Leather Waste Research Articles

Extraction and Optimization of Tanning Material from Osyris lanceolata Barks: Cleaner Leather Tanning Processing

Tanning is a processing mechanism that prevents the collagen fibers from putrefaction to maximize the hydrothermal stability of leather. Tannin agents extracted from plants were used in leather production in a process called vegetable tanning. Vegetable tanning is an eco-friendly tanning method when compared to chrome tanning. Chrome tanning is the most common method of tanning hides. Currently, chrome tanning, which is extracted from chrome ores, is used in more than 80–90% of the leather tanning industry, but the most serious environmental issue associated with tanneries is chromium. This implies that the presence of chromium both in wastewater and in leather waste has a significant environmental impact and a high cost for landfills. However, currently, vegetable tanning and other tanning materials take up a 10–20% share of the leather tanning industry. Even today, most commercial vegetable tanning is a mimosa. In this study, a new alternative material and chrome-free tanning process using the barks of the Osyris lanceolata plant barks which reduces the environmental pollution load in terms of wastewater and solid wastes would be introduced. The study also aimed to improve the extraction and optimization mechanisms of tannin material from the bark of the Osyris lanceolata plant, which grows in Dera Hamusit Woreda in Ethiopia’s south Gonder Amhara region. In addition to these, the chemical and physical properties of experimentally treated leather were analyzed. This study’s results show that the bark of Osyris lanceolata contains (18.72%) tannin with 96% tanning strength (96%), and 49 percent purity. Also, leather treated with this tannin showed good shrinkage temperature (84.5°C), and organoleptic properties results such as tensile strength, tear strength, and elongation were 7.1 N/mm2, 19 N, and 45%, respectively. Besides that, the FTIR analysis shows that the bark of the Osyris lanceolata plant has a phenolic compound that is used for tanning purposes. This study clearly shows that extracted tannin from Osyris lanceolata has the potential to be used as an alternative tannin material in the leather tanning industry.

Preparation and characterization of composite sheets from solid leather waste with plant fibers: a waste utilization effort

Preparation and characterization of composite sheets from solid leather waste with plant fibers: a waste utilization effort

Pyrazole-directed functionalization of activated collagen fiber for highly specific capture of iodine vapor

The highly specific capture of radioactive iodine vapor generated during spent fuel reprocessing exerts a pivotal influence on ensuring the sustainable development of nuclear energy. In this study, we successfully prepared pyrazole-directed functionalized leather waste collagen fiber composite (Pyrazole@ACF) by immobilizing pyrazole ring through Schiff base reaction on the alkaline-activated collagen fiber (ACF) interface. The peak capacity for capturing iodine vapor by Pyrazole@ACF is shown to be 3.494 g/g, which is markedly higher compared to that of ACF (0.928 g/g). Pyrazole@ACF was characterized using FE-SEM, FT-IR, and XPS, revealing the release of numerous active functional groups from ACF that facilitated iodine-induced capture and pyrazole ring immobilization. Furthermore, the interaction mechanism between functional groups and iodine was further elucidated through Density Functional Theory (DFT) calculations. The iodine capture effect of Pyrazole@ACF is primarily ascribed to the existence of active functional groups (C = O, –OH, and –NH2) on ACF, as well as the charge transfer occurring between the grafted pyrazole moieties and iodine, ultimately leading to the generation of I3− polyiodide complexes and subsequent iodine capture. Consequently, Pyrazole@ACF exhibits a strong specific capture capability for iodine vapor, along with excellent thermal stability and iodine immobilization properties, meeting the application requirements under practical conditions.

Collagen hydrolyzed extract derived from leather waste as a multifunctional additive for the preparation of granular fertilizer

Effective treatment and high-valued utilization of chrome leather scraps have always been desired by all tanneries, which is of great significance for green and sustainable development of leather industry. In this paper, we first devised a green and effective approach to obtain collagen hydrolyzed extract (CHE) from chrome leather scraps, and then the obtained CHE was used in the granulation of pastoral soil to prepare CHE-Soil granular fertilizer. The results indicated that chrome leather scraps were effectively dechromed with sodium oxalate and then hydrolyzed by a high-pressure hydrothermal method without any chemical to obtain high-purity CHE. When the 4.5 wt%∼12.5 wt% CHE solution was introduced into the granulation process, the granulation rate of pastoral soil was up to 89.8%∼95.6%. However, the effective granulation rate was decreased due to the increase in large granule size (>5 mm). CHE-Soil granular fertilizer prepared by adding more CHE exhibited better surface roundness and more excellent crush resistance. Moreover, this type of granular fertilizer possessed excellent water retention and slow-released nutrient properties. Pine leaf peony cultivation experiments further showed that the presence of CHE-Soil granular fertilizer rapidly promoted plant growth and effectively increased the harvest of plants. This study indicated that CHE obtained from chrome leather scraps could be effectively used as a nutritious additive with adhesiveness to prepare the granular fertilizer for plant growth, which provides a novel idea for designing valorization methods of leather waste.

Study of the effects of bio-silica nanoparticle additives on the performance, combustion, and emission characteristics of biodiesel produced from waste fat

Numerous countries are investigating alternative fuel sources in response to the escalating issue of energy inadequacy. Using environmentally sustainable biodiesel as a potential alternative to fossil fuels, particularly from waste sources, is a developing prospect. This study aims to examine the feasibility of utilizing industry leather waste as a diesel fuel substitute. Traditional transesterification was used to obtain methyl ester out of leather waste. After processing, 81.93% of methyl ester was produced. Bio-silica (Bio-Si) is used as a fuel additive to enhance combustion and decrease emissions. This work utilized a leather industry waste fat biodiesel (LIWFB), LIWFB blend (B50), LIWFB blend with Bio-Si nanoparticles (B50Bio-Si50, B50Bio-Si75, and B50Bio-Si100 ppm) to analyze the engine outcome parameters at standard operating conditions. Experimental results revealed that adding Bio-Si in the biodiesel blend increased thermal brake efficiency (BTE) but was lower in diesel fuel. The biodiesel blends reduced NOx emissions more than Bio-Si nanoparticle blends. Furthermore, the smoke opacity was reduced by 31.87%, hydrocarbon (HC) emissions were reduced by 34.14%, carbon monoxide (CO) emissions were decreased by 43.97%, and oxides of nitrogen (NOx) emissions were slightly increased by 4.45% for B50Bio-Si100 blend compared to neat diesel. This investigation determined that all the emissions remained lower for all combinations than neat diesel, with a small increase in NOx emissions. Therefore, the LIWFB blend with Bio-Si nanoparticles was a viable diesel fuel alternative in diesel engines.

Mechanical, Drop Load Impact and Fatigue Properties of Silane-treated Chitosan and Waste Leather and Areca Fibre Epoxy Composite

Mechanical, Drop Load Impact and Fatigue Properties of Silane-treated Chitosan and Waste Leather and Areca Fibre Epoxy Composite

Supercomputer simulation of chip separation process during dimensional dispersion of elastoviscoplastic materials

Aspects of leather waste processing for their use in a dispersed state in the preparation of composite materials for various purposes are considered. It is shown that to reduce the relaxation and creep of the material, it is necessary to increase the cutting speed. A method is developed for dimensional dispersion with a claw-shaped impact-cutting tool, the complex movement of which is provided by a high-frequency vibration drive. In the LSTC LS-Dyna software for continuum mechanics modeling, a model of the process of dispersing leather waste is developed. Keywords: chip formation, modeling, leather waste, dimensional dispersion, impact cutting tool, elastoviscoplastic medium. sergeevys@susu.ru, sergeev-sv@list.ru, mr.maks.134@gmail.com

Fabrication of leather-like yarns using waste leather for textile application

The escalating focus on emulating natural textiles has prompted a concurrent surge in research aimed at developing leather-like materials. However, traditional leather products are mostly represented as sheets or blocks, which limit their reprocessing. Therefore, in this study, waste leather scraps were processed into powders with an average particle size of 5–10 μm. Subsequently, these recycled powders were wet-spun alongside a polyurethane matrix and polyester yarn to fabricate leather-like yarns. The leather-like yarns prepared in this study had good hygroscopic properties, mechanical properties (51.71 % strain and 4.49 cN/tex), and environmental stability (no more change withstood 24 h of bending, 50 cycles of immersion in 75 % ethanol solution, and 7 d of high and low temperature treatment). A no-salt and low-temperature dyeing method is further used to prepare color leather-like yarns, which requires less energy than polyester. These results provide guidance for the transition of recycling leather waste move to application, enabling the timely advancement of reusing leather waste initiatives in the textile industry.

Boosting the low-temperature NH3-SCR performance via metals co-doping with inequality Mn/Ce ratios in the carbon-based catalyst prepared by Cr-containing leather waste

The resource utilization of Cr-containing leather waste is still a great challenge. In this work, waste from leather production as raw material was attempted to be used to synthesize activated carbon, a series of MnxCe1-xZr0.5/AC composite catalysts were prepared via loading three metal elements onto activated carbon by impregnation method, the NH3-SCR performance was measured in a low temperature range of 50 ∼ 200 °C. Among them, the catalyst Mn0.7Ce0.3Zr0.5/AC displays the optimal low-temperature SCR activity, excellent resistance to GHSV, H2O and SO2. The characterization results indicated that increasing the Mn/Ce inequality ratios within a certain range would promote the electron transfer between the active metal components, thereby enhancing the synergistic effect and the redox capacity of the catalysts, and it also could significantly improve the concentration of Lewis acid sites to accelerate the adsorption and activation of NH3, resulting in different catalytic activities. The in situ DRIFTS results prove that the Lewis acid site plays a vital role in the “fast SCR” reaction, and the whole reaction process conforms to the Langmuir-Hinshelwood (L-H) mechanism.

Carbonized Leather Waste with Deposited Polypyrrole Nanotubes: Conductivity and Dye Adsorption.

This paper reports the conversion of a waste to a conducting material, exploiting the ability to adsorb pollutant organic dyes. Leather waste was carbonized at 800 °C in an inert nitrogen atmosphere. The resulting biochar was used for in-situ deposition of polypyrrole nanotubes produced by the oxidative polymerization of pyrrole in the presence of methyl orange. The composites of carbonized leather with deposited polypyrrole nanotubes of various composition were compared with similar composites based on globular polypyrrole. Their molecular structure was characterized by infrared and Raman spectra. Both conducting components formed a bicontinuous structure. The resistivity was newly determined by a four-point van der Pauw method and monitored as a function of pressure applied up to 10 MPa. The typical conductivity of composites was of the order of 0.1 to 1 S cm-1 and it was always higher for polypyrrole nanotubes than for globular polypyrrole. The method also allows for the assessment of mechanical features, such as powder fluffiness. The conductivity decreased by 1-2 orders of magnitude after treatment with ammonia but still maintained a level acceptable for applications operating under non-acidic conditions. The composites were tested for dye adsorption, specifically cationic methylene blue and anionic methyl orange, using UV-vis spectroscopy. The composites were designed for future use as functional adsorbents controlled by the electrical potential or organic electrode materials.

Exploring Tannery Solid Wastes as a Source of Animal Feed

This review delves into the processing of tannery solid waste, emphasizing fleshings and chromium-tanned leather waste. This paper centers on fat recovery, chromium elimination, and protein preservation, aiming to make them apt for animal consumption. This paper also assesses the potential of introducing such recycled products to the global market. Drawing on the literature from the past two decades, sourced comprehensively from Scopus and Web of Science, 36 articles were selected because of their significant contributions from leather production powerhouses such as India and Brazil. Fleshings have shown immense potential as animal feed, and the extraction of tallow and collagen from rawhide trimmings yields up to 98% and 93%, respectively. Fermented tannery fleshings, notably with Enterococcus faecium HAB01, also demonstrate strong antioxidant capabilities. The overarching consensus emphasizes the need for rigorous purification when dealing with chromium-containing wastes, addressing concerns tied to Cr (III) and Cr (VI). Furthermore, raw tannery fleshings stand out as a sustainable, cost-effective, and globally marketable solution for animal feed production.

Fabrication of Graphene Oxide Reinforced Biocomposite: Recycling of Postconsumed Footwear Leather

The increasing concerns about solid waste disposal have led to the development of innovative strategies for repurposing waste materials. This paper describes a simple solution casting process for recycling postconsumed footwear leather fiber (PCF) into a biocomposite film reinforced with graphene oxide (GO) and polyvinylpyrrolidone (PVP). PVP was utilized as a compatibilizer to strengthen the interfacial bonding of GO and leather fiber via π–π interactions. UV–visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy were used to examine the material dispersibility bonding between GO and PCF, structural properties, thermal properties, and surface morphology of the biocomposite films, respectively. Compared to pure PCF film, the oxygen transmission rate of the prepared biocomposite films is elevated by 64% as well as the biodegradability rate is intensified up to 60%. In addition, the film’s tensile strengths are raised by 216%, while their elongation at break is increased by 164.64% as compared with PCF. The versatility of these eco-friendly and biodegradable composite films extends to its possible applications in packaging and interior design. The outcomes of the research reveal the viability of manufacturing affordable and sustainable biocomposites through the utilization of waste leather from consumed footwear.

Ultrasonic vibration effect in the development of Al/CCLW/alumina metal matrix composite to enhance mechanical properties

This study represents the enhancement in mechanical, metallurgical, and thermal properties of composite synthesized by ultrasonic vibration effect. Collagen powder in the form of Cr2O3 was derived from chrome-containing leather waste (CCLW). Collagen powder and Al2O3 ceramic particles have been used to reinforce the development of an AA6061 aluminum alloy-based composite. Results showed that the composite developed under the ultrasonic vibration process showed better results by adding only 7.5% reinforcement particles (3.75% collagen + 3.75% Al2O3) to the matrix material as compared to the composite developed by the stir casting technique. The tensile strength and hardness were improved by about 40.41% and 44.27%, respectively when the composite was developed under the ultrasonic vibration effect. The compressive strength of composite material developed under the ultrasonic vibration effect was also improved by about 13.80% concerning the base material.

Carbonisation of chrome waste: sustainable energy, cost-effectiveness and recycling

The leather industry is currently under severe threat from efforts to eliminate environmental pollution issues caused by the generation of leather waste. Landfills must be used to dispose of leather waste, which harms the environment. Use of different chemicals during leather processing produces wastes in solid, liquid and gaseous forms, contributing to environmental pollution. The development of leather/paper-waste-based materials is a solution promoted by the recycled leather industry. A study was conducted in this work to prepare a polymerised electrolytic solution (PES) from chrome-containing leather waste using carbonised particles, microfibrillated cellulose and poly(ethylene glycol) to investigate their potential use in sustainable energy production. In this method, the consumed power (rechargeable) is based on the redox process. Field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy were used to investigate the physical and chemical features of the PES. On the PES, energy generation was demonstrated using a multimeter and rheological properties. The results show that energy was produced with a voltage of 1101.12 ± 1.00 mV per cell, a current of 639.12 ± 0.42 mA per cell and a resistance of 88.77 ± 0.17 Ω per cell. Rheological tests were conducted at 25°C with 8% (w/v) PES and gradually increased shear-strain rates of 0.01–100 s−1. This work presents the environmental results of a comparative examination of solutions for material and energy recovery from waste, along with those derived from mass and energy balances.

Coating of Carbonized Leather Waste with the Conducting Polymer Polyaniline: Bicontinuous Composites for Dye Adsorption

Leather waste carbonized at 800 °C in an inert atmosphere was coated in situ with the conducting polymer polyaniline. The composition of composites varied from neat carbonaceous to polyaniline. Due to the fibrous collagen structure of the original leather after carbonization, the composites had a bicontinuous conducting morphology. The resistivity of composites determined as a function of applied pressure from 0.1 to 10 MPa fell mainly into the range of units to tens of Ω cm. In contrast to neat polyaniline, the composites maintained a good level of conductivity even under alkaline conditions. The application of a composite as an adsorbent of organic-dye pollutants in water treatment was illustrated using methylene blue and methyl orange with an eye to future functional adsorbents controllable by applied electrical potential.

Acrylic Finished Leather Upgraded with Thermoplastic Polyurethane Filament using 3D Printing – A New Generation Hybrid Leather of Synthetic and Natural Polymer

Leather manufacturing process involves a lot of waste disposal which pollutes environment, some of the processes are inevitable. In the present investigation, 3D printing technology was used to reduce the wastage and to cover defective regions in leather. The present study focuses on synthesis of acrylic binder using emulsion polymerization technique. These binders were analysed for solid content for better optimisation of the amount of binder to be utilised for finishing operation. The experimental binder was prepared with 26% solids. Particle size and thermogravimetric analyses were carried out to understand the size and shape of the particles and their thermal resistance. These binders were used for leather finishing and the performance of leather was studied. Surface morphology changes of leathers were studied using Scanning Electron Microscopy (SEM). Wet and dry rub fastness, finish film adhesion, light fastness and organoleptic properties were studied and found to be superior compared with control leathers. The acrylic finished leather with minor defects was taken for 3D printing and designed using Thermoplastic Polyurethane (TPU) as filament. The acrylic finished leather shows good adhesion for TPU and it results in numerous designs in short duration. The new additive was added to leather using 3D printing technology to produce a tailor-made valuable design without any waste disposal and chemical discharge. This invention may convert the rejected waste leather into valuable material and lead to the new generation hybrid leather for use.

Study on the Pyrolysis Kinetic Behaviors of Different Vegetable-Tanned Sheepskin Leathers

The pyrolysis behaviors of leathers tanned with hydrolyzable tannins (Tara and Chestnut extracts), and condensed tannins (Quebracho and Mimosa extract) were studied by Thermogravimetric (TG) analysis in the present work. The TG/derivative thermogravimetry (DTG) results showed that the thermal stability of Tara- and Chestnut-tanned samples is poorer than that of Quebracho- and Mimosa-tanned ones. In order to study pyrolysis kinetics, TG experiments at different heating rates were carried out. Two methods of Flynn-Wall-Ozawa (FWO) and Friedman (FR) were employed to calculate the pyrolysis activation energy (Eα) of the samples. It was found that the average Eα of the vegetable-tanned samples is located at the range of 191.7-206.1 kJ/mol. The thermodynamic parameters (pre-exponential factor, Gibbs free energy, enthalpy, and entropy) of the samples were subsequently calculated based on the average Eα by the FR method. The Gibbs free energies of the Chestnut-, Tara-, Quebracho-, and Mimosa-tanned leathers were 176.9 kJ/mol, 179.8 kJ/mol, 179.3 kJ/mol, and 178.2 kJ/mol, respectively. The difference between the average enthalpies and the Eα is less than 5 kJ/mol, which indicated that the pyrolysis process is conductive to the product formation. The mean entropy (ΔS) of the four vegetable-tanned samples is all positive, which suggested that the pyrolysis of the samples could easily take place. This work might provide theoretical guidance for the optimization of vegetable-tanned leather waste pyrolysis.

Synergistic Adsorption and In Situ Catalytic Conversion of SO2 by Transformed Bimetal-Phenolic Functionalized Biomass.

SO2 removal is critical to flue gas purification. However, based on performance and cost, materials under development are hardly adequate substitutes for active carbon-based materials. Here, we engineered biomass-derived nanostructured carbon nanofibers integrated with highly dispersed bimetallic Ti/CoOx nanoparticles through the thermal transition of metal-phenolic functionalized industrial leather wastes for synergistic SO2 adsorption and in situ catalytic conversion. The generation of surface-SO32- and peroxide species (O22-) by Ti/CoOx achieved catalytic conversion of adsorbed SO2 into value-added liquid H2SO4, which can be discharged from porous nanofibers. This approach can also avoid the accumulation of the adsorbed SO2, thereby achieving high desulfurization activity and a long operating life over 6000 min, preceding current state-of-the-art active carbon-based desulfurization materials. Combined with the techno-economic and carbon footprint analysis from 36 areas in China, we demonstrated an economically viable and scalable solution for real-world SO2 removal on the industrial scale.

Waste leather derived porous carbon boosted Fenton oxidation towards removal of diethyl phthalate: Mechanism and long-lasting performance

The acceleration of Fe(III)/Fe(II) conversion in Fenton systems is the critical route to achieve the long-lasting generation of reactive oxygen species towards the oxidation of refractory contaminants. Here, we found that waste leather derived porous carbon materials (LPC), as a simple and readily available metal-free biochar material, can promote the Fe(III)/H2O2 system to generate hydroxyl radicals (•OH) for oxidizing a broad spectrum of contaminants. Results of characterizations, theoretical calculations, and electrochemical tests show that the surface carbonyl groups of LPC can provide electron for direct Fe(III) reduction. More importantly, the graphitic-N on surface of LPC can enhance the reactivity of Fe(III) for accelerating H2O2 induced Fe(III) reduction. The presence of LPC accelerates the Fe(III)/Fe(II) redox cycle in the Fe(III)/H2O2 system, sustainable Fenton chain reactions is thus initiated for long-lasting generation of hydroxyl radicals without adding Fe(II). The continuous flow mode that couples in-situ Fenton-like oxidation and LPC with excellent adsorption catalytic properties, anti-coexisting substances interference and reusability performance enables efficient, green and sustainable degradation of trace organic pollutants. Therefore, the application of metal-free carbon materials in Fenton-like system can solve its rate-limiting problem, reduce the production of iron sludge, achieve green Fenton chemistry, and facilitate the actual engineering application of economic and ecological methods to efficiently remove trace organic contaminants from actual water sources.

Preparation and characterization of polyvinyl alcohol/secondary collagen fiber gel membrane with excellent mechanical property

AbstractThe reuse of leather waste is a global challenge because of the increase of leather products. In this paper, collagen fiber (CF) was extracted from leather waste and polyvinyl alcohol (PVA) gel membranes containing CF with high mechanical property are fabricated by freeze–thaw method. Results shows that the composite gel membrane maintains the helical structure of CF. The tensile strength of the PVA/3CF‐FW increases to 58.5 MPa, while its elongation at break increases to 365%. The swelling ratio increases with the addition of CF, and the PVA/7CF composite gel membrane has the highest swelling ratio, which is 11.65. However, the crystallinity reduced with the addition of CF. Compared to the pure 24PVA gel membrane and the PVA/GA gel membrane, the PVA/CF composite gel membrane prepared by freeze–thaw method has a better mechanical property.Highlights Taking leather waste as raw material to extract collagen fiber. The gel membranes containing collagen fiber have hardly been reported. The gel membranes show good swelling ratio and mechanical properties.