Development of sustainable tannin with low carbon footprint to obtain high quality leather

Abstract

Today we are experiencing an "eco friendly boom"; which includes the developing of ecological processes that have a smaller impact in the environment. This is the reason that prompted me to carrying out this thesis; the aim is to use a vegetable extract as a sustainable product for the pre-tanning processes. This study considers the use of the fruit of the Tara tree as a raw material source of tannins with low carbon footprint and proposes alternatives to avoid or reduce the use of commercial vegetable extracts, synthetic products and mineral salts that require non sustainable processes. Various experimental designs have been developed as to obtain new tailored Tara tannins by both chemical and physical modification, in order to obtain a higher percentage of tannins, and therefore improve its tanning capability, also reducing the astringency and improving the penetration of the tannin molecules through the leather structure. In chemical modifications, several aqueous extractions at different temperatures and combined with some chemicals, have been developed and optimized in order to increase the tannin content and reduce the astringency. The degree of hydrolysis has controlled by measuring the Gallic acid content by means of HPLC (High performance liquid Chromatography). In the physical modification part, the Tara has been milled and sieved, at several particle sizes, with the aim of obtaining a smaller molecular size. Both chemical and physical modifications were tested in hides, in a wet-white pre-tanning process, combining them with the fewest possible commercial vegetable extracts and syntans. The formulations have been optimized by experimental design. All the resulting leather products and final baths have been analyzed with physical and chemical tests respectively, to determine if they comply with the parameters established by the IULTCS (International Union of Leather Technologists and Chemists Societies). Finally, a life cycle assessment has been developed, in order to determine the environmental improvement of the new modified product, obtained in this thesis. This thesis is also supported with articles published in magazines specialized in the Leather sector. There are two articles published in the Journal of the American Leather Chemists Association (JALCA), named: *Low carbon products for the design of innovative leather processes. Part I: determination of the optimal chemical modification of tara. . (JALCA, Vol. 108, pag. 386-391, 2013) *Low carbon products for the design of innovative leather processes. Part II: determination of the optimal physical modification of tara. (JALCA, Vol. 109, pag. 25-31, 2014) One article pending to be published in the Journal of AQEIC (Spanish Leather Chemists Association) Application of Sustainable tannins with Low carbon footprint,And presented in the 62nd Congress of AQEIC, Lorca (Murcia), May 10th and 11th, 2013 Presentation: "Aplicación de taninos sostenibles con baja huella de carbono"