Life Cycle Assessment for Chrome Tanning, Chrome-Free Metal Tanning, and Metal-Free Tanning Systems

Abstract

Life cycle assessment (LCA) was applied to compare environmental impacts of a chrome tanning system (CTS) using basic chrome sulfate (Cr), a chrome-free metal tanning system (CFMTS) using complexes of highly oxidized starch and Al−Zr (HOS−AZ), and a metal-free tanning system (MFTS) using oxidized sodium alginate (OSA). The preparation processes of Cr, HOS−AZ, and OSA were first evaluated by LCA to make the life cycle inventory available for their tanning systems. Life cycle impact assessment results showed that Cr, HOS−AZ, and OSA were the most significant substance factors in their tanning operations. The tanning operation was the main contributor to the environmental impacts of a tanning system followed by retanning and fatliquoring operations. The environmental impacts on resource consumption and climate change presented CTS > CFMTS > MFTS, while those on ecosystem quality and human health were comparable. The MFTS is a more sustainable tanning system for leather production. This work provides basic data support for the ecological design of leather products and gives new insights into the LCA of complex leather processing systems.

Tara Tannin-Cross-Linked, Underwater-Adhesive, Super Self-Healing, and Recyclable Gelatin-Based Conductive Hydrogel as a Strain Sensor

“…Tara tannin is widely distributed in Latin America as a kind of abundant, cheap, and easily available natural biomass. The chemical structure of Tara tannin has been confirmed by previous researchers, which is formed by the combination of polygallic acid and quinic acid through an ester bond. − Tara tannin belongs to the hydrolyzable tannins and is often used as a tanning agent in the leather industry due to its astringent property and very light color. , During the tanning process of the hide/skin, Tara tannin first approaches collagen fibers in the form of hydrophobic bonds, and when tannin molecules are firmly bonded, cross-linking networks are generated between collagen fibers, which transforms the hide/skin into leather. − Similarly, we believe that if Tara tannin was introduced into the gelatin hydrogel, it can act as an effective cross-linking agent by producing multipoint hydrogen bonding and hydrophobic interactions with gelatin molecules to form the 3D network of the gelatin hydrogel.…”

Development of Leather Fiber/Polyurethane Composite with Antibacterial, Wet Management, and Temperature-Adaptive Flexibility for Foot Care

“…Therefore, leathers inevitably contain a small amount of unbound chromium. When it contacts skin, the free chromium on the product surface may be released by the aid of sebum and sweat derived from skin, which is harmful to human body and the environment . Typically, it is known that Cr­(VI) is easily absorbed into the human body because the active form of Cr­(VI) as chromate structurally resembles sulfate and therefore readily penetrates the cell membrane, including those of red blood cells, by sulfate transporters.…”

Sustainable metal-free leather manufacture via synergistic effects of triazine derivative and vegetable tannins

“…However, conventional chrome tanning generates substantial non-renewable chrome-containing wastewater [2] and solid wastes [3,4]. These unfixed Cr(III) in leather and wastewater may be oxidized to carcinogenic Cr(VI) [5,6], which seriously threatens human health and environment. Therefore, various countries or regions have released stringent restrictions regarding the Cr discharge.…”