Search Results (7)

Finished tanned leather is usually covered by a thin polymeric layer. This layer has the scope to change the morphological aspect of the last leather layer as well as improve the impermeabilization properties. Often, the finished product is refused by the final client, and tanneries must restore significant quantities of materials. Therefore, it is very important to remove this finished polymeric layer, recover the underneath tanned leather, and predispose it to a new finishing. The bonding between the polymeric film and leather is so strong that, today, only a blade shaving process can perform this separation at the expense of also removing a layer of tanned leather and consequently reducing the leather thickness. Here, a novel separation method was developed based on the significant difference in the dilation properties between the tanned hide and the polymeric film at low temperatures. The use of cryogenic fluids, in particular the direct application of liquid nitrogen, can freeze the polymeric layer below the glass transition temperature, inducing brittle behavior. The result is an easy separation without any alteration of the tanned leather layer; for a demonstration of that, some techniques were used, such as FTIR, SEM, Tensile strength evaluation, DSC, and TGA. By this last analysis, it is possible to check how a decrease of weight to 90% happened for the polymeric layer at about 400 °C against the complete blank at about 600 °C. A similar great distance of results exists in the case of tensile strength, where an average value of 34.5% is the deformation stress for blank samples, against 34.8% for processed samples. Thus, the process here developed allows the reuse of the tanned leather towards a new life in respect of the principles of the circular economy. Full article

Currently, the methods to identify leather materials have limitations, and identifying natural leather types is also relatively complex. In this research, the microstructures of four types of mammalian leathers (cattle leather, pig leather, sheep leather, and deer leather), three kinds of reptilian leathers (crocodile leather, lizard leather, and snake leather) and regenerated leather were characterized by scanning electron microscopy. The spectral curves (from 900 to 1700 nm) of these leather samples were extracted using a hyperspectral imaging system, and their spectral characteristics were analyzed. A method of leather identification by the hyperspectral imaging system combined with chemometrics was established. The results showed that the spectral curves of natural and regenerated leather differed in the number, position, and depth of the characteristic peaks, enabling the classification of regenerated leather by comparative analysis with the naked eye. The first-order derivative processing–principal component analysis–discriminant analysis model achieved a 98% correct classification rate, confirming the hyperspectral imaging system’s feasibility in the leather material identification field. We believe that his research is beneficial for the leather industry to understand the classifications scientifically, in order to protect consumer rights and further develop the leather testing industry. Full article

To increase the sustainability of footwear and align it with the circular bioeconomy, there is a pressing need to develop novel bio-based materials to replace the synthetic polymers currently used. In this study, casein-based films were prepared by solution casting with a tannic acid cross-linker, and a glycerol plasticizer. The properties important to footwear materials were characterised, including tensile strength and elongation, stitch strength, hardness, grain cracking strength, water vapour permeability, and thermal properties. The tannic acid imparted a brown colour to the films with good resistance to light-induced fading. Their tensile strengths were 4–5 N/mm², elongation at break 45%–73%, and water vapour permeability 0.2–0.6 mg/(cm²h), depending upon the levels of the cross-linker and plasticiser. The strength of the films was close to those of some non-leather footwear materials such as compact rubbers and insock materials, but below that required for leather shoe vamps/uppers. The casein films were successfully used in sneaker- and ballerina-style shoes as components of the insock and decorative design elements on the vamp. This work has demonstrated the concept of using casein films in footwear. The properties of the films could be improved by further research, particularly with respect to cross-linking, plasticizing, and combining with bio-based fibers and fabrics. Full article

The untreated effluents discharged by different industries, such as metallurgy, fertilizers, pesticide, leather, mining, electroplating, surface finishing, aerospace, and electroplating, have increased the risk of the contamination of bodies of water by heavy metals. Herein, hybrid biosorbent–nanofiltration processes for Pb(II) removal from wastewater was studied. The hybrid biosorbent was prepared from date seed waste and Ganoderma lucidum. Hybrid biosorbent characterization was performed by SEM and FTIR. SEM micrographs showed that the HB surface is irregular. For the adsorption studies, various sorption parameters were optimized. The maximum biosorption capacity of immobilized heat-inactivated hybrid biosorbent was 365.9 mg/g, with the Langmuir isotherm model to present the best fit. Desorption experiments were conducted for regenerating immobilized heat-inactivated hybrid biosorbent for three consecutive cycles using different desorption agents, with acetic acid to be the optimum. Going a step further, nanofiltration was also applied as a post-treatment process to elevate the remediation effectiveness for wastewater of high Pb(II) initial concentrations. The reasonably low cost and high removal of Pb(II) make hybrid biosorbent–nanofiltration processes a prosperous and potentially attractive hybrid approach against heavy-metal-polluted wastewater. Full article

Diisocyanates, particularly toluene diisocyanate (TDI), are useful for the preparation of various polyurethanes with specific applications as leather-like materials, adhesives and insoles, etc. Blocking agents can be used for the operational simplicity and to reduce the hazards of TDI. In this paper, we reported the use of 3-(4-bromo-phenyl)-1H-pyrazole to block toluene diisocyanate (TDI). FTIR, NMR, thermogravimetric analysis, contact angle analysis and differential scanning calorimetry (DSC) were used for the characterization. The effectiveness of the blocking was confirmed by spectroscopic techniques. The DSC thermogram showed that blocked adducts deblock at 240 °C, causing the regeneration of TDI, and causing the diisocyanates to react with polyols of different molecular weights, forming polyurethanes. The characterization of the polyurethanes was performed by infrared spectroscopy, nuclear magnetic resonance spectroscopy, thermogravimetric analysis, differential scanning calorimetry and a contact angle study. Full article

A large amount of cow hair solid waste is produced in leather production, and a reasonable treatment should be developed to reduce the pollution. In this study, cow hair waste was utilized as the carbon precursor, and N₂ was determined to be the most appropriate atmosphere for biochar preparation. We performed a comparison of the properties of biochars that were prepared with different methods, including direct pyrolysis, KOH activation, and the MgO template method. The characterization results show that the highest specific surface area reaches 1753.075 m²/g. Subsequently, the keratin that was extracted from cow hair and purified was used to prepare a biochar with the MgO template method, obtaining an orderly sponge structure. The biochar from cow hair waste was further used to absorb direct blue dye wastewater, and its adsorption capacity reached 1477 mg/g after 10 h with a high efficiency of regeneration. This study successfully utilized keratin-containing hair waste and provides a new source for synthesizing carbon materials for dye wastewater treatment. Full article

The biomedical properties of a porous bio-collagenic polymer extracted from leather industrial waste residues have been investigated in wound healing and tissue regeneration in induced wounds in rats. Application of the pure undiluted bio-collagen to induced wounds in rats dramatically improved its healing after 7 days in terms of collagen production and wound filling as well as in the migration and differentiation of keratinocytes. The formulation tested was found to be three times more effective than the commercial reference product Catrix^® (Heal Progress (HP): 8 ± 1.55 vs. 2.33 ± 0.52, p < 0.001; Formation of Collagen (FC): 7.5 ± 1.05 vs. 2.17 ± 0.75, p < 0.001; Regeneration of Epidermis (RE): 13.33 ± 5.11 vs. 5 ± 5.48, p < 0.05). Full article