Utilization of Tannery Flesh Waste for Production of Sustainable Leather Coating Substance

Abstract

The leather tanning industry is one of the most polluting industries because it generates a gigantic amount of solid, liquid, and gaseous waste. Solid wastes are raw trimmings, fleshings, chrome shavings, buffing clouds of dust, and keratin wastes. Flesh wastes are generated from tanneries during leather processing, especially in sheep liming. These skin-flesh wastes from tanneries contain significant fat content, which is being wasted and dumped in open areas or at dumping sites. As a result, this flesh waste disposal has created a major environmental problem. This research aims to extract a sustainable functional substance that can be used for imparting aesthetic properties (polishing) to a leather product. In this research, a calculated amount of flesh waste was washed, de-limed, and cut into small pieces for solvent extraction of fat using the Soxhlet apparatus and hexane as solvent. Chemical analysis of the extracted fat showed a saponification value ranging from 189 to 192. These values indicate that extracted fat has a triglyceride, which can be used as a lubricant. However, when the extracted fat was applied to leather products like shoes, the surface showed an increase in their aesthetic properties (lustre, and gloss) giving excellent polishing results. The acid and saponification value, fat content, melting point, density, and viscosity of extracted fat showed stability making it a promising substance to impart functionality for leather products and usage as a polishing material. The extracted fat could replace synthetic, functional, and polishing materials overcoming the environmental challenges posed by the leather tanning process.