Developing Ecofriendly Chrome-Free Leather Processing-Based Polymer-Intercalated Layered Double Hydroxide Supramolecules

Abstract

Development of eco-friendly chrome-free tanning agents is an inevitable way to realize the sustainable development of the leather manufacturing industry. A sustainable chrome-free leather processing based on polymer-layered double hydroxide (LDHs) supramolecules is reported in this work. P(MAA-IA)-LDH (P-LDH) and GEP(MAA-IA)-LDH (GEP-LDH) supramolecules are constructed by an ion exchange method using P(MAA-IA) (P) and GEP(MAA-IA) (GEP) as intercalators, strengthening the interface interaction between the supramolecules and collagen fibers by improving their dispersion in the resulting leather. Our results indicate that P and GEP enter the LDH interlayer and increase the interlayer distance of P-LDHs and GEP-LDHs from 0.783 nm of LDHs to 1.252 and 1.158 nm, respectively, resulting in an increase in the specific surface areas of P-LDHs and GEP-LDHs. Moreover, compared with LDHs, P-LDHs and GEP-LDHs can be more easily diffused into collagen fibers and uniformly bound onto collagen fiber strands and between the collagen fibrils. The hydrogen bond, ionic bond, and coordination bond formed among collagen with LDH supramolecules can stabilize the integral triple-helical conformation of collagen, giving the resulting leather enhanced thermal stability, porosity, mechanical properties, enzymatic resistance, and decreased swelling ratio. Meanwhile, the incorporation of LDH supramolecules can improve the flame retardancy and smoke suppression property of the resulting leather, and the peak heat release rate (PHRR), total heat release (THR), and smoke production rate (SPR) of GEP-LDH tanned leather decrease by 23.1, 45.1, and 55.5%, respectively, in comparison to those of the pickled pelt. The GEP-LDH tanned leather exhibits better multifunctional properties due to more uniform dispersion in collagen fibers. Moreover, the absorption rate of dyes (91.2%) and fatliquoring agents (85.7%) of GEP-LDH tanned leather is higher than that of F-90 and TWS, close to the traditional chromium tanning agents, and the GEP-LDH tanning system exhibits a better degradability in comparison with the F-90 and TWS tanning systems. This work provides insights for developing a sustainable chrome-free leather system for versatile eco-leather manufacture.

Lignin Demethylated by Protic Ionic Liquid as a Novel and Sustainable Chrome-Free Tanning Agent for Eco-Leather Production

“…Therefore, attenuated total reflectance (ATR)–FTIR and XPS analyses of leather samples were utilized to explore the interactions formed between the tanning agents and collagen. As shown in Figure a, all leather samples exhibited clear amide characteristic bands: amide A band (peaks at 3309 and 3062 cm –1 , attributed to N–H stretching vibrations and confirming hydrogen bonding), amide B band (2924 cm –1 , N–H stretching and – CH 2 asymmetrical stretch vibrations), amide I band (1643 cm –1 , CO stretching vibrations), amide II band (1535 cm –1 , N–H bending and C–N stretching vibrations), and amide III band (1234 cm –1 , C–N stretching, N–H bending vibrations, and −CH 2 wagging). , The positions of the amide I, II, and III bands were almost unchanged among all samples, indicating that the triple-helix structure of collagen was well maintained after tanning . As shown in Figure b, the amide A band of R1, R2, L1, and L2 after tanning was shifted compared to that of PS.…”

“…New peaks in R2 and L2 spectra (530.09 and 530.56 eV, respectively) were attributed to the coordination of Al 3+ /Zr 4+ with oxygen on collagen, indicating that Al 3+ /Zr 4+ tanning agents formed strong interactions with carboxyl groups on collagen. , As for N 1s, deconvolution peaks were observed at 399.03 and 399.60 eV. Compared with those of PS, the O–H and N–H binding energies of R1 and L1 shifted to higher values, indicating that RL and LP could form interactions with carboxyl and amino groups on collagen . Interestingly, the increase in the O–H binding energy was more pronounced for L1 (0.26 eV) than for R1 (0.04 eV), suggesting that LP can form stronger interactions with carboxyl groups on collagen than RL.…”

Nanoparticle Usage in Leather Processing: Worker Safety and Health

“…Nanomaterials, owing to their distinct design, superior performance, and novel characteristics, have earned the title of “materials of the 21st century”. Within the framework of nanomaterials, considerable attention has been given to engineered nanoparticles (NPs) of various kinds. − The unique mechanical, electrical, and optical properties of nanoparticles, owing to their small size, make them suitable for a diverse range of potential uses, ranging from general medical applications to human health devices, industrial productions, electronics, energy, environmental applications, and beyond, including the leather industry . Indeed, to enhance the performance of the final leather, nanoparticles have been utilized across multiple stages of leather manufacturing.…”