Influence of different tanning agents on bovine leather thermal degradation

Abstract

The objective of the paper consists in studying the thermal behavior of chrome-free tanned bovine leather (wet-white), using a new product based on titanium and aluminum salts, compared with the same leather tanned by chromium salts (wet-blue). The aim is to find a possibility for replacing the wet-blue leather, containing Cr (III) salts, with the environmentally friendly wet-white leather. The thermal behavior was studied by dynamic thermogravimetry in nitrogen atmosphere, up to 700 °C. Global kinetic thermal decomposition parameters values were obtained with the isoconversional integral method of Flynn–Wall–Ozawa. The kinetic model best describing the thermal degradation process and the kinetic parameters for each individual stage were determined from non-isothermal data by means of a multivariate nonlinear regression method. The evolved gases analysis was conducted on a coupling to a quadrupole mass spectrometer and a Fourier transform infrared spectrophotometer equipped with external modulus for gas analysis. FTIR, microscopic, and elementary composition studies of residues were conducted. There was found that the differences in non-isothermal decomposition kinetics, evolved gases, and residue analyses were dependent on the nature of the two used tanning agents. It was observed that the wet-white leather exhibited lower thermal stability and temperatures of evolved gases. The metal concentrations in the residues and their porous and fibrillar morphologies recommend them as possible candidates for obtaining cost-friendly adsorbents.