Leather Manufacturing Research Articles

Salt-free Chromium Tanning: Practical Approaches

Chromium tanning finds a prominant place in leather manufacturing for permanent stabilization of hide/skin matrix. Though, it has multiple advantages in terms of high thermal stability, easy process and low cost etc., the current practice is not environmentally sustainable. Poor chromium exhaustion and TDS load generation are the major environmental threats of conventional chromium tanning systems. On the other hand, salt-free chromium tanning is identified as one of the efficient alternative approaches for hide/skin matrix stabilization. However, it has not been commercially practiced due to the several practical difficulties. In this work attempts have been made to develop a practically viable high-performance salt-free chromium tanning system using deliming liquor as tanning float and changing the order of addition of masking salt. The developed methodologies completely avoid the use of salt/basification process and it is suitable for all kinds of raw materials and tannery houses. Besides, the process enjoys 71-77% reduction in TDS load and the uptake of chromium is around 90%. The physical strength characteristics are on par with conventional process and the leathers exhibit good grain tightness and roundness. The developed methodologies are simple and do not require any specialty chemicals.

Leather and footwear industry in Albania

This paper aims to give an overview of the history of the development of Albanian leather and footwear manufacturing sector covering the whole production chain from leather processing to footwear production as well as the perspective of this sector in the country and its challenges.

Waste Collagen Peptide Based Amphoteric Organic Chrome-Free Tanning Agents for Cleaner Leather Manufacturing: From Self-Taking to Self-Using

Waste Collagen Peptide Based Amphoteric Organic Chrome-Free Tanning Agents for Cleaner Leather Manufacturing: From Self-Taking to Self-Using

A salt-free pickling and chrome-free tanning technology: a sustainable approach for cleaner leather manufacturing

An EHBP-based salt-free pickling and chrome-free tanning system with a promising development for large-scale production was proposed to prevent the pollution of tannery effluents (Cl− and Cr3+).

Optimization of Collagen Extraction from Sheep Raw Trimming Wastes Using Acid Hydrolysis

Although leather industry plays a significant role in the global economy, it has been categorized as one of highly polluting industries due to its generation of huge amount liquid and solid wastes. Large amount of solid and liquid wastes is generated from tanning industries during leather manufacturing process. These wastes bring about various problems to the environment and human health. Tannery wastes contain significant amount of raw skin wastes that are produced in hide/leather trimming process. The recycling and use of these raw skin/hide wastes (trimming wastes) is very important from environmental as well as economic point of views. The aim of this work was to investigate production of collagen from sheep skin trimming waste. The trimming waste was first pre-treated and then acetic acid hydrolysed to extract collagen. The extracted collagen was characterized using Fourier Transform Infrared (FTIR), UV-spectrometer and Scanning Electron Microscope (SEM). Response Surface Methodology (RSM) was used to optimize collagen extraction parameters (acetic acid, mixing ratio and extraction time). A three-factor, three-level Box-Behnken Design (BBD) based RSM was applied to determine the optimal conditions to obtain maximum collagen yield. A maximum collagen yield of 25.75% was obtained at optimum conditions (acetic acid concentration of 0.54 M, skin to acetic acid ratio of 0.03 g/ml and extraction time 3.33 day) using the RSM. Under these optimum conditions, experimental determined collagen yield of acid-soluble collagen was 25.85% which is in good agreement with the predicted value.

IMPACT OF THE COVID-19 PANDEMIC ON THE INDUSTRIAL SECTOR: IMPLICATIONS FOR ECONOMIC POLICY

The COVID-19 pandemic had a major impact on the economy around the world, damaging many areas of daily life. The industrial sector has been affected by the effects of industrial closures, reduced economic activity, and disruptions in logistics and transportation. The damage caused by the crisis has not yet been specifically assessed, as the industrial sector was not the most affected by the pandemic compared to other sectors of the economy. The subject of the study is the industrial sector of Ukraine and the EU. The aim of the article is to assess the impact of the COVID-19 pandemic on industrial development in Ukraine and the EU, as well as to propose economic policy measures to achieve stabilization in the industrial sector. Since industry is the foundation of economic growth and development, it is necessary to assess the depth of its decline and find possible solutions to get out of the recession. The theoretical analysis of the article is based on recent work by scientists in the field of industrial development, as well as on the authors' developments assessing the impact of the COVID-19 pandemic on the economy. The COVID-19 pandemic created the following problems for Ukraine's economy and industry: a decrease in aggregate global demand and a decline in business activity, which led to lower prices on world commodity markets; strengthening of government regulation; raw-material orientation of Ukraine's exports and the significant dependence of industrial enterprises on world prices for raw materials; transport and logistics problems with raw material supply chains; lower business expectations and reduced investment due to significant uncertainty. The findings showed that the coronavirus crisis hit the industrial sectors mainly in April 2020, leading to a 16.1% decline in industrial production in Ukraine and an 18.6% decline in the EU. Such industries as automobile manufacturing, leather manufacturing, light industry, furniture manufacturing, coal mining, oil and gas extraction were hit the hardest. The following measures to stabilize the industrial sector are proposed: support for domestic demand for the products of industries, namely metallurgy, machine building, and chemical industry, which are mainly export-oriented and very sensitive to changes in global demand; stimulation and development of high value-added production; acceleration of the digitalization process within national borders; support for the industrial sector in its pursuit of environmentally friendly production, and others.

Manipulate the nano-structure of layered double hydroxides via calcination for enhancing immobilization of anionic dyes on collagen fibers

In this work, we present an effective approach for promoting the immobilization of anionic dyes on the collagen fibers of the leather matrix via introducing layered double oxide (LDO), which is obtained by calcining layered double hydroxides (LDH), inspired by incorporating their memory effect and charge effect. The results indicate that the calcination increases specific surface area, oxygen vacancies, and Al3+ defects of LDH nanosheets, and the structure of LDH nanosheets can be reconstructed by rehydration. Diffusion behavior of both LDH and LDO nanosheets into the collagen fibers follows the Langmuir model. The LDO nanosheets can penetrate into the collagen fibers more easily and evenly than that of the LDH nanosheets. Moreover, the formation of ionic bonds, hydrogen bonds, and coordination bonds between the nanosheets and the collagen stabilizing the collagen microstructures can endow the collagen fibers with improved thermal stability. Increased porosity of the collagen fibers results in enhanced adsorption and immobilization capacity for anionic dyes on the collagen fibers of the leather matrix in leather post-tanning process. Furthermore, adsorption behavior of anionic dye on the collagen fibers can be well accorded with pseudo-second-order and Langmuir model, exhibiting a monolayer adsorption process. This established cooperative approach will be helpful to extend the application of clay for improving the dyeing performance of leather matrix towards eco-leather manufacture and effectively reduce emission of dyes from the source in leather manufacturing.

Development of Leather Cutting Board from Plastic Waste

Cutting is the process in which goods or garment material are cut and converted into pattern shapes of the goods or garment components. There are two methods of Leather cutting, which are hand cutting and machine cutting. Hand cutting is done with the use of hand knife, cutting board and cutting patterns. Machine cutting can be done using semi-automatic cutting machines or fully-automatic cutting machines. Currently, in Ethiopia, different local and foreign investors are participating in leather products manufacturing. Most of the leather product manufacturing industry and some Small and Medium enterprise’s (SME’s) in the country are using leather cutting machines in order to cut leather goods or garment parts. Most of the industry and SMEs are using imported cutting board made of plastics and rubbers. However, these cutting boards are expensive.
 
 This research aimed at developing a cutting board made from HDPE (High-Density Polyethylene) plastic waste as main material, calcium carbonate as a filler and glass fiber as a reinforcing material. Primary and secondary data gathering techniques were applied simultaneously. Primary data were collected through interview and field observation. Secondary data was gathered by reviewing different literature. The cutting board developed through collecting HDPE plastic waste, washing, shredding and melting the shredded plastic with filler and reinforcing material. The melted plastic poured in to cutting board mold and cooled. The developed cutting board was compared with HDPE cutting board available in the local market. The developed board showed relative compression and hardness properties with the HDPE cutting board available in the market. In the cost analysis, the developed cutting board is cheaper than the cutting board which available in the market. However, the cutting board in the market has better surface texture and quality than the developed cutting board. Melting HDPE plastic waste using metal or clay cooking pots and charcoal fire is a tedious task and smoke from the fire will cause human health problem and will affect environment. Consequently, manual plastic melting method is not feasible for mass production, because it is difficult to control the amount of heat (charcoal fire) during melting process. Based on this the authors recommend using machine based plastic melting and molding during HDPE and related plastic recycling.

Evaluation and improvement of the oxidative stability of leather fatliquors

Fatliquor oxidation may give leather unpleasant odor, and excessive amounts of Cr(VI) and volatile organic compounds. The accurate evaluation and improvement of the oxidative stability of fatliquors are of great significance to high-quality leather manufacturing. We proposed a set of practical methods for evaluating the oxidative stability of fatliquors on the basis of oxidation induction time, change in iodine value (∆ IV), and change in acid value (∆ AV) under accelerated oxidation conditions (at 100 °C with 10 L/h of air). Oxidation induction time is a highly sensitive marker for quantifying the oxidative stability of fatliquors, and ∆ IV and ∆ AV that are low cost and easy to operate are useful in evaluating the oxidative stability of fatliquors when the oxidation induction time is less than 22 h. The number of double bonds in fatliquors is an important factor affecting oxidative stability. The sulfation modification of fatliquors that greatly reduces double bonds and the addition of antioxidants, especially butylated hydroxyanisole and butylated hydroxytoluene, markedly improve oxidative stability of fatliquors.

Effective utilization of tannery hair waste to develop a high-performing re-tanning agent for cleaner leather manufacturing

Accumulation of hair waste is a major burden to the leather industry, causing a negative impact on the industry's sustainable development. The industry is already bogged down by the usage of synthetic re-tanning agents that are not only extremely challenging for biodegradation but also release free-form of formaldehyde in the final leather stage. This research work focuses on developing a formaldehyde-free bio-based re-tanning agent from hair waste. In order to do so, hair waste is subjected to alkali hydrolysis and subsequently graft-copolymerized with methacrylic acid (MAA). These treatments were optimal using 20 % (w/w) sodium hydroxide and thermal activity at 90 °C. This resulted in effective hydrolysis of red sheep hair, which was the ideal candidate in this study. The hydrolysate was subjected to monomer in situ polymerization (using MAA) with potassium per sulfate/sodium meta-bisulphite redox system, leading to the development of keratin hydrolysate-g-methacrylic acid (KH-g-MA) copolymer (this was noted both at a laboratory level and pilot scale). The obtained KH-g-MA copolymer exhibited ideal characteristics such as increased protein content (78.3 ± 1.2), appropriate particle size (1516 nm), suitable pH (5) and required viscosity of 512 cP. The developed KH-g-MA copolymer was then applied as a re-tanning agent in the leather manufacturing process. Significant improvement in leather's mechanical strength characteristics was observed. In addition, the organoleptic properties of leather such as fullness, softness and grain tightness showed much improvement. Scanning electron microscopy (SEM) showed an enhanced surface smoothness and filling of the voids in experimental leather in comparison to the control leather. This recycle and reuse strategy of hair waste not only helps resolve issues with handling of hair solid waste but also results in producing an eco-friendly re-tanning agent in leather manufacturing, thereby paving the way for cyclic economic utilization and cleaner environment.

Evaluation of Antifungal Activity of Carbonate Solvent – Part:1

Antimicrobial agents have been used in leather manufacturing to prevent leather products from microbial contamination. In this work, the antifungal activity of green solvent such as propylene carbonate was investigated against the mixed culture of fungi isolated from wet-blue using broth dilution/well diffusion. A concentration of 5% and above (propylene carbonate) showed effective antifungal activity against the mixed culture of fungi and the efficiency of propylene carbonate on the mixed culture increased with increasing concentration/volume. Propylene carbonate exhibited fungistatic activity against the mixed culture of fungi but it lost its activity after a certain period and fungal growth was observed again. It was also found that 2% propylene carbonate in chrome tanning process effectively inhibited the fungal growth and the wet-blue can be preserved up to 30 days without any fungal attack.

«Faux Leather»: What Are We Talking About? A Sustainability Project

The tanning sector is a strong point of the so-called ‘Made in Italy’, but for a long time the leather supply chain has been considered responsible for pollution. This project, developed as practice during the training course on Agenda 2030 organized by AIB Emilia-Romagna, has the long-term objective of highlighting the stereotypes related to the vision of leather manufacturing, and of illustrating the possibility of a sustainable tanning process. The project includes some exhibitions (both on-site and virtual) focused on three aspects of the tanning activity: the scientific books on vegetal tanning process, the leather bindings and parchment in antiquarian books as materials of animal origin, and the plants traditionally used in leather tanning. A thematic web portal brings together the various exhibitions. The common goal is to widespread some adequate knowledge on the 2030 Agenda, in order to make people aware of the importance of the Sustainable Development Goals.

Current available treatment technologies for saline wastewater and land-based treatment as an emerging environment-friendly technology: A review.

Different industrial activities such as agro-food processing and manufacturing, leather manufacturing, and paper and pulp production generate highly saline wastewater. Direct discharge of saline wastewater has resulted in pollution of waterbodies by very high magnitudes. Consequently, an enormous number of pollutants such as heavy metals, salts, and organic matter are also released into the environment threatening the survival of human and biota. Saline wastewater also has significant effects on survival of plants, agricultural activities, and groundwater systems. Several treatments and disposal technologies are available for saline wastewater, but the selection of the most appropriate treatment and disposal technology still remains a major challenge with respect to the economic or technical constraints. Considering the sustainable management of saline wastewater, the present review is an attempt to compile the existing and emerging technologies for the treatment of saline wastewater. Among all the individual and hybrid technologies, land-based treatment systems are proven to be the most efficient technologies considering the energy demands, economic, and treatment efficiencies. Likewise, new and sustainable technologies are the need of hour integrating both the treatment and management and the resource recovery factors along with the ultimate goal of the protection in terms of human health and environmental aspect. PRACTITIONER POINTS: Physico-chemical treatment technologies for saline wastewater. Combined/Hybrid technologies for the treatment of saline wastewater. Land-based treatments as the environment friendly and sustainable method for saline wastewater treatment and disposal. Role of phytoremediation in land-based treatment.

Application of value stream mapping (VSM) in low-level technology organizations: a case study

PurposeThis research aims to improve the performance and productivity of low-level technology organizations using lean tools – value stream mapping (VSM). In order to investigate the application of VSM in low-level technology organizations, this study takes footwear manufacturing organizations as a case study.Design/methodology/approachIdentifying a suitable organization was the first step for conducting the case study, followed by product family identification. Time and motion studies are used to determine the cycle time and identify the value-adding and non-value-adding activities, respectively. After making necessary observations and calculations, the current state map was developed. Different improvement proposals were identified, and the future state map was constructed.FindingsAs a result, 56.3% cycle time reduction and 69.7% reduction in lead time were obtained, confirming its application in low-level technology organizations to improve their performance and productivity. This promising result indicates that a significant improvement can be achieved if VSM is applied in low-level organizations other than footwear industries, such as the clothing and furniture industries. Speed is investigated to be one of the parameters in motion study.Research limitations/implicationsThis study focuses on low-level technology organizations, specifically leather shoe manufacturing industries. But experiences gained from implementing this study are realistic and applicable in similar organizations.Practical implicationsPerformance and productivity improvement are critical issues to be addressed in low-level technology organizations, especially in the leather footwear manufacturing sector. This can be achieved through VSM by identifying and removing the wastes. VSM can be applied to low-level organizations as well. VSM is a powerful tool that helps managers and practitioners in identifying wastes and opportunities for improvement.Originality/valueThe paper addresses applicability of VSM in the production process of low-level technology organizations with an original industrial case study in Ethiopia.

Metal-Free Combination Tanning with Replenishable Polyphenols and Marine Oil

In line with the resurgence of natural products in the global manufacturing industry, the leather industry is also relooking the increased use of organic materials. To exploit the benefits of the vegetable tanning materials and to couple with suitable organic material for overcoming the inherent shortcomings of vegetable tanning materials, studies were undertaken. Tanning materials like raw fish oil have advantageous properties to impart on leather such as softness, lightweight, and washability characteristics. Hence studies were undertaken on polyphenol-fish oil combination tannages.
 The quantities of wattle and fish oil and process conditions were standardized. The study indicated that the oxidation of fish oil could take place in the presence of vegetable tannins. The leathers tanned by this combination tanning system could be converted into garment leathers of rich shades and possessed good strength and physical properties. Propelled by encouraging results, investigations were also made on the nature of interaction between vegetable tannins and fish oil with collagen. It was also observed that the vegetable tannins probably do not hinder the oxidation of oil. To sum up, the study leads to the development of a viable, versatile organic tanning system to gain eco-acceptability for the leather manufacturing process.

Preparation and application of polyethylene glycol triazine derivatives as a chrome-free tanning agent for wet-white leather manufacturing.

Leather manufacturing is the process of transforming animal skin into high value-added commodity. As a crucial step in the leather producing process, conventional chrome tanning could lead to discharge of chromium contaminant due to the low efficiency of chromium uptake. In this paper, a series of polyethylene glycol triazine derivatives' tanning agent (PT) with different molecule weight was synthesized with one-step method and applied in the main tanning of hide. The chemical structure of the PT was detected by FT-IR and 1H-NMR. The application experimental results indicated that after 16% of PT tanning at pH of 6, the wet-white was endowed with shrinkage temperature over 80°C and thickening rate over 108%. The experimental results indicated that the PT tanning leather not only have a better physical and mechanical properties than commercial triazine derivatives tanning agent, but also the leather is endowed with the effects of outstanding thermal properties. Considering that the pickling process became unnecessary, a large number of neutral salts could be avoided, the chromium load in spent liquor decreased from 1288 mg/L to 0, and the total dissolved chlorine in spent liquor decreased from 15,360 to 9581 mg/L; no toxic and harmful substances such as chromium and aldehyde are introduced into the tanning process. Compared with the leather tanned with commercial triazine derivatives' tanning agent, the leather tanned with PT showed a similar overall tanning properties and better environmental friendliness, which makes PT matches the integral requirements of the modern sustainable leather industry.

A “Taiji-Bagua” inspired multi-functional amphoteric polymer for ecological chromium-free organic tanned leather production: Integration of retanning and fatliquoring

Comprehensive promotion of chrome-free organic tanning system has become an inevitable trend for cleaner production in leather manufacturing industry. However, the imbalance of interface charge between conventional anionic wet finishing material and organic tanned leather leads to poor quality of finished leather. Herein, a novel amphoteric polymer P (AA-AM-C12DM) as retanning and fatliquoring dual-functional wet finishing material was prepared by free radical polymerization using acrylic acid (AA), acrylamide (AM), and (2-methacryloyloxyethyl) dodecyl ammonium bromide (C12DM) as raw materials in an aqueous system and further applied in TWS organic tanned leather. Comprehensive structural and performance characterization of P (AA-AM-C12DM) confirmed the presence of amphoteric groups and hydrophobic long chains in its structure. Number average molecular weight and isoelectric point were determined to be 6396 g mol−1 and 5.16, respectively. The physical and mechanical properties, morphology of the P (AA-AM-C12DM)-treated leather, and their reactivities to anionic dye were investigated. The effect of hydrogen bond and ionic bond, which resulted from reactions between the carboxyl groups, amide groups, cation N+ in P (AA-AM-C12DM), and the pendant amino groups, hydroxyl groups, carboxyl groups from collagen fibers, benefitted in enhancing the physical and mechanical properties of crust leather and their reactivity to anionic dye. Moreover, P (AA-AM-C12DM) showed remarkable environmental benefits compared to the commercial fatliquor, by significantly promoting dye absorption as high as 96.57%. These findings provide a potential application of P (AA-AM-C12DM) to coordinate well with an ecological chrome-free organic tanning system, significantly promoting the cleaner production in the leather industry.

Structural analysis and the effect of the chromium on LTA (Na) zeolite synthesized from kaolin

The release of heavy metals ions into water resources is an environmental issue due to their high toxicity, long-lasting stability, and bioaccumulation in the food chain. Currently, the discharge of Mayan leather manufacturing plants’ wastewater into the Aji Chai River in East Azerbaijan (Iran) has increased the concentration of heavy elements such as chromium, copper, and zinc, so that the upper free aquifer of the Mayan Plain has become salty due to the feeding from this River. To overcome such a problem, we synthesized a highly functional Linde Type A (LTA) Na-zeolite from Kaolin as the raw material. In this regard, the impact of parameters such as synthetic temperature, adsorption temperature, and pH on the Cr adsorption capacity of zeolite on wastewater solutions obtained from this area was investigated. The structural analysis through XRD, SEM, BET, and FTIR, coupled with the Rietveld refinement method demonstrated that upon adsorption of Cr ions into the LTA zeolite structure, the lattice parameter decreases. Additionally, the results of this study suggest that the synthesized LTA zeolite has a very high adsorption rate in both acidic and alkaline environments in a way that a 100% removal rate was recorded at pH = 3. The as-synthesized zeolite has efficiently removed chromium from industrial waste waters flowing into this area.

A decision-aid model for evaluating challenges to blockchain adoption in supply chains

ABSTRACT Blockchain, emerging technology, has immense potential to transform supply chain activities. Though blockchain offers more benefits, industries face many challenges in blockchain adoption. This paper aims to develop a framework to identify and evaluate various challenges in adopting blockchain in supply chain management. First, 40 prominent challenges to blockchain adoption were identified using the fuzzy Delphi technique. The challenges were then assessed using an integrated methodology that included the grey-decision-making trial and evaluation laboratory (DEMATEL) and the weighted aggregated sum product assessment (WASPAS) method. Case studies of five leather garment manufacturing companies were conducted to test this integrated strategy. To ensure the proposed framework's robustness and viability, a sensitivity analysis was performed. Results indicate lack of knowledge about blockchain technology, non-existence of universal regulatory binding, new organisational policies, reputation-based attack, and vulnerable to cyber-attack as the top five challenges faced by the leather garment manufacturing companies. This study imparts the knowledge, significance and challenges in adopting blockchain technology in supply chain management. The outcome of this study provides structural assistance to the managers by exposing the causeand-effect group challenges in blockchain adoption. By understanding the cause and effect relationship among the challenges, industrial practitioners may devise adequate strategies.

ФОРМУВАННЯ ПОКАЗНИКІВ ЯКОСТІ ШКІР РІЗНИХ ВИДІВ ШКІРЯНОЇ СИРОВИНИ ІЗ ВИКОРИСТАННЯМ МОНТМОРИЛОНІТУ

The tanning process is important in stabilizing the collagen structure of the derma. Сhrome tanning is the traditional option. The basic chromium sulfate is used in the production of 80% of leather in use. A peculiarity of chromium tanning turns out to be an inefficient use of chromium compounds, since almost 40% of tannins remain in wastewater. Considering the disadvantages of using chromium compounds, scientific research on the replacement and use of rather eco-friendlier substances has been conducted for a long time. One of the directions of ecologization of leather manufacturing is the use of modified montmorillonite dispersions in various technological processes such as tanning, filling, dyeing, fat-liquoring, etc. Researches have been aimed at identifying the feasibility of making leather for the uppers of children’s shoes from different types of leather raw materials using modified dispersions of montmorillonite at the stage of tanning. According to the technology of making leather, cattle (medium heifer), goat and sheep skins were used for the upper of the shoes. The analysis of leather quality indicators from different types of raw materials obtained with the use of chromefree tanning. It is proved that hides from raw materials of goats and sheepskins in comparison with cattle are characterized by increased yield area by 3.5-7.2 %, thickness by 0.8-2.6 %, volume yield by 4.5-6.1 % and uniformity of quality indicators in different topographic areas. The level of indicators of physical and mechanical, hygienic properties and chemical composition of leather of different types of raw materials is almost identical within the requirements of regulatory documents. It is advisable to use for children’s shoes leather from raw goat and sheepskin given the peculiarities of the manufacture of children’s shoes, dimensional characteristics of parts, requirements for dimensional stability and shape conservation.