BIO-INSPIRED DUAL CROSSLINKING OF COLLAGEN USING ELLAGIC ACID– CHITOSAN FOR SUSTAINABLE CHROME-FREE TANNING

Woldeamanuel Wondaferash Atinafu (MSc), Teklay Asgedom Teferi (PhD)*

ABSTRACT

Chromium(III) tanning remains the dominant leather manufacturing technology due to rapid processing, excellent hydrothermal stability, and balanced mechanical properties, but is increasingly associated with environmental and health concerns.Existing chrome-free tanning systems often fail to simultaneously provide highthermal stability, mechanical strength, and environmental compatibility. Here, wereport a bio-inspired dual crosslinking strategy that integrates plant-derivedpolyphenols with enzyme-activated in situ carbonyl generation to stabilize collagenfibers without metals or externally added aldehydes. Polyphenols initially stabilizecollagen via hydrogen bonding and hydrophobic interactions, while laccase-catalyzed oxidation generates reactive carbonyl intermediates within the matrix, enabling covalent crosslink formation under mild conditions. Sheep skin leathers producedusing this system exhibited shrinkage temperatures up to 96 °C, tensile strength of 19 N mm⁻⊃2;, and 18% higher water vapor permeability than chrome-tanned controls.Effluent chemical oxygen demand (COD) and biological oxygen demand (BOD) were reduced by approximately 58%, and chromium-containing solid wastes wereeliminated. The process demonstrates chrome-like performance viaenzyme-generated crosslinks, offering a sustainable and industrially compatiblepathway for leather manufacture.

Keywords:

Chrome-free tanning; Bio-inspired materials; Polyphenols; Enzymatic
oxidation; Sustainable leather technology; hydrothermal stability.

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