Abstract

The paper develops a method for determining Al2O3 in plant-aluminum and aluminum tanned leathers. A leather sample of 2.000g is burnt to ashes at 700°C; Al2O3 in the ash is melted with 1.5g Na2B4O7 at 950°C for 20 minutes. The melt is dissolved in nitric acid, 1M, and diluted in a 250.0ml measurement flask. Al3+ in the sample solution is back-titrated with standard solutions of EDTA and Pb(NO3)2. Using this method, we analysed samples of lamb and pig leather, tanned with the plant-aluminum tans sumac and quebracho. The results have good reproducibility, 0.04% Al2O3 for a sample containing 2.39% Al2O3. The losses of Al2O3 during melting are less than 4%.