Effects of different salt-enzymes on opening up of collagen fiber bundles for leather making

Traditional leather industry involves mechanical, chemical and biological processes, and a lot of leather chemicals are widely used annually. In the beamhouse, especially in liming and re-liming, enormous pollution is usually released because of the traditional use of Na2S and lime. Many researchers have devoted to clean production for leather making. In this study, salt-enzyme liming process was studied in modern leather process to remove the inter-fibrillary matter. Three such salts as Na2SO4, NaCl, and MgCl2 were used with such enzymes as neutral protease and cellulase. The enzyme activity was evaluated by Folin Method. The opening up degree of collagen fiber bundles was observed by SEM and microscopic image of histological staining. The waste water was analyzed. The tannin absorptivity of the samples was evaluated by colorimetry. It was demonstrated that enzyme activity is not affected by salt, but it helps the action of enzymes on hides. Salt might accelerate the penetration of enzymes into the hide to promote the removal of inter-fibrillary and the opening up of collagen fiber bundles. The best fiber opening result was found by SEM at the MgCl2 content of more than 0.4 wt.% in liming. Microscopic observation by histological staining as well as waste water analysis indicated a good removing effect for the inter-fibrillary. This work may provide a cleaner leather making technology. © 2019 VGCT.