Abstract

The treatment and utilisation of chromium containing tannery waste has been of increasing concern because of the environmental pressure for safe disposal. The aim of this work is a development of the intermediate acids of the syntan to hydrolyse chrome shavings, then the hydrolysed mixtures were condensed with formaldehyde and urea to obtain a composite condensation retanning agent by the one-pot method. The effects of hydrolysis temperature, hydrolysis duration and the amount of chrome shavings were investigated. The molecular weight of the hydrolysate was controlled. The prepared composite condensations were applied for retanning bovine upper leather. The results showed that the prepared composite condensates have an excellent thickening [substance increase], filling and good level-dyeing effect on bovine upper leather. Furthermore, two benefits exist in this development, one is that no extra acid need to be added in the hydrolysis step and the other is that the chromium present does not need to be separated since the final composite product contains Cr(III).