CIRCULAR TECHNOLOGY FOR SHEEPSKIN TANNING

Abstract

The circular economy is synonymous with the production of "zero waste" in the context in which valuable resources are lost and the European development agenda aims for a program of smart, sustainable, inclusive growth. At present, finding alternatives to tanning with chromium salts is considered one of the most important objectives of the leather industry. The present paper includes original results regarding the formulation, characterization and testing of some organic pre-tanning composites for the processing of sheepskins within the concept of circular technology. The collagen hydrolysate extracted from untanned and organic pre-tanned sheepskins was used to design a new circular technology. Four kinds of pre-tanning agents were formulated based on renewable materials such as collagen hydrolysate, whey and/or vegetable tannins. The characterization of new products by ATR-FTIR spectra showed common wavelength bands of whey and vegetable tannin suggesting a potential interaction and less carboxylic and methyl groups for oxidized pre-tanning agents. The new pre-tanned sheepskin leathers were retanned with a full organic formulation and showed different affinity for anionic chemical auxiliaries due to different chemical functional group activation. Physical-chemical, softness determination and SEM images confirmed the similar morphology with vegetable leathers, with more compact structure of leathers pre-tanned with oxidized products as compared to non oxidized composite products, with a more soft and relaxed aspect. The non oxidized pre-tanning agents were selected for further experiments at pilot level in view of circular technology design with prospect to save 40% sheepskin waste.

Keywords

• biotechnology
• waste recycling
• biodegradable pre-tanning
• organic tanning
• circular economy
• bio-based technology
• renewable materials