Sustainable products in the leather industry (original) (raw)
Related papers
2016
In today's move to "sustainable production" the leather industry, as well as many other industries is recognized as a polluting one. Traditional chemical operations are polluting because of the levels of inorganic chemical waste. Process chemicals which are not consumed within the reactions necessary to convert collagen to leather are currently discharged to waste. These are usually applied during bulk production, such as inorganic agents from beam house and tanning processes, e.g. lime, sulphide, ammonium salts, sulphuric acid and sodium chloride, mineral tanning agents – mainly Cr(III) and the less common Al(III), Zr(III), Ti(III), Fe(III) salts -, whereas depending on the tanning process and the leather article produced organic chemical waste discharged comprises aldehydic and polyphenolic tanning products, bating enzymes, organic carboxylic acids and excess electrolyte stable synthetic fat liquors. It is rare for chemicals and water to be recovered for re-use from ...
Chemical and physico-mechanical characterizations of leather for restoration
2020
Leather is a complex material mostly consisting of a matrix of collagen, chemically stabilized by various tannins. This matrix, sooner or later undergoes alterations as a consequence of interactions between their structure and environment. A comprehensive study based on multiple chemical and physico-mechanical standard tests regarding leather samples which were artificially aged from 7 to 112 days has been made at 70°C. The behavior in artificial aging of calf leather samples tanned at pilot level with two different vegetal tannins, mimosa and quebracho, were investigated due to its’s similarity to the natural degradation of historical leather samples. Physico-mechanical characteristics of historical leather can be corelated with the high impact of degree of deterioration even though there are no standard regulations. To be able to choose the proper way to achieve compatibility with an appropriate material in the restoration-conservation process, multiple sample characteristic must ...
Coatings
The leather industry is currently between two opposing paths: on the one hand, recent legislative trends in terms of the eco-sustainability of industrial processes are leading leather manufacturing towards the development of cleaner production methods; on the other hand, the spread of new alternative materials to leather is driving the leather industry to improve its competitiveness by developing new innovative and high-quality products. Leather finishing is one of the most important phases of leather production, and is capable of improving its quality and organoleptic properties. However, this phase is characterized by the use of polluting chemical products, such as volatile organic compounds, potentially toxic crosslinking agents, and hardly biodegradable resins. In this context, this research work aims to develop a finishing formulation capable of giving leather the durability and quality properties required by the market, while at the same time, being eco-sustainable. Specifical...
Trends and advancements in sustainable leather processing: Future directions and challenges—A review
Journal of Environmental Chemical Engineering, 2020
In spite of sustained efforts by researchers, the gap between desired objectives with respect to sustainable leather technologies and achieved levels is still at large. At this juncture, this review presents an array of sustainable greener options addressing all major unit operations of leather making. As an alternative to traditional preservation, phyto-based preservation options for raw skins & hides reducing total dissolved solids and chlorides around 70 % are discussed. Oxidative unhairing reducing biochemical oxygen demand & chemical oxygen demand around 40 % is detailed as an alternate to traditional unhairing that is both harmful and polluting in nature. High-exhaust tanning technologies based on co-polymers increasing uptake to 95 % level are presented. The case of metal-free, organic only glyoxal/ wattle-tanned leathers with enhanced organoleptic properties is discussed. A starch-grafted collagen hydrolysate co-polymer exhausting dye up to 96 % is presented as high-exhaust dyeing system in this paper. Also, laccase-enzyme-based bio-degrading system for recalcitrant post-tanning effluent is furnished. A new method for extracting cellulose derivative from downstream wastes of sugar sector to be used in leather finishing is deliberated. A novel bio-filter based odour abatement system capturing noxious gaseous emissions from tannery environment is showcased as well. In all, this review reflects on the recent sustainable leather technologies that have potential for commercial exploitation in the near future.
Waste Management, 2019
One of the long lasting problems associated with leather industry is to meet environmental standards for both liquid and solid wastes. Statistics show that one tonne of wet-salted hides/skins yields around 650 kg of solid waste. Among various wastes generated, trimmings for the most part have been underutilized. Collagen presents in trimmings waste are effectively used but hair goes unutilized or at the most as feed for boilers during gelatin manufacturing. Hence, newer technology is needed for complete and effective utilization of raw trimmings. In leather manufacture, formaldehyde condensates polymers are used as re-tanning agent to enhance the compaction of leather. However, these products are hard for biodegradation and also cause the release of free formaldehyde in leather, which is a known carcinogen. Here, there is a need for development of formaldehyde free re-tanning agent for eco-benign leather processing. In this work an attempt had been made to develop formaldehyde free biodegradable eco-benign retanning agent from raw trimming of tannery solid waste as a circular economy model. Alkaline (7.5% w/w NaOH)-hydrogen peroxide (10%w/w) pre-treatment followed by thermal hydrolysis at 100°C for 5 h was an optimized method for effective hydrolysis of trimmings and the process of preparation of product results in the holistic utilization of raw trimmings. The developed product was characterized using Dynamic light scattering and FTIR techniques. The product prepared was further used in leather manufacture as a re-tanning agent and was found to impart multifunctional properties to leathers such as fullness, grain tightness and shade of dye brilliance. Product improves the mechanical strength characteristics of leather and also the exhaustion of post-tanning chemicals. SEM analysis shows that the experimental leather is more compact and flat than control. This novel strategy had not only solved the issue of solid waste but also resulted in a greener leather auxiliary leading to greener environment.
A potential new commercial method for processing leather to reduce environmental impact
Environmental Science and Pollution Research - International, 2008
Introduction Current leather processing method involves dehairing and fibre opening employing lime and sulphide, which results in higher negative impact on the environment due to its uncleanness. This method of dehairing and fibreopening process accounts for nearly 70-80% biochemical oxygen demand and chemical oxygen demand (COD) in tannery wastewater and also the generation of H 2 S gas. Materials and methods Hence, an attempt has been made to reduce the environmental impact of the leather processing through a biochemical approach, employing proteolytic enzyme and sodium metasilicate for performing the above process more cleanly. Results and discussion The developed process exhibits significant reduction in environmental parametres such as COD and total solid loads by 55% and 25%, respectively. This method completely avoids the formation of lime sludge. Conclusion The functional properties of the leathers are also on par with conventionally processed leathers. Further, the process seems to be commercially viable.
Study and Practice on Alternative Eco-Friendly Processes for Leather Manufacture
2010
The inclusion of environmental issues in the definition and implementation of other policies is essential for achieving the objective of sustainable development. Leather industry, which has a considerable pollutant impact, must find efficient technological and economical solutions for this problem. Efficient raw material and energy usage, optimum process chemical utilisation, recovering and recycling of waste and substitution of harmful substances are important principles of the IPPC Directive. For tanneries the focal points are water consumption, efficient use and substitution of potentially harmful process agents and waste reduction within the process in conjunction with the recycling and re-use options. Chromium (III) salts are extensively used in the tanning process; about 90% of the leather manufactured worldwide is tanned using chromium (III). It has been used in the leather industry for almost 150 years, because it remains the most efficient and versatile tanning agent availa...
The Use of Sulfonated Jatropha curcas Oil for the Processing of Mechanically Improved Leather
Chemistry Africa, 2020
Fatliquors are oil-in-water emulsions added during the fatliquoring process of leather manufacture to lubricate and prevent the fibre structure resticking during drying. They also increase softness, flexibility, and tensile strength of fixed leather. In this study, Jatropha curcas oil of no commercial value in Nigeria was sulfonated. The physicochemical properties of both the sulfonated and unsulfonated oils were determined. The sulfonated and unsulfonated oils were also characterized using DSC, FT-IR, 1 H NMR, 13 C NMR, and 13 C NMR DEPT. The prepared sulfonated J. curcas oil was applied onto goatskin and compared with commercial sulphated fatliquor in the processing of shoe upper leather. Physical/mechanical analyses were carried out on fixed leather. Tensile strength, Sudan stain, elongation at break, and double edge tear test results showed notable improvement in the mechanical properties of the leather processed with the sulfonated J. curcas oil. The microscopic analysis also showed fibre structures that were adequately opened up. This study revealed that the sulfonated J. curcas oil can be a good sustainable substitute for commercially available fatliquor as its application in the processing of shoe upper leather shows properties that are comparable with the renowned fatliquors which are normally utilized in leather industries. It also raises the possibility of commercialization.
Production of a biopolymer for leather. A life cycle assessment perspective
The aim of this paper was to develop a biopolymer based on raw materials not originating from petroleum chemistry to reduce the environmental impact. To this end, an acrylic-based retanning product was designed where part of the fossil-based raw materials was replaced with biomass-derived polysaccharides. Life cycle assessment (LCA) of both the new biopolymer and a standard product was conducted to determine the environmental impact caused by each product. The biodegradability of both products was determined by BOD5/COD ratio measurement. Both products were characterized by IR, gel permeation chromatography (GPC), and Carbon-14 content. The new product was experimented as compared to standard fossil-based product, and the main properties of leathers and effluents were assessed. The results showed that fossil-based raw materials can be partially replaced with biomass derivatives while providing the leather with similar organoleptic characteristics. The new biopolymer showed higher bi...
Development of bio-acceptable leather using bagasse
Journal of Cleaner Production, 2019
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.