Sustainable Tanning Processes in Leather Manufacturing

Leather tanning traditionally relies on chromium(III) salts but faces mounting environmental concerns due to effluent toxicity and heavy metal accumulation. Sustainable tanning processes seek to reduce or replace harmful reagents by employing plant-derived polyphenols, metal-free complexes and innovative solvent systems. Vegetable tanning uses tannins extracted from tree bark or seeds to crosslink collagen fibres in a biodegradable manner. Chrome-free strategies include oligosaccharide-based masking agents produced via controlled oxidation of cellulose and combination tannages that integrate silicic acid with plant polyphenols for enhanced thermal and storage stability. Retanning and fatliquoring steps are increasingly adopting bio-derived polymers, enzymatic hydrolysates and valorisation of solid wastes such as fleshing fat or hide trim. Deep eutectic solvents and ionic liquids have emerged as alternative media to improve reagent penetration, reduce water consumption and facilitate reagent recovery. Life cycle assessment and circular-economy frameworks guide optimisation of supply chains, quantifying impacts from raw-material sourcing through wastewater discharge. Process intensification and digital control ensure reproducibility and low environmental footprint. The cumulative effect of these advances is a shift towards eco-efficient tanning operations that meet regulatory requirements while opening markets for sustainably produced leather.

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Sustainable Tanning Processes in Leather Manufacturing publication trend

The graph below shows the total number of articles in sustainable tanning processes in leather manufacturing across all publications each year (not limited to Nature Index journals).

Technical terms

Vegetable tanning: Stabilisation of collagen fibres using plant-derived polyphenols, typically extracted from bark or seeds.

Chrome tanning: Conventional process employing chromium(III) salts to crosslink collagen, valued for fast reaction but associated with environmental hazards.

Life cycle assessment (LCA): Systematic evaluation of environmental impacts associated with all stages of a product’s life, from raw-material extraction to disposal.

Masking agent: Molecule that coordinates metal ions to moderate their reactivity and penetration in chrome-free or low-metal tanning processes.

Deep eutectic solvent: Mixture of hydrogen-bond donors and acceptors that forms a low-melting-point solvent, used to enhance reagent solubility and reduce water usage.

References

1. Advanced masking agent for leather tanning from stepwise degradation and oxidation of cellulose. Green Chemistry (2021).
2. A chrome-free combination tanning strategy: based on silicic acid and plant tannin. Collagen and Leather (2021).
3. Extraction of a novel tanning agent from indigenous plant bark and its application in leather processing. Collagen and Leather (2022).
4. Life cycle assessment and leather production. Collagen and Leather (2020).