Chemical modification of carboxymethylcellulose and its application as an innovative tanning agent

The leather manufacturing process, one of the oldest human activities, is a significant industry with a considerable impact on the global economy. The leather industry is an example of a circular economy: an unwanted putrescible byproduct of the meat industry can be transformed into a high added-value, stable product. To do so, hides collagen fibers need to be chemically stabilized by a tanning agent. This process employs a huge amount of water and chemicals (some of them hazardous) and generates a considerable quantity of solid, liquid sludge and volatile emissions. Given the growing need to make the process more sustainable, a relatively unexplored approach consists in using polysaccharides as tanning agents. Thanks to their abundance, biodegradability and chemical structure rich in polar groups, polysaccharides can interact with amino and carboxylate groups of collagen amino acids. The aim of this thesis is to develop new carboxymethylcellulose-based (CMC) tanning agents. For this purpose, the influence of different chemical modifications and molecular weight of CMC on the tanning efficiency, has been tested. The products synthetized were characterized by NMR spectroscopy (1H, COSY, HSQC, HMBC), Gel Permeation Chromatography (GPC), ATR-FTIR and elemental analysis. Finally, products synthesized were tested on collagen powder to verify their tanning efficiency and samples analyzed by Differential Scanning Calorimetry (DSC) in order to evaluate the final shrinkage temperature (Ts) of the treated material.