Abstract

The fluorescence quenching of gelatin with Fe3+/Cr3+/Al3+ was studied by spectrofluorimetry, and the reaction mechanism was analyzed with the Stern-Volmer equation. Meanwhile, the number of binding sites, the binding constant, the thermodynamic functions of the reaction between gelatin and Fe3+ were calculated. The results suggest that the fluorescence quenching of the gelatin is static quenching with Fe3+, dynamic quenching with Cr3+, but no quenching with Al3+. As a result, it is selective for the metal tanning agents complexing to the collagen. Also, the binding ratio of the gelatin and Fe3+ is about 1:1, Moreover, the thermodynamic functions (ΔHmθ and ΔSmθ) in the reaction indicate that the reaction of the gelatin and Fe3+ is endothermal and the entropy increases in the process. The study should help to understand the mineral tanning machanism.