Greener approach to leather tanning process: d-Lysine aldehyde as novel tanning agent for chrome-free tanning

A greener and eco-friendly method to leather tanning process has been developed in the present investigation, which is based on d-Lysine aldehyde complex. This can be considered as a substitute for chrome-free tanning process. The physico-chemical and morphological characteristics, resistance to collagenolytic activity and organoleptic properties of the d-Lysine glutaraldehyde tanned leather were evaluated in terms of environmental impact assessment. The shrinkage temperature, denaturation temperature and mechanical strength of tanned leather were analysed by using shrinkage, differential scanning calorimetric and thermomechanical analysis techniques. It has been shown that the above properties of the tanned leather are better than that of glutaraldehyde alone or equal to chrome tanned leather. The density of the fibre structure throughout the cross section indicates the even structure and fibre bundles seem to be less dispersed compared to glutaraldehyde alone; were analysed by using scanning electron microscopic and atomic force microscopic techniques. This tanning tanned leather demonstrated a higher resistance to collagenolytic activity than conventional tanned leather. The tanned leather exhibited good fullness, softness, smoothness, colour and general appearance compared to glutaraldehyde alone. The significant reduction in total solids content such as dissolved solids and suspended solids present in the effluent compared to conventional tanning method is evident from environmental impact assessment studies. This tanning process has the cost advantages due to the possible decrease in chemicals consumptions and net saving from the reduced effluent treatment costs. The improved tanning process reduces generation of toxic waste compared to chrome tanning process and can be regarded as eco-friendly, which reducing the environmental impacts and contributes to the development of greener or cleaner process.