Abstract

The future of the tanning industry is concerned fundamentally with three areas: (a) raw materials, (b) energy and (c) environment. With regard to raw materials the trend is towards making the fullest possible use of these products, which involves the processing of all by-products of the tanning industry. In this work a pilot plant for the treatment of the different by-products of the tanning industry has been devised. The essential chemical process is based on the oxidising action by hydrogen peroxide in an alkaline medium of the chrome (III) present in the by-products, which permits the formation of inter and intrafibrilar peroxochromate compounds which have great oxidising capacity. By adjusting the amount of hydroxyl ions in the bath, the amount of hydrogen peroxide and the volume of the bath; we may obtain either, the total solubilization of the by-products, or a dechroming effect, whilst maintaining the original macromolecular fibrous structure. Furthermore, the chemical process of dechroming is without doubt of great importance due to the overall volume of chromed by-products as a result of the import of skins in wet-blue state. Therefore, the large number of by-products generated by mechanical operations, such as: splitting, shaving, and trimming are chrome tanned. For this reason, we sought to produce a collagenic material with unchanged physico-chemical characteristics and with a zero chrome level. To this end, we made an optimization study of the Box-Behnken type to enable us to study the most significant variables that intervene in this process and, to allow us to obtain the optimum conditions in order to achieve an end product with a zero chrome level. Thus, this represents new openings for the application of chromed by-products in the fields of medicine, food, cosmetics with a substantial increase in the added value of the recovered final product.