Hydrogen Peroxide-oxidized Soybean Polysaccharides as Novel Masking Agents for Zirconium Tanning

A series of hydrogen peroxide-oxidized soybean polysaccharides (HPS) were prepared using H2O2 and copper catalyst, which were then used as novel masking agents for zirconium tanning. The HPS samples were characterized by Fourier transforms infrared (FT-IR) spectroscopy, dynamic light scattering (DLS), and X-ray diffraction (XRD). FT-IR suggested the formation of carbonyl and carboxyl groups after hydrogen peroxide oxidation. DLS indicated that the HPS particle size decreases with increasing the H2O2 dosage. HPS with carbonyl and carboxyl groups and medium particle size was able to coordinate with zirconium to remarkably facilitate the tanning process. The shrinkage temperature of the tanned leather reached 92oC. Meanwhile, the fullness, softness, and mechanical properties of the leather were greatly improved by the tanning. The function of HPS and its interaction with zirconium were studied by FT-IR, XRD, and it was found that the triple helical structures of collagen fiber were not changed greatly. Scanning electron microscopy (SEM) showed that collagen fibers were dispersed and tanning agents were evenly distributed in collagen fibers. A new strategy for chromefree tanning is suggested and a strong support for the application of zirconium tanning is provided.