Oxidized sodium lignosulfonate: A biobased chrome-free tanning agent for sustainable eco-leather manufacture

Lignin Demethylated by Protic Ionic Liquid as a Novel and Sustainable Chrome-Free Tanning Agent for Eco-Leather Production

“…Meanwhile, the absorption peak attributed to CO stretching at 1697 cm –1 was weakened and slightly shifted to 1681 cm –1 after complexation. These changes suggested that Al 3+ /Zr 4+ formed unequal coordination with –OH and −O–CO groups in LP. , The intensity of the absorption peak at 833 cm –1 , attributed to the stretching vibrations of the aromatic skeleton, was also slightly weakened in LP-AZ compared to that in LP. Since phenolic –OH groups dissociate more readily than aliphatic –OH groups, they are more susceptible to form coordination sites with Al 3+ /Zr 4+ .…”

“…According to our previous research, [EOA]­[OAc] used in this study is approximately $0.70–1.40 kg –1 . In addition, the demethylation process of lignin by [EOA]­[OAc] to prepare LP can be operated under mild and halogen free conditions (e.g., 90 °C, 2 h). , Therefore, LP tanning has good sustainability in both economic and environmental aspects …”

“…26,58 Therefore, LP tanning has good sustainability in both economic and environmental aspects. 25 Tanning Trials. Tanning experiments consisted of two sections: (1) lignin-based tanning; (2) combination tanning with aluminum/ zirconium salts and RL or LP.…”

“…However, producing these tanning agents generally requires harsh conditions or toxic reagents, limiting their largescale development. 24,25 Meanwhile, less effort has been focused on the direct use of crude lignin from industrial waste for tanning. We recently demonstrated that enzymatic lignin can be treated with a halogen-free protic ionic liquid (PIL), [EOA][OAc], to prepare LP.…”

“…To the best of our knowledge, only a few lignin-based tanning agents have been reported to date, including the repolymerized degradation products of lignin sulfide and sodium lignosulfonate decolored with hydrogen peroxide. However, producing these tanning agents generally requires harsh conditions or toxic reagents, limiting their large-scale development. , Meanwhile, less effort has been focused on the direct use of crude lignin from industrial waste for tanning. We recently demonstrated that enzymatic lignin can be treated with a halogen-free protic ionic liquid (PIL), [EOA]­[OAc], to prepare LP .…”