Leather Dyeing Research Articles

Challenges of Lab-Scale Study and the Influence of Wet-Finishing Agents in the Leather Dyeing Process

Challenges of Lab-Scale Study and the Influence of Wet-Finishing Agents in the Leather Dyeing Process

Traditional Fish Leather Dyeing Methods with Indigenous Arctic Plants

Along the Arctic and sub-Arctic coasts of Alaska, Siberia, north-eastern China, Hokkaido, Scandinavia and Iceland, people have dressed in clothes or worn shoes made of fish skin for millennia. (Within this article, the terms fish skin and fish leather are used to indicate different processes of the same material. Fish skin: Skin indicates the superficial dermis of an animal. Fish skin is referred to as the historical raw material that is tanned following traditional methods such as mechanical, oiling and smoking tanning, using materials such as bark, brain, urine, fish eggs and corn flour. Fish leather is used to refer that the fish skin has passed one or more stages of industrial vegetable or chrome tanning production and is ready to be used to produce leather goods). These items are often decorated with a rich colour palette of natural dyes provided by nature. In this study, minerals and raw materials of plant origin were collected from riverbanks and processed by Arctic seamstresses who operated as designers, biochemists, zoologists, and climatologists simultaneously. During our research, an international team of fashion, tanning and education specialists used local Arctic and sub-Arctic flora from Sweden, Iceland, and Japan to dye fish leather. Several plants were gathered and sampled on a small scale to test the process and determine the colours they generated based on the historical literature and verbal advice from local experts. This paper describes the process and illustrates the historical use of natural dyes by the Arctic groups originally involved in this craft, building on the traditional cultural heritage that has enabled us to develop sustainable dyeing processes. The results are promising and confirm the applicability of these local plants for dyeing fish skins, providing a basis for a range of natural dye colours from local Arctic flora. The aim is to develop a moderate-sized industrial production of fish leather in this colour palette to replace current unsustainable chemical dyeing processes. This project represents an innovation in material design driven by traditional technologies, addressing changes in interactions between humans and with our environment. The results indicate that new materials, processes, and techniques are often the fruitful marriage of fashion and historical research of traditional methods, helping the industry move towards a more sustainable future.

Preparation of cationic waterborne polyurethane and its application in leather dyeing

The development of organic chromium-free tanning agents is currently a major research focus in leather tanning. However, these agents decrease the electrical potential of the tanned leather, which hampers the absorption of subsequent anionic dyes and fatliquoring agents. Consequently, issues such as lower color fastness, poor dyeing effects and environmental pollution arise. To address these challenges, this study proposes the utilization of anionic polyurethane (CWPU) as a dye fixing agent to enhance its performance and application in the leather preparation process. CWPU was successfully synthesized using polycarbonate diol (PCDL), isophorone diisocyanate (IPDI), polypropylene glycol (PPG), and N-methyldiethanolamine (MDEA) as raw materials, and the optimal synthesis conditions were optimized. The experimental results showed that the synthesized CWPU color fixing agent exhibited excellent emulsion properties and comprehensive performance when the PCDL: PPG ratio was 1:1 and the MDEA addition amount was 6 wt%. When applied to leather color fixation, the leather not only achieved improved dry and wet rubbing fastness levels of 4–5 but also demonstrated significant improvements in solvent wash resistance and perspiration fastness. Furthermore, the leather treated with CWPU color fixing agent exhibited deeper color and improved physical and mechanical properties and tactile quality. Therefore, this study provides an effective choice of color fixing agent for environmentally friendly chromium-free tanning systems and has broad prospects for the application of acid dyes.

Eco-friendly dyeing of leather and wood samples using Parthenocissus quinquefolia L. fruits aqueous extract

The present study is relevant to extracting natural colorant from Parthenocissus quinquefolia L. fresh fruits and applying the extracted dye on leather and wood samples in the presence and absence of various mordants. The effect of mordant type (copper sulfate (CuSO4.5H2O) ferrous sulfate (FeSO4.7H2O) and alum (KAI(SO4)2.12H2O) with different mordanting methods (pre-mordanting, meta-mordanting, post-mordanting) on dyeing quality was also examined. The effects of mordants on the color of dyed samples were investigated in terms of CIELab (L*, a*, b*) and K/S values. The dyed samples' light, washing, and rubbing fastness were evaluated according to ISO standards. Although generally good fastness values were obtained for all three mordants, light fastness was low. These results suggest that P. quinquefolia fruits have sufficient potential in dyeing leather and wood.

Manufacturing of isocyanate-based oligomeric dyes with high coloring capabilities: synthesis and application in the dyeing of organic chrome-free leather

Leather dyeing is a critical step in leather manufacturing, as it is responsible for providing leather products with an eye-catching visual aspect and adequate quality properties to meet customers' expectations. This step is becoming more and more challenging as the leather industry advances hand in hand with new environmentally friendly policies and regulations to achieve a safer and healthier planet by replacing the highly polluting Cr-based leather tanning technology with greener alternatives. As a result, achieving high-performance dyeing of organic chrome-free leather is one of the bottlenecks for the sustainable development of the leather industry. Herein, we propose a novel strategy to fabricate an isocyanate-based oligomeric dye (IBD) with high coloring capabilities (component content higher than 62.8%) based on toluene 2,4-diisocyanate and reactive red dye 180. This material has been tested for the dyeing of biomass-derived aldehyde (BDA)-tanned leather with excellent outcomes. The experimental results showed that the crust leather dyed with our novel IBD dyeing agent had higher color fastness and better fullness than the leather dyed with conventional anionic (CAD) or reactive red 180 (RRD-180) dyes. These excellent and promising results open new avenues in manufacturing high-performance organic Cr-free leather products and help to ensure the sustainable transition of the leather industry from Cr-based leather tanning to more sustainable alternatives, maintaining the final quality of the leather products.Graphical abstract

Biosorption of a Leather Dye (Dycem TTO) onto Banana Peel: Characterization, Isotherm, Kinetic, Thermodynamic, and Mechanism Studies

Biosorption of a Leather Dye (Dycem TTO) onto Banana Peel: Characterization, Isotherm, Kinetic, Thermodynamic, and Mechanism Studies

Leather dye from Trema orientalis (L.) and its antibacterial effects

Synthetic leather dyes are chromatic agents specially formulated to impart color to leather substrates through dyeing. The current study involves the extraction of natural dye from the stem bark of Trema orientalis (L.) at different temperatures using water (with or without the addition of sodium hydroxide and sodium sulfide as additives). The optimal extraction was achieved at 80 °C without additives. Concentrating the extract using a rotary evaporator followed by freeze-drying resulted in a yield of 12.14%. The efficacy of the extracted dye was assessed by measuring the phenolic content, viscosity, and particle size. The highest value of total phenolic content of extract found, 266.13 mg GAE/g of dry extract, indicated the possibility of dyeing leather. The viscosity of the dye showed the temperature range of 51–54 ºC as optimum application criteria. The particle size of the dye exhibited a range spanning from 449 to 867 nanometers, indicating superb penetration ability through the leather pores. The antimicrobial efficacy was observed to be positive against a limited number of gram-positive as well as gram-negative bacteria. Final evaluation of the experimentally dyed sample against a control sample regarding relevant parameters viz. exhaustion, fastness, strength, SEM image indicated its potentiality as a colorant for leather industry.

Microwave-assisted cleaner extraction of tannin from Terminalia chebula: A promising green method for sustainable leather dyeing

Natural dyes have gained significant attention in recent years due to their environmentally friendly characteristics. This research paper focuses on the dyeing of leather using a natural dye extracted from hulela zard (Terminalia chebula). The objective of this study was to evaluate the efficiency of microwave-assisted extraction in isolating tannin from hulela zard and its subsequent application in leather dyeing. The research involved optimizing various dyeing parameters, such as temperature, time, pH, salt concentration, and extract volume, using a central composite design and response surface methodology. The results showed that microwave treatment significantly improved the extraction yield of tannin from hulela zard, while also enhancing the sorption behavior of leather. Scanning electron microscope (SEM) analysis confirmed the surface modification of leather without affecting its chemical structure. Fourier transform infrared spectroscopy (FTIR) revealed no significant changes in the functional groups of dyed and undyed leather samples, indicating the preservation of the leather's chemical integrity. The colorfastness properties of the dyed leather were evaluated, and it was found that the combination of specific chemical mordants and bio mordants resulted in desirable colorfastness ratings. Overall, this research demonstrates the effectiveness of microwave-assisted extraction for obtaining tannin from hulela zard and its successful application in leather dyeing, offering a sustainable and environmentally friendly alternative to synthetic dyes.

Antimicrobial Activity of Natural and Synthetic Dyes Used in Leather Dyeing: A Comparative Study

Both natural and synthetic dyes have gained increasing attention in the leather dyeing process due to environmental and health considerations. This research was designed to determine and compare the antimicrobial efficacy of four natural dyes (Acacia catechu, Trema orientalis, Camellia sinensis, Swietenia macrophylla) with four synthetic dyes (brown BFR, brown NG, brown EDK, red G) to develop safer leather dyeing process. The above eight dyes were evaluated against eight prevalent pathogenic and opportunistic pathogenic bacteria Bacillus megaterium, Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Salmonella sp., Escherichia coli, Shigella sp., Pseudomonas aeruginosa, and four fungi. Dyestuff from Acacia catechu, Trema orientalis, and Swietenia macrophylla was effective against the three Bacillus strains, and Staphylococcus aureus with an inhibition zone extending from 6.3 mm to 11 mm. Synthetic dye brown BFR was effective against the three Bacillus strains, and Staphylococcus aureus with zone diameter of 14.8 mm to 19.7 mm. Brown EDK and Red G showed activity against Bacillus megaterium and Bacillus cereus. Camellia sinensis and brown NG showed no antimicrobial efficacy. Also, all eight dyes showed no antifungal activity. For both types of dyes, the zone of inhibition increased approximately linearly as dye concentrations increased. Of the natural dyes, Acacia catechu showed the highest activity. Brown BFR showed the maximum zone diameter of the eight dyes tested. The results indicated that both natural and synthetic dyes were quite effective. Synthetic dyes had remarkable antibacterial properties compared to natural dyes. These dyes having antimicrobial activity can be used in a safer leather dyeing process.

Ficus sycomorus as a Sustainable Source of Leather Dyeing Material: An Ecofriendly Approach

Natural colorants play a vital role in the production of eco-leather by substituting environmentally hazardous and toxic synthetic dyestuffs. In this study, a natural dye is extracted and optimized from the bark of Ficus sycomorus, a plant species locally known as shola, by designing different combinations of concentration, temperature, and time parameters. A dye extracted from 120 g/l concentration at a temperature of 1000°C for 60 minutes showed the highest absorbance value, and it has been used for further dyeing processes with and without mordant. Properties such as color strength (k/s), L ∗ a ∗ b ∗ values, and color fastness of a dyed leather specimen were measured and analyzed. Oxalic acid mordant-dyed leather samples mordanted with the postmordanting method have revealed the highest k/s value among other experimental samples. Moreover, better color fastness properties were obtained from a leather sample mordanted with oxalic acid. Consequently, a dye extracted from the bark of Ficus sycomorus can be used as a leather dyeing material.

Structure analysis and molecular docking studies of laccase from “Bacillus licheniformis NS2324”

Laccase in prokaryotes have enormous application as biocatalysts. Nevertheless, very few laccases have been characterized structurally till date. Recently, a prokaryotic laccase from“Bacillus licheniformis NS2324” have been was cloned and expresses in E. coli. The present research was focused on in silicostructure prediction and characterization of cloned laccase gene isolated from “B. licheniformisNS2324”.In this study various homology modeling servers were used to predict the protein structure of the cloned laccase. Total 17 models were predicted with servers like SWISS-MODEL, ModWeb, Geno3D,I-TASSER,HHPRED using different template structures. All of these models were further validated through PROTSAV, PROCHECK and SAVES server.The best scoring model predicted by SWISS MODEL was selected and submitted in PMDB database. Selected and submitted protein structure was used further for in silico protein structure characterization and docking studies on leather dyes. It was found that all the 33 tested acid leather dyes were docked perfectly to laccase structure with good binding affinity. Acid orange 56 was having highest affinity of − 9.6 kcal mol−1for binding site. A binding affinity of − 9.3 kcal mol−1 and − 9.2 kcal mol−1 was achieved by docking acid red 97 and acid yellow 110 with laccase respectively. The docking studies were further validated by wet laboratory dye decolorization studies which showed a maximum of 96.26 ± 2.51% of (acid orange 56) and a minimum of 61.87 ± 1.30% (acid red 18) This is, to the best of our knowledge, the first study that reports model building from extracellular B. licheniformis laccase and docking with acid leather dyes.

Novel Biomass-Based Polymeric Dyes: Preparation and Performance Assessment in the Dyeing of Biomass-Derived Aldehyde-Tanned Leather.

High-performance chrome-free leather production is currently one of the most concerning needs to warrant the sustainable development of the leather industry due to the serious chrome pollution. Driven by these research challenges, this work explores using biobased polymeric dyes (BPDs) based on dialdehyde starch and reactive small-molecule dye (reactive red 180, RD-180) as novel dyeing agents for leather tanned using a chrome-free, biomass-derived aldehyde tanning agent (BAT). FTIR, 1H NMR, XPS, and UV-visible spectrometry analyses indicated that a Schiff base structure was generated between the aldehyde group of dialdehyde starch (DST) and the amino group of RD-180, resulting in the successful load of RD-180 on DST to produce BPD. The BPD could first penetrate the BAT-tanned leather efficiently and then be deposited on the leather matrix, thus exhibiting a high uptake ratio. Compared with the crust leathers prepared using a conventional anionic dye (CAD), dyeing, and RD-180 dyeing, the BPD-dyed crust leather not only had better coloring uniformity and fastness but it also showed a higher tensile strength, elongation at break, and fullness. These data suggest that BPD has the potential to be used as a novel sustainable polymeric dye for the high-performance dyeing of organically tanned chrome-free leather, which is paramount to ensuring and promoting the sustainable development of the leather industry.

Analysis of the Capacity of the Fenton Process for the Treatment of Polluted Wastewater from the Leather Dyeing Industry.

In this work, the capacity of the Fenton oxidation process for the degradation of color and organic matter contained in the wastewater generated in the leather dyeing stage (WWDS) of an industrial tannery was evaluated. The wastewater characteristics included, among others, high toxicity (lethal concentration for Artemia salina, 24 h test, 50% of population = 93.71 ppm), high dye concentration (36 mg/L, yellow color), high chromium concentration (3.34 mg/L), and low biodegradability index (BOD5/COD ratio = 0.083). From an experimental design, the response surface methodology, and the multiobjective optimization analysis, the following optimal operating conditions were established: initial pH = 3.15, [Fe2+] = 0.981 mM, and [H2O2] = 5.38 mM. After 10 min of oxidation (determined from kinetic studies), it reached approximately 97% decolorization, COD reduction of approximately 82%, and TOC mineralization of approximately 92%. A synergistic effect of Fenton's reagents for TOC removal (S TOC = 0.8) and decolorization (S CN = 0.28) of the WWDS under study was confirmed experimentally. An increase in the biodegradability index, to a value of approximately 0.3, was confirmed. The cost of the treatment was estimated at 0.0112 USD/m3. Thus, the Fenton oxidation process allowed compliance with current Colombian environmental regulations and considerably improved the biodegradability and toxicity characteristics of the studied industrial effluent. It can be considered as an efficient alternative, easy to carry out on an industrial batch scale, and economically viable for the treatment of wastewater from the leather dyeing stage of an industrial tannery.

Determination of dye uptake in leather coatings for waterless leather dyeing by ScCO2 impregnation

During leather finishing the surface of leather is coated with coloured binder systems. In conventional finishing, two to five grams of dyestuff are used per square foot of leather. Due to so-called overspray, 40–60 % of dyestuff is lost. To increase resource efficiency, we examine the impregnation of dyestuff-free leather coatings using supercritical CO2 at 100 bar and 40 °C as a solvent for Solvent Red 111. The focus of the investigation is the effect of the layer thickness on the colour intensity. Furthermore, the dyestuff absorption capacity of the binder layer is determined. As result, a layer thickness of 23 µm allows the maximum achievable colour intensity. The dyestuff absorption capacity at this thickness is 35 mg of dyestuff per square foot of leather. This results in a saving potential for dyestuff of over 95 %.

The effect of calcination temperatures on the structural and optical properties of zinc oxide nanoparticles and their influence on the photocatalytic degradation of leather dye

The challenge of dealing with synthetic dye pollution in waste from the leather industry requires continual research and development. Although numerous dyes used in the textile, food, and other industries have been found to be degraded by photocatalyst based on zinc oxide nanoparticles (ZnO NPs), no thorough studies on the degradation of leather dye from dye-containing wastewaters from tanneries have been reported to date. Hence, this study investigates the efficient photocatalytic destruction of leather dye using ZnO NPs produced by chemical precipitation method. The influence of calcination temperatures ranging from 400 to 600 °C on the structural and optical characteristics of ZnO NPs was investigated. XRD examination revealed an increase in crystallite size as the calcination temperature increased, presumably due to the merger of smaller crystallites into larger ones. Meanwhile, the polycrystalline and wurtzite structure of the synthesized ZnO NPs was observed, with particle diameters ranging from 40 to 90 nm and an average size of around 62 nm. UV–vis spectra revealed a decrease in energy band gap (3.15 to 3.05 eV), which was ascribed to an increase in crystallite size produced by higher calcination temperature from 400 to 600 °C. The photocatalytic degradation of leather dye was studied further. It has been demonstrated that ZnO NPs synthesized at a calcination temperature of 400 °C can remove 90% of the leather dye in 30 min. The dynamics of deterioration were also studied. It was discovered that the degradation of leather dyes best fitted the pseudo-first-order kinetics, with superoxide ions being the most likely species.

A review of plant-based natural dyes in leather application with a special focus on color fastness characteristics.

Dyes/colorants are normally used to improve the aesthetic of consumer products, and leather is one of them. The leather industry plays a significant role in the global economy. However, the leather-making process causes severe environmental pollution. Synthetic dyes are one of the major classes of leather chemicals that are responsible for the enhanced pollution load created by the industry. Over the years, excessive use of synthetic dyes in consumer products created severe environmental pollution and health hazard. Many of these synthetic dyes are carcinogenic, allergic, cause serious health problems for human beings, and have been restricted by regulatory authorities for use in consumer goods. Since ancient days, natural dyes and colorants have been used to make lives colorful. Amid the green movements and environment-friendly products/processes, natural dyes are back to mainstream fashion. Moreover, natural colorants have become a trend due to their eco-friendly nature. The demand for non-toxic and eco-friendly dyes and pigments is increasing. However, the question remains "is natural dyeing sustainable" or "how to make it sustainable." Here, we review the literature reports on natural dye's application in leather in the last two decades. This review article provides a detailed overview and current knowledge base on the various plant-based natural dyes used in leather dyeing, their fastness properties, and the need of the hour in terms of product and process development to make natural dying sustainable. The color fastness characteristics of the dyed leather to light, rub, and perspiration have been critically discussed.

Manipulating Indigenous Vegetable-Tanned Leather for Use in Crocheting Art

The study explores techniques and methods used in converting indigenous vegetable-tanned leather into yarns that can serve as an alternative material and convert the locally made yarns into crocheted ladies containers and footwear using different stitches. It embraces a qualitative research of which the approach implements two various approach’s (Descriptive and Studio-based research). The novelty of the study came from sampling, which consisted of Crochet Artisans, Leatherworks Teachers, and Leather Technologists within the above areas. The Crocheting Artisans were selected through the snowball sampling technique, whereas the Leatherwork Teachers and Leather Technologists were selected using the purposive sampling technique. The results from data gathered via the project experiments involved studio activities in converting the local vegetable-tanned leather into yarns and crocheting the yarns into ladies containers and footwear using different stiches were analysed and discussed. The study concludes that indigenous vegetable-tanned leather is suitable for use in making crocheting yarns and crocheting artefacts due to its strength, flexibility, and hook construction. Moreover, spiral cutting techniques came out to be the most appropriate technique for cutting leather into yarns for use in crocheting art. The study recommends that the use of leather in making crocheting yarns should follow these steps - the cutting of leather, softening of leather (wet pounding) and dyeing of leather (vat dye and the mixture of suede and insoluble dye). In addition, the study suggests that to create diversity in crocheting yarns, crocheting artefacts and expand leather usage, the potential leather should be tapped by both Crocheting and Leather Artisans.

Removal of Anionic Dye from Tannery Wastewater Using Peanut Shell Waste as a Biosorbent

Contamination of water bodies by organic substances, such as dyes, cause impacts on the environment and human health. Furthermore, the search for environmentally appropriate destinations for solid waste, such as those from agro-industries, has been intensifying, to minimize the impact of the growing generation of waste as a result of population growth. Thus, this work aimed to evaluate the use of raw peanut shells as an alternative adsorbent for the removal of Brown acid dye from synthetic leather dyeing wastewater. The peanut shells were milled and sieved. The material was characterized by Fourier Transform Infrared Spectroscopy. The parameters evaluated in the adsorption tests were pH, contact time, and mass of adsorbent material. The maximum adsorption capacity verified for the peanut shell was 7.753 mg/g and up to 93% of the dye was removed. The best adsorption conditions were at pH 2.5, 10 minutes, and adsorbent mass of 0.3 g in 50 mL of effluent. The results showed relevant removal of the Brown acid dye by the peanut shells’ adsorbent material.

Hollow silica nanoparticles loaded with industrial dyes for high exhaustion leather dyeing and its sustainability impact

The impact of hollow spheres contains modified industrial dyes for leather dyeing application.

Investigation on corrosion behaviors of silver and LDB coated silver wires in 0.5 M NaCl

Silver (Ag) is used widely in the semiconductor industry for its good conductivity and stable corrosion behaviour in various environments. However, a chloride attack on Ag could change its properties and affect other sensitive behaviours of Ag. In the present work, the corrosion behaviours of Ag wire and Ag wire coated with black leather dye (LDB) through dip coating are examined in 0.5 M NaCl by electrochemical impedance spectroscopy (EIS), Tafel polarisation curves (TPC), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDX). LDB structure is investigated through Fourier transform infrared spectroscopy (FTIR), and LDB is found to contain numerous functional groups. Based on this fact, it is assumed that LDB can significantly suppress Ag corrosion; however, the results have not supported this assumption, and only a slight improvement in the corrosion behaviour of Ag wire has been noticed. The corrosion study on Ag and LDB coated Ag wires is also performed after 1 and 3 h of immersion in NaCl; however, the degradation in corrosion behaviour is acknowledged. Based on results, it is found that LDB is protecting Ag, but for short time immersion.