Scientific journal
Scientific Review. Chemical sciences

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THERMAL STABILITY AND PROTOLYTIC PROPERTIES OF SILICA, MODIFIED BY SOME AMINO ACIDS

Шаров А.В., Филистеев О.В., Воронцов Б.С.
Leucine, proline and tyrosine modified silica were synthesized with sol-gel method. Samples thermal stability and protolytic properties studied by the methods of complex thermal analysis and potentiometric titration. Found that the amino acid fix in the silica matrix by reason of amino groups and silanol groups interaction. The dependences of immobilized amino acids ionization concentration constants on ionic strength described and approximated using Pitzer model. The ionization constants at zero ionic strength of immobilized carboxyl groups were not significantly different from the constant of such groups in water solution. The ionization constants of immobilized amino groups on 2 – 3 order lower than that for the amino groups in water solution. This is explained by intermolecular bonds between the amino groups and the silanol groups.