Trends and advancements in sustainable leather processing: Future directions and challenges—A review

• Published in: Journal of environmental chemical engineering 2020-10, Vol.8 (5), p.104379, Article 104379
• Main Authors: J., Kanagaraj, Panda, Rames C., M., Vinodh Kumar
• Format: Article
• Language: English
• Subjects: Eco-benign finishing; Odour abatement system; Oxidative unhairing; Phyto-based preservation; Sustainable high exhaust tanning & dyeing systems
• ISSN: 2213-3437; 2213-3437
• DOI: 10.1016/j.jece.2020.104379

[Display omitted] •A state of art review of 91 articles on sustainable eco-friendly options of leather making.•Cleaner preservation of skins using phyto based preservatives: neem cake, leaves of Cassia &Psidium, polymer of ethylene oxide is developed.•Oxidative dehairing using sodium percarbonate, protease has resulted in reducing pollution loads.•High-exhaust sustainable tanning using co-polymers PVA, PEG, glyoxal tanning has been established.•Novel post-tanning and finishing operations for obtaining better organoleptic properties has been proposed. Global leather trade fetches 150 billion US$ annually. However, solid, liquid & gaseous emissions from the sector cause imbalance in the environment. In spite of sustained efforts by researchers, the gap between desired objectives with respect to sustainable leather technologies and achieved levels is still at large. At this juncture, this review presents an array of sustainable greener options addressing all major unit operations of leather making. As an alternative to traditional preservation, phyto-based preservation options for raw skins & hides reducing total dissolved solids and chlorides around 70 % are discussed. Oxidative unhairing reducing biochemical oxygen demand & chemical oxygen demand around 40 % is detailed as an alternate to traditional unhairing that is both harmful and polluting in nature. High-exhaust tanning technologies based on co-polymers increasing uptake to 95 % level are presented. The case of metal-free, organic only glyoxal/ wattle-tanned leathers with enhanced organoleptic properties is discussed. A starch-grafted collagen hydrolysate co-polymer exhausting dye up to 96 % is presented as high-exhaust dyeing system in this paper. Also, laccase-enzyme-based bio-degrading system for recalcitrant post-tanning effluent is furnished. A new method for extracting cellulose derivative from downstream wastes of sugar sector to be used in leather finishing is deliberated. A novel bio-filter based odour abatement system capturing noxious gaseous emissions from tannery environment is showcased as well. In all, this review reflects on the recent sustainable leather technologies that have potential for commercial exploitation in the near future.