Biodegradability of leather: a crucial indicator to evaluate sustainability of leather

AbstractBiodegradability is a crucial indicator to evaluate the sustainability of leather. Herein, a rapid method for biodegradation test in an aqueous medium by measuring biochemical oxygen demand was used to determine the biodegradability of leather from different tanning methods, tanning conditions and process stages. In addition, the difference in biodegradability between leather and leather-like synthetic materials were investigated. Chrome-free tanned leather showed higher degree of biodegradation and faster biodegradation rate than chrome tanned leather. Among them, leathers tanned with biomass-based tanning agents were much easier to biodegrade because the crosslinking network of tanned leather constructed with biomass was more susceptible to microbial attack. The enhancement of tanning effects through changing tanning methods and conditions (such as tanning agent dosage, pH and temperature) resulted in the decline of leather biodegradability. Future development of novel chrome-free tanning technologies should balance between these two aspects. The biodegradability of leather from tanning to post-tanning to finishing showed a stepwise decrease because various chemicals were applied and bound to leather during processing. Even so, finished leather still possessed significantly higher biodegradability compared to leather-like PU and microfiber synthetic materials, demonstrating superior environmental sustainability of natural leather. The results are expected to provide support for the evaluation of the ecological properties of leather and green upgrade of the leather industry. Graphical abstract