Sustainable Leather Research Articles

Superhydrophobic Modification of Collagen Fiber

Tanning is considered to be the crosslinking reaction between collagen fibers and tanning agents, and a majority of tanning reactions result in suppressed water absorption and enhanced hydrophobicity of leather. However, extensive use of tanning agents may bring a burden to the environment. Herein, to facilitate a sustainable leather manufacturing industry, we propose a revolutionary strategy of “tanning” without tanning agents. Based on this strategy, superhydrophobic collagen fibers (FAS-CFs) were fabricated through dehydration, followed by superhydrophobic modification. Dehydration aimed to eliminate the “sticky” effect of water on collagen fiber to obtain a dispersed hierarchical structure. Superhydrophobic modification not only dispersed and stabilized the fiber structures, but also protected the fiber dispersity from water immersion. Compared with chrome-tanned collagen fibers (Cr-CFs) and glutaraldehyde-tanned collagen fibers (G-CFs), FAS-CFs showed higher hydrophobicity, lower water absorption, and superior mechanical properties. Meanwhile, FAS-CFs exhibited a high thermal denaturation temperature of 92.5°C and retained their original shape after being heated to 100°C. Therefore, our proposed strategy is expected to be a potential substitute for conventional tanning and might contribute to cleaner and sustainable leather manufacturing.

A hierarchical framework for the transition to sustainable manufacturing practices: Technical and social developments drive eco-friendly tanning in Ethiopia

The leather industry is identified as the priority sector in Ethiopia's industrial development strategy for accelerating sustainable development. However, the transition to sustainable manufacturing practices (SMPs) has been disappointing. A framework that explains the process and pathways to guide the transition is lacking. This research adds to our understanding of the transition by building a valid hierarchical model and determining the causal links between sustainable leather processing attributes. This study also investigates the dynamics of sustainability transition attributes in leather tanning and identifies the driving factors in adopting SMPs. The causal attributes for transitioning to sustainable leather processing are highlighted, with recommendations for best practices. In addition, the drivers require qualitative assessment and are subject to uncertainty due to the linguistic preferences of experts. Thus, this study adopts the fuzzy Delphi method (FDM) to arrive at a valid set of attributes and the fuzzy decision-making trial and evaluation laboratory (FDEMATEL) to address the interrelationships of the proposed attributes. The findings demonstrate that 15 relevant indicators are grouped into five categories, with technical performance and social development as causal factors capable of improving environmental, economic, and regulatory attributes. Therefore, in leather tanning, sociotechnical systems drive the transition to more sustainable alternatives. For decision-makers, the most critical indicators to improve practices are green design, electro-oxidization, regular supervision, site waste management plans, and increasing the level of regulatory compliance. The theoretical and managerial implications are discussed.

Polygonum hydropiper in goatskin preservation: A sustainable leather processing approach

In conventional preservation of hides and skins, the use of NaCl (50%) evolves enormous salinity and total dissolved solids (TDS) in soaking effluent during leather processing. Plant-based skins preservation is a sustainable solution in reducing salinity and TDS from leather industry to replace conventional curing. In this study, the application of Polygonum hydropiper-based dry powder paste over flesh side of goatskin following 10%, 10%, and 15% paste mixing with 5%, 10%, and 5% salt, respectively, was done with periodical monitoring of organoleptic properties, moisture content, hydrothermal stability, and bacterial load. As compared to conventional curing, these Phyto-based salt minimized curing formulations had preserved goatskin for 30 days, resulting in a maximum 81% and 52% salinity and TDS reduction, respectively, in soaking liquor. The preserved skins were processed into shoe-upper leather in the same manner, and the ultimately produced leather offered the equivalent physical qualities. SEM images corroborated the structural orientation of collagen fibers was more suited than leather produced from salt-preserved skins. The correlation analysis demonstrated strong interdependencies among goatskin preservation efficacy metrics, particularly moisture content and hydrothermal stability, with the highest correlation (r = −0.919). Phytochemicals like alkaloids, flavonoids, coumarin, quinones, terpenoids, tannin, and phlobatannin were present in P. hydropiper extracts. The acetonic and water extract of the examined plant demonstrated modest antibacterial efficacy (11 mm) against Staphylococcus aureus compared to chloramphenicol (27 mm). Therefore, P. hydropiper can be a potential curing agent with comparable leather strength while minimizing the environmental impact and endorsing sustainable developments of leather industry.

Cyclic carbonate: A green multifunctional agent for sustainable leather manufacture

“Go Green” manoeuvre is gaining prominence due to environmental sustainability, where chemical consumption needs to be subjugated. In order to alleviate this issue, industries have adopted the use of multifunctional chemicals as an alternative to mono-functional agents. The global interest in cyclic carbonate is emerging because of its solvent-cum-reagent characteristic. In this work, we have attempted to use “Propylene Carbonate (PC)” as a green multifunctional agent in the different unit processes of leather making. The antimicrobial activity of PC against gram-negative (Bacillus subtilis, Staphylococcus aureus), gram-positive (Escherichia coli, Klebsiella pneumonia) bacterial strains, and mixed culture prepared from putrefied skin extract enables to use of PC in the preservation process as an alternative to common salt (NaCl). The goatskins treated with 15% PC can be stored for up to 2 months without any putrefaction. Further, the developed method reduces the 85% of TDS load from the soaking process and also completely eliminates the generation of contaminated salt. Spectroscopic investigation and molecular dynamic simulation studies clearly indicate that the structural stability of collagen is not affected in the presence of PC. However, it inhibits the activity of collagenase on collagen. The use of PC as an alkali neutralizing agent in the deliming process completely avoids the generation of toxic ammonium gas. The possibility of using PC as an antifungal agent in the chrome tanning process has been attempted. The wet-blue leather treated with 3% PC has been preserved for 30 days without any fungal attack. Hence, the application of PC in various unit processes has a great potential in reducing chemical consumption thereby leading to sustainable leather manufacturing.

Vegetable wastes as a bio-additive for low-salt preservation of raw goat skin: An attempt to reduce salinity in leather manufacture

Preservation or curing of hides/skins is performed as the primary step of leather processing to conserve them from putrefaction. Normally preservation is carried out using common salt (NaCl), which is discharged in the soak liquor contributing to ~ 70%, of total dissolved solids (TDS) load of entire leather manufacturing. In an attempt to reduce the TDS and chlorides, phyto-based preservation using garlic peel (Allium sativum) and white onion peel (Allium cepa) was carried out. Different concentrations of salt in combination with garlic peel and white onion peel were applied on freshly flayed goat skins based on its green weight and compared to control (40% salt). Sensory evaluation of the preserved skin was done by assessing different parameters like hair slip, putrefaction and odour. Estimation of hydroxyproline (HP) release, moisture content and microbial load were carried out at regular intervals. Skins that remained in good condition for 14days were further processed into leather and properties were examined which were found comparable to the conventionally cured skins. Hence, this cleaner curing technique helps in reducing the TDS and chlorides in the effluent, thus controlling the pollution caused by tanneries through sustainable leather processing.

Analysing drivers of efficiency in the leather industry: a two-stage double bootstrap DEA approach

PurposeThe Indian leather industry contributes to economic growth at a significant environmental cost. Due to the rising global demand for sustainable leather products, promoting efficient input utilisation has become vital. This study measures input efficiency and its determinants for leather industry in order for it to improve its future performance.Design/methodology/approachIn the first stage, bootstrap data envelopment analysis (DEA) approach is used for measuring efficiency and analysing firms' differences based on their geographical location, organisational structures, urban-rural location and sub-industrial groups. A second stage regression examines efficiency determinants using size, age, skill and capital-labour intensity as the explanatory variables.FindingsEfficiency result shows a significant potential of minimising inputs by 47% provided the firms adopt best practices. West Bengal firms, urban located firms, individual and proprietorship owned firms and leather consumer goods firms are found to be relatively efficient to their counterparts. Size, skilled managerial staff and labour-intensive firms positively affect efficiency.Practical implicationsConstruction of well-connected roads for accessing urban retail markets and provision of reliable electricity would improve efficiency of rural firms. Small-scale enterprises have a larger share in Indian leather industry; therefore, policy should focus on enhancing the firms' scale and investing in training facilities to skill employed labour for ensuring optimal use of inputs.Originality/valuePrevious studies on the leather industry have used the conventional DEA efficiency measurement approach. This study uses DEA bootstrapping model for robust efficiency estimates and provides consistent inferences about the determinants.

Synthesis of an amphiphilic amphoteric peptide-based polymer for organic chrome-free ecological tanning

The development of an ecological chrome-free tanning system is a research hotspot and is of great significance to green and sustainable leather production. However, most of the chemicals used in the system exhibit poor compatibility, which means the overall performance of chrome-free tanned leather is not comparable with that of chrome tanned leather. Moreover, the chemicals tend to exhibit poor biodegradability and cause pollution, which, of course, belies the original aim of green chrome-free tanning. With this in mind, amphoteric peptide-based fatliquor (APF) was prepared by introducing a flexible long chain into collagen polypeptide and compounding it with castor oil. The resulting amphiphilic amphoteric peptide-based structure of the APF ensured it had good compatibility with chrome-free tanning systems. In terms of the properties of the chrome-free tanned leather, the softness = 7.88 ± 0.21 mm, air permeability = (2.19 ± 0.04) × 103 mL·(cm−2·h−1), the burst height = 13.32 ± 2.22 mm, and tear strength = 17.77 ± 4.22 N/mm, with its overall performance, were comparable with that of chrome tanned leather. Furthermore, the absorption of the fatliquor and the dye increased to 89.68% ± 0.99% and 92.82% ± 0.93%, respectively, while the APF demonstrated excellent environmental friendliness, meaning the hazardous chemicals used in the leather fabrication process and discharged into the environment would be significantly reduced. This work is of great significance in terms of improving organic chrome-free ecological tanning systems and further promoting cleaner production within the leather industry.

Application of Modular Design in Upcycling Solid Leather Waste: A Sustainable Development Approach from Ethiopia

Fast changes in fashion trends have stimulated customers’ buying behavior; this has increased the demand for leather products. Fulfilling this demand requires unsustainable practices of overproduction and utilization of resources leading to increased waste generation. By far, the highest percentage of waste generated in the leather product industry is from the cutting section. Since leather scraps retain most of the chemicals added in the processing stage, disposal of this waste in landfills contributes to a higher degree of environmental pollution. This paper introduces modular design techniques for the upcycling of solid leather wastes created at the cutting stage. This contributes to creating a more sustainable approach in leather product development through the reuse of waste material, reducing required resources, and avoiding waste disposal to the environment. Primary data gathered from export-oriented leather goods manufacturing industries in Ethiopia identified a percentage of waste created at the cutting stage. Further, the physical property characterization of leather scraps was carried out to determine the appropriate modular design that can reuse the highest percentage of solid waste. The project concludes that most of the solid scraps disposed of in the leather product industry are in both areas and quality useable as raw material for the manufacturing of marketable sustainable leather products.

Life cycle assessment of processing for chrome tanned cowhide upper leather

Pollution has become a serious problem in leather industry, however, current method to evaluate its environmental effect usually used data from literature review, those data generated while leather manufacturing were rarely collected and analyzed. Thereby, the aim of this study was to evaluate the environmental effect of manufacturing process of chrome tanned cowhide upper leather by applying the Life Cycle Assessment protocols. Following the guidance of ISO 14010, we first combined data obtained from field study and empirical review; and then these data were input into eFootprint for calculation. Results, including four environmental indicators (global warming potential [GWP], primary energy demand [PED], water utility [WU] and acidification [AP]), show that producing 1 kg of cowhide upper leather releases 7.040 kg of CO2 eq, consumes 106.793 MJ of energy and 89.144 kg of water and emits 0.058 kg of SO2 eq. Sensitivity analysis of inventory data demonstrated that chrome tanning and retanning processes accounted for more than 40% of PED, AP and GWP, whereas the beamhouse was more than 78% of WU. Therefore, we could optimise the tanning process by using alternative materials or technologies in the critical sections to achieve cleaner production and sustainable leather manufacturing.

Chromium-free and waterless vegetable-aluminium tanning system for sustainable leather manufacture

Intensifying researches in leather sector are focusing on eco-benign tanning chemicals with less environmental impact processing route. The present study aims to design an eco-acceptable shoe upper leather process that could potentially eliminate use of chrome from the leather industry. Possible conversion of Cr3+ to Cr6+ in suitable oxidant environment during leather manufacture is always a threat to the ecosystem. Water load for leather processing is very high, also becoming a precious resource that needs to be reduced for industrial applications. Further without water usage for a process, generation of wastewater could be averted. With this context, a combination tanning using wattle and aluminium has been developed in a pickle-less and waterless medium. The experimental leather possesses a shrinkage temperature of 84 °C with a fully loaded compact fibre structure indicating that tannin penetration is not affected in waterless medium. Experimental leathers exhibit better physical strength and comparable organoleptic characteristics. The process enjoys environmental benefits as it shows significant pollution load reduction in Biological Oxygen Demand (BOD), chemical oxygen demand (COD), Total Dissolved Solids (TDS) by 88, 89, and 97%, respectively. Hence, a viable option is made available to manufacture eco-acceptable leather without water usage and chrome salts in tanning.

Development of hyperbranched poly-(amine-ester) based aldehyde/chrome-free tanning agents for sustainable leather resource recycling

A series of epoxy-terminated hyperbranched poly-(amine-ester) materials were synthesized as aldehyde/chrome-free tanning agents for sustainable leather manufacturing.

Preparation, Characterization and Application of Lubricating Protein Filler for Sustainable Leather Production

ABSTRACT In this study, collagen hydrolyzate was obtained from bovine shaving wastes of leather production with the alkali hydrolysis reaction. Total amino acid, total carbon and total nitrogen amounts of liquid collagen hydrolyzate (CH) were determined. Fourier-transform infrared spectroscopy (FTIR) characterization of collagen hydrolyzate was performed. Obtained CH was emulsified with hydrogenated castor and amino functional silicone oils to prepare lubricating protein filler (LPF). Particle size and zeta potential of the LPF were analyzed. 10%, 15%, and 20% LPF was used in the retanning/fatliquoring process of chromium tanned bovine leathers. Performance characterizations of leathers treated with LPFs were carried out with tensile strength, tear strength, filling efficiency, light fastness, shrinkage, and denaturation temperature analyses. Moreover, bounded fat content in leather was also determined. Results showed the increased thermal stability, strength performance and good filling effect in leather by application of the prepared LPF. Consequently, LPF had a good potential as natural retanning/fatliquoring agent via achieving reuse of the solid leather wastes and providing satisfactory leather properties and cleaner production by one product itself.

Amino Acid Enriched Proteinous Wastes: Recovery and Reuse in Leather Making

Environmental constraints have become the key issue for sustenance of industries worldwide. In leather industry, solid wastes create major problem to the environment, among which animal fleshing constitute a major portion. The main objective of this study is to evolve a simple, eco-benign method for the utilization of solid wastes to produce value added product. The product was developed by hydrolysis using alkaline protease (a novel Bacillus crolab 5468), which can be potentially used for surface upgradation of leather. Molecular mass of the polypeptides was found to be 9 kDa at 30 min and 6 kDa at 60 min of hydrolysis by MALDI-TOF. Furthermore, the polypeptides treated leather exhibited uniform grain pattern, better filling and strength properties compared to untreated leather. High value-added product presents a strong case for sustainable leather production as it adds both economic and environmental benefits to leather making.

Alkaline protease for an efficacious rehydration of skin matrix by a novel Bacillus crolab MTCC 5468 in sustainable leather production: a green approach.

The utilization of biotechnology in leather sector has more extensive in modern years; more particular to proteolytic enzymes and employed in several steps of the leather making such as soaking, dehairing, bating, solid waste management etc. The current study evaluates the performance of alkaline protease from Bacillus crolab MTCC 5468 in single soaking of goat skins matrix by comparing with the conventional multiple soaking processes. According to the obtained results, the optimum concentration for maximum rehydration of goat skins was accomplished at 1.0% (v/w) of alkaline protease at duration of 3h over traditional rehydration method (4-6h). The moisture level, total protein, chloride content and total organic carbon of enzymatic rehydration was superior to that of conventional rehydration and it was also used to measure the effectiveness of rehydration process. Scanning electron microscopic images of enzymatically processed leather exhibits enhanced opening of fiber bundles and smooth grain surface than conventional method. Furthermore, the alkaline protease treated leather exhibited improved moisture uptake, removal of chlorides and suppleness because of hydrolysis of non-collagenous proteins as indicated by well opened up fiber bundles in histological analysis. The application of alkaline protease in rehydration operation of leather production confirmed scope for diminishing water quantity around 66.6%, soaking duration at 50%, minimizing use of harmful dehairing chemicals at 50-60%, thereby, eliminating the bating operation during pre-tanning. These outcomes suggest that alkaline protease have potential application in rehydration of skins for immense environmental concerns of leather tanning sectors.

Exploring the Sustainability Concepts Regarding Leather Apparel in China and South Korea

Sustainability in business and personal life has increased over the past few years and is continuing to develop. Consumption in the clothing and textiles industry causes a significant impact on the environment and utilizes unsustainable practices, from clothing production to use and disposal. With shifts toward a more sustainable future within the government, businesses, and society, the apparel industry and consumers must prepare for a sustainable future. This study examines the determinants of sustainable apparel consumption behavior in China and South Korea. Theoretical and practical evidence from the literature on sustainable consumption is applied to develop a model for investigating the consumers’ behavioral intentions to buy, use, and recommend sustainable leather apparel products. Environmental knowledge, perceived consumer effectiveness, sustainable consumption beliefs, and self-enhancement are proposed as key determinants of behavioral intention to buy, use, and recommend eco-friendly faux leather apparel (E-FLA). The hypothesized antecedents of these concepts are part of the model, as modified by the theory of planned behavior, and the model is examined using structural equation modeling on data from a sample of 450 respondents collected in China and South Korea. An analysis of data is carried out to identify the underlying dimensions of sustainable consumption beliefs and behaviors including pro-environmentalism, social responsibility, and animal conservation. The results show that the key determinants of behavioral intentions to buy, use, and recommend E-FLA are pro-environmentalism and social responsibility, which are related to sustainable consumption belief dimensions and consumers’ self-enhancement. The positive determinants of sustainable consumption beliefs are found to be both environmental knowledge and perceived consumer effectiveness. These results suggest the need for greater environmental knowledge and perceived consumer efficiency in the effort to achieve more sustainable clothing consumption. The implications of the findings for public policy and recommendations for further studies are outlined and discussed.

Interaction of glyoxal with collagenous matrix and its behavioral aspects for non-toxic and sustainable tanning system

Sustainable leather processing is viable through conventional organic tanning processing that provides scopes for quality to match with the chrome-tanned leathers. Hence, there is a need to develop sustainable tanning technology for leather processing. Glyoxal alone and in combination with wattle extract has been tried to establish a new tanning system. Glyoxal as the solo-tanning agent, optimized at the level of 5%, can produce shrinkage temperature up to a level of 72 °C, whereas the combination tanning system with the help of wattle extract yielded leather with shrinkage temperature of 92 °C. The tanned leather was further processed into crust leather, and organoleptic properties are evaluated. Thermogravimetric analyses revealed better thermal stability at 113.52 °C, with a residue of 86.94%, in comparison with the leather tanned with combination tanning system using wattle extract showing stability at 110 °C and residue of 87.29%. The visual assessment results showed that the leathers produced from experiments were soft, with smoother grain, uniform dyeing properties and overall comparable strength properties. The plausible mechanism for present tanning systems has been elucidated. The results of scanning electron microscopic analysis revealed that leather produced from glyoxal tanning was of empty type where the fibers are tightly bounded, however, having less angle of weave as compared to control sample. The reduction in Bio-chemical oxygen demand and Chemical oxygen demand values from effluent stream in the case of solo tanning showed 64–70% and 68–71%, respectively.

IKEA: global sourcing and the sustainable leather initiative

The leather industry has traditionally been characterized by global operations across both developed and developing countries. Due to the long distance and contextual differences, there are numerous sustainability issues occurring along the global leather supply chain. Addressing these issues is both a responsibility and a challenge for multinational companies, especially in their global sourcing (GS) activities. This teaching case provides an example of implementing the sustainable leather initiative in the global sourcing process at IKEA. The case demonstrates IKEA’s sustainable leather initiative supported by its tailored GS strategy and GS structure and provides a benchmark of Sustainable GS for multinational companies and allows for a thorough discussion of how to implement a sustainability initiative while conducting GS. The case can be used to teach graduate/postgraduate in agricultural business, MBA and executive students on sustainable supply chain management and corporate social responsibility.

Tailoring Nanostructured Dyes for Auxiliary Free Sustainable Leather Dyeing Application

Tailoring the dye functionality by nanoparticle structures offers a new opportunity for a sustainable leather dyeing process in the way of an auxiliary free dyeing process irrespective of substrate charge. Encapsulated nanoparticles, which are nanocages from a polymeric silicalike material, have been widely exploited as a template to guide the fabrication of nanostructures, because of their homogenized particle size, easy functionalization, and preparation through a viable route. In this work, functional rich and pH stable dye-encapsulated nanostructured dyes were used as dyeing agents with commercial use in mind. Due to its uniform particle size (50 nm) and surface potential (−48.7 ± 1 mV) over different pH ranges, the fabricated dyeing system showed uniform penetration and fixation irrespective of the different stages of leather processing at different conditions. Thus, the integration of compatibility and ready absorption by proteins provides a practical way to resolve the problem of intensity variatio...

Exploration of GSK'S solvent selection guide in leather industry: a CSIR-CLRI tool for sustainable leather manufacturing

Exploration of GSK'S solvent selection guide in leather industry: A CSIR-CLRI tool for sustainable leather manufacturing.

Cleaner approach in leather dyeing using graft copolymer as high performance auxiliary: related kinetics and mechanism

Solid wastes from leather industry especially trimming waste can be converted to useful auxiliaries for minimization of pollution problems. A copolymer from trimming hydrolysate has been developed using starch and poly vinyl alcohol and is characterized. The application of copolymer at the level of 10% gave improved dye exhaustion of 96%. Optimal operating conditions for dyeing obtained were at pH 5, temperature 60 °C and duration 80 min. Kinetic models have been developed to understand mechanism of adsorption using response surface method supported by design of experiments. Fourier transform infrared spectra analysis showed presence of stretching frequency of hydroxyl groups at the peak of 3278 cm−1 for the copolymer sample. The plausible mechanism for the interaction of -collagen -copolymer-dye- is predicted. The presence of dye and carboxylic reactive sites were confirmed by 13C-nuclear magnetic resonance and mass spectra. These carboxylic acid groups that are present in the co-polymer are responsible in enhancing the adsorption of dye. Emission factors namely, bio-chemical-oxygen-demand and chemical-oxygen-demand have been reduced to the level of 44–66%. The color measurement study showed improvement in dyeing properties. It has been found that copolymer plays a major role in the improving uptake of dye by through active functional groups. This improved dyeing process paves a cleaner way for making sustainable leather production. This method helps to reduce solid waste, especially collagenous waste, generated in leather industry.