Silicate enhanced enzymatic dehairing: a new lime-sulfide-free process for cowhides.
A conventional dehairing process with sodium sulfide and lime is a major source of the pollution from the tanning industry. In other words, conventional dehairing processes degrade the hair to the extent that it cannot be recovered; thus, these processes become a major contributor to wastewater pollution. In this study, an attempt has been made to develop a lime and sulfide-free dehairing process using a commercial enzyme formulation with the activation of a silicate salt. A dip and pile method of application has been standardized. The amount of enzyme and sodium metasilicate has also been optimized based on complete removal of hair. Enhancement of enzyme activity by the addition of silicate has been demonstrated through activity measurements. Hair removal is found to be complete using scanning electron microscope analysis. Strength and bulk properties of the experimental leathers are comparable to that of control leathers. The process enjoys a significant reduction in chemical oxygen demand (COD) and total solids (TS) by 53 and 26%, respectively. More importantly, the application of enzyme for dehairing results in an 8% area increase in the final leather. Also, the process is proven to be techno-economically feasible.
Saravanabhavan
Subramani
S
Chemical Laboratory, Centre for Leather Apparel and Accessories Development, Central Leather Research Institute, Adyar, Chennai 600 020, India.
Thanikaivelan
Palanisamy
P
Rao
Jonnalagadda Raghava
JR
Nair
Balachandran Unni
BU
D000818:Animals; D002417:Cattle; D006204:Hair Removal / Q000379:methods*; D007220:Industrial Waste / Q000032:analysis; D008855:Microscopy, Electron, Scanning; D010447:Peptide Hydrolases / Q000378:metabolism*; D017640:Silicates / Q000737:chemistry*; D013633:Tanning; D014876:Water Pollution / Q000517:prevention & control*
D007220:Industrial Waste; D017640:Silicates; C025349:sodium metasilicate; D010447:Peptide Hydrolases