OPTIMIZATION OF TANNIN-BASED TANNING CONDITIONS USING RESPONSE SURFACE METHODOLOGY FOR IMPROVED LEATHER QUALITY

Abstract

This study investigates the optimization of tannin-based leather tanning using Response Surface Methodology (RSM) to improve leather quality parameters. A Central Composite Design (CCD) was employed to model the effects of four independent variables—tannin concentration, pH, water content, and tanning time—on key leather performance metrics such as shrinkage temperature, tensile strength, and water vapor permeability. Goat skins were treated with tannins extracted from Acacia nilotica and Caesalpinia coriaria, both individually and in combination. The statistical models revealed significant interaction and quadratic effects among the variables, with tannin concentration and tanning time exerting the most substantial influence on leather performance. Optimal tanning conditions were achieved at approximately 27.5% tannin concentration, pH 5.5, 95% water content, and 80 minutes of tanning time. These conditions resulted in leather with superior shrinkage temperatures (up to 99?°C), tensile strength (38.52 MPa), and acceptable water vapor permeability. The study highlights the synergistic potential of combining hydrolysable and condensed tannins and supports the viability of indigenous plant-based tannins as eco-friendly alternatives to synthetic tanning agents, particularly chromium salts. The findings advocate sustainable leather production practices aligned with circular economy principles and local resource utilization.