Starch-Leather Waste Gelatin Films Cross-Linked with Glutaraldehyde

Abstract

Gelatin extracted from chromium-tanned leather wastes (CTLW) has a lower molar mass because of the more aggressive extraction process needed to disrupt chromium-collagen bonds when compared to gelatin extracted from the bones, skin, and connective tissues of animals. As a consequence, CTLW gelatin is more hydrophilic, thus it is harder to apply in the production of polymers. To overcome this issue, in this study, films produced with starch, CTLW gelatin, commercial gelatin (as a comparative), and their blends were cross-linked with glutaraldehyde. The cross-linking reduced the crystallinity of the films, impairing the reorganization of gelatin chains into a triple helix structure, which balanced the effect of the higher molecular chain, while not altering the films' tensile strength. It increased the elongation at break and reduced the solubility and the swelling degree by up to 53% and 69%, respectively. These results stand as a great advance for the practical use of starch-CTLW gelatin films.

Physico‐mechanical, thermal, and ultraviolet light barrier properties of collagen hydrolysate films from leather solid wastes incorporated with nano TiO2

“…Jin et al noticed that EAB (%) of jackfruit filum polysaccharide film increased after the addition of TiO 2 NPs. Scopel et al also reported that the CH/starch/glycerol films had the highest value of EAB (60.11%) when comparing with films used as mulches in agriculture.…”

Combined effect of transglutaminase and phenolic extract of Spirulina platensis in films based on starch and gelatin recovered from chrome III tanned leather waste

“…Comparing the films produced with CTLW and COM gelatin (control), it can be noted that the CTLW films show higher interaction with water, characterized by higher water vapor permeability and solubility in water. This is can be attributed to the hydrolysis of the gelatin molecules during the extraction process, which renders them more hydrophilic and reduces their molecular mass 9 . There are also hygroscopic salts present, enhancing water interaction properties 10 …”

“…For example, the extraction of gelatin for the application in biodegradable films is a sustainable alternative. Its application in cosmetics or food is not indicated because it is a waste containing chromium 9 …”

“…The elaboration of films from gelatin extracted from leather residues tanned by chrome (III) (CTLW) and corn starch has already been studied 9–11 . However, they have some disadvantages, such as lower tensile strength values, higher degradation rate, and high hydrophilic capacity, especially in humid environments, rendering their application for long periods unfeasible 10 .…”

A ‘Trojan horse strategy’ for the development of a renewable leather tanning agent produced via an AlCl3-catalyzed cellulose depolymerization

“…However, their use is becoming more and more restrictive, due to their potential risk to human health and environmental issues, especially when Cr(III) is oxidized to Cr(VI), which is a human carcinogen. [10][11][12] Therefore, the development of an ecofriendly chrome-free metal, tanning agent is of paramount importance for the sustainable development of the leather science and industry. In addition, because of the high coordination ability of metals as the tanning agents, the metal species can strongly react with the collagen fibers in the initial stage of the tanning process, leading to a metal overload on the leather surface, which results in a non-uniform penetration and a consequently weak tanning effect.…”