Possible Application of Using Modified Black Liquor from Rice Straw in Leather Tanning

Ensuring environmental and human safety is a crucial requirement in modern industrial practices. Consequently, the utilization of natural substances in the tanning industry could serve as a reliable approach to prevent chemical contamination associated with the use of traditional chromium salts during the tanning process. This study aimed to assess the potential application of black liquor derived from rice straw as a tanning agent for leather. The black liquor was prepared using the Kraft method, and a modified version called modified black liquor (MBL) was created by gradually reducing the pH from 13 to 7. Subsequently, MBL was employed in the tanning of pickled sheep pelts using four different concentrations: 10%, 20%, 30%, and 40% of the pelts' weight. The physical, chemical, and organoleptic properties of the resulting MBL-tanned leathers were compared with those of leathers tanned with quebracho extracts to evaluate the suitability of MBL as a tanning agent. The findings demonstrated that MBL leathers exhibited slightly lower physical and organoleptic properties when compared to the quebracho-tanned leathers. Increasing the concentration of MBL up to 30% was sufficient to enhance the properties of the tanned leathers, while concentrations exceeding this threshold did not yield any significant improvements in the leather's properties. Consequently, the study recommends the use of MBL in leather tanning either in combination with other tanning agents or as a re-tanning agent to enhance the fullness, smoothness, and overall physical quality of the leather, thereby elevating its overall quality