Interaction of cations with SH-modified silica gel: thermochemical study through calorimetric titration and direct extent of reaction determination

Abstract

The reaction of silica gel with 3-(trimethoxysilyl)propane-1-thiol, MPTS, produced a thiol-modified silica gel, Sil–SH. This material removes silver, mercury, copper, zinc and nickel ions from aqueous solutions. Enthalpy changes that occur in the interactions between Sil–SH and these cations were obtained by a calorimetric titration technique, in which thermal effects and the quantities of cations that interact at each titration point were determined simultaneously. From this procedure, values of the maximum capacity of interaction (N^s), enthalpies of interaction at different coverages of the surface [Δ_int(i)H_m ] and integral enthalpy of interaction for a monolayer (Δ_monH_m) have been established. It is shown that this method permits charting the basic sites created upon modification. From Δ_int(i)H_m values, the sequence of the interaction strength between the basic sites of the silica-attached MPTS and the cations is Hg²⁺>Ag⁺>Cu²⁺>Ni²⁺>Zn²⁺ , in agreement with the concept of hard and soft acids and bases. The influence of some parameters concerning the thermodynamics of solvation of the indicated transition metals has been also taken into account in the investigation of these interaction processes.

References

1. J. Nawrocki and B. Buszewski, J. Chromatogr., 1988, 449, 1.
2. W. Wasiak, Chromatographia, 1995, 41, 107.
3. B. B. Wheals, J. Chromatogr., 1979, 177, 263.
4. M. Capka, M. Czaksová, E. Hillerová, E. Paetzoldi and G. Oehme, J. Mol. Catal., 1995, 104, L123.
5. A. Aydin, U. Koklu and S. Tascioglu, Chim. Acta Turc., 1987, 15, 91.
6. E. Nishio, I. Abe, N. Ikuta, J. Koga, H. Okabayashi and K. Nishikida, Appl. Spectrosc., 1991, 45, 496.
7. K. Terada, Anal. Sci., 1991, 7, 187.
8. A. G. Howard, M. Volkan and D. Y. Ataman, Analyst, 1987, 112, 159.
9. S. Akman, H. Ince and U. Kokler, Anal. Sci., 1991, 7, 799.
10. C. P. Tripp and M. L. Hair, J. Phys. Chem., 1993, 97, 5693.
11. G. K. Dirk and B. Thomas, Langmuir, 1993, 9, 2965.
12. A. R. Cestari and C. Airoldi, J. Braz. Chem. Soc., 1995, 6, 291.
13. D. D. Perrin, W. L. F. Armarego and D. R. Perrin, Purification of Laboratory Chemicals, Pergamon Press, Oxford, 2nd edn., 1980.
14. G. Schomburg, A. Deege, J. Kokler and U. Bien-Vogelsang, J. Chromatogr., 1983, 282, 27.
15. L. C. Sande and S. A. Wise, J. Chromatogr., 1984, 316, 163.
16. K. D. Lork, K. K. Unger and J. N. Kinkel, J. Chromatogr., 1986, 352, 199.
17. B. Buszewski, L. Nondek, A. Jurasek and D. Berek, Chromatographia, 1987, 23, 442.
18. R. G. Bowman and R. L. Burwell, Jr., J. Am. Chem. Soc., 1979, 101, 159.
19. S. Brunauer, P. Emett and E. Teller, J. Am. Chem. Soc., 1938, 60, 309.
20. C. Airoldi, P. L. O. Volpe and J. M. M. M. Lira, Polyhedron, 1983, 2, 1125.
21. H. Onishi, Photometric Determination of Traces of Metals, Part II, John Wiley & Sons, New York, 4th edn., 1986.
22. T. J. Porro and S. C. Pattacini, Appl. Spectrosc., 1990, 44, 1170.
23. A. R. Cestari and C. Airoldi, J. Therm. Anal., 1995, 44, 79.
24. A. Pines, M. G. Gibby and J. S. Waugh, J. Chem. Phys., 1973, 59, 569.
25. C. E. Bronnimann, R. C. Zeigler and C. E. Maciel, J. Am. Chem. Soc., 1988, 110, 2023.
26. P. Van Der Voort, I. Gillis, D. Hamers, K. C. Vranken and E. J. Vansant, J. Chem. Soc., Faraday Trans., 1991, 87, 3899.
27. B. A. Marrow and A. J. MacFarlan, J. Phys. Chem., 1992, 96, 1395.
28. A. W. Adamson, Physical Chemistry of Surfaces, Wiley, New York, 5th edn., 1990.
29. E. M. Arnett and T. Ahsan, J. Am. Chem. Soc., 1991, 113, 6861.
30. J. R. Jerorez, K. H. Faltynski, L. G. Blackburn, P. J. Henderson and H. D. Medina, Talanta, 1985, 32, 763.
31. Y. Marcus, J. Chem. Soc., Faraday Trans., 1991, 87, 2995.
32. Y. Marcus, J. Chem. Soc., Faraday Trans., 1987, 83, 339.
33. W. Wasiak, Chromatographia, 1987, 23, 423.
34. R. G. Pearson, J. Chem. Educ., 1968, 9, 581.