Leather Process Research Articles

Potential of Cactus Leather in Pakistan's Leather Industry: A Qualitative Analysis.

The rising trend of sustainability worldwide has significantly influenced various industries, transformed not only retail but also reshaped the luxury sector. One notable shift is the increasing focus on vegan leather, with cactus leather emerging as a promising alternative. This study explores the potential of cactus leather in Pakistan, particularly how it can contribute to sustainability in the country's leather industry. By introducing cactus leather, the research aims to raise awareness about sustainable practices and offer a viable alternative to traditional animal leather. The methodology employed in this study is qualitative, based on interviews with leather manufacturers, and the data was analyzed using a thematic analysis framework. The key findings highlight the potential of cactus leather as a sustainable substitute for animal leather, emphasizing its durability, aesthetic appeal, and environmental benefits. Cactus leather not only provides a cruelty-free option but also addresses issues related to pollution and water usage in leather production. The research aims to introduce cactus leather to the Pakistani market, particularly in regions like Thar and Kharan in Sindh and Baluchistan, where cactus farming could thrive and benefit local communities. Cactus leather eliminates the need for animal-based materials, allowing consumers to wear leather products without the associated guilt of animal cruelty. Additionally, the production process of cactus leather is less water-intensive and requires fewer toxic chemicals than traditional leather processing, further reducing its environmental impact. This study underscores the potential for cactus leather to revolutionize the leather industry in Pakistan, aligning with global sustainability trends and offering a practical solution to environmental and ethical concerns.

Keratin hydrolysate as a chrome exhaust aid and keratin filler in leather processing: A cleaner technology approach for tannery solid waste management and leather manufacturing

Hair burning unhairing and dampening of tannery wastes during the hair-saving unhairing process are becoming significant problems in the tanning industry. Therefore, this research article focuses on the extraction of keratin hydrolysate (KH) and its application as a chrome exhaust aid and keratin filler in leather manufacturing process. The structure, morphology and functional groups of the extract were examined using X-Ray Diffractometer (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrometer (FTIR), respectively. To study and contrast the degree of improvement in chromium uptake, the KH solution was applied both before tanning on the pickled pelt and after tanning during basification. The thermal stability, physical strength characteristics and organoleptic properties of the leathers obtained were characterized. Furthermore, the environmental impact of the tanning system was assessed through a comparative analysis of the spent liquors. Finally, experimental retanning process was conducted to replace the commercial protein filler (Celatan F: 50, 75, and 100 %) with KH solution, with concurrent processing of control leather using conventional chrome tanning agent at 6 % dosage of chromium. The FTIR analysis of the extract confirmed the presence of alkyl side chains of amino acids as well as carboxylic, amide, carboxyl group and aldehyde functional groups at 1400-1700 cm−1,3,303.46 cm−1,3270 cm−1 and 2752 cm−1, respectively. XRD spectrum showed two diffraction peaks at 2 theta values of 9.36° and 21.16°, respectively. Leathers with improved mechanical strength, organoleptic properties and thermal stability were obtained with 100 % substitution of Celatan F at pH 6 and 10 % chromium dosage. It was also discovered that the shrinkage temperature of the experimental leather was enhanced to more than 105 °C. Environmental impact evaluation on the spent liquor showed that the complete replacement of Celatan F with KH solution brought about a notable decrease in COD and TDS in the spent liquor. The extraction and application of tannery hair waste-based keratin hydrolysate as an efficient, environmentally friendly chrome exhaust aid and keratin filler has been attempted and established in this research article.

Proposal of an environmental performance index to assess leather-manufacturing companies

Despite the global economic and environmental importance of the leather industry, the specialized literature still presents an important gap in analyzing the environmental performance of the leather manufacturing process from the waste generated. This paper aims to propose an unprecedented index (Index of Leather Manufacturing- ILM) to evaluate the environmental performance of leather manufacturing processes. The development of the index combines Life Cycle Assessment (LCA) and a Multicriteria Decision Method (MCDM) and is oriented to consider the impact of waste on environmental health. Its estimate is based on: the calculation of the environmental potential impact of the waste; the waste quantity produced by the company over a given period; the relative geographic coverage that each waste can achieve; the assessment of the appropriateness of the disposal of waste generated by the firm. The proposed index was tested on a large Brazilian leather manufacturer. The results showed that the waste management in the company is not perfect but is well rated, and residues with the greatest environmental impact are: wetblue shavings, wetblue sawdust, and gaseous emissions from beam house operation.

Experimental Study on the Removal of Toluene from Water by PTFE Hydrophobic Microporous Membrane Using Air Gap Membrane Distillation Process

Toluene is used for various purposes such as a cleansing agent, paint thinner, lacquers, printing, and leather tanning process. However, it has an adverse effect on human bodies, such as skin irritation, leukemia, respiratory issues, mutagenicity, etc, when the chemical gets mixed in drinking and rainwater by the above routes. Therefore, there is a threat to the environment and society because of the presence of toluene in water bodies through industrial effluent. Henceforth, in this study, toluene is separated from water using the air gap membrane distillation (AGMD) process. The hydrophobic microporous poly-tetra- fluoro-ethylene has been employed for this purpose. Primarily, this work focussed on the study of operating parameters such as feed solution temperature and coolant temperature on the AGMD performance namely permeate flux and toluene selectivity. It was observed that the permeate flux increased exponentially from 2.07 kg/m2h to 9.23 kg/m2h, and 0.94 kg/m2h to 3.53 kg/m2h. However, it was found that the permeate flux decreased from 9.48 kg/m2h to 8.12 kg/m2h, and 3.78 kg/m2h to 2.42 kg/m2h on increasing the coolant temperature from 5°C to 25°C at 3 mm and 11 mm air gap, respectively. The membrane selectivity was found to be less than 1, which signifies the efficient toluene-water separation. In order to study the membrane performance in the long run, the permeate flux was estimated continuously till 60 h wherein the estimated flux was found to be almost constant. The membrane morphology before and after the 60 h experimental run was analysed using capture FE-SEM micrographs. The toluene concentration was estimated using a spectrophotometer at a wavelength of 264 nm.

Klasifikasikan Jenis Cacat Kulit Menggunakan SMOTE-GoogLeNet

Deep learning has been proven to be able to provide significant contributions to several fields, including industry. It has also been proven that it has resulted in an outstanding performance for classification, detection, and even segmentation processes. In the leather industry, it also successfully gave valuable results, especially for the leather defect inspection process. However, despite its outstanding performance, it remained a drawback because it produced insignificant results if employed in a small or imbalanced dataset. This research work focuses on the analysis of the implementation of the data balancing method for improving the performance of the deep learning method for classifying the types of leather defects. This research work was done by employing three processes. In the first step, we utilized the data balancing method to balance the data proportion. In the next step, we employed GoogLeNet as a deep learning architecture for training and testing processes. Our experiment was conducted in two scenarios. The first scenario was done by using the original dataset. Whereas the second scenario was accomplished by utilizing the data balancing method before training and testing. According to the experiment results, implementing the data balancing method successfully increased the performance of the deep learning method by more than 15%. It can be inferred that the proportion or the number of data strongly affected the performance of deep learning models.

Influence of Retanning Agents on Physical Characteristics of Snow-White Glove Leather from Goat Skin

The quality of leather is subject to various elements, such as the specific raw material used, and the processing techniques implemented throughout the production process. Goatskin, renowned for its exceptional softness and durability, is frequently employed in the production of gloves owing to its desired attributes, notably its capacity to produce snow-white gloves. Retanning is an essential step in the leather manufacturing process as it significantly improves the characteristics of the leather. Through an investigation into the impacts of distinct retanning agents on goatskin leather gloves, this research endeavor seeks to offer significant knowledge regarding the most effective retanning procedures that can augment the tactile attributes of snow- white leather gloves. In this study, formaldehyde, alum, chromium, and chromium alum were employed as retanning agents. The retanned leathers were assessed by physical parameters, Principal Component Analysis (PCA), and Fourier Transform Infrared spectroscopy (FTIR), then compared to a commercially available snow-white leather glove. The physical characteristics of chrome alum retanned leather showed a high degree of softness (6.60±0.02 mm), good tear strength (1.530±117 N/cm), and tensile strength (1.500±100 N/cm 2 ). The principal component analysis (PCA) also supported that the properties of chrome alum retanned snow-white glove leather closely resemble commercial leather and the result from this study suggested that all factors notably impact the skin's physical quality, except for thickness. Additionally, the FTIR analysis reveals similar functional groups from the different retanned leathers indicated by comparable peaks and stretching patterns. Therefore, chrome-alum could be a well alternative retanning agent for the production of snow-white glove leather.

Ultrasound-Assisted Extraction, Characterization and Assessment of Vegetable Tannins from Guava (Psidium guajava) Leaves for Leather Tanning

For commercial leather processing, chrome tanning is the most used approach but it significantly contributes to environmental pollution. Vegetable tannins, which are large polyphenolic compounds, form strong interactions with proteins and carbohydrates, thereby enhancing the adaptability and value of vegetable-tanned leather as well as reducing environmental impact. In this study, vegetable tannins were extracted from the leaves of Guava plants (Psidium guajava) using ethanol as the solvent, facilitated by ultrasound. Extracted tannins were quantified using the Folin–Ciocâlteu reagent with ultraviolet-visible spectroscopic method. Ultrasound enhanced the extraction process producing a high yield in less time due to its mechanical, thermal, and cavitation impacts. The extracted tannins were characterized by a variety of spectroscopic techniques, including Proton (1H) Nuclear magnetic resonance, Fourier-transform infrared, and ultraviolet-visible spectroscopy. The effect of various process variables, such as temperature, solid-liquid ratio, ultrasonic power, extraction period, and powder fineness, were also investigated to optimize the extraction process. Finally, the extracted tannins were employed in leather tanning processes to assess their potential as tanning agents. The extracted tannins ensured uniform diffusion of tannins, improved thermal stability and reduced the number of tannins in effluent by 68% making it an environmentally friendly leather tanning process.

A New Synthesis Method and Characterization of Graphene Oxide Nanocomposites for the Leather Tanning Process

Environmental pollution caused by wastes generated from chrome tan is a major concern nowadays. This study aimed to develop an eco-friendly alternative tanning agent using graphene oxide (GO) based nanocomposite materials. GO was synthesized by a new approach with modification of the Hummers method. Two types of GO-based nanocomposites, GO-TiO2 (GT) and GO-TiO2-PEG (GTP) were prepared by adding TiO2 nanoparticles and polyethylene glycol (PEG) as surface modifiers. They were successfully applied to leather tanning processes at different concentrations (2%, 4%, and 6%). Both synthesized GO, GO-nanocomposites, and the resulting tanned leathers were characterized by Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), and Fourier-transform Infrared Spectroscopy (FT-IR). Different physico-mechanical properties of leathers tanned with nanocomposites were evaluated and the results were compared with chrome-tanned leathers. The tensile strength of chrome-tanned leather was 223 (kg/cm) whereas the maximum tensile strength was found at 228 (kg/cm) and 233 (kg/cm) in 6% GO-TiO2 and GO-TiO2-PEG tanned leathers respectively. The environmental pollution impact of the effluents generated by the new tanning process was assessed. The COD of effluents generated from chrome tanning was 4800 ppm which was significantly reduced to 2400-1440 ppm and 2880-1920 ppm when GO-TiO2 (GT) and GO-TiO2-PEG (GTP) were applied in leather tanning respectively. The TDS and BOD were found at 183.8 and 200 ppm in conventional chrome-tanned wastewater which were significantly reduced to the range of 47.5-18.3 and 100-50 ppm respectively in liquid wastes obtained from the GO-composite tanning process. The maximum reduction of COD, BOD, TDS, and TSS in leather waste liquid was found with the application of 2% GO-nanocomposites in tanning. The results revealed that leathers tanned with nanocomposites possess characteristic properties which were very similar to those observed in chrome-tanned leathers whereas the new tanning agents drastically reduced the intensity of pollutants in leather effluents. The application of new nanocomposites in the leather tanning process is an innovative effort. This new nanocomposite-tanning method showed minimal consequences regarding environmental pollution with the generation of less toxic effluents from the respective tanning process.

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.

An augmented reality approach for communicating intangible and architectural heritage through digital characters and scale models

Intangible cultural heritage (ICH) represents living cultural expressions and practices that are part of the heritage of a community, and their preservation and transmission are considered highly important. Various methods and tools have been applied so far for the digitization and dissemination of ICH content including a wide range of technologies. Mobile augmented reality is a promising solution along this path that enables the overlap of digital and real-world information in an engaging and efficient manner. Despite the widespread use of AR in cultural heritage, there are not many studies regarding the user experience, the learning outcomes, and the way in which users observe and interact with the virtual content. This paper presents a mobile augmented reality installation that re-enacts the stages of leather tanning process, adopting a novel approach that augments 3D content upon a physical scale model of an old tannery. This approach pursues to transmit the cultural value of traditional craftmanship to visitors of the building and associate its architectural elements to its history and use. A user evaluation was conducted aiming to measure the users’ engagement, learning, and experience using the installation. The encouraging results led to a follow-up study about the impact of the physical scale model on the experience. Two variations of the experience have been studied, one with a physical scale model and one with a digital-only version in a between-subject design. The results of the two studies provide evidence that the proposed approach generated a positive user experience and evident learning gain and was considered easy to use, highlighting its potential to be widely adopted in buildings with architectural value.

Assembly and analysis of the genome of Notholithocarpus densiflorus.

Tanoak (Notholithocarpus densiflorus) is an evergreen tree in the Fagaceae family found in California and southern Oregon. Historically, tanoak acorns were an important food source for Native American tribes, and the bark was used extensively in the leather tanning process. Long considered a disjunct relictual element of the Asian stone oaks (Lithocarpus spp.), phylogenetic analysis has determined that the tanoak is an example of convergent evolution. Tanoaks are deeply divergent from oaks (Quercus) of the Pacific Northwest and comprise a new genus with a single species. These trees are highly susceptible to "sudden oak death" (SOD), a plant pathogen (Phytophthora ramorum) that has caused widespread deaths of tanoaks. In this study, we set out to assemble the genome and perform comparative studies among a number of individuals that demonstrated varying levels of susceptibility to SOD. First, we sequenced and de novo assembled a draft reference genome of N. densiflorus using cobarcoded library processing methods and an MGI DNBSEQ-G400 sequencer. To increase the contiguity of the final assembly, we also sequenced Oxford Nanopore long reads to 30× coverage. To our knowledge, the draft genome reported here is one of the more contiguous and complete genomes of a tree species published to date, with a contig N50 of ∼1.2 Mb, a scaffold N50 of ∼2.1 Mb, and a complete gene score of 95.5% through BUSCO analysis. In addition, we sequenced 11 genetically distinct individuals and mapped these onto the draft reference genome, enabling the discovery of almost 25 million single nucleotide polymorphisms and ∼4.4 million small insertions and deletions. Finally, using cobarcoded data, we were able to generate a complete haplotype coverage of all 11 genomes.

Klasifikasi Jenis Cacat pada Kulit Menggunakan Arsitektur GoogLeNet

Deep learning has been proven to be able to provide significant contributions to several fields, including industry. It has also been proven that it has resulted in an outstanding performance for classification, detection, and even segmentation processes. In the leather industry, it also successfully gave valuable results, especially for the leather defect inspection process. This study aims to develop deep learning architecture for classifying leather defect. We used 3600 leather digital images distributed in six types of leather defects. In this study we employed GoogLeNet for classifying the data. Our experiment successfully achieved accuracy of 0.904 in training process and 0.885 in testing process. This result indicated that GoogLeNet provided powerful performance for classifying the type of leather defects.

Risk Analysis of Upper Limb Musculoskeletal Disorders in Industrial Skin Measurement Workers Using the Assessment of Repetitive Task Method

In the leather industry production process in the Piyungan area of Yogyakarta, Indonesia, the operators do a lot of repetitive activities with intensity and frequency of movement for a long time, for 8 hours in a sitting position. Operators measure on average 4700 pieces of leather per day. This leads to fatigue and complaints of musculoskeletal disorders (MSDs). For this reason, research was conducted to measure the level of risk of MSDs and improve them to reduce muscle complaints. This research was conducted experimentally on all skin-cutting operators at companies in the Piyungan area of Yogyakarta. Measurement of the risk level of upper limb musculoskeletal disorders using the Assessment of Repetitive Tasks (ART) method. The data was analyzed based on ART scores obtained, ranging from low, medium, and high risk level scores. The conclusion of the results showed that the risk level of upper limb musculoskeletal disorders in this skin measurement operator included medium and high risk levels on the left and right upper limb operators. Improvements that can be made to reduce the level of risk are improvements to work facilities in the form of chairs, additional short rest periods, and stretching muscles before and after doing work on all skin measurement production operators.

Interaction amongst calcium salts, trypsin, and hide proteins and its application for high-quality leather bating process

Bating animal hides with trypsin is an essential step for making leathers. But the mechanism why the calcium in the hide influences the bating performance remains unclear. Here, the enzyme activity of trypsin was determined using N-alpha-benzoyl-L-arginine ethyl ester, bovine albumin (BSA) and collagen fibres as substrates in the presence and absence of calcium salts. The interactions of calcium with trypsin, BSA and collagen were analysed by fluorescence spectroscopy and molecular docking. Data reveal that calcium which binds to BSA and collagen improves the structural stability and enzyme resistance of hide proteins. As a result, a high calcium content of delimed hide is useful to obtain an intact surface of bated hide. However, a low calcium content of hide for pickling is necessary for producing leathers with high physical properties and uniform colour. According to these results, a novel bating system involving deliming, bating and redeliming operations was developed. This system provides a high calcium content of hide for bating and a low calcium content of hide for subsequent pickling and tanning, which effectively reduces the risk of hide damage and improves the physical properties and colour uniformity of leather.

Leather Industry Waste Management for Architectural Design

The leather and footwear cluster in Tungurahua state has a main role in the country’s production chain, supplying 76% of the country’s tanned hides for the textile, footwear, and furniture industries, among others. The processes involved in leather tanning generate liquid, gaseous, and solid waste, the latter including the shavings from the leather trimming process, which, due to their composition and volume, are compressed and disposed of in sanitary landfills. Through Strategic Design and circular processes, as axes of change in production, new processes and strategies are established for the creation of products derived from the reuse of tannery waste; as a result, a decorative block is obtained for the design of architectural spaces with dimensions of 150 × 75 × 355 mm, 300 g in weight, and a compressive strength of 15.72 MPa. This is subjected to physicochemical tests for its validation.

Eco-friendly Chrome Tanning of Leather using Ultrasound Technique

This article describes the development of an environmentally friendly chrome tanning process of leather using ultrasound. Most of the leathers are tanned by the conventional method using basic chromium sulfate. It is one of the most polluting and time-consuming steps in leather processing. Investigations were carried out on ultrasound assisted eco-friendly tanning process so that the chrome tanning agent could provide better quality leather. Effects of using ultrasound in chrome tanning process were studied at different pH, tanning time, tanning agent dosage, and then compared with that of conventional method. Tanned leathers were characterized by scanning electron microscopy (SEM), photomicrographic analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and energy dispersive X-ray (EDX). SEM analyses of the surface and cross-section of the tanned leather showed that fiber structures were not affected by ultrasound. It was also found that the shrinkage temperature of leather tanned with ultrasound was increased by about 5-29 °C. Chrome uptake and content were found to increase by 30-50% and 1-7%, respectively. Tanning time was shortened from 6 hours to 2 hours and the quantity of leachable chromium in ultrasound assisted chrome tanned leather was also decreased significantly. The noteworthy enhancing effects have been attributed largely because of the increased penetration of tanning agents into pickled leather. Photomicrographic analysis of the cross-section of the tanned leather also showed a higher penetration of tanning agents in presence of ultrasound.

Multifunctional leather finishing vs. applications, through the addition of well-dispersed flower-like nanoparticles

In the present paper, multifunctional flower-like nanoparticles were synthesized to be used in the leather finishing. They are capable of conferring simultaneously and synergistic antimicrobial, self-cleaning, light resistance, hydrophobic, mechanical, thermal, and fluorescent properties due to the presence of Ag, TiO2, and SiO2 NPs. These nanoparticles form a “flower-like” structure in which the “pistil” is made up of TiO2 and the “petals” that surround it of silver nanoparticles and silica nanoparticles, whose dimensions are of the order of ten nanometers. Their surfaces enjoy abundant hydrophilic functionalities to be dispersed within inks commonly used during the leather finishing process. Leathers functionalized with these nanomaterials showed significantly improved self-cleaning properties after 15 h of exposure to UV light, and antibacterial properties 10 times higher than that shown by the untreated samples. Aging tests were performed (ISO 105-B02, ISO 17228, SAEJ 2412). ΔE, color variation decreased by approximately 30%, if compared with samples not refined with flower-like NPs. Furthermore, the results of the mechanical tests (ISO 17076, FCA 50444) evidence amazing properties, e.g. abrasion resistance more than significantly improved, increase in resistance from 1500 cycles for the untreated samples to 3000 cycles for the leathers finished with flower-like NPs. The contact angle analysis, capturing the angle that traces the air–water to water–substrate interface from the origin of the air–water-substrate contact point at the edge, is practically unchanged after 10 s in the case of nanoparticles containing finishing.

Optical fiber gas sensor with multi-parameter sensing and environmental anti-interference performance

Formic acid finds widespread applications in numerous fields, including the petrochemicals production, rubber industry, and leather tanning process, in which the operational environments are complex and diverse. The corresponding industrial systems are often intricate and highly integrated. Indeed, formic acid gas is insidious and poses a hazard to both operating personnel and industrial equipment. The existing detection technologies for formic acid gas suffer from inherent technical limitations, making it challenging to effectively shield against industrial interference in complex environments while accurately conveying information. Furthermore, the simultaneous transmission of essential environmental data alongside formic acid gas concentration remains a formidable challenge, which is crucial for facilitating the integration and simplification of industrial system. In response to the aforementioned challenges, this research firstly employs an optical fiber structure (SNS: single mode fiber-no-core fiber-single mode fiber) with natural resistance to electromagnetic interference as the substrate. Subsequently, considering the characteristics of spectral variations and the response mechanism of formic acid gas, and addressing the issue of humidity interference of the current-stage sensors based on sensitive material, the chitosan and chitosan@PDMS are chosen as sensitive membranes. Finally, a correction formula was introduced to address the temperature and humidity coupling issue of the sensor, resulting in the successful development of two formic acid gas sensors. The chitosan-based sensor has a detection sensitivity of up to 7.7 pm/ppm, whose dual parameter detection performance for temperature and formic acid gas has been experimentally demonstrated. It can also correct the humidity-induced detection error in real-time by the correction formula. The chitosan@PDMS-based sensor was fabricated by plating a hydrophobic and breathable PDMS membrane on the surface of the chitosan-based sensor. In addition to maintaining the performance compared to the original sensor (response and recovery time was increased), the latter sensor can effectively resist the humidity interference from the environment. Furthermore, the new capability has been complemented for the simultaneous detection of temperature and humidity. That is, it realizes the dual parametric detection for formic acid gas and humidity, meanwhile providing the compensation ability for temperature change. The proposed sensors have the outstanding sensitivity, selectivity, immunity, and safety. This research not only effectively resolves the interference problem in formic acid gas detection, but also provides a new idea for equipment simplification and information integration in complex industrial systems.

Application of some Plant Extracts as Biocolorants for Leather During Finishing Process

In this research, chrome-tanned bovine crust leathers were dyed during the finishing process using plant extracts: walnut shell (Juglans regia), oak bark (Quercus cortex), and onion peel (Allium cepa). In this study, the standard recipe applied by the factory was used in the leather finishing process. For this recipe, various plant extracts were used instead of pigments, and groups that did not contain pigment and any dyestuff were formed as the control groups. After these processes, color measurement analyzes were performed on Konica Minolta CM 3600d spectrophotometer. In order to investigate the effects of walnut shell (Juglans regia), oak bark (Quercus cortex), and onion peel (Allium cepa) on the other performance properties of leather, dry and wet rub fastness test according to standard method TS EN ISO 11640 (2001) was performed. The results of the study were statistically evaluated using the NCSS method (Number Cruncher Statistical System). As a result of the study, it was noticed that, depending on the extract, different colors were obtained. It was found that the dry and wet fastness of leathers treated with plant extracts improved.

Production and biochemical characterization of keratinase enzyme from Bacillus subtilis ES5 and its potential application in leather dehairing process: a clean leather tanning process

The traditional leather industry releases different chemical wastes into the environment, which calls for the use of alternative, nonpolluting processes. The use of biological catalysts in industrial processing has received a great deal of attention in recent years, mainly for environmental reasons. The main objective of this study was to produce and characterize keratinase enzyme from Bacillus subtilis ES5 and evaluate its potential application for leather dehairing. The gene encoding keratinase was validated with a fragment length of approximately 1100 bp. The keratinase exhibited maximum activity at temperature and pH of 45 °C and 8, respectively. Among the tested metal ions, Ca2+ and Mg2+ improved keratinase activity by 132.56 and 111.78%, respectively, at concentrations of 5 mM. β-mercaptoethanol enhanced keratinolytic activity. However, ethylenediaminetetraacetic acid (EDTA) significantly inhibited it, indicating that the enzyme is a member of the metalloprotease family. It completely dehaired goat/sheep skins within 14 h, resulting in decreased biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), and overall pollution load by 57.39, 70.53, 93.59, 94.90, and 79.10%, respectively. The results demonstrated the pivotal advantages of this keratinase, addressing environmentally friendly processing and sustainable solid waste management. The improved properties of enzyme-treated dehaired pelts suggest that crude keratinase could be used in ecologically friendly holistic leather manufacturing to avoid the pollution issues associated with the use of chemicals.