Studies on the Physico-chemical Behavior of Synthetic Tanning Agents in Non-aqueous Medium

Green labelling is a high priority issue in the modern society that has lead to several green technology initiatives in day-to-day applications. Among the several industry sectors, leather industry, is known to contribute to environmental pollution. Though, there are several alternate cleaner technologies available, till date no drastic shift in methodologies of clean technology has been implemented. In our efforts to use 'green' methodologies, in the present investigation, we have chosen green solvents like ethanol and heptane as possible carrier medium for synthetic tanning agents in leather processing. These tanning agents are performance chemicals that impart special properties to leather depending on end applications. In this study, tunable interfacial properties that arise between the solvated syntans and different solvents + water mixtures have been employed judiciously. Representative class of synthetic tanning agents have been chosen for the evaluation. The interfacial properties of liquid/liquid (solution) have been examined to understand the influence of solvents in the post tanning applications in leather making. Physical characteristics like tensile and tear strength have been determined for experimental leathers. Results show that syntans in ethanol and heptane medium form uniform dispersion and act as diffusing vehicle. The results suggest that the bound and unbound water in the leather matrix can form interfacial tension gradient with the solvent enabling effective diffusion of the chemicals even with non-polar solvents like heptane. Physical strength characteristics of experimental leather have met standard norms. The results have demonstrated an insight into the fundamental behavior of syntans in non-aqueous medium and provide clues for real time application in leather processing.