Nanocellulose production from waste textiles by using deep eutectic solvents (DES) and its functionalization for hide treatment

In the last years, the large scale production in the textile sector and the consequent waste generation have massively increased. The phenomenon of fast fashion, which consists in the rapid replacement of new designs, is the major responsible for this crisis, bringing serious environmental issues regarding water, air and soil pollution. Thus, it’s necessary to employ waste optimization strategies, among which chemical recycle is one of the most effective and interesting when it comes to producing value added materials. In this scenario, deep eutectic solvents (DES), an emerging class of green solvents, play a crucial role because of their capability to dissolve cotton and produce nanocellulose (NC). The most attractive DESs features are the low volatility, their recyclability and biodegradability, as the most common components are organic compounds from natural sources. In the present thesis project novel DES formulations, comprising choline chloride as hydrogen bond acceptor and organic acids as hydrogen bond donors, are presented as medium for the production of NC from waste textiles. The complete characterization of the best performing DESs and of the corresponding NC samples is carried out. The second part of the thesis deals with the need for greener and more eco-friendly alternatives to chromium based hide tanning for the leather manufacture. In this field, every step, including the finishing, makes use of a huge amount of energy and materials, causing greenhouse gases emissions and water contamination. In this work, we explored the modification of the NC from waste textiles, in order to generate reactive functional groups towards collagen amino groups, providing an actual tanning reaction. Bifunctional molecules were employed, in order to have one reactive side for the OH groups of cellulose, leaving the other side available for the collagen grafting. With this strategy, our aim is to create a greener alternative to the polysaccharide oxidation with sodium periodate, typically employed for the synthesis of tanning materials. Moreover, the NC sample from waste textiles is tested in the finishing treatment of a real chrome-tanned leather specimen.