Montmorillonite. Can. J. Chem., 38, 1003-1016.
10. Hutson, N.D., Hoekstra, M.J., Yang, R.T. (1999). Control of Microporosity of Al2O3-Pillared Clays: Effect of pH, Calcination Temperature and Clay Cation Exchange Capacity. Micropor. Mesopor. Mater., 28, 447-459.
11. Jankovich, L., Komadel, P. (2003). Metal Cation-Exchanged Montmorillonite Catalyzed Protection of Aromatic Aldehydes with Ac2O. J. Catal., 218, 227-233.
12. Koh, S.M., Dixon, J.B. (2001). Preparation and Application of Organo- Minerals as Sorbents of Phenol, Benzene and Toluene. App. Clay Sci., 18, 111-122.
13. Kurian, M., Sugunan, S. (2005). Characterization of the Acid-Base Properties of Pillared Montmorillonites. Micropor. Mesopor. Mater., 83, 25-34.
14. Madejova, J., Bujdak, J., Janek, M., Komadel, P. (1998a). Comparative FT-IR Study of Structural Modifications During Acid Treatment of Dioctahedral Smectites and Hectorite. Spectrochim. Acta Part A, 54, 1397-1406.
15. Madejova, J., Arvaiova, B., Komadel, P. (1998b). FTIR Spectroscopic Characterization of Thermally Treated Cu2+, Cd2+ and Li2+ Montmorillonites. Spectrochim. Acta Part A, 55, 2467-2476.
16. Madejova, J. (2003). FTIR Techniques in Clay Mineral Studies. Vibrational Spectros., 31, 1-10.
17. Melo, D.M.A., Ruiz, J.A.C., Melo, M.A.F., Sobrinho, E.V., Schmall, M. (2000). Preparation and Characterization of Terbium Palygorskite Clay as Acid Catayst. Micropor. Mesopor. Mater., 38, 345-349.
18. Noyan, H., Önal, M., Sarıkaya, Y. (2007). The Effect of Sulphuric Acid Activation on the Crystallinity, Surface Area, Porosity, Surface Acidty, and Bleaching Power of a Bentonite. Food Chem., 105, 156-163.
19. Önal, M., Sarıkaya, Y., Alemdaroğlu, T., Bozdoğan, İ., 2002. The Effect of Acid Activation on Some Physicochemical Properties of a Bentonite. Turk. J. Chem., 26, 409-416.
20. Reedy, C.R., Nagendrappa, G., Prakash, B.S.J. (2007). Surface Acidity Study of Mn+-Montmorillonite Clay Catalysts by FT-IR Spectroscopy: Correlation with Esterification Activity. Catal. Commun., 8, 241-246.
21. Rodriguez, M.A.V., Barrios, M.S., Gonzalez, J.D.L., Munoz, M.A.B. (1994). Acid Activation of a Ferrous Saponite (Griffithite): Physico-Chemical Characterization and Surface Area of the Products Obtained. Clays Clay Miner., 42, 724-730.
22. Tabak, A., Afsin, B. (2001). Firmly Adsorbed Ammonia and Pyridine Species at Activated Kaolinite Surfaces. Ads. Sci. Technol., 18, 673-679.
23. Tanabe, K., Hölderich, W. (1999). Industrial Application of Solid Acid-Base Cataysts. Appl. Catal. A: General, 181, 399-434.
24. Varma, R.S. (2002). Clay and Clay-Supported Reagents in Organic Synthesis. Tetrahedron, 58, 1235-1255. ****