Nanocomposite-based green tanning process of suede leather to enhance chromium uptake

A nanocomposite-based green tanning process of suede leather was developed, which could be recognized as an eco-friendly chrome-less tanning process. In this study, nanocomposites were applied in tanning and retanning process during suede leather making. Effects of nanocomposites on shrinkage temperature, mechanical properties, softness, biodegradability of the leather samples were investigated; The resulting leather was characterized by scanning electron microscopy and atomic force microscopy; Effects of nanocomposites on the chromium load, biochemical oxygen demand, chemical oxygen demand in the wastewater were analysed. The results show that the addition of nanocomposites could endow the leather with high hydrothermal stability, biodegradability and softness; The mechanical properties of the leather treated with nanocomposites were close to those of the chrome-treated leather; The SEM and AFM indicated the resulting leather treated with nanocomposites contained well-dispersed fibrils and uniform fluff. Additionally, it was found that nanocomposites applied in the tanning and retanning processes brought better chromium uptake and reduction of chromium load in the wastewater. The ratio of biochemical oxygen demand and chemical oxygen demand in the wastewater was 0.37, which demonstrates that the effluent of less chrome combination retanning systems was more easily biodegradable than that of the chrome retanning process and the experimental process exhibited lowest chemical cost as compared to the chrome tanning process. Nanocomposites applied in the suede leather making process could improve the properties of the resulting leather and help to realize the cleaner production.