| Abstract [eng] |
Public awareness of the environment, which is gradually increasing, has begun to be reflected in various industrial sectors. Leather industry is considered to be one of the most polluting because of the big amount of liquid, solid and gaseous waste, as well as other generated side products. The aim is to find suitable ways to recycle and reuse solid proteinic waste (trimmings, splits, shavings, etc.), or that which remains after wearing leather products (used leather products) because it contains valuable proteins, fats and other chemicals. Unfortunately, nowadays, the most commonly used method of disposing of such waste is dumping it into landfill, but the effect on the environment, obviously, is considered to be negative. The aim of the presented research was to evaluate the possibilities of finished leather hydrolysis and to identify hydrolysates structure. As the research has shown that finished leather can be hydrolyzed by alkaline-enzymatic method using Ca(OH)2 with NaOH or MgO, and for the enzymatic stage, the proteolytic enzyme preparation Vilzim Pro Conc. The method of hydrolysis has an impact on chromium compounds, total and collagenous protein quantities in hydrolysates and in solid residues. The penetration of the dye, the tensile strength of the leather, the relative elongation, the boiling temperature and other properties of the exploited leather were investigated in order to find out the possibilities of using the hydrolysate for leather treatment. It has been found that the obtained hydrolysate can be used for chromed leather dyeing. In the process of dyeing, the dye penetrates into derma deep enough for the dye to meet the requirements for surface dyeing, and the leather semi-finished product itself incorporates some of the chromium compounds (23.3–39.1%) and protein substances (23.3–26.2%) which are in the hydrolysates. Infrared spectroscopy and thermogravimetric analysis were used to analyze structural changes in hydrolysates and leather. |
