Collagen structure changes during chrome tanning in propylene carbonate

Green solvents,such as propylene carbonate(PC),can be used in leather processing to improve the efficiency of chrome tanning and reduce wastewater.Here we report a combined small-angle X-ray scattering(SAXS)and differential scanning calorimetry(DSC)study on PC and its efficacy as a carrier medium during chrome tanning.SAXS analysis on the collagen structure of chrome tanned leather using PC,compared to conventionally tanned leather using water,showed an increase in Cr uptake in addition to the more uniform penetration of Cr through the leather cross-section.The increased binding of Cr to the collagen matrix drives the decreased hydration environment of the collagen triple helix.Furthermore,DSC studies show a uniform hydrothermal stability for the PC samples due to the more even distribution of Cr through the collagen matrix.Understanding the mechanisms by which chrome tanning occurs in non-aqueous solvents can guide us towards a more sustainable future for the leather industry.

A Novel Approach to Clean Tanning Technology

Traditional chrome tanning technology is still widely used today. In this technology, chrome shaving as well as chrome contained effluent in tanning and retanning processes is a big issue in the industry. Wet white tanning technology has been gaining in importance in recent years, but in general, the comprehensive performance of chrome-free tanned leather is not comparable with that of chrome tanned leather. In the present work, chrome-free tanning and chrome tanning are combined in a reversed procedure, which produces leather with chrome tanned leather quality without chrome tanned leather waste problems. In this procedure, a special amphoteric organic compound, no pickle, no salt chrome-free tanning agent TWT was used to tan delimed hides （no pickle） making wet white with shrinking temperature at 80-85 ~C. Then, new method called reversed tanning further process the wet white into chrome-tanned crust. In this reversed method, retanning, fatliquoring and coloring processes were carried out before chrome tanning. This technology eliminates chrome waste issue in tanning, shaving, post tanning processes. The chrome contained effluent is only concentrated in the last chrome tanning process. The leather made with this technology has complete conventional chrome-tanned leather quality. In this way, chrome leather quality without chrome waste problems was achieved. So, it is a new clean tanning technology.

Valorization of sustainable vegetable oil deodorizer distillate as a novel fatliquor

The deodorizer distillate(DD)is a byproduct of vegetable oil processing industry and is rich in functional bioactive components.This study aimed to employ phosphorylation modification for DD to produce a new sustainable fatliquor.The bioactive ingredients in DD,namely fatty acids,sterols,and tocopherols,were determined by using HPLC and GLC.The results revealed that the DD sample contained a high percentage of unsaturated fatty acids(72.3%)and high levels ofγandδ-tocopherols(54.8%and 31.60%,respectively).Mechanical parameters(tensile strength,elongation at break,and tear strength)of leather were improved after being treated with the prepared fatliquor emulsion.Eventually,SEM showed that the texture of the fatliquored leather had been remarkably enhanced.Moreover,the fatliquored leather possessed effective antibacterial effect against the specified+ve,-ve bacteria,and Candida albicans microorganisms.The strength,fullness,soft handle,and elasticity of leather were all improved,and the grain of leather was protected from becoming loose after drying.