Search Results (39)

The possibility of using pyrolysis for the valorisation of leather and textile wastes constituting post-consumer clothes is analysed in this paper. The effect of gas type was investigated on the physico-chemical properties, composition, structure, and formation of the specific surfaces of carbonised materials produced by the pyrolysis process. The differences in the elemental composition of the carbonised materials derived from textile and leather wastes may be due to the specific chemical compositions. Both textile and leather wastes are rich in organic compounds, but their structural and compositional differences significantly influence the element content of carbonised materials. The characteristic feature of carbonised material made from leather waste is a relatively high nitrogen content (approx. 9 wt. %). In turn, in the case of carbonised material made from textile waste, a high carbon content is characteristic (75–80 wt. %). Moreover, G- and D-bands were detected in all the analysed carbonised materials. The presence of these bands confirms the transformation of leather and textile wastes into carbon materials. It was found that maintaining a high degree of order in the structure (calculated as I_D/I_G ratios based on the D and G peak intensities) of carbonised materials is advantageous to conducting the pyrolysis process on textile materials in N₂ and on leather materials in CO₂. The carbonised materials produced using these gases are characterised by an I_D/I_G ratio at a level of 0.05. Pyrolysis carried out in these gases also has a positive effect on the size of the BET surface area. However, it was shown that the carbonised products from textile materials are characterised by a higher BET surface area than that of carbonised products from leather materials regardless of the type of gas used during the pyrolysis process. Furthermore, all the carbonised materials are characterised by a high percentage content of mesopores in the carbon structure. These types of carbon materials have widespread application potential. The presented studies contribute data about the pyrolytic processing of post-consumer clothes (such as leather and textile waste) into carbonised materials to reuse, according to the circular economy model. Full article

Recycling upholstery textiles is challenging due to the complexity of materials, which often include a mix of fabrics, foams, and adhesives that are difficult to separate. The intricate designs and layers in upholstered furniture make it labor-intensive and costly to dismantle for recycling. Additionally, contaminants like stains, finishes, and flame retardants complicate recycling. Despite these difficulties, recycling upholstery textiles is crucial to reducing landfill waste and conserving resources by reusing valuable materials. It also helps mitigate environmental pollution and carbon emissions associated with producing new textiles from virgin resources. The presented research aimed to establish the feasibility of incorporating textile fibers from waste artificial leather fibers from the upholstery furniture industry into the structure of high-density fiberboards. The bulk density of samples with wood fiber was 28.30 kg m⁻³, while it was 25.77 kg m⁻³ for textile fiber samples. The lowest modulus of elasticity (MOE) was 2430 N mm⁻², and it was 3123 N mm⁻² for the reference sample. The highest bending strength (MOR) was 42 N mm⁻², and the lowest was 27.2 N mm⁻². Screw withdrawal resistance decreased from 162 N mm⁻¹ in the reference sample to 92 N mm⁻¹ with 25% artificial leather fibers. The internal bond (IB) strength ranged from 1.70 N mm⁻² (reference) to 0.70 N mm⁻² (25% of artificial leather fibers content). Water absorption ranged from 81.8% (1% of artificial leather fibers) to 66% (25% of artificial leather fibers content). It has been concluded that it is possible to meet the European standard requirements with 10% addition of the artificial leather fiber content. This approach positively contributes to carbon capture and storage (CCS) policy and mitigates the problem of such waste being sent to landfills. The research shows that while selected mechanical and physical parameters of the panels decrease with a rising content of recycled textile fibers, it is possible to meet proper European standard requirements by adjusting technological parameters such as nominal density. Full article

Leather waste contains up to 10% nitrogen (N); thus, combustion or gasification only for the energy recovery would not be rational, if safety standards are met. On the other hand, the chromium (Cr) content exceeding 5% in half of the waste stream (w/w) is too significant to be applied in agriculture. In this work, four acid hydrolysates from leather waste shavings, both wet-white free of Cr and wet-blue with Cr, were used: two with a mixture of acids and supplemented with Cu, Mn, and Zn, and the other two as semi-products from collagen extraction using hydrochloric acid. Additionally wet-green leather waste shavings, e.g., impregnated with olive extract, were used followed by the two treatments: amendment with a biochar from “wet white” leather waste shavings and amendment with this biochar incubated with the commercial phosphorus stimulating microbial consortia BactoFos. They were applied as organic nitrogen-based fertilizers in a glasshouse experiment, consisting of 4–5 subsequent harvests every 30 days, under spring–autumn conditions in northern Poland. Biochar-amended wet-greens provided the highest nitrogen use efficiencies, exceeding 100% after 4 months of growth (for 20 kg N/ha) and varying from 17% to 37% in particular months. This is backed up by another parameter (relative agronomic effectiveness) that for these materials exceeded 150% for a single month and in total was around 33%. Biochar amendments significantly increased agronomic parameters for wet-greens, and their microbial treatment enhanced them even further. Recycling this type of waste can replace inorganic fertilizers, reducing greenhouse gas emissions and carbon footprint. Full article

This paper presents an investigation into the use of pyrolysis to valorise solid waste in the form of post-consumer footwear uppers. A heterogenous leather and textile mixture is studied, produced by crushing some representative samples of post-consumer footwear uppers. The waste has a low ash content and a high net calorific value, which translates into the high gross calorific value of the material. In addition, it contains relatively little S and Cl, which is promising for its use in the process of pyrolysis. The effect of the pyrolysis temperature on the efficiency of carbonising leather and textile mixtures, their physico-chemical parameters, elemental composition, and structure, as well as the development of a specific surface, is investigated. The research results imply that as the pyrolysis temperature grows, the carbonisation efficiency declines. The produced materials consist primarily of C, O, N, and H, whose contents depend on the pyrolysis temperature. Moreover, all the carbonised materials display the presence of two G and D bands, which is typical for carbon materials. Based on the peak intensities of the bands, I_D/I_G coefficients are calculated to assess the organisation of the materials’ structures. As the pyrolysis temperature rises, the structural organisation declines, contributing to an increased material porosity and, thus, a greater specific surface of the carbonised materials. This study contributes data on the thermal management and pyrolysis of leather and textile waste into useful carbonised materials. Investigating the applicability of carbonised materials is projected as the next stage of research work. Full article

Plant polyphenols are potential inhibitors for the anaerobic treatment of wastewater from the wood processing, pharmaceutical, and leather industries. Tannic acid (TA) was selected as a model compound to assess the inhibitory effect of plant polyphenols in simulated wastewater in this study. The influences of TA on methanogenic activity, sludge morphology, and the microbial community were investigated under glucose and sodium acetate as carbon substrates, respectively. The results show that a threshold concentration of TA above 1500 mg·L⁻¹ that triggers significant methanogenesis depression and volatile fatty acids (VFAs) accumulation. In addition, granules might be weakened by TA addition, reflected in changes in extracellular polymeric substances (EPS) within the granules and an increase in floc in the effluent. The anaerobic granular sludge (AnGS) fed with sodium acetate was more sensitive than the presence of glucose as the substrate when facing the challenge of TA. The concentration of the mcrA gene in granular sludge decreased markedly in response to TA stress, providing direct evidence that a high concentration of TA caused the inhibition of specific gene expressions. This study provides details about the adverse impacts of TA stress on methane production, the microbial community, and granule integrity, deepening our understanding of the anaerobic treatment of plant polyphenols contained in wastewater. Full article

With the continuous development of global economic and trade activities, environmental problems have become an important factor restricting the sustainable development of all countries. How to realize the coordinated development of international trade and environmental protection has become a major issue facing the international community. Since China joined the WTO, its share of international trade has been increasing continuously. In order to deeply analyze the influence of international carbon emission trading policy on domestic carbon emissions, we use an input–output model and a GTAP analysis method to theoretically calculate the carbon emissions of the international trade of various departments in Shandong Province. At the same time, the implicit carbon emission index of various industries in 2022 is calculated through the direct energy consumption coefficient. The results show that there are significant differences in the impact of the carbon tariff system on different industries. In terms of the carbon emission index, the food processing industry showed a decrease of 18.99 Mt, while the implied carbon emission of the tobacco, textile and leather manufacturing industry reached 30.56 Mt due to the continuous expansion of trade scale. In contrast, the implied carbon emission level of the metal product processing industry reached 5.3 Mt, while the carbon emission of traditional trading industries such as coal mining was almost unaffected by international trade, and its carbon emission index reached the highest level of 5.89 in 2020. In terms of trade impact, high-trade industries such as the food processing industry are significantly affected by the carbon tariff policy, and their share has dropped from 5.89% to 3.95% in the past decade. The carbon emissions generated by GDP growth established by the GTAP model are more convincing. This model can directly reflect the energy efficiency of a region from the side. Based on the present situation of international trade, this paper analyzes the inequality of the current carbon tariff system, and puts forward some policies to optimize the energy structure to reduce carbon emissions and expand domestic demand to reduce the dependence on international trade. Through the GTAP model, we put forward policy suggestions to optimize the energy structure to reduce carbon emissions and the dependence on international trade by expanding domestic demand. Full article

Polyvinyl chloride (PVC) foam, valued for its mechanical and thermal properties along with cost-effectiveness, is extensively utilized across diverse industries. However, its high volatile organic compound (VOC) emissions hinder its adoption in eco-friendly synthetic leather. This study proposes a solution by optimizing the formulation design and foaming processes and achieving mechanical property enhancement via carbon-fiber-reinforced PVC composite foam (CF/PVC). The aim is to reduce PVC usage via enhancing its intrinsic properties. Systematic investigations were carried out on the impact of foaming raw materials, foaming processes, fiber content, and fiber length on the foaming performance, mechanical properties, and VOC emissions. The material formulation and process parameters were successfully optimized. Further assessment of various indicators such as the density, mechanical properties, and tear resistance of synthetic leather samples confirmed that the innovative CF/PVC foam developed in this study meets the requirements for automotive interior applications. Notably, the tensile strength and tear resistance of CF/PVC composite synthetic leather increased by 50% and 29%, respectively, compared to pure PVC, while VOC emissions decreased by 28%. It is anticipated that a more pronounced reduction in VOC emissions will be achieved in practical automotive interior leather applications when further considering the reinforcing effect of fibers, which leads to a reduction in PVC usage. The findings present a technical reference for innovative applications, aiming to enhance PVC foam performance and minimize emissions. Full article

Wastewater-containing dyes are an environmental problem. The prime source of dye pollutants is the textile industry, such as paper manufacturing, food processing, leather, pigments, etc. Dye removal from wastewater using nanotechnology has received attention in recent decades thanks to efficient nanomaterials improving traditional technologies. In recent years, multiple research reports on carbon nanotubes for dye removal and photocatalytic dye degradation provided substantial insight into the comprehension of nanotechnology and remediation. This work presents a review and bibliometric analysis of carbon nanotubes for dye removal and photocatalytic dye degradation, which have an environmental impact today. The bibliometric study showed that the current research tendency on carbon nanotubes applied in dye removal and photocatalysis is still growing. According to research, this work observed that carbon nanotubes for dye removal exhibit high removal and efficient photocatalysis activity, indicating the functionality of nanotechnology for environmental remediation. The analysis of the parameters involved in the removal studies, such as temperature and pH, showed adsorption behavior. The photodegradation of methylene blue demonstrated the photocatalytic activity of carbon nanotubes attributed to the sp² lattice of graphitic configuration. Full article

In the present research, a plant-based leather substitute material or leather alternative was developed from natural rubber (NR) and pineapple leaf fiber (PALF) using a simple process. Pineapple leaf fiber was extracted from waste pineapple leaves using a mechanical method. Untreated PALF (UPALF) and sodium hydroxide-treated PALF (TPALF) were then formed into non-woven sheets using a paper making process. PALF non-woven sheets were then coated with compounded natural rubber latex at three different NR/PALF ratios, i.e., 60/40, 50/50, and 40/60. Epoxidized natural rubber with an epoxidation level of 10% (ENR) was used as an adhesion promoter, and its content was varied at 5, 10, and 15% by weight of the total rubber. The obtained leathers were characterized in terms of tensile properties, tear strength, and hardness. The internal structure of the leathers was observed with a scanning electron microscope. Comparison of these properties was made against those reported in the literature. It was found that the leather with NR/PALF equal to 50/50 was the most satisfactory; that prepared from TPALF was softer and had greater extension at break. With the addition of ENR at 5%, the stress-strain curve of each respective leather increased significantly, and as the amount of ENR was increased to 10 and 15%, the stresses at corresponding strains dropped to lower values but remained higher than that without ENR. PALF leather prepared in this study has comparable or better properties than other alternative leathers reported in the literature and is much stronger than that made from mushrooms. Thus, this type of leather alternative offers unique characteristics of being bio-based and having a lower carbon footprint. Full article

This paper reports the conversion of a waste to a conducting material, exploiting the ability to adsorb pollutant organic dyes. Leather waste was carbonized at 800 °C in an inert nitrogen atmosphere. The resulting biochar was used for in-situ deposition of polypyrrole nanotubes produced by the oxidative polymerization of pyrrole in the presence of methyl orange. The composites of carbonized leather with deposited polypyrrole nanotubes of various composition were compared with similar composites based on globular polypyrrole. Their molecular structure was characterized by infrared and Raman spectra. Both conducting components formed a bicontinuous structure. The resistivity was newly determined by a four-point van der Pauw method and monitored as a function of pressure applied up to 10 MPa. The typical conductivity of composites was of the order of 0.1 to 1 S cm⁻¹ and it was always higher for polypyrrole nanotubes than for globular polypyrrole. The method also allows for the assessment of mechanical features, such as powder fluffiness. The conductivity decreased by 1–2 orders of magnitude after treatment with ammonia but still maintained a level acceptable for applications operating under non-acidic conditions. The composites were tested for dye adsorption, specifically cationic methylene blue and anionic methyl orange, using UV-vis spectroscopy. The composites were designed for future use as functional adsorbents controlled by the electrical potential or organic electrode materials. Full article

Wastewater production is a major environmental issue for the leather and textile industries: in a modern plant, several synthetic dyes are used in separated coloring batches whose wastewaters are usually mixed, diluted with other process water streams, and sent to a unique wastewater treatment plant. This includes specific physical and biochemical tertiary treatments to remove dyes efficiently. One of the main difficulties of these processes is the presence of multiple dyes, which cannot be treated with the same efficiency as a “wide-spectrum” process. This work explores the possibility of using conventional granular activated carbon (GAC) and a new polyurethane foam (PUF) for the adsorption of an acid red dye in the wastewater of a specific coloring batch of the tanning industry. The aim of this work is twofold: on the one hand, we aim to explore the performance of the new PUF sorbent; on the other hand, we aim to explore the possibility of using adsorption as an optimized pre-treatment for single-dye batches, which may take advantage of the presence of a single type of target dye and its higher concentration. The effluent is then sent to the wastewater treatment plant for further depuration. Full article

Due to the variety of benefits over traditional cutting techniques, the usage of laser cutting technology has risen substantially in recent years. The attributes of laser technology for leather cutting include adaptability, mass production, capability of cutting complicated patterns, ease of producing tailored components, and reduction in leather waste. In the present study, vegetable chrome-tanned buffalo leather specimens were cut using a 20 W laser diode with conventional and pulse width control in a photodiode-assisted laser cutting process. Emission rate, kerf width, carbonization, and material removal rate were considered as quality indicators. The higher power density associated with the pulse width approach reduces the interaction with the specimen, which results in a better emission rate and material removal rate, along with a lesser kerf width and carbonization. Using the MOORA approach, the optimal parameters of the present study were found to be a stand-off distance of 22 mm, a feed rate of 200 mm/min, a duty cycle of 75%, and a frequency of 20 kHz. The duty cycle can effectively control the pulse width at which the energy has been dissipated across the cutting zone. Full article

Leather waste carbonized at 800 °C in an inert atmosphere was coated in situ with the conducting polymer polyaniline. The composition of composites varied from neat carbonaceous to polyaniline. Due to the fibrous collagen structure of the original leather after carbonization, the composites had a bicontinuous conducting morphology. The resistivity of composites determined as a function of applied pressure from 0.1 to 10 MPa fell mainly into the range of units to tens of Ω cm. In contrast to neat polyaniline, the composites maintained a good level of conductivity even under alkaline conditions. The application of a composite as an adsorbent of organic-dye pollutants in water treatment was illustrated using methylene blue and methyl orange with an eye to future functional adsorbents controllable by applied electrical potential. Full article

In this study, thirty-seven alkaline protease-producing bacteria were recovered from different regions of Saudi Arabia. The proteolytic strain with the highest productivity was identified as Bacillus sp. Mar64. Maximum productivity of Mar64P alkaline protease was reached at 60 h, pH 9.0, and 45 °C using 1% tyrosine and 0.5% maltose as nitrogen and carbon supplies, respectively. Specific activity was intensified to 8.5-fold with a recovery of 12.4% and SDS—PAGE revealed one band at 28 kDa after enzyme purification. Mar64P was maximally active at 55 °C and pH 11.0 with thermal stability up to 70 °C and pH stability at 7.0–12.0 for 1 h. It was inhibited by EDTA and unaffected by PMSF, therefore tentatively classified as metalloprotease-type. Storage efficacy was effective for up to eight weeks and it was durable in presence of organic solvents (20%, v/v) such as acetonitrile, acetone, and isopropanol upto to 15 days. The enzyme was compatible with dry detergents at both low and high temperature, in addition, was successful in removing various stains such as blood, egg yolk, chocolate, tea, coffee, and sweat. Furthermore, it was successful in removing skin hairs and hydrolyzing gelatin of waste X-ray films. Collectively, due to these unique properties, Mar64P could be considered an environmentally friendly candidate in both detergent and leather industries. Full article

Petroleum-based resources used in the manufacturing of products and the recycling of products at the end of their life cycles are not environmentally friendly. Various studies have shown that vegan leather alternatives are particularly suitable because they mimic the properties of real leather, and the qualities of the bio-based materials combined with textile substrates are relatively close to real leather. In addition, cactus plants require less water and can completely replace real leather. The use of cactus as a source of sustainable textiles and leather offers numerous environmental benefits. This is due to the fact that harvesting the cactus does not harm the plant or its roots, allowing it to keep growing and sequestering carbon dioxide. This paper discusses sustainable materials based on cactus species that can replace leather products, for example, and explores the development of bio-based textiles in the near future. Full article