Extraction of a novel tanning agent from indigenous plant bark and its application in leather processing

Abstract

The use of vegetable tanning materials in leather processing has drawn attention as an alternative to basic chromium sulphate for its natural abundance and environmental aspects. In this work, an attempt has been made to extract vegetable tannins from Xylocarpus granatum bark using different solvents (e.g., water, methanol, ethanol, and chloroform) and compare with conventional vegetable tanning agents such as mimosa and quebracho. The highest extraction efficiency was observed 31.22% by methanol. The presence of tannin content and polyphenolic compounds, e.g. (-)epicatechin (503 mg/100 g dry extract), catechin hydrate (218 mg/100 g dry extract), catechol (29 mg/100 g dry extract) were ensured by UV–Vis, FT-IR spectroscopy and HPLC. Again, condensed tannins, moisture content, and pH of the methanol extracted tannin were found 47.80%, 5.82%, and 3.97 respectively. The leather tanned by Xylocarpus granatum tannin showed a shrinkage temperature of 86.34 ± 1.52 °C. Other properties such as tensile strength, tear strength, grain cracking load, and distention at grain cracking were comparable to conventional vegetable-tanned leather. The cross-sectional morphology of the tanned leathers was also characterized by scanning electron microscopy (SEM) which revealed a compact structure of the leather fibers. In light of the findings from the study, X. granatum bark tannin could be a well alternative to chromium and a new source of vegetable tannin for the leather industry. Graphical Abstract

Application of Indigenous Plant-Based Vegetable Tanning Agent Extracted from Xylocarpus granatum in Semi-Chrome and Chrome Retanned Leather Production

“…Extract of X. granatum bark (vegetable tanning agent) was prepared using 100% methanol by rotary evaporator in a previous study of the same author and found 31.22% extraction efficiency of tannin [22]. The extracted tannin was found to be a condensed type of tannin whereas the Xylocarpus granatum bark tannin contained 48% of condensed tannin [22]. It was applied in leather to produce semi-chrome and chrome retanned leather for evaluating their necessary properties.…”

Potential Use of Quercus dalechampii Ten. and Q. frainetto Ten. Barks Extracts as Antimicrobial, Enzyme Inhibitory, Antioxidant and Cytotoxic Agents

“…Quercus species, commonly known as “oaks”, belong to the group of the most exploited deciduous trees, which are a source of wood for the manufacture of furniture as well as for fuel. The main waste resulting from the primary processing of oak is represented by its bark, which is mostly used as an alternative fuel or tanning agent in the leather industry [ 6 , 7 ]. Moreover, the bark of different oak species is cited as a herbal product with long-term documented use in human and veterinary medicine, especially for their tannin-rich content correlated with astringent, hemostatic, antibacterial, or antidiarrheal properties [ 8 , 9 , 10 , 11 ].…”

Insights into the Development of Imine-Bond-Stabilized Organic Tanning and a Heteropolymer for the Post-Tanning Process─A Metal-Free Sustainable Leather Process

“…Several organic tannins extracted from plants have been used as organic tanning agents, including tannins extracted from Tessmannia burttii Harms. Xylocarpus granatum produces leather with good thermal stability and has been reported as an eco-friendly source of veg tannins for a chromium-free process. , Glutaraldehyde is the most commonly used aliphatic aldehyde in the tanning process. Still, its usage is restricted because of free aldehydes, potential carcinogenic agents that cause oxidative cell damage in living cells.…”