Effect of different ions in assisting protease to open the collagen fiber bundles in leather making

Large amounts of water and leather chemicals such as sodium sulfide and calcium hydroxide are used in conventional leather production, resulting in huge amount of wastewater and serious environmental pollution . Enzyme is eco-benign, and an ideal alternative to conventional chemicals attributed to its excellent characteristics and high efficiency. In this work, enzymes with different ions are used in beamhouse to remove the interfibrillar substance and open collagen fiber bundles. Analysis of the opened collagen fibers shows that the enzyme with both hydrogen phosphate and magnesium ions have the best effect in opening collagen fiber bundles. Results of wastewater analysis and the staining of hematoxylin-eosin (H&E) and Verhoeff’s Van Gieson (EVG) indicated the excellent removal of interfibrillar substance by all ion-assisted trials, suggesting an improved removal efficiency. The mechanical properties and shrinkage temperature of the leathers are similar to those of the conventional leathers. Since both deliming and bating are no longer required, a large amount of water can be saved, the leather making time can be shortened, and the cost of wastewater treatment can be reduced. Ion-assisted enzyme method is more efficient and environmentally friendly than the conventional one with sodium sulfide. This work presents a promising path for the cleaner leather making.