Abstract

Nowadays people are seeking natural products, and advocating the preparation of leather products from green chemicals. Therefore, it becomes an important task of chemists in leather manufacture to research and develop clean and green tanning agents to replace chromium-containing tanning agents. In this study, a combination tanning process based on garad powder (Acacia nilotica sub. sp. nilotica) and tetrakis hydroxymethyl phosphonium sulphate (THPS) for the production of upper leathers is presented as a cleaner alternative. Two tanning methods, garad followed by THPS (garad-THPS) and THPS followed by garad (THPS-garad), have been tried. The combination tannage, employing 20% garad powder and 1.5% THPS results in leathers with shrinkage temperatures of 100°C. The change in the order of addition of garad and THPS showed a marginal difference in thermal stability, but significant variations were observed in the physical characteristics of leathers.

The combination tanning system provides a significant reduction in the discharge of total dissolved solids in the wastewater. The characteristics of the leathers indicate that the garad-THPS combination tanning system provided leathers with good organoleptic properties and comparable strength properties. The leathers were further characterized by chemical analysis. The work presented in this paper establishes the use of garad and THPS as an effective alternative cleaner tanning method.