Abstract
When carrying out work on the manufacture of leather materials, a number of complex processes are performed. During these operations, many chemicals and additives are used that are harmful to the environment and dangerous to human health. The main goal of the leather industry is to replace chemicals with the most natural extracts. Natural extracts can be used as tanning materials, as well as in the process of finishing processes. The chemical composition of the natural extract prepared from walnut shells was determined using an LCMS-9030 mass spectrometer and a number of acids with antioxidant properties and flavone with coloring properties were found. Trivalent chrome tanning is widely used in the leather industry. After all, this type of tanning is one of the most suitable methods for production. Trivalent chromium free radicals present in the leather, under the influence of temperature, photoaging, humidity and the external environment, turn into hexavalent chromium. Hexavalent chromium causes life-threatening diseases such as carcinogenic, liver and kidney failure, and skin diseases. The antioxidants contained in natural extracts prevent the formation of hexavalent chromium. The amount of hexavalent chromium in leather trimmed with a natural extract made from walnut shells with antioxidant properties was determined by Shimadzu UV- 1601 PC UV-Visible equipment, in accordance with EN ISO 17075 standard. The amount of hexavalent chromium in the leather finished with natural walnut shell extract was significantly reduced than in the samples finished with chemical pigment, water and without finishing.