Preparation of a Highly Effective Organic Tanning Agent with Wide Molecular Weight Distribution from Bio-Renewable Sodium Alginate

摘要

Dialdehyde sodium alginate (DSA) with wide molecular weight distribution was prepared by periodate oxidation without alcohol-precipitation. Its tanning properties in fur processing were investigated. It was found that this DSA could endow fur with high shrinkage temperature (Ts, 89°C) and area yield (107%), showing better tanning properties than conventional dialdehyde sodium alginate product that was prepared by repeated alcohol-precipitation process and thus had narrow molecular weight distribution. Low molecular weight components in DSA mainly contributed to crosslinkage and dispersion of the collagen fiber network, viz. tanning effect, while high molecular weight DSA components contributed to filling performance. SEM analysis illustrated that satisfactory dispersion of skin matrix and intact scale layer of wool were achieved by DSA tanning. The DSA tanned fur exhibited reasonable resistance to oxidation bleaching and presented a better performance in physical properties compared with traditional chrome tanned fur after fatliquoring. Besides, the DSA tanning system led to a better treatability of tanning and post-tanning wastewaters in view of chrome-free and higher biodegradability. The DSA with wide molecular weight distribution is a potential sustainable tanning agent in terms of both preparation and tanning processes.